The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevy/GMC Suburbans & Panels Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-13-2020, 06:35 PM   #1
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
???Coolant Temperature Sending Unit???

I just got back with the Beach-Burban from a 3 1/2 hour drive (7 hour round-trip...longest distance since I've owned it) and I had a little anxiety because my temperature gauge would pin itself under certain conditions, causing me to pull over just to find that the engine was NOT overheating! The Burb drove beautifully in every other way: Plenty of power (454); speeds between 65 and 75; long uphill grades; TH400 never acted up; oil pressure held firm; no pre-ignition or detonation; no loss of coolant (not even in the overflow tank); no extreme heat radiating from the engine bay; and no crackling noises when shutting the engine down. This held true even when driving with air temperatures of 101 degrees! The gauge would float between the high mark to the pinned position depending on the grade I was on, but never affected drivability to the point that I had to say, screw it...there must be a communication problem between the sending unit and the gauge!?!? The radiator was flushed a couple years ago and fitted with a new pressure cap, as well as having a new sending unit installed because the old (original?) was dead...but during that time period, I had only been driving an hour or so at a time (and mostly coastal areas) so the gauge maxed out a little above the middle line. Do sending units have different ranges of temperature levels? Is it possible I installed the wrong unit...or is it more likely that the original gauge needs calibration? Baffled, yes...but very happy with the overall performance of the Beach-Burban! Any help would be appreciated!

Woody
Beach-Burban is offline   Reply With Quote
Old 07-13-2020, 06:51 PM   #2
maynardogle
Registered User
 
Join Date: Mar 2017
Location: Huntington Beach, CA
Posts: 17
Re: ???Coolant Temperature Sending Unit???

Your problem is the reason most older vehicles end up with an aftermarket gauge pack. I hate staring at an OEM gauge and wondering if it is right or wrong. Stewart-Warner i still around for a reason. That being said, make sure your block, frame and cab all have good clean grounding straps. Then look at the sensor, and maybe swap it. If that doesn’t fix it, it means the gauge or voltage regulator for gauges is bad.
maynardogle is offline   Reply With Quote
Old 07-13-2020, 07:02 PM   #3
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by maynardogle View Post
Your problem is the reason most older vehicles end up with an aftermarket gauge pack. I hate staring at an OEM gauge and wondering if it is right or wrong. Stewart-Warner i still around for a reason. That being said, make sure your block, frame and cab all have good clean grounding straps. Then look at the sensor, and maybe swap it. If that doesn’t fix it, it means the gauge or voltage regulator for gauges is bad.
Thanks maynardogle...I'll look into that! I felt like I was violating a major car-guy code by driving with a pinned temp gauge! It goes against everything I was ever taught!

Woody
Beach-Burban is offline   Reply With Quote
Old 07-13-2020, 10:14 PM   #4
LockDoc
The Older Generation

 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,270
Re: ???Coolant Temperature Sending Unit???

-
You might want to read through this thread.

http://67-72chevytrucks.com/vboard/s...d.php?t=808324

He was having the same problem recently....

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 07-14-2020, 03:19 PM   #5
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by LockDoc View Post
-
You might want to read through this thread.

http://67-72chevytrucks.com/vboard/s...d.php?t=808324

He was having the same problem recently....

LockDoc
Thanks for the link, Leon...very similar indeed! I copy and pasted my post into that thread and will be following along to see if I can learn more.

Woody
Beach-Burban is offline   Reply With Quote
Old 07-15-2020, 05:17 PM   #6
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by Beach-Burban View Post
Thanks for the link, Leon...very similar indeed! I copy and pasted my post into that thread and will be following along to see if I can learn more.

Woody
***kind of an update***

The other thread Leon linked for me has more than just one person with the same issues...so I went looking at old threads on the subject. This problem has been going on for many years, and it appears that it could be related to the quality of replacement parts!? I also read that with the inferior replacement parts, they will be accurate from "cold" to 180 degrees...but above 180, they start reading way hotter than the actual temperature. This could be why I haven't had an issue for two years? This is what I posted on the other thread:

While searching for additional threads on this topic, I read a number of posts that "might" explain the problem that some of us are experiencing. Apparently there is a consensus that GM temperature gauges for our trucks "changed" in 1979 and the new resistance values of the gauges required a temperature sending unit that had a different resistance curve. That could explain some issues if the wrong year sending unit was used. Additionally, a number of members reported that even when they ordered a replacement sending unit for the right year of their gauge, there was no certainty that the replacement would have an accurate resistance curve...and I guess that this issue was so widespread, that American Autowire started making a reproduction of the GM #1513321 sending unit with a precise resistance curve to match the 1978 and older gauges. I read enough success stories to situations that sounded so much like our issues, that I payed the $27 to have one sent to me. I'll let you all know if it was worth it!

Woody
Beach-Burban is offline   Reply With Quote
Old 07-15-2020, 07:28 PM   #7
FLYNAVY30
Registered User
 
Join Date: Apr 2013
Location: Austin, TX
Posts: 592
Re: ???Coolant Temperature Sending Unit???

Hey Woody, just ran through this thread. For what its worth, my '72 big block had the exact problem you describe when I purchased it....

my solution however was to install a built 6.0L LS motor lol:

But seriously, that did "fix" the problem, but is definitely not why I did the LS swap. Hopefully your fix is equally effective while being far more economical!!
__________________
1972 C20 Suburban
1964 Corvette Coupe
1997 Lexus LX450
FLYNAVY30 is offline   Reply With Quote
Old 07-15-2020, 08:09 PM   #8
LockDoc
The Older Generation

 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,270
Re: ???Coolant Temperature Sending Unit???

-
Yes, it will be interesting to see if that cures it.

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 07-22-2020, 05:54 PM   #9
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by LockDoc View Post
-
Yes, it will be interesting to see if that cures it.

LockDoc
Well...I just got back from a 2 1/2 hour (one way) drive to monitor the readings with the new sending unit...and I would say that it was a "semi-successful" remedy!? If any members are familiar with "the 5 Freeway Grapevine" in So Cal, you'll know what a grueling test that is for a cooling system (more so for our older vehicles). This has been the site of countless "boil-overs" thoughout the years...to the point that there are radiator water spickets all along that section of the grade. Anyway...that's where I conducted my testing, and overall the answer is yes...the readings on the gauge more closely represent what's going on under the hood! The gauge never once pegged itself, even though it was indicating a very high temp reading...but then recovered quickly when the grade flattened out. I can live with that, however, I still want/need to know what the actual coolant temperature is when it gets that high...so I'm going to install an under dash gauge (and matching sending unit) that has gradient numbers in degrees. I'll report back after more testing!

Woody
Beach-Burban is offline   Reply With Quote
Old 07-22-2020, 11:35 PM   #10
LockDoc
The Older Generation

 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,270
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by Beach-Burban View Post
Well...I just got back from a 2 1/2 hour (one way) drive to monitor the readings with the new sending unit...and I would say that it was a "semi-successful" remedy!? If any members are familiar with "the 5 Freeway Grapevine" in So Cal, you'll know what a grueling test that is for a cooling system (more so for our older vehicles). This has been the site of countless "boil-overs" thoughout the years...to the point that there are radiator water spickets all along that section of the grade. Anyway...that's where I conducted my testing, and overall the answer is yes...the readings on the gauge more closely represent what's going on under the hood! The gauge never once pegged itself, even though it was indicating a very high temp reading...but then recovered quickly when the grade flattened out. I can live with that, however, I still want/need to know what the actual coolant temperature is when it gets that high...so I'm going to install an under dash gauge (and matching sending unit) that has gradient numbers in degrees. I'll report back after more testing!

Woody

Glad to hear things are more "normal". Not at all familiar with that highway but it sounds like that would be the supreme test.

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 07-31-2020, 07:54 PM   #11
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

***Update on Temperature Gauge***

So I ordered a couple of Stewart Warner gauges and a two hole under-dash panel bracket...an Ammeter, as my original hasn't worked since I bought the Burb, and a mechanical Temperature gauge to help analyze what my original gauge is telling me. I did a little research and found that these mechanical gauges will accurately measure the temperature of any liquid, so I plan on using this one to monitor my A/T fluid after I sort out things with my water temperature.

I utilized a plugged 1/2" NPT hole on the drivers side head of my 454 so that I could still keep the electric sending unit operating...which makes comparing the two gauges much easier. As this tapped hole is located a little above the exhaust manifold, I used a couple feet of 1/4" ID X 1/2" OD rubber hose to insulate and protect the capillary tube (all the way past the firewall and into the cab), as well as some thin metal tape (crumpled up for a better insulation factor) from the Sender Bulb out past the manifold a ways (as a heat shield).

After refilling and "burping" the coolant to the best of my ability, I went out for a 45 minutes drive in our local hills of Palos Verdes. Not much of a test compared to the "Grapevine", but I mainly wanted to get any air pockets filled in with coolant, check for leaks and compare "around town" readings. At the halfway point of the drive, I stopped and found that the radiator had sucked coolant in from the recovery tank (it was at the "Full Hot" line when I left, and was now at the "Add" line) so I topped off the recovery tank and headed for home. Once home, I checked the recovery tank again, and as it was still at the "Full Hot" line, I believe all air pockets should be gone.

Results:
Spoiler alert...the two gauges did not read anything close to what I had expected, but I didn't take any pictures until I got home! While driving, the S/W gauge read between 200 and 210 almost the entire drive (after initial warm-up of course), but when I pulled into my driveway and sat with the motor running, it stabilized at what looked like 212 degrees. While driving, the factory gauge had been holding steady just about on top of the first mark past "C" (well technically, it's the second mark past "C"), but in my driveway with the motor running, it rose to about halfway between that first mark and straight up. I then decided to shut the motor off (with the key in the "ON" position) and see how much the temperature would rise without any circulation/fan. The S/W topped out at just above 230, and the factory gauge made it to just above straight up.

Now I do realize that there are "control issues" with the testing methods in place here...brand new mechanical gauge verses a 48 year old electric gauge (with a new American Autowire sending unit)...and...mechanical sender bulb installed in the water passage of the head verses electric sending unit installed in the water passage of the intake (right next to the T-Stat)...but I was expecting/hoping for something that I could say "well, that makes sense"...but I'm still puzzled! I guess I need to return to the "Grapevine" so I can compare what the S/W gauge reads when the factory gauge reads past the "H". Once again...I'll report my new findings!

Woody

Name:  IMG_1754.jpg
Views: 312
Size:  54.6 KB

Name:  IMG_1748 (1).jpg
Views: 316
Size:  75.7 KB

Name:  IMG_1749 (1).jpg
Views: 304
Size:  86.5 KB

Name:  IMG_1750-1.jpg
Views: 304
Size:  58.1 KB

Name:  IMG_1753 (1).jpg
Views: 309
Size:  96.4 KB

Last edited by Beach-Burban; 07-31-2020 at 08:06 PM.
Beach-Burban is offline   Reply With Quote
Old 07-31-2020, 10:38 PM   #12
LockDoc
The Older Generation

 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,270
Re: ???Coolant Temperature Sending Unit???

-
The more accurate reading would be where you have the mechanical sender bulb in the head, the intake port where you have the electric will read cooler....

210º is not out of line for a big block. There should be another one of the head ports on the passengers side at the back of the head by #8. The temp there usually reads a little higher than the one on the drivers side by #1.

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 08-01-2020, 10:03 AM   #13
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by LockDoc View Post
-
The more accurate reading would be where you have the mechanical sender bulb in the head, the intake port where you have the electric will read cooler....

210º is not out of line for a big block. There should be another one of the head ports on the passengers side at the back of the head by #8. The temp there usually reads a little higher than the one on the drivers side by #1.

LockDoc
Thanks Leon...what you said about Head port readings verses Intake port readings makes total sense, especially considering that the heads/block are what we are trying to protect (as opposed to the Intake)...but how much difference should we expect? If I was a little more "obsessed " with knowing that answer, I'd swap locations of the sender bulb and electric sending unit...then record those results...but I just got everything buttoned-up so nice, and what I really want to know is whether or not I am close to doing damage when the factory gauge is maxed out?

So if 210 isn't out of line for a big block...when should I start to worry?

Woody
Beach-Burban is offline   Reply With Quote
Old 08-01-2020, 05:34 PM   #14
LockDoc
The Older Generation

 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,270
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by Beach-Burban View Post
Thanks Leon...what you said about Head port readings verses Intake port readings makes total sense, especially considering that the heads/block are what we are trying to protect (as opposed to the Intake)...but how much difference should we expect? If I was a little more "obsessed " with knowing that answer, I'd swap locations of the sender bulb and electric sending unit...then record those results...but I just got everything buttoned-up so nice, and what I really want to know is whether or not I am close to doing damage when the factory gauge is maxed out?

So if 210 isn't out of line for a big block...when should I start to worry?

Woody

I never did a scientific test on it but I think 10 - 15º higher at the head.

220 - 225 all the time on the open road I would start to worry. Others may disagree.

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 08-02-2020, 07:14 AM   #15
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by LockDoc View Post
I never did a scientific test on it but I think 10 - 15º higher at the head.

220 - 225 all the time on the open road I would start to worry. Others may disagree.

LockDoc
Thanks Leon...When I do the next "Grapevine" test, the results should be very telling!

Woody
Beach-Burban is offline   Reply With Quote
Old 08-02-2020, 10:49 PM   #16
LockDoc
The Older Generation

 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,270
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by Beach-Burban View Post
Thanks Leon...When I do the next "Grapevine" test, the results should be very telling!

Woody
Let us know how it goes.

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 08-05-2020, 12:37 PM   #17
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Got back yesterday from another "Grapevine" road-test...and the results are indeed "very telling"! Bottomline is: my radiator needs an old fashion boil-out, rodding...or core replacement. The block and head water passages might need some "descaling" as well. It's my intention to stick with the copper/brass original style 4 core, which is why I'm going to a friend recommended shop, as they actually work with your radiator instead of the quick "scrap and replace with new junk" approach. I hear a lot of pros and cons regarding aluminum radiators...but I'm not sold on that idea (yet).

Temperature gauge results:

Photos one and two: my normal around town and freeway temps when fully warmed-up.
Photos three and four: my "new" normal freeway temp with just a slight grade.
Photos five and six: Going up the Grapevine!!! Truth is, right before I hit the summit, the gauge was kissing 250 (no photo), but over the summit on the down side, it did back off to the 230ish range!
Photo seven: The recovery tank was doing it's part on this drive, where it wasn't needed on the last one (without knowing the numbers). My fresh green coolant is now a rusty brown color, but I still didn't lose any coolant and the motor did not "act" as though it was over-heating...but I can tell things are going in the wrong direction!

I stopped at the bottom of the grade and had a "Dave's Double" at Wendy's...and sat for a while. When I finally started it back up, the radiator started guzzling up the coolant from the recovery tank...but no more than it expelled into it (as far as I can tell?). Nothing significant to report on the way home, but of course, my "new" normal freeway temp stayed in the 230 range. I stopped for a while at my best friend's house when I was about an hour from home...and got stuck in traffic (an accident) when I left, but things stayed pretty much the same at the slower speeds. Off the freeway and in beach city driving conditions, the "new" normal stayed around 220ish, so a stop at my friend's repair shop confirmed what I already suspected...dirt/rust/debris clogging the radiator is the prime suspect. A flushing will be the first step, but it's doubtful that this will be a cure...but when it's all sorted out, I will once again compare the readings between the Stewart Warner mechanical gauge and the factory gauge utilizing both of the electrical sending units (TS6S and American Autowire). Report will be coming...but don't hold your breath...it's going to take me a while!

Woody

Name:  IMG_1766.jpg
Views: 250
Size:  38.8 KB

Name:  IMG_1765.jpg
Views: 276
Size:  73.1 KB

Name:  IMG_1764.jpg
Views: 245
Size:  68.8 KB

Name:  IMG_1763.jpg
Views: 247
Size:  65.4 KB
Beach-Burban is offline   Reply With Quote
Old 08-05-2020, 12:39 PM   #18
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Name:  IMG_1760.jpg
Views: 205
Size:  54.9 KB

Name:  IMG_1757.jpg
Views: 261
Size:  91.8 KB

Name:  IMG_1767.jpg
Views: 250
Size:  30.9 KB
Beach-Burban is offline   Reply With Quote
Old 08-05-2020, 01:04 PM   #19
HO455
Post Whore
 
HO455's Avatar
 
Join Date: Feb 2016
Location: Portland Oregon
Posts: 10,755
Re: ???Coolant Temperature Sending Unit???

I've got both aluminum and copper radiators in vintage vehicles. The cost of a completely rebuilt copper radiator is more.
In my experience copper lasts longer and are repairable. The only way an aluminum radiator can be repaired is with epoxy.
A friend of mine just tried to have his brand new aluminum radiator epoxied and it didn't work. He is going to try it again doing it himself this time. They took their newly (LS) repowered Nova out for a test run with no grille installed and took a rock dead center in the new radiator and broke 2 tubes. And I thought I had bad luck!
Anyway long stupid post, but yeah copper is good. That's what I have in my Burban. The aluminum radiators I have used are generic roundy round ones that are dirt cheap but require making mounts.
__________________
Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help.
RIP Bob Parks.
1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 85 Alfa Romeo
If it breaks I didn't want it in the first place
The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377
HO455 is offline   Reply With Quote
Old 09-08-2020, 04:22 PM   #20
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Woody’s Cooling Saga Continues:

Wow…this has turned into a job and a half, mostly because I have been trying to figure it out and do the work myself. Doing one “fix” at a time had me repeating some of the same labor more than once, but I really wanted to know which part was the culprit!

Having the new Stewart Warner mechanical temperature gauge kept the results (or lack of results) easy to track, and the first thing I did was pull the radiator with the intention of dropping it off to be professionally flushed/boiled out. After doing the labor of the removal, I figured that I might as well stick a garden hose in it to see what comes out…and man, it seemed like half of the Lancaster desert was hiding in there. It was a red claylike material that came out in chunks, but would not break down with water unless I mashed it with my fingers, then it became very fine and silky. It took probably an hour and a half of flushing until the reddish water was running clear, so I felt like I had accomplished the task at hand…and I also found that the bottom third of the recovery tank had the same substance in it, which required using a long spoon like device to scoop it out as water had little power over this “clay”. Even though I was feeling confident that I had found the main issue, I decided to set up a recirculating flush system out of a submersible pump I had, and purchased a rust dissolver called Thermocure, which is safe for all metals, gaskets and seals. First, I flushed out the engine water passages by hooking into the radiator hoses and ran that until the water was clear. A lot of reddish water came out but no clumps. I had already removed the T-stat, so I ran it in both directions for quite a long time…and felt confident with that, so now I put the radiator into the loop with the engine block and circulated the Thermocure through both for a few hours…then flushed with clean water until it was all out. As if this wasn’t enough, I reinstalled the radiator, filled it with the Thermocure solution and took it on a two hour freeway drive, came home, flushed it clean, replaced T-stat (now using a 160), refilled with 50/50 coolant…then went for a drive so I could revel in my success! Unfortunately, there was not any improvement at all???

At this point, it had to be the Fan-Clutch or the water pump…so I ordered a Hayden severe duty fan clutch and an Edlebrock high volume water pump, along with assorted gaskets, etc…and after installing the new parts, took it for a test drive. The results were insignificant, with just a slight improvement that I attributed to the high volume pump pushing more water through the radiator…but I was back to blaming the radiator! I once again removed the radiator, dropped it off at the shop for a old fashioned “rodding”, but then got the news that the core was beyond repair internally…and needed a new core. A couple days later, I picked up my “new” radiator which was still an all copper 4 core radiator using all USA materials and manufactured about 50 miles from my home…and it fit back in perfectly! Somehow, they assembled it with more cooling tubes and fins per sq. in., so it had to do the trick this time, right? The results were okay…but not as substantial as I was hoping for (205 to 210 around town…and 215 to 220 pushing it on the grade). The temperature did stabilize back to 205 once off the grade quicker than before, so I knew everything was working right, and as my S/W gauge was installed in the driver’s side head water passage, I concluded that my results would have more conventional readings if I relocated it to the T-stat housing. Well guess what…on my 454, the readings were identical, so I don’t know if it is really true that head water readings are higher than T-stat water readings…but on mine, there’s no difference?

Like so many others have reported, the temperature also climbs while sitting in traffic or at a light…so electric fans were already on my mind. I started taking measurements and researching online…but haven’t come to a decision yet (and I’m open for recommendations), however, while looking at the space available in front of the radiator, I started thinking about the gaps that my shroud has between it and the radiator. It wasn’t an issue with the old radiator (before my troubles began) but because the new radiator has more tubes and fins per sq. in., I surmised that it must be harder to pull air through it. I cleaned the needed areas, then applied a wide aluminum tape all the way around the shroud and sealed up any places that air could sneak-in…and went on another test drive. This was the most significant improvement of all with readings of 190 to 195 around town and 200 to 205 pushing it up the grade! Sitting at lights still gets to almost 210, so I’m still going to add some electric fans at some point, but for now I want to start driving places again!

I know this was a long-winded report and a lot of members are probably sick of hearing about “MY” cooling issues, but I was really hoping for better results than 190…so is this just how hot BBC’s run or is it possible the water passages in the block are restricted with hard corrosion that doesn’t break down through conventional methods? If you got to this final question…I thank you for reading this entire novel!

Woody

Name:  IMG_1800.jpg
Views: 210
Size:  55.1 KB

Name:  IMG_1810.jpg
Views: 213
Size:  96.4 KB

Name:  IMG_1802.jpg
Views: 210
Size:  90.9 KB

Name:  IMG_E1806.jpg
Views: 204
Size:  27.2 KB

Last edited by Beach-Burban; 09-08-2020 at 04:40 PM.
Beach-Burban is offline   Reply With Quote
Old 09-08-2020, 11:53 PM   #21
LockDoc
The Older Generation

 
LockDoc's Avatar
 
Join Date: Aug 2006
Location: Montezuma, Iowa
Posts: 25,270
Re: ???Coolant Temperature Sending Unit???

-
I think you are lucky to hit 190º and I wouldn't want it to run any cooler, but that's just me. My White '67 with the 454/TH400 ran a minimum of 195º and usually closer to 200º on the highway. I put many miles on it that way.

LockDoc
__________________
Leon

Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles

(My Dually Pickup Project Thread)

http://67-72chevytrucks.com/vboard/s...d.php?t=829820

-
LockDoc is offline   Reply With Quote
Old 09-09-2020, 07:29 AM   #22
FLYNAVY30
Registered User
 
Join Date: Apr 2013
Location: Austin, TX
Posts: 592
Re: ???Coolant Temperature Sending Unit???

Did the big blocks come with any sort of fan shroud? Someone correct me if I'm wrong, but I believe the old adage is that if you're running hot while driving, you have radiator issues, but if you run hot in traffic, you have fan issues?

I know my Corvette has a shroud, and the depth the fan sticks into the shroud is very specific and has a big impact on airflow through the radiator.

If there was no shroud for the big block trucks, I would definitely start looking into an electric fan set up with shroud that covers the entire radiator. I'm running a similar set up, although mine now has an LS motor, so its not comparable.
__________________
1972 C20 Suburban
1964 Corvette Coupe
1997 Lexus LX450
FLYNAVY30 is offline   Reply With Quote
Old 09-09-2020, 04:30 PM   #23
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by LockDoc View Post
-
I think you are lucky to hit 190º and I wouldn't want it to run any cooler, but that's just me. My White '67 with the 454/TH400 ran a minimum of 195º and usually closer to 200º on the highway. I put many miles on it that way.

LockDoc
I quite agree with you, Leon...I was lucky to finally hit 190. My thoughts run to having a system that has a surplus of cooling...so that the T-stat actually does control what temperature the motor runs at. My preference would be around 180 as the TH400 wants to stay around 175 or so...and as I plan on towing, would love to have a little cushion...but compared to what I was running, I'm thrilled with 190!

Woody
Beach-Burban is offline   Reply With Quote
Old 09-09-2020, 04:30 PM   #24
BAD1916
Registered User
 
Join Date: Oct 2012
Location: VENTURA COUNTY CALIFORNIA
Posts: 268
Re: ???Coolant Temperature Sending Unit???

My 71 Suburban with a 454 runs right around 190ish almost always while driving. It will hit 220 in bumper To bumper traffic and will creep up to 210 at stoplights but cools down quick once I start moving again.
BAD1916 is offline   Reply With Quote
Old 09-09-2020, 05:27 PM   #25
Beach-Burban
Registered User
 
Beach-Burban's Avatar
 
Join Date: Mar 2019
Location: So. Torrance, CA
Posts: 460
Re: ???Coolant Temperature Sending Unit???

Quote:
Originally Posted by FLYNAVY30 View Post
Did the big blocks come with any sort of fan shroud? Someone correct me if I'm wrong, but I believe the old adage is that if you're running hot while driving, you have radiator issues, but if you run hot in traffic, you have fan issues?

I know my Corvette has a shroud, and the depth the fan sticks into the shroud is very specific and has a big impact on airflow through the radiator.

If there was no shroud for the big block trucks, I would definitely start looking into an electric fan set up with shroud that covers the entire radiator. I'm running a similar set up, although mine now has an LS motor, so its not comparable.
Good first question, Greg...mine has a nicely sized shroud that fits the radiator well, but the original owner pulled the big block set-up out of a brand new 1989 1 ton truck to replace the original 350...so I can't really say for sure? (first picture)

I have been told the same adage, and I was running hot both while driving and while in traffic...but before my cooling issues began, the temperature only slightly raised while in traffic which was most likely the fan clutch not locking-up under hot conditions (but it's replaced now?). With the new radiator having more tubes and more fins, I'm sure it is more difficult for the fan to pull air through it, which is why I had such good results when I sealed the gaps between the shroud and radiator. My fan is a factory 7 blade in perfect shape and well sized for the shroud and fan clutch...but knowing how far the fan should be riding in or out of the shroud is unknown to me. I have read that "universally" half in and half out is correct? I have also read that other vehicles came from the factory with the back edge of fan just peeking out? In the second picture, you can just barely see that mine only peeks out...and other than getting the Hayden "short shaft" fan clutch (which moves the unit closer to the water pump by about an inch), I don't know what to do (as I already have a "short" water pump). Problem is that Hayden says the short shaft fan clutch is not right for my set-up as it's only Heavy Duty instead of Severe Duty. I could (and maybe will) buy it anyway to see if it possibly makes a difference...but that wouldn't happen anytime soon.

An electric fan set-up is most likely in the works for the Beach-Burban, but it will be a pusher type to supplement the puller clutch fan. That will probably help move air through the A/C condenser as well...and I do plan on getting the A/C working (which is another reason I'm not quite settled on accepting 190 as my normal) but for now, I plan to drive it as is...and we are leaving for San Diego on Friday!

Thanks for the input!

Woody

Name:  IMG_1811.jpg
Views: 192
Size:  67.1 KB

Name:  IMG_1812.jpg
Views: 192
Size:  55.0 KB
Beach-Burban is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:30 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com