mikehayes

So I've been rebuilding a 16V motor. Had the crank mic'd and polished and checked for run-out, everything looked good. Installed new main bearings today, greased them all very well with assembly lube. Put the girdle on with 574 and followed the tightening pattern/levels.

Everything went together nicely, but I couldn't turn the crank by pulling on one of the counterweights like I could before, so I put the front bolt in the crank and measured how many foot pounds it required to turn the crank; 22. Is this typical after a rebuild because of tighter clearances and lack of oil?

odonnell

No. It should spin by hand strength acting on one of the counterweights. I just checked on my 951 engine, since it's actually on a stand in my bedroom.

mikehayes

Well that's not what I was hoping to hear... Any ideas on what I messed up this time? It occurred to me that the #1 main bearing has a hole in it that a small peg goes into. I had the bearing oriented correctly when I tightened, but I never actually watched the peg go into the hole as I had the oil pump attached. I have to imagine if it didn't align I would have noticed though. I took the oil pump off and looked at the side of the bearing and couldn't see any sign that it didn't.

MAGK944

Did you platiguage?
Did you use genuine Porsche Bearings?

mikehayes

I did not plastigage. They're glyco.

MAGK944

I know it's not what you want to hear, after the event and all that.

<rant>I cannot understand why people don't Plastigague, I know, it's one extra step, but it's so important in telling you everything is correct and in tolerance.</rant>

There have been reports of oem Glyco bearings from the aftermarket not being as good as the factory bearings that come in a Porsche box bought directly from Porsche. I get factory bearings and have never had a problem so I am reapeating what I've heard and read.

mikehayes

You're absolutely right, I knew beforehand that I should, but because this is my first ever engine build I was too stupid to take the time.

My logic was as follows: I don't have an engine stand, just a hoist, so I had to lower the block onto the girdle, which would have made plastigaging difficult. I also figured since I knew the crank was in spec, and there was only one set of bearings I could buy (or so I thought), what was I even going to do if the plastigage came up bad?

I guess I've learned my lesson, because now I either have to leave it and hope it'll loosen up, or tear off the brand new glue and start all over again.

V2Rocket

Glyco makes the Porsche bearings - the difference is that Porsche re-measures them to verify the tolerances.

Van

If you don't have an engine stand, drill some holes in a wood-topped table and stick the head studs through them so you can work on the block upside down.

Take it all apart and verify that the bearings are in correctly.

When you retorque it the next time, do it in stages, and see if the crank spins while you're torquing the girdle down. Also, make sure the oil pump is installed when torquing the girdle.

If you do all of that, and it's still tight, then either your bearings are out-of-spec, or the crank is bent.

mikehayes

Thanks Van; good ideas as always. I'll try them out and see what I find. The crank was not bent when I took it out, so it seems unlikely that's the problem. It also spun nicely when it was just sitting in the girdle before I lowered the block.

MAGK944

I also read once that Glyco makes them in Germany for Porsche and in Mexico for the aftermarket. True or not?

951and944S

Mike, if you have no reason to believe your bearings are not installed right, using a flywheel bolt partially threaded and an angled prybar or large screwdriver, try to push the front of the crank in at the front while prying the bolt at the rear and try to achieve a front to back rocking motion.

If you don't have any noticeable end play (min=.004"), use a block of wood and a moderate hammer and tap the crank to the rear using front snout and to the front using rear main seal flange, back and forth a couple of times.

The thrust bearing (middle one) is the one with saddle flange 90 degrees to the bearing surface. Sometimes the edges are sharp from forming leaving no gap for clearance. If the crank spins free after, you'll be ok.

The same action would happen to the bearing once the engine was running and you depressed the clutch anyway (pull type diaphragm)

I always put those two bearings together to form a circle and cup them in my hand while lapping them on 600 wet/dry sandpaper on a flat surface with wd40 because I have seen defects at the lip and the coating.

T

951and944S

And buy and danged engine stand you will need it anyway.

You can get a cheap one for $50.

I'd send you one that you could have for free but the shipping would be more than a cheap local one.


T

mikehayes

Well there's yer problem.

Shows what I know lol.

Bearing bent when the peg went into it. Was probably squeezing the crank. Thank God the bearing is softer than the peg.

Guess I need a new #1 bearing. Anyone know if it's possible to just get one bearing? Also, I can't think of a good way to ensure this bearing seats correctly, but I'm sure it'll be easier not trying to do this upside down. I'm on my way to HF tomorrow for a stand lol.

odonnell

The silver lining is it's an easy fix, and you didn't finish/install the motor and then have it destruct within minutes.