jetrainor

Well, got the 5liter on the engine stand, turned it upside down and started pulling oil pan bolts. Interesting that most of them were only finger tight....anyway to backtrack a bit, my 87 euro has 110,000 kms and after TB/WP, valley service, thermostat, this summer, it developed a knock 1500 kms after being buttoned back up. Mechanic where i had the work done cut open the oil filter and we saw bearing material in there. I got the car back from this shop and i intended to take it back to them for rebuild however decided i wanted it back within my lifetime, so some friends, two of them mechanics and i decided to do it ourselves. First think we noticed was an aluminum spacer lying loose in the pan....its like a small tube about a quarter inch tall....any idea what that might be?. We also found the remains of a tiny black plastic tube and some bearing stuff on the oil pickup filter. Taking a pry bar, we measured crank play at 5 thousands. The thrust bearing on the back engine side of the center main journal is not visible...on the front side of the journal it appears normal. We haven't had a look at the back side of the block where flywheel connects so i don't know what kind of wear there is there...i will take pics tomorrow. My question at this point is if there is no block damage, can we re-bearing and button it up?

87 euro auto

Jim_H

What do you think the knock was from?

jetrainor

Well Jim, when the mechanic heard the noise as i drove it down to his shop, he guessed rod bearing....the engine never seized and except for the noise, idled fine for the very limited time i ran it after seeing the bearing material. We havn't got past the oil pan yet and just noticed some very slight wear on the journal side, where the crank lobe may have been rubbing. Taking a pry bar, we measured the back and forth play on the crank shaft, at 5 thou. I'm wondering if we're going to find rod bearing and are discovering very early stage thrust bearing failure....hopefully before the block is screwed...i'll take pics.

FBIII

If you had a rod knock you're probably looking at a rod that's big end is no longer round and a crank journal that is likely not very round either. You are probably looking at tearing the bottom end down unfortunately. But hey if you have it down this far you might as well do it right the first time.

SteveG

Sounds like the spacers on the valve cover bolts on my '85. Don't know what's under your covers.

jetrainor

Steve G.....think your right on the valve cover spacer....only time the covers were off were when i was re-finishing them this summer....Pmech re and re'd them.....anyway, dug a bit deeper this am and there is NO play in the rod bearings...the only thing visible from the crank side is slight rubbing where the crank lobe was beginning to rub on the center main journal....it appears the shoulder on the center main bearing is gone on the front engine side.....when we released the pinch bolt on the drive shaft there was negligible movement on the flex plate....I'm hoping at this point we can re and re the rod and main bearings, have a peek at the top side....eg, the plastic chain tensioners and replace if necessary, and be good to go. I wonder if the knocking noise from the engine was the crank lobe against the main journal...once i figure out how to post pics, i will do so.

87 euro auto

jetrainor

Well i think we are coming to the sad conclusion that this engine has thrust bearing failure...what we can't understand is why it sounded like rod bearing knock when we pulled it out of the car. With the pan off, we can try and move the rods but they are tight, so we're thinking its not rod bearing noise.
We also know from others that with TBF, there is no noise....just a quiet grinding away of the main journal where the thrust bearing no longer exists....could the noise be from a rod wrist pin allowed to move because of the play in the crank shaft. With a pry bar, the crank moves back and forth about one eigth of an inch. I don't know if this is enough to consider the block toast. You can definitely see where the crank lobe has rubbed against the back side main journal, basically smoothing it out however i wouldn't say it was 'grinding'. My initial thought was to re-bearing rods and mains, but without the knocking noise explained i guess we have to pull the whole thing apart. I've got a feeling the block is too worn on the main journal fora new main bearing to seat properly. Wish i had an exper ience set of eye's to give us a second or third opinion.
It really blows me that this thrust bearing issue, at least with auto's, is so deadly to these cars. This engine has 65.000 miles on it, didn't use a lick of oil, and after spending 7 thousand dollars on it this summer, was running awesome. The whole tourque tube, pinch collar, flex plate fiasco is just so bloody mickey mouse on such an otherwise overengineered, expensive piece of mac hinery

87 euro auto

Jim_H

That sucks... don't know what else to say.

EB338

Forgive my momentary laps of memory but this failure is an automatic only thing, right?

ErnestSw

EB338,
Correct.

EB338

Thank god.......oops..thank you

the flyin' scotsman

Given where we live in this world there's not much 928 engine expertise to make a block decision. Why not call Dave Roberts or Devek after sending digi pics for their expert opinion.

Even if it is 'worn' perhaps there's a solution other than throw away. Thats what seperates true mechanical geniuses from the rest.

GlenL

So the entire rear of the thrust bearing (third one back) is gone? If it's worn away and the block is scored then it's toast. Don't despair, though. Call around for a "short block" and post a request here. Check eBay, too. Might be pleasantly surprised by the cost.

Prionace Glauca

Jetrainer,
Please see attached (I hope?) pictures of the #3 main/TB from an engine that I have rebuilt. The engine/car had only 7804 miles on it. The PO's employee spun the 2/6 rod bearing on his way back from a smog check session.
The machining marks on the bearing webs in these pictures are normal and came from porsche that way. Don't give up until you have completely disassembled the lower-end. Lets see some pictures of what your working with.

FBIII

That engine had 7800 miles and is already down to copper on the thrust surface!!!!!