Re: Mutha' Fu**in' TQC head

[rdh@sli.com (Robert D. Houk)]

   So, the car's all put back together, right?  New big valve hydraulic 
   head, Schrick 272, RS2 turbo, etc.  I've been running it for the past few 
   weeks and noticed a squeeking sound synchronous with the engine 
   rotation.  Changed both the hydraulic pump and water pump to no avail.  
   Finally, last night I pulled the cam, and low and behold, discovered 
   the last bearing cap was deeply scored, along with the camshaft.  Funny 
   thing is, the cam bearing surface is scored more deeply than the bearing 
   cap - why?

Someone obviously (well, not so obviously, I guess) didn't Plastigauge
all the bearing clearances, eh?

   Why did this happen?  Here are a few thoughts:

   1) Blocked oil passage to cam bearing.  Maybee the head machinest dropped 
      a filing in the oil passage or something.

One good "filing" would certainly do the damage needed, without having to
"block" the oil passage at all!

   2) Somehow the cam bores got out of alingnment.

Shouldn't happen, if the head has the proper cam bearing caps! Now if
someone managed to swap bearing caps on ya . . .

   3) The diameter of the bearing surface on the Schrick was too large, 
      preventing proper lubrication clearance.  This one might be kind of 
      tough to check because the cam is so chewed up.

The head or the cam could be warped (wouldn't take much). Should be easy
to check the cam at least (and get some warranty dollars if it is the
culprit!)

   Solutions?  The top bearing cap is deeply scored and needs to be 
   replaced, but the bottom part that's integrated into the head casting 
   only has two shallow scores in it on either side of the oiling hole.  The 
   top bearing cap cannot be ordered as a seperate part because when the 
   head is machined at the factory, the cam bearings are all bored on the 
   head without the cam in place.  Do y'all think that they'd be close 
   enough that a rear bearing cap out of a junkyard might fit?

Could be, especially if you "try several". You'd probably be wise to
re-align-bore it in any case.

   Barring that, I guess I have no choice but to pull the frigging head 
   again and have the bearing over-bored and shimmed.  Sound right?

Um...the UrQ heads don't have separate bearings, do they? They just ride
directly in the head. Bummer...don't know if you can over-bore it. Maybe
you can "ream it out" to accept standard bearings, like con-rod/crank
bearings? (My Lotus' head was like this; I was really amazed that the
Audi didn't have "replaceable" cam bearings!)

   One last thing - the brand new $600 Schrick looks like it might now be a 
   worthless hunk of metal.  Does anyone know if it's possible to have some 
   weld laid down on the cam bearing surface and lathed back to the proper 
   diameter, or would that just be a waste of time/money?

Should be "trivial" for any competent machinist. It might be easier to
just grind the bearing surfaces undersized, in conjunction with over-boring
the head and fitting convenient "conventional/replaceable" bearings.

All told, I suspect this is more of a RoyalPainInTheAss class of problem
than it is one of RampantDestruction -- i.e., $250 in parts and 40 hours
labor (as opposed to $2500 in parts and 40 hours labor). Worst case, I
would think would be a few hundred bucks for replacement/bare head, plus
few hundred for welding-up/regrinding the bearing surface on the cam.
(Plus all the grief and aggravation involved...in reassembling the whole
mess)

Oh, this is your "hydraulic-lifter head upgrade" isn't it? Don't know
anything about Audi hydraulic-lifter heads.

   Any insights/sympathy greatly appreciated.  Hark, is that the growl of a 

Well, you certainly have my sympathy (and empathy too; I had to cringe
in commiseration as I read the first paragraph!).

   brand new M3 I hear deep inside my imagination?  Anyone want to buy an 
   '83 TQC cheap?  Needs work .... :-(

I'll give ya $250 for your turbo . . . (heh heh heh)

					-RDH