Destroyed Thrust Bearing in Newly Built 327
 

I am far from a frequent poster but I hope someone can point me in the right direction here. I built a 327 to replace the original 305 in my 1978 Custom Deluxe which had a newly-rebuilt TH350 transmission. I turned the engine, with a new converter (2400 stall) and flexplate, to a local mechanic for installation. An oil leak that developed during the first approximately 2500 miles, finally led to pulling the pan to find that the thrust bearing was badly damaged and that debris from it had reached the rear seal, causing the leak.

The engine is in my garage now and the truck is at the installer's shop waiting for a repaired engine. The crank is ready to be lifted out, but is still in the block. Closer inspection reveals a heavily worn rear thrust bearing flange as well as very heavy damage to the thrust ring on the crank. There is virtually no wear on the forward flange of the bearing. Being that the damaged bearing flange is the rearmost flange (corresponding damage to thrust ring on its forward-facing surface) it appears that something had been pushing hard on the rear of the crank. The installer is sure that the converter was fully engaged with the transmission and that appropriate end play existed in the converter before it was bolted to the flexplate.

My questions to the group are, given all of the above, is there anything related the build that could, if done improperly, could cause the above damage or, is the damage definitely due to externally-applied force? If the crank is being forced forward externally, what would you suspect? I am really concerned about repairing the damage only to have a repeat performance. One final observation; the pilot recess in the rear of the 327 crank is significantly shallower (approx. 3/16) than that on the old 305 crank.

I apologize for the length of this post, but I was trying to provide all of the info that I thought was pertinent. Any input from you folks will be greatly appreciated.

Re: Destroyed Thrust Bearing in Newly Built 327
 

I've only seen excessive thrust bearing wear once on an employers 1991 F150 4x4 plow truck that was still under the factory warranty.
According to the dealership the cause was a faulty torque converter that was shoving the crank forward. I got a look at the actual mess it caused because I was friends with one of the Ford Dealerships' mechanics. They installed a warranty replacement 302, AOD transmission, and torque converter and the problem went away permanently... fairly extreme remedy but effective.

It could easily be the transmission and apparently it's difficult to track down. This article may be a good jumping off point...
https://dannysengineportal.com/crank...aring-failure/

Re: Destroyed Thrust Bearing in Newly Built 327
 

It does sound like the converter was pushing the crank forward . When installing be sure you have about 3/16 between the flywheel and the converter bosses for the bolts . If you mate the trans and there is no clearance this will do it . It is the installers responsibility to check this . This also will damage the trans pump as well . Being you changed most everything this could be a good possibility .

Re: Destroyed Thrust Bearing in Newly Built 327
 

Thanks for all the good info. I'm thinking now that perhaps the way to go is to have the engine reinstalled after repairs are complete, but not started. Then trailer it to a transmission shop for them to thoroughly check out the transmission.

Re: Destroyed Thrust Bearing in Newly Built 327
 

I have seen this several times and the transmission builder knows his cheap converter caused this. Take the defective torque converter off and make the trammy man eat it.

Re: Destroyed Thrust Bearing in Newly Built 327
 

Like Ron says, it's the converter. If you google torque converter ballooning and thrust bearings you will hear the same story you told us, word for word.

Re: Destroyed Thrust Bearing in Newly Built 327
 

Thanks for the reply Ron

Re: Destroyed Thrust Bearing in Newly Built 327
 

Thanks Al

Re: Destroyed Thrust Bearing in Newly Built 327
 

This is the reason for the clearance between the converter and flywheel . Most all regular converters will balloon some unless you have a billet front on the converter . Most will just bolt it up and go with out checking .Most will get by with it but some will not . It is still the installers responsibility to check the clearance and correct it if necessary . 3/16" will take care of ballooning in stock form unless you are a very high HP engine . Then you may want to consider a billet front .

On the other end it is still just as important to shim the converter if to much clearance . It will be running out of the pump to much and either break the converter or pump .

Clock , I am hoping it did not do any damage to the trans pump . Not only was it pushing on the crank it was pushing on the trans pump .

Let us know how it turns out

Re: Destroyed Thrust Bearing in Newly Built 327
 

Thanks Homemade. I'm planning to trailer the truck from installer to trans shop before I drive it. I'll post on how things turn out

Re: Destroyed Thrust Bearing in Newly Built 327
 

Take the convertor and test fit it inside the end of the crank....it should seat all the way in with little effort...

There could also be an issue with the trans oil pump gears being assembled backwards, keeping the convertor hard up against the crank....

Also check for clogged trans cooler lines and cooler...a plugged cooler line or cooler will make the convertor balloon and push forward against the thrust face...

Re: Destroyed Thrust Bearing in Newly Built 327
 

Thanks much Aussie. Very helpful info!

Re: Destroyed Thrust Bearing in Newly Built 327
 

Hello again guys. I made a little progress today I think. I've arranged for the transmission to be pulled from the truck and delivered to a trusted transmission shop for a complete going over, while I continue to rebuild the engine. Should save some time.

I am thinking of buying a B&M converter just for further insurance. Do you think I should also replace the flexplate? Many thanks for the helpful information you have provided.

Re: Destroyed Thrust Bearing in Newly Built 327
 

Also, make sure there isnt a pilot bearing in the end of the crank. I bought a 1 ton that the PO swapped in an automagic and did not pull the pilot bearing out and it ate the thrust bearing.

Re: Destroyed Thrust Bearing in Newly Built 327
 

If you want an actual quality converter look at Precision Industries or Yank. More money but much higher quality i.e. billet etc

Re: Destroyed Thrust Bearing in Newly Built 327
 

Suggest you discuss the convertor needs with the trusted trans shop....if this is a street daily driver...no need for a billet...

As someone who has built well over a thousand transmissions I would never provide a trans without my own fully rebuilt convertor....rebuilt as in cut stripped pressure hot washed, and re-assembled with new parts as required.

Also, when installing the trans and convertor, make sure you / they fully flush the cooler circuit and preferably install an external cooler system that totally bypasses the oem radiator cooler system....plug those radiator cooler ports to keep out the crud...

:chevy::chevy::chevy:

Re: Destroyed Thrust Bearing in Newly Built 327
 

Another chapter. Noticed last night, when I was stripping bearing shells, that all of the interior main bores had been damaged by the crank working against them. So, this morning I ordered 355 short block from Summit and will dress it with the top end of the damaged engine. Checked with Summit and everything can move over to the new block. Estimated delivery is Monday the 10th.


I really appreciate the responses to my questions.

Re: Destroyed Thrust Bearing in Newly Built 327
 

Couple of things to check before you put that new unit together....

What heads are you using ?

Is the new engine a roller cam engine? If it is, you will need to change distributor drive gear....

Does new engine have fuel pump boss ?

What did you end up doing with the trans?

This is becoming an expensive exercise...but IMO you did the right thing getting rid of that lower assembly.

:chevy::gmc2::chevy::gmc2::chevy:

Re: Destroyed Thrust Bearing in Newly Built 327
 

Heads are Edelbrock E-Street aluminum heads (2.02/1.60)-- 64cc. I will be using the Edelbrock 7102 flat-tappet cam and lifters lift:.488/.510 -- duration:308/318. Also using roller rockers from Howard Cams. Edelbrock 2703 intake and 1406 carburetor. Long-tube Flowtech headers. The new engine comes without cam and with a fuel pump boss. The transmission should get to the trans shop this weekend. Keeping my fingers crossed. Expensive but, hopefully better than having to go through this again. It's gotten to be personal at this point. Thank you for your interest.

Re: Destroyed Thrust Bearing in Newly Built 327
 

That's a pretty healthy camshaft.

Re: Destroyed Thrust Bearing in Newly Built 327
 

It produces 11 inches of vacuum at idle and I have added a vacuum pump for brakes but idle is not too rough.

Re: Destroyed Thrust Bearing in Newly Built 327
 

Hello again folks. I've completed the 355 replacement engine but still know nothing about the transmission. The holidays have bogged things down apparently. I had to buy a new flexplate because this block is a one-piece seal block (internal/external balance). The flexplata received has two different size holes for mounting the converter. Two holes are 0.516 in. dia. and the third is oblong (0.413 W X 0.478L). I called Summit about the different hole configurations and they sent me another flexplate at no charge. It is identical to the first one. So now I have two flexplates that appear to be useless to me. Can anyone explain the odd mounting holes?

I'm attempting to include a pic of the completed engine.

Re: Destroyed Thrust Bearing in Newly Built 327
 

You start the mounting bolt in the round hole 1st & tighten it, and then rotate & start the others in the oblong holes & tighten them.
This is done so that you can install & "Tighten As You Go". With a three bolt hole round pattern you stand the chance of not being able to tighten as you go & the last bolt won't go in the hole.
While you have the engine out it would be a good time to freshin up your starter & clearance the drive pinion to your new flexplate.
You not gonna run a PCV?

Re: Destroyed Thrust Bearing in Newly Built 327
 

Thanks for the reply Andy. Yes, I will be running a PCV. It's just not in the hole in the picture. I am not as concerned about the elongated hole as I am about the sizes of the holes. Two of the holes are an easy clearance for a 1/2 inch bolt and the third hole won't clear anything larger than a 3/8 inch bolt. While I know there are 3/8 converter bolts available, I've never seen a 1/2 inch converter bolt. My converter is drilled for 7/16 bolts.

Re: Destroyed Thrust Bearing in Newly Built 327
 

You should be fine just be sure to use a grade 8 flat washer on your bolts. You may have to drill out the small hole to fit your 7/16" bolts.
OK I see the PCV grommet in the left rocker cover now. I was thrown off by the 327 style oil filler on the manifold plus the breather on the right cover. For the most efficient operation of the PCV system you should do away with the front filler / breather. The fresh air should enter one side of the engine & draw ACROSS the engine to exit at the PCV. Having multiple air inlets COULD cause crankcase evacuation problems (Dead Spots) which could lead to condensation.
If you want to fill the engine oil from the front hunt up a late 327 style tube that had the twist filler cap on it.
Nice looking engine hope it runs as good as it looks!