Compression Test Blues

Roa, Greg greg.roa at
Tue Mar 31 12:43:05 PDT 2009

>I did a compression test on my 95 A6q last night. Looks like I bent at  least
>2 valves, as two of the cylinders registered 0 PSI. The others were 168, 170, 150 and 110. 
>So, it looks like I'll be r and r'ing the heads. More  work than I wanted to do, but that's life at times.
>Is there a post  covering this procedure. I'm flying a bit blind due to a computer hard drive  that died, leaving me Bentley-less for a while.
>Right now, I'm most  interested in how the EM's disconnect. Do I do this at the head for easiest  removal or at the downpipe, then disconnect the EM from the head when it's off  the car.
>Also, my current headbolts seem to be of a unique configuration,  in that the male end is on the bolt head, whereas the replacement bolt heads  will have a female end. Seems like a Torx or polydrive >head on the current  bolts. 
>Anybody familiar with this, and what's the tool needed to remove. A  12-point 11mm socket will fit snugly on the headbolt. Is it worth trying to use  this to remove the bolts, or will I risk rounding >the bastards off?

Simple answer for that.  You're looking for a torx socket set.  I think I found mine at autozone or some other FLAPS.

I tried the 12 point socket initially, but after breaking a two sockets and nearly ruining two head bolts, I found the right tool.

Depending on what the whim of the day is for replacement bolts, you could get those for replacements, a regular torx socket bolt, or poly drive.

The first set of replacement bolts I got was a mix of torx and poly drive.  Second set was all poly drive.  I got the poly drive socket from here:
About 3/4 of the way down, under "head bolt bit for 1.8t and 2.0 engines".  I got the set for both poly and torx.

As for disconnecting the EM's, I found that it was easier to remove the bolts at the downpipe and pull the head with the EM attached, and remove it when it's off the car.  The job isn't too bad overall, especially in the C4 chassis.  There's pretty much room in there.

My sad story to add to this.  I bought a 92' 100q avant with broken timing belt for $500.  Replaced all of the valves, headgasket, ect.  Put it together and gave it to the wife for a winter car.
It made it through 500 miles of daily commuting for her before the oil pump cavitated at 7am on new year's day after she worked a 12 hour night shift.  It was snowing, 2 degrees F outside, she was 30 miles from home, and 4 months pregnant with our first child.

It wasn't a good morning for me.

She had driven it for 5 miles with the oil light on, and the gauge showing zero oil pressure.  She stopped after a mile or so to check the oil level and add a quart, thinking it might have been out of oil.  It melted one of the camshafts in half, and the cam bores were all destroyed.

The good side of the story is I got a complete replacement engine from a local upull-it for $125.  I replaced all of the seals and gaskets on that engine, and the car is back on the road running better than ever.  Oh, and she loves the car now.

Greg Roa
Cincinnati, OH
86' 4kcsq
87' 5kcstq
92' 100qa
95' 90Q sport
00' Jetta TDI
83' 944

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