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Motor Builder vs. transmission Builder

jack montgomery

Well-Known Member
Please chime in with any opinion on this matter if you have experience or knowledge regarding my dilemma.
I recently got my Chevy 572 motor back from the engine builder after I had a valve breakage. He went through it and changed a piston, new oil pump,all crank and rod bearings , re sleeve and new head.

This truck is supposed to be going to Norra and have been working diligently to get it ready. I took it out for break in and noticed oil pressures that were not like they used to be especially around Idle,1000 rpms and 7-10 lbs ( Added mechanical gauge for testing along with new sending unit to be sure ) .The TH400 transmission had no issues but took it to culhane who built it just to go through it along with the torque converter.

Well I had to drop the pan to see if the meling oil pump had issues with the bypass so I cut out crossmember tubes that were in the way and came to find the thrust bearing wiped out along with a couple other bearings with heat marks. Metal in the pan along with the oil filter which I cut open that had brass looking particles.

500 miles on this rebuild and the motor builder is pointing fingers to the transmission , torque converter ballooning or line pressure issue.He commented on a report that Ed Hale did years ago on how he devised a test to check pressures at the crank as you do not want to exceed 200lbs of pressure at the crank. This came about because of the finger pointing that would happen after a thrust bearing failure would occur.

I trust Culhane and have never had issues with faulty assembly of my transmissions SO....

Let me know if anyone has come down this path as I am going to get another short block and try again and do not want the same thing to happen. Thanks Jack
 

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partybarge_pilot

Well-Known Member
Did you check the clearance on the TQ when you installed it? With all the different parts going on in an off-road truck, they are not plug and play. Even Steve will tell you that.
 

Zambo

Well-Known Member
Yeah I've always used 1/8" as the target. Agree .25 is too much. I have no idea if that caused the problem though. Definitely correct about this stuff not being plug and play. I've had to do small snout extensions and tc bolt spacers on all mine to get it just right. Hope you get it figured out Jack.


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jack montgomery

Well-Known Member
1/4" is way to much. .060-.090 is more like it. With that much you risk pulling the drive dog's out of the pump.
I may be wrong on the 1/4" as I never measured it really , it just looked like that much. It is the same converter and transmission that has given me about 6000 dirt miles so there have been no changes regarding that, just motor rebuild.
 

jack montgomery

Well-Known Member
Yeah I've always used 1/8" as the target. Agree .25 is too much. I have no idea if that caused the problem though. Definitely correct about this stuff not being plug and play. I've had to do small snout extensions and tc bolt spacers on all mine to get it just right. Hope you get it figured out Jack.


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I am going to double check that measurement tomorrow but since everything is the same as it was before as far as the converter and the transmission I can't believe they could be the culprit. I just can't have this happen again, norra is 40 sum days left. Searching for a short block tomorrow.
 

Zambo

Well-Known Member
Was your tc rebuilt? Maybe the dimensions changed? BTW I'm not saying it's the trans at all. Hell I got a motor one time that leaked like crazy from the rear main seal...when I took it apart I found that the builder had put it in backwards.


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jack montgomery

Well-Known Member
Was your tc rebuilt? Maybe the dimensions changed? BTW I'm not saying it's the trans at all. Hell I got a motor one time that leaked like crazy from the rear main seal...when I took it apart I found that the builder had put it in backwards.


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I dropped it off with the trans at Cullhanes to just have it checked, I would assume they split it open or had it sent out ,whatever they do because it wasn't cheap. The trans was working fine I just figured it had miles on it and wanted it gone through since it was out.
 

_

Well-Known Member
Jack, you never mentioned which side of the thrust bearing was "wiped out". If it is the forward side only, its is definitely not related to the torque converter pull-up. If it's front and rear, it is more likely result of low oil volume/pressure -or- improper crank end play/float. If its rear only, it may be related to Pull-Up.
 

jack montgomery

Well-Known Member
Jack, you never mentioned which side of the thrust bearing was "wiped out". If it is the forward side only, its is definitely not related to the torque converter pull-up. If it's front and rear, it is more likely result of low oil volume/pressure -or- improper crank end play/float. If its rear only, it may be related to Pull-Up.
Side toward the torque Converter
 

jack montgomery

Well-Known Member
Jack, you never mentioned which side of the thrust bearing was "wiped out". If it is the forward side only, its is definitely not related to the torque converter pull-up. If it's front and rear, it is more likely result of low oil volume/pressure -or- improper crank end play/float. If its rear only, it may be related to Pull-Up.
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Not really sure if its 1/4" as the crank has movement
 

partybarge_pilot

Well-Known Member
Wow, that is really messed up!

Also, way to much clearance. When you pull the converter, inspect the pump drive dogs well.
 

Josh 8

Well-Known Member
Wow. Sorry to hear your having issues. I was in the same spot last year too.

Ok so here is a really stupid question. Did you happen to change any thing with the cam like the lifers? Is there any other way that the engine could have lost oil pressure knocking the bearings out like a new set of solid roller lifters that my need galley oil restictors to oil the bearings right.

Just a thought.
 

jack montgomery

Well-Known Member
Converter
The torque converter is the same and no changes whatsoever, the only thing that happened was when we we took it for its first test drive , and by the way we had run this in the shop 10 times at least doing fluid flow and timing,looking for leaks, etc. The oil lines adapter broke off at the motor ( Aluminum piece of sh!!! that you would never expect to break ), 0- oil pressure and the light was the only thing that caught my eye. We went 75 ft to stop at a speed of only around 50 mph. We bypassed that and put an oil filter in it to get back. That is the big mystery, as we speak the motor builder is taking it apart , I had the transmission looked at internally and no signs of wear that might have shown line pressure problems or any push??? Norra please wait I'm coming.

And by the way did I mention that I fell off the trucks motor cage pulling the distributor! pizza lady wanted a signature and when I turned to get it lost my balance and ladder gave away and slammed my shoulder to the ground from 6 ft up straight on.

I AM NOT GIVING UP!!!!!
 

JEFFRPM

Non Sugar Coated
Here goes the converter pullout of .200 or more can cause the drive "flats" on the snout to be far enough away from the front pump drive "flats" allowing under power not enough connection between the two causing the flats to climb up on each other pushing on the weakest part IE; The thrust bearing taking the entire load. The other thing running it out of oil momentarily dident help the situation either it doesn't take much pressure pushing on the bearing with no oil long to destroy it I'm shure you were just "mothering it" on your initial test drive, I never did I was usually egged on by my friends & shop spectators
 

jack montgomery

Well-Known Member
Here goes the converter pullout of .200 or more can cause the drive "flats" on the snout to be far enough away from the front pump drive "flats" allowing under power not enough connection between the two causing the flats to climb up on each other pushing on the weakest part IE; The thrust bearing taking the entire load. The other thing running it out of oil momentarily dident help the situation either it doesn't take much pressure pushing on the bearing with no oil long to destroy it I'm shure you were just "mothering it" on your initial test drive, I never did I was usually egged on by my friends & shop spectators
OK now your information is above my pay grade and sounds like you have some more knowledge than I. I don't understand why I would have more pullout from the same converter that has given this truck 6000 miles of dirt time but I can assure you you there will be no more than 1/8" on re-assembly. Thanks for your time and will keek you posted.
 

JEFFRPM

Non Sugar Coated
Is it the same block, crank, trans case, front pump, front pump housing, converter not been cut open? Look at the flats on the converter are they "rounding off" from a not enough engagement situation?
 

jack montgomery

Well-Known Member
Is it the same block, crank, trans case, front pump, front pump housing, converter not been cut open? Look at the flats on the converter are they "rounding off" from a not enough engagement situation?
Yes, yes, yes, the rest all I can say is I took it to cullhane off road transmisions for just a go through. Nothing wrong with the transmission at the time, just wanted a ckeck up as we were rebuilding the motor and needed to get it ready for Norra.

I am going to check on some of the things you commented on when I get to my shop , one thing about the converter is the bill for that check up was expensive and I would believe it was cut open and hopefully dynoed
 
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