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Got a ton too much of crankshaft end play



Many-many years ago before I restored my 1967 the previous owner had a main seal leak. He not only tried once, but twice to have it repaired.

Once I got the car & drove it - it seemed to be fixed but after about 100 straight miles I saw the leak form again. Knowing that its pretty easy to pull the engine I did just that & replaced the leaking main seal. I replaced it with a new style seal though ~ and in short order (100 miles) it was leaking again. After reading up I read that the new style seal that I used had a second lip that should have been trimmed off for my 912 application. That or use the 36HP bug main seal that did not have this second lip. So I ordered a low HP beetle seal & a new style seal again (that I trimmed) so that I could have choices.

Again the engine came out & I replaced the seal. I used the VW seal chosen by a coin toss.

But... Leaked again. In about 100 miles.

I asked a mentor of mine what his thoughts were & he advised me to check the crank end play. He noted that if the crank moved much at all the seal would have difficulty with that & fail. So out it came again.



I checked the end play and found that its past spec. I am thinking that it may have been this all along. Well back many years. The thing runs great, but the leak has beaten me down.

Its all numbers matching so I want to work with what I have. Enjoy as I will add to this thread as I discover & uncover.
Old 09-28-2017, 05:22 PM
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There have been end play shims that were made of too soft metal and wear quickly; there is also the possibility of #1 main bearing being loose in the case (worst case - will case major oil leak). Either way, you're going to need to pull the flywheel (always use a new soft iron gasket when reassembling). To check to see if the bearing is loose in the case, install too much shim (taking up all end play) and snug the gland bolt. If there is end play, the motor will need to be taken apart and the case fixed (aligned bored for oversize bearings or machined back to stock). If it's just a matter of setting the end play, buy the proper thickness Porsche shim (from Porsche or Porsche parts supplier). The soft shim topic has been extensively discussed on the 912 BBS. The viton VW 36HP seal is the way to go.

Peter
Old 09-29-2017, 04:25 AM
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Thanks Peter. I do have some play (rotationally left to right) in that main bearing behind the shim. I understand there is a pin there & it seems as if it is allowing some movement in that bearing.
Old 09-29-2017, 05:35 AM
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Movement in any bearing shell with respect to the case is not good. The case should provide 'bearing crush' that actually changes the dimension of the bearing shell slightly, holding the shell tightly. All main bearings have anti-rotation fixing: since #1 and #4 are full circle, the anti-rotation is fixed by a pin: #1 is a dowel pin, #4 is a special bolt with pin end. #1 is particularly critical in that it takes both axial (end play) and radial (flywheel/crank imbalances, oscillations: yes, cranks do flex) loads.

If the #1 main is moving with respect to the case, your motor needs to come apart before it runs again, sorry...

Peter

Last edited by Peter Graham; 09-30-2017 at 04:05 AM..
Old 09-30-2017, 04:01 AM
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Peter thats okay, and your professionalism is so very appreciated. I felt the same way when I saw the bearing movement, but I don't mind really. I adore the car, and will be happy to make it 100%. Its not the end of the world for us. Plus after doing this several times - & assuming the problem was me - this is actually (in a twisted way) some style of relief.

I am going to try your 1st suggestion ~ even if it is only for my own curiosity - then plan my repairs.
Old 09-30-2017, 05:13 PM
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Been there, done that. I have an otherwise "good" motor now sitting in the garage that needs to be torn down and have the case reworked due to this problem. Winter project I guess.
Old 10-06-2017, 01:05 PM
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Finally got a chance to work with the shims (I bought some through a member on this sight ~ it took a bit of a long time to get them... But I digress). Anyhow so I pulled some measurements, added some shim thickness and tried it. Viola! it worked. The clearances were much better. But I still had a bit too much play over spec so I continued shimming. Once I got the clearance jusssst right I was excited... But! With a quick yank on the flywheel I found that the engine could not turn over. It would move sure (keeping my hopes up), then make contact internally with the case & stop the progress.

Thats enough for me. I know what I have to do & will start the process of teardown.

More soon!
Old 10-25-2017, 10:48 AM
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While car engines have changed a lot since I did any serious work on one, crank end play sounds like a tapping, metal on metal that get louder as the engine increase or decreases rpm. It is had to tell the difference between this and a lot of other similar noises. Overhead cams can also sound like this. Cam pushrods can make this sound too.
Old 11-09-2017, 12:31 AM
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