Just finished replacing my right side head in a '96 2.8 12v. Also changed the cam and lifters. All three were from a 55k car, and seller said they were from right side, so I have to take his word, since he is very reliable. BUT... after I took all precautions, used the correct cam sprocket holding tool, and crank holding tool, I have no compression on #1 cyl. When the two cam plates are correctly lined up the #1 lifters are up (exh) and down (int). Is that right for TDC? The marks all line up on damper and hand painted marks on belt and covers. Chilton says TDC is on #1 for the SOHC engine. I would have guessed that both valves would be closed at TDC, so I should see both lifters up, correct? I've rotated the engine by hand several revolutions, and there are no interference issues. The previous mechanic supposedly made a mess of the left side head and perhaps the timing as well, before I bought the car, so maybe he installed the other cam backwards, but who knows. Can anyone help solve the zero compression mystery?

 

Every Audi V6 I've worked on uses cylinder 3 (rear passenger side) as the index cylinder. The 1.8T indexes #1 but not the V6. Cylinder 1 should have valves open with the cam tool bolted on.

You're not trying to check compression with the bar on are you? Check each cylinder and post your numbers.

 

And the cams can't be installed backwards due to the way the journals line up and the bolt point for the cam sprocket at one end.

 

So, Chilton was wrong, no surprise. They take apart a Passat and say it's the same as an A4. I agree that #3 has to be the index cylinder, by observation alone. But I still don't get why I have no compression. All cylinders except #1 had compression before I replaced the right head and cam. That was due to a broken lifter. Now all are at zero. And no, the bar is not on when I rotate, otherwise no rotation! I thought I might have the cam flipped over, but not backwards, since I know the taper has to point forward. But unless I forced it, the lock plate only fits over the notched end of the cam in one direction. Both lock plates have the large holes to the inside, and fit perfectly in the locking tool at TDC. The #3 lifters are up, the piston is up (I tested it with a long coat hanger wire) and the crank lock pin fits into place. Maybe I'm not using the compression gauge the right way. Do you recommend hooking up the battery and giving it a spin or two using the ignition (without spark plugs in)? Maybe that will give a more accurate reading.

 

I've always done it by disabling spark and fuel and then flooring it while cranking. I took a few readings per cylinder and averaged them, using that as my official number.

 

Yeah, you gotta disable the engine (no spark) then crank it. Three revolutions will build proper compression, else you have an issue. If the engine was sitting in pieces for some time, especially older engines, the rings can dry up and loose their seal. you can add a few squirts of oil to each cylinder and retest. That would be a dry, then wet compression test.

 

Good advice guys. I squirted oil in all cylinders, disabled fuel and spark, and after several seconds of cranking I got 170 lbs on each cylinder on the right bank, but only around 100 on the left. I think that's because I never touched the left side until today. The engine hasn't run in over a year, so I drizzled the lifters with fresh oil before cranking. I assume compression will improve when everything is reconnected and warmed up after restart. Or, should I do more right now before I try to start it up?

 

Well, the lifters are probably dry, I'd dump a lot of oil on them. I usually take em out and soak them in oil for a bit. As for compression, if you squirted a few shots of oil in, It should reach proper compression within 3 cycles of the engine. Count the needle bounces, each time it jumps, the cylinder compressed. Unfortunately, whatever that number is, is what that cylinder is doing. It won't magically get better. It's possible you have a collapsed lifter on that cylinder, no allowing the valve to open enough to get any air in there...but that's a stretch.

Oil the crap out of everything, don't be shy with it. Get the engine turning and hope for the best. I've seen stranger things happen. Make sure the timing is spot on, that can cause low compression too.

 

With an engine that hadn't run in that long a period, it would have been a good idea to rotate it slowly by hand a couple times in case the rings stuck. That way they break free gently rather than violently from cranking. I'm hoping the rings didn't take any damage. And he's right, oil the living hell out of everything - it'll burn off without harm.

 

Actually, I rotated by hand before I used the starter. I squirted more machine oil in the spark plug holes last night. Should I use 30w oil instead? I poured about a quart over the left side lifters, without removing them. The right side (with new cam and lifters) got a good 30 minutes soak in oil prior to install.