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Old 12-06-2004, 04:19 PM   #1
cib101abn
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402 bb bearing wear...

I have a 402 bored .030 that was rebuilt by a reputable company and sat for a year in prev. owner's garage before I bought it. I questioned the rebuilder and he said the bearings were put on with white grease and there should be no problem with it sitting that amount of time..I have about 2000 miles on the engine and started getting a low end engine knock just after my last oil change. Found out I had a quart too much in oil, drained 1 qt, checked next day and it was 1 qt too low....don't ask me how!

Pulled the engine and broke it down, #8 bearing badly worn, crank has some scarring that may not polish out, may need turning, signs of wear on others.

Looking for a possible cause...did it sit too long or did I screw up on the oil level somehow? Only had 100 miles on new oil change when the knock became a serious concern....now I am second guessing if I shouldn't have broke it down at first and made a visible inspection before cranking it up.

Any ideas as to what may have happened...I don't rap it out, only once or twice just to see what it would do, the last time may have been about the time the knock started, but it should have had enough miles on it for the oil circulation to work, unless the caps weren't torqued right, dunno...
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Old 12-06-2004, 04:39 PM   #2
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lots of things it could be but with an engine with that low of a mileage im going to lean toward the clearances between the bearings and the crank being too tight. also how was the oil pressure?
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Old 12-06-2004, 05:11 PM   #3
cib101abn
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mistake number two...don't have an oil pressure gauge, or at least I don't think it works right, it is maxed out to the right side of the dial and never moves.

step two is putting in a new gauge after get the engine back together, fortunately my son is doing the labor with my help at n/c, just have to pay for the bearings and gasket kit, about $200 unless I have to have the crank turned. thanks for the input...

by the way...when you have a crank turned, what does that do to the bearing fit, do you get special spec bearings...?
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Old 12-06-2004, 05:15 PM   #4
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they arent going to turn just one journal on that crank. they all need to be turned then have the crank rebalanced otherwise your going to have more problems. and if the crank is the least bit chewed up new bearings are nothing more than a band aid with bad adhesive it wont last long and will be knocking again. take the crank to a machine shop and let them look at it. its cheaper to fix it right now than to have to do it all a second time.you would get oversized bearings its a standard thing the crank will either be cut .010 under or .020 under or .030 under i dont like cranks cut more than .010
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Old 12-06-2004, 05:25 PM   #5
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thanxz, my son is supposed to be totin' it to the machine shop even now while i type...will just have to see what they say. thanxz again, bob
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Old 12-06-2004, 05:41 PM   #6
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no problem good luck i had close to this same thing happen with a small block the machinist that assembled the engine apparently didnt check any clearances cooked 2 rods and the bearings the rods got soo hot they were blue when i pulled the engine apart and the crank became a paper weight. engine was also extremely out of balance broke a main cap in half. needless to say i wont step foot in that machine shop ever again
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Old 12-06-2004, 05:56 PM   #7
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you need to get those rods checked out to and use some plasti gauge when you put it back together
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Old 12-06-2004, 06:18 PM   #8
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me? those rods are in the trashcan motor has been back together. totally different block rods crank and pistons and a different machinist
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Old 12-06-2004, 11:02 PM   #9
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I have a 396 cranks that has been turned and never used. I also have the clevite bearings 150 for all of it.
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Old 12-06-2004, 11:43 PM   #10
cib101abn
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Report back from son: crank needs turning (why am I not suprized) I wish I were not so cynical but to me asking a machine shop if something is needed is like asking a crook if he wants to rob you or wait for the next person to come along.

(had bad experiences with some shops)
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Old 12-07-2004, 12:50 AM   #11
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not all machine shops are bad believe me a lot of times it might seem your getting screwed because things appear to you to be ok but they really arent your talking about hundreths and thousands of an inch being the difference between an engine having a long happy life or a very short very fatal end
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Old 12-07-2004, 10:43 AM   #12
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Grind crank

Cib, Just curious, What does it run to have a crank ground down in Tx.? Did you prime the engine good before you started it or just light it? Good Luck...
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Old 12-07-2004, 12:12 PM   #13
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If that crank needs tuning you better get the rods re checked or thr same thing could happen as soon as its put together. The crank ass. is the most delicate part of the whole build.
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Old 12-07-2004, 02:59 PM   #14
cib101abn
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Turning crank is about $60 +/- a few, depending on crank I guess.

What should I have the rods checked for? Does that mean taking them off the pistons, cause it will cost a bunch more to do that, but if needed I would rather buy the insurance of having them checked than pay the claim if something goes wrong again.

and I gues if I ask: "what does priming the engine mean?" that would be a question and an answer all in one.
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Old 12-07-2004, 04:15 PM   #15
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normally if an engine has sat for a long time you manually spin the oil pump with an oil pump primer attachment that fits on the end of a drill until you have oil coming out of all of the rockers. it ensures that the bearing are well lubed before you light the engine off
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Old 12-07-2004, 04:48 PM   #16
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Quote:
Originally Posted by cib101abn
Turning crank is about $60 +/- a few, depending on crank I guess.

What should I have the rods checked for? Does that mean taking them off the pistons, cause it will cost a bunch more to do that, but if needed I would rather buy the insurance of having them checked than pay the claim if something goes wrong again.

and I gues if I ask: "what does priming the engine mean?" that would be a question and an answer all in one.

You need to take the rods to the machine shop and have them checked that they are not the problem that made the bearings go out. (not sized correctly the first time by the machine shop) You wont have to take the pistons off unless they need to resize them. When you do get it all back together make sure you prime the engine. That is what they are talking about. Make sure you use the correct primming tool (under $20.00) used on a drill. Hook an afetrmarket gauge up to be sure you have correct oil preassure before firing that engine up.
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Old 12-07-2004, 06:48 PM   #17
cib101abn
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thanks, on the way to the machine shop with the rod/piston assemblies.
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Old 12-08-2004, 03:00 PM   #18
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The $60 price on turning the crank is what my son brought back home from his visit to take the crank in, don't know who he talked to; when I took the rods in I asked the price for turning the crank and the boss quoted me $97.50, another $30 to check out the rods..

How does those prices compare around the country..?

(another reason why I distrust machine shops..why didn't they tell my son when he brought the crank in that it was important to check the rods too? Had it not been mentioned on this site the shop would have turned the crank and possible let me bruise it up again! I just hate it when you not only have to know the right questions to ask, but to be able to ask them in the manner to get the right answer...in my opinion the shop should have been the first to mention this...not the last)>
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Old 12-08-2004, 05:20 PM   #19
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Quote:
Originally Posted by cib101abn
The $60 price on turning the crank is what my son brought back home from his visit to take the crank in, don't know who he talked to; when I took the rods in I asked the price for turning the crank and the boss quoted me $97.50, another $30 to check out the rods..

How does those prices compare around the country..?

(another reason why I distrust machine shops..why didn't they tell my son when he brought the crank in that it was important to check the rods too? Had it not been mentioned on this site the shop would have turned the crank and possible let me bruise it up again! I just hate it when you not only have to know the right questions to ask, but to be able to ask them in the manner to get the right answer...in my opinion the shop should have been the first to mention this...not the last)>
They should have but some just do what you take them and dont ask any questions. I think they figure your using new rods, or if your that far into the engine you know about it. I like to use the shop I use, when I first started years ago, I would ask there opinion and they would tell me why they wanted to do this or that. It builds a nice trust between you and them. When they would tell me that I needed some thing done, I didnt even question it. I have never got bad service from them in in 18 yrs. You need to find a good shop and stick with it, I know it is hard to find quality work nowadays anyware..
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Old 12-08-2004, 05:49 PM   #20
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I was gonna say i know everything is more expensive up here in the Northeast..but $60 to turn a crank..thats pretty cheap.

the shop that i deal with is a bit on the high end cause they do good work and have a waiting list a mile long...but they get $130 to do a crank - turn, micro polish, and jet clean
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Old 12-08-2004, 06:06 PM   #21
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Crank grinding

$125 here in the St. Louis area. It varys all over the country. I think I seen someone say it cost $50 to grind one on the east coast and $5.00 a rod to recondition them. $12.00 here each.
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Old 12-09-2004, 01:02 AM   #22
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crank turn clean polish here is $125.00 $12.00 per rod to resize or $5.00 to clean or polish
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Old 12-11-2004, 12:02 AM   #23
cib101abn
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Here's how my final ticket reads (as best as I can make out)

Turn crankshaft (r040, m030 97.50
check conn rods bump 5 60.00
8 3190 CA 040 R. Brg 44.64
1 4400M 030 M Brg 46.70


with tax (8.67) freight (7.90) and something listed as csc (5.85) total is $271.26

I suppose the freight in on the bearings, the csc is probably shop expendables that everyone usually does as a percent of something.
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Old 12-11-2004, 01:20 AM   #24
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Start hunting another crank, cause that one just made its last trip to the machine shop. The good engine builders I know won't even turn a crank past 20/20. What's happening is your crank is getting smaller and your bearings are getting thicker,this is not a good thing.
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Old 12-11-2004, 05:59 PM   #25
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wow they turned that crank wayyyyy far i wouldnt use it personally normally a good shop wouldnt have used anything more than r020 m020. the machine i use and used to work for wont use anything more than a .010 .010 crank. thats making those journals awful thin
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