Can an AC Installed make the engine run hotter than before?

[motorcritter]

Adding an auxiliary trans cooler is cheap insurance- pulling trailers, running a high-horsepower engine and extreme road conditions (mountains) all are tough on automatic transmissions. When I ran a transmission shop, on FL, coolers went on nearly every overhauled unit. We didn't have many come-backs or warranty work because of it. A transmission can run too cool, so a thermostat is a good idea if you're in one the areas where winter temperatures get below freezing on a regular basis.

[CST10]

Thanks for the tranny temp validation motorcritter. Do you know about what type of temp drop to expect with those air cooler types?

[motorcritter]

Temp drop depends upon size of cooler and location. Bigger is better, for towing or severe duty. The newer style laminar flow types are more efficient than the older tube-and-fin style. As noted before, don't run the add-on cooler as the sole cooler, plumb it into the existing lines, on the return line. Another 'mod' for cooler, more efficient transmission operation is LubeGard additive. It is the only stuff any OEM approves of, and it works. It's not a miracle worker, fix whatever ails ya, type of additive- but it does lower fluid temps and smoothes out shifting. I put it in every auto trans I have, or work on (except Frod MerconV units- it's a unique and highly-friction modified synthetic fluid)- the GM TurboHydros, the wife's Honda, my Benz gas-engine sedan and MoPar items (that need all the trans help they can get). All the other 'additives' range from useless to criminal- the proof is in the tear down before the rebuild. I'd always ask what got put in it, to try to 'fix' the progressively failing unit. Amazing what people dump into the most complex bit of engineering in the whole car!

[CST10]

Good info. Thanks guys.

Installed a new electric fuel pump to get rid of the vapor lock issue.

Found the lower radiator hose kinked about 40% restricted. Got a new hose and installed today.

Tomorrow if weather permits. It will torture test day again to see if the new hose and fuel pump gets rid of the overheating and vapor lock issue.

I will post the results.

Thanks everyone for the advice.

[Stocker]

Originally Posted by motorcritter

A transmission can run too cool, so a thermostat is a good idea if you're in one the areas where winter temperatures get below freezing on a regular basis.

True, and I have read that lines should be plumbed through the aux. cooler first, then through the radiator. That way, if the fluid is too cool, it can actually be warmed while passing through the radiator, before going to the transmission.

[CST10]

Update.

Changed the lower hose and torture tested today.

Ran 210-215 degrees with ac on. Temp dropped only 5 degrees with ac turned off. Idling in both tests. Total run time was 60 minutes.

Thing that puzzles me is that this engine use to run 170-175 all day long without ac running. What changed? Surely the outside temperatures have increased with August heat waves so I can understand maybe running 190, but 210?

Awhile back I tried some plugs with a step up temp range. Use to run ac delco r44t plugs and changed to Ac delec r45ts plugs. Also adjusted timing from 18 initial. And 40 all in to 16 initial and 38 all in.

I have since gone back to the original plugs BUT I did not change the timing back.

Can 2 degrees retarded initial timing cause a increase of about 10 degrees hotter?

At a loss here of the reason the temp change. If the temp idling only drops 5-7 degrees with the ac off that still does not explain the increase of the other 10-15 degrees temp increase.

[CST10]

I know retarded timing can affect idle temperatures.....but only 2 degrees differance? Can that really make that much differance?

[motorcritter]

Check out temps on various points throughout the system, with a infrared sensor. When you find your 'bottlenecks', it should explain the temp discrepancies. A big engine is gong to throw a lot of heat. Also, what poet temps are you getting on your A/C- if they're higher than normal, that could be a factor in radiator & condenser efficiency. All that being said, running 210-215 is not out of an acceptable range, if it doesn't rise into unacceptably hot temps when under load.

[knomadd]

I'd leave it alone. You said about 94* outside temp, idling (no air flow) and it only got to 210? Modern vehicles operate around 210* all the time. Everything's fine. Except I'd change that 165* t-stat. It's so low that you're not allowing the coolant to sit in the radiator long enough to cool efficiently. When you run a t-stat that's more than about 20* below the operating temp, it will never close and let the coolant in your radiator cool off like it should. If you ran a 185-195* t-stat, it would close when the coolant was below that temp, allowing what's in the radiator to cool more. It doesn't take long to get back up to the t-stat opening temp, but it does help the cooling system run efficiently. It could be as little as a 10 second delay on a hot day, but if it's that warm out, a 165* t-stat wont close.

As for going with an aluminum radiator... it won't help you that much. IIRC, copper actually allows heat to escape faster than aluminum. It's the brass that's used to hold it together that reduces the efficiency of the copper radiator. A good 4 core copper/brass radiator should be very competitive to an aluminum radiator. Also, aluminum radiators are the weak link in electrolysis. If you have a charge in your coolant that erodes the metal (electrolysis), your radiator would be the first thing to go.

[CST10]

Update.

Adjusted timing to 18* initial and 40* all in mechanical.

Outside air temperature 95*.

Idled in the sun for 30 minutes with truck in drive and emergency brake set, hood also closed....temp gauge reads 195* degrees. Verified several spot on the heads, intake and radiator. Hood only opened to verify temperature with the laser gun. All readings the same.

Still idling as before but now turned on AC with windows down to keep system running for another 30 minutes. Temp gauge reads 210*-215* degrees. Again verified with laser temp gun in several location. All readings the same.

Only air movement was from twin electric fans that are rated to put out 4600 CFM.

I could see the heat monkeys coming out all around the truck with the fans running.

I would imagine that driving down the road may provide additional cooling, I hope.

Maybe that is what this engines best running temperature can run. It is a 454 bbc that has been bored out .040", making it a 462 ci. Maybe the boring out of the cylinders allows the now thinner cylinder walls to transfer more heat to the cooling system.

Any other thought? Change the thermostat to a 185 and add an additional tranny cooler into the existing system have been suggested. Both of these I plan on doing by the way, makes good sense to me.

Thought about adding an additional pusher fan on the condenser, but tested that theory out by placing a fan in front of it at the end, no change in temperature of the coolant system was noted after another 20 minutes.