Testing for bad rings with the head off?

[Smilinjay]

Hey everyone, I have a 1990 tsi awd that was 100% stock when I got it. It has 99k and has never seen more than stock boost. Long story short, im in the middle of a head gasket job and I was wondering if anyone has a sure fire way to test the health of rings with the head off. Sadly, I already took the timing belt off so a leak down test is out of the question. My reason for doubting the health of the rings is that I did a compression test after I got the car and it was very low and uneven (unfortunately I don't remember any numbers, but between 50-130 psi across the board). The car burnt coolant only on cold starts (due to head gasket issues), but never burnt oil or smoked when it was up to temp.

 

[bryanwheat]

About the only thing that you can do is a fluid test, or build a plate that bolts to the block to seal the cylinder and add air pressure.

 

[Smilinjay]

By fluid test do you mean pour oil in the cylinders and see if it seeps through? Thanks for the quick reply btw.

 

[bryanwheat]

Yes, some sort of fluid test.

 

[Smilinjay]

Ok. How conclusive is that kind of test?

 

[yamaripper415]

How do the cylinder walls look? Scores in the wall could indicate you have worn rings.

 

[Smilinjay]

The walls looked pretty good imo. Theres some wear but nothing unusual, cross hatching is very easy to see. I can post pics if/when the oil drains out of the cylinders. It has been in there an hour and a half and still shows no sign of draining.

 

[miliman13]

Set all pistons evenly aligned across fill them all with oil measure the depth ensuring each bore has The same measurements. Check after a few hours then by next day. If one is dramatically lower in oil; that can point to ring failure. But their is no defined or set standard at how fast or slow or how much should be empty to establish a concrete diagnosis.

 

[bryanwheat]

It

Set all pistons evenly aligned across fill them all with oil measure the depth ensuring each bore has The same measurements. Check after a few hours then by next day. If one is dramatically lower in oil then the rest that will point to ring failure. But their is no defined or set standard at how fast or slow or how much should be empty to establish a concrete diagnosis.

Correct, it won't tell you the overall condition of the rings, just whether they are shot or or still doing their job, but not to what degree they are doing their job.

 

[Smilinjay]

Ok thank you that sounds perfect. I did all of that except for measuring the depth. So far I cant see any signs of draining (after 4 hours), and if they are, it is exactly even.[DOUBLEPOST=1407477134][/DOUBLEPOST]Yea im not expecting it to be a perfectly definitive test. I know that the only way to get that is to do a leak down. At least this will tell me whether or not I can expect it to run normally after I put it back together. Thanks for the responses guys.

 

[DSM1G90]

You still have compression rings to wonder about.

You can have a bad compression ring the two oil rings are still doing their job nicely

DSM.

 

[Smilinjay]

So you're saying this test does nothing to determine the health of the compression rings?

 

[arrowhead]

If you are this far into the engine why chance it, these tests are not really going to do anything for you, and you already have doubts about your motor, go the rest of the way and replace what is needed If you had overall low compression across your cylinders, dont chance it.

 

[92AWDHX40]

while your there do fix whats broken why have to come back tot and say I wish I would I learned that when I did my first clutch job years ago, I learned.

 

[Smilinjay]

I've never changed rings, but it looks like a PITA to do with the engine in the car. With that being said you guys are probably right..

 

[bryanwheat]

If the fluid test didn't indicate anything was wrong i would at very least bolt the head on with a new composite gasket and throw the timing belt on and do a compression test. I would much rather put in a little extra work to throw the head back on and do a compression test before pulling the bottom end apart, especially for someone who hasn't done it before. I personally have not seen too many of these engines that the rings were worn out on. I have pulled apart engines with 200k miles and the rings were barely worn and there is no ridge at the top of the cylinders.

 

[Smilinjay]

I agree, in fact my new head gasket and timing belt kit is on the way. This is a rather mild build (20g on pump gas) and as long as there isn't any major loss in compression I think ill be fine. Also if I dig in and do rings im sure I'll get carried away! "while you're in there" kind of thing.. I have a spare short block on a stand that I will most likely build up in the meantime so I'm not too worried. Thanks again guys