Type 4 Engine Case, Crank & cam won't turn with new bearings Options

[914sgofast2]

We are rebuilding the 1.7 engine in my son's 914. Crank and cam have standard size bearings journals. Bought new standard size main and cam bearings. Installed in case halves and crank would not turn. Opened case and discovered one of main bearings had slipped and was off the dowel. Placed back on dowel and put case halves back together. Crank still would not turn. Took cam out, rechecked main bearings were all centered on their dowels and reinstalled just the crank. Crank still would not turn. WTF? Took crank out and just put cam by itself in case with its new bearings, and put case halves back together. Cam would not turn!
Son took case and crank to machine shop that had re-bushed the connecting rods. They said crank was ok and had standard bearing journals; but that case halves had worn bearing saddles that were too big and the case needs to be align bored. Does not sound logical to me. If the bearing saddles were too big, then why would they cause standard size bearings to be so tight that neither the crank or cam will turn? Could the case simply be tweaked? Any ideas?
Anyone know of a machine shop in the Sacramento, California area that knows their way around the Type 4 engines? The shop who did the connecting rods does not know VW or Porsche engines.

[r_towle]

first off, as you are putting the case halves together, with NEW bearings, you need to be turning the crankshaft all the way around each time you torque down the bolts a little bit.

Then you will know when it binds.

I would send the case to one of the known machine shops in CA, shipping is not that big a cost to get a case done right.

rich

[ConeDodger]

Bolts on cam gear contacting case?

[914sgofast2]

Bolts on cam gear contacting case?

No, it is the stock cam with rivets on the cam gear (not bolts) and the oil pump was not installed. Even the cam alone would not rotate when the case halves were bolted back together with the new bearings.
Could the case have become that deformed over time that the main and cam bearing saddles are all now oblong, instead of perfectly round?

[jmill]

Are you sure your bearings are not undersized? Are you torquing the case in the pattern per manual? Did you machine anything especially the case halves?

[DBCooper]

Could the case have become that deformed over time that the main and cam bearing saddles are all now oblong, instead of perfectly round?

Yes, extremely common with T1 magnesium cases, after years they get pounded oval so you need to align bore and use oversize (external) bearings. The aluminum T4 cases are less prone but eventually have the same issues.

[Series9]

I went through this in the last year.

I mostly specialize in /6 engines and hadn't built a T4 in a while.

I had a customer come in who wanted a 2056 T4, and I thought it would be a fun, simple build.

I could not have been more wrong. I allowed him to supply the PC set and the cam.

What a nightmare. Nothing fit correctly.

I had to buy two sets of Mahle rod bearings in order to create one good set. (I threw the rest away)

I had to carefully wet sand the thrust bearings on the cam and then test-assemble the bottom end several times before I could get everything to rotate smoothly.

In the same way Type I engines are either "top shelf" American parts or Chinese junk, so goes the T IV.

Either be prepared to pay $10k for good quality new, or find really good used German parts, or learn to deal with the junk that fills the rest of the market.

As far as I'm concerned, there can be no stronger advocacy for a /6 than to understand the quality issues associated with everything in the /4 market at this time.

[stugray]

In an engine build last year (not a 914) I had main bearings brand new (apparently) from a reputable parts vendor that were NOT what was printed on the box.

You need to measure your bearings, but that is not a trivial task without the correct tools.

[0396]

Line bore?

[TheCabinetmaker]

I rebuilt an engine that had been ran out of oil and seized. Upon reassembly I had the same problem. A trip to my machinist quickly determined a warped case. Scrap metal.

[rick 918-S]

Any competent machine shop should be able to CHECK the line bore for you. Not all shops will be able to correctly repair any issues that may exist. Check everything first, dry fit the bearings then check again. Check the crank for cracks and straightness. If you torqued the case with a bearing off the dowel you could have damaged the case.

[toadman]

I think that the bearing that had slipped off the dowel should have been replaced and not re-used.

[0396]

I rebuilt an engine that had been ran out of oil and seized. Upon reassembly I had the same problem. A trip to my machinist quickly determined a warped case. Scrap metal.

That's my thinking too.

[Series9]

The phrase is "align bore", not "line bore".

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[stugray]

The phrase is "align bore", not "line bore".

(IMG:style_emoticons/default/hide.gif)

And because most people say "I need a line bore" instead of "I need an align bore" (IMG:style_emoticons/default/biggrin.gif)

Im thinking its something more basic....
Really the case can warp to where even the Cam cant turn all by itself?

Try removing one of the three cam bearings and reassemble (carefully of course).
You might find the offending bearing race (if that is the problem).

[r_towle]

Or a lifter is wedged in wrong....

[worn]

We are rebuilding the 1.7 engine in my son's 914. Crank and cam have standard size bearings journals. Bought new standard size main and cam bearings. Installed in case halves and crank would not turn. Opened case and discovered one of main bearings had slipped and was off the dowel. Placed back on dowel and put case halves back together. Crank still would not turn. Took cam out, rechecked main bearings were all centered on their dowels and reinstalled just the crank. Crank still would not turn. WTF? Took crank out and just put cam by itself in case with its new bearings, and put case halves back together. Cam would not turn!
Son took case and crank to machine shop that had re-bushed the connecting rods. They said crank was ok and had standard bearing journals; but that case halves had worn bearing saddles that were too big and the case needs to be align bored. Does not sound logical to me. If the bearing saddles were too big, then why would they cause standard size bearings to be so tight that neither the crank or cam will turn? Could the case simply be tweaked? Any ideas?
Anyone know of a machine shop in the Sacramento, California area that knows their way around the Type 4 engines? The shop who did the connecting rods does not know VW or Porsche engines.

Based on my own experience it is easier than I would have believed to get a bearing off of the dowel pin. After that it is mostly a question of how much torque before the problem is discovered. Just as a guess that would be my focus. Good luck!

[injunmort]

i am gonna get flamed for this but here goes: whenever i split a crankcase motorcycle, car or tractor, upon reassembly, i put the whole mess in my welding over and heat it to 250 for an hour, then unplug the over and let it slowly cool. it relieves the stress and lets the cases align themselves. i have had norton engines that were tolerance loose by measurement bind upon reassembly, a hour in the oven they turn like they were married forever. fwiw, let the slamming begin.

[PotterPorsche]

You mentioned that the crank didnt rotate. The bearing that had the "dowel slip" can no longer be used without measuring inside diameter. I had this happen the bearing was no longer usable.

[914sgofast2]

You mentioned that the crank didnt rotate. The bearing that had the "dowel slip" can no longer be used without measuring inside diameter. I had this happen the bearing was no longer usable.

Thanks for all the ideas. I did not re-use the main bearing that had slipped off the dowel. I had another set of new std size Mahle's that I used. ALL bearings that came out were std, and were replaced with std. size Mahles from Brazil. The cam bearings were std size Mahles too from Brazil too. From what I have read here, it sounds like this case is junk. I did not try to reuse the bearing that jumped off the dowel. However, that does not explain why the cam won't turn when installed all by itself. As one member mentioned, I had to adjust the thrust clearance on the new cam bearings before indtallation. This case has never been machined before and all old bearings that I am replacing were std size.