I doubt that your piston rings are worn. If they are the car will likely smoke due to oil getting past the pistons and combusting in the chambers. Does the car smoke? However, a wet compression test will ease your mind or help you find the reason for low compression.

I was recently going through the same situation when I thought my car had low compression and bent valves (the car was also misfiring), and came to a conclusion that it would be cheaper to buy a used engine or new bottom end. I believe a new bottom end would of cost about 2,500$ in parts alone, excluding the cost of labor. Its to late for me to find the actual numbers, so that's an approximation. If you have to replace all the piston rings, you or the shop would have to remove the head of the engine, the oil pan to disconnect the rods, slide the pistons out, replace the rings, inspect the crank for damage, hone the cylinder walls, possibly re-sleeve them if they are damaged, than reinstall everything, and maybe replace all gaskets to eliminate possible leaks. Its a lot of work and I say at least 2000-3000$, for a cheap estimate. You might as well just buy a new or used block.

If there is something wrong with the valves they are either bent or burned and not sealing properly. Im not sure if valves can be replaced without pulling the head. Either way, I looked at some posts on s2ki and found one guy who took the head to a machine shop and had it rebuilt for about 500$ and another guy who got a quote from a dealership to replace valves for 2200$. The dealership quoted me 8000$ to fix my "low compression" issue (New bottom end). Either way, anything that had to do with low compression is not a cheap fix. It will be in the thousands. On a happier note I think a bent valve or low compression *should throw a misfire code. Maybe a more experience member can put in their input.

 

Thanks for the great info. I'll definitely be doing a wet compression test really soon to see if it really is the rings or if its in the head. And no, my car does not smoke.

I really hope I won't have to buy a new bottom end or something like that. I will also do a valve adjustment and see what sort of difference that can make. My car isn't giving me any misfire codes, which most people seem to get when they have similar compression issues. Because the compression is even throughout, no codes, and drives perfect, I am really hoping the problem isn't a major one that will drain the wallet. Fingers crossed, because I'm not sure if I can even afford to do repairs like that at this very moment. Kind of going crazy and paranoid about all this lol...

 

Sorry for the delay and to bring back my own old thread, but I have finally done a wet compression test along with another dry test to see if the numbers changed at all. Here is the new result:

Dry: 170, 160, 175, 160 (these numbers are different from the original post, I guess I read the first set wrong)
Wet: 195, 190, 210, 220

Now of course I did the tests correctly, double checked everything. I poured in maybe slightly less than a oil bottles cap full of oil in each cylinder. Obviously, the numbers go up. So would this confirm that the problem is the piston rings? Because the numbers did rise quite a bit. Or is it still in the head, probably the valves? I do plan on getting a valve adjustment done soon to see if that will change anything, as it probably is time for one regardless. A few people say doing it has helped them with their compression. What do you guys think? Any feedback is greatly appreciated!

 

Never heard of flywheel damage on the S. my starter has been doing this going on 10yrs. Anyone else have any info on this?

 

Theoretically, the sticking starter could damage the teeth on the flywheel. I've never seen an instance of this on this forum. To the OP, you are more than likely stressing yourself for nothing. A few things can cause different numbers from a compression test; altitude as others have mentioned, and also the quality of the gauge. Consistency is the important thing, which your numbers seem to be. If the car is driving fine, leave it alone. If you had worn piston rings, you'd be burning oil quite noticeably.

 

I live in Texas and the altitude isn't much. I used two gauges and same results for both. But I really do hope you're right that I am stressing out for nothing. Yeah, although I do have low compression, numbers are consistent, no CEL and car drives just fine. I am really really hoping that the valve adjustment will fix it.

 

The starter is only in danger of damaging itself. The bendix is being over sped by the flywheel. The teeth are not grinding into the flywheel teeth. The flywheel will be fine.

On your comp test:

-Engine at operating temp, ran within last 15 minutes
-all spark plugs out
-WOT
-injectors unplugged

If you pull the fuel pump fuse, raw fuel will still be sprayed into the cylinders until the pressure in the rail bleeds off.
Test again with injectors unplugged.

 

Thank you for the reply Billman. Will doing that possibly change the compression that much? Will definitely try it and post an update!

 

Perhaps that is the variable that made your compression test differ from mine. I also did mine with injectors unplugged.

 

Sorry to bring back my old thread but I have the update. Finally got a valve adjustment done, and redid a compression test, this time with injectors unplugged as Billman said to do. Same similar results, 165, 165, 175, 177. Still very consistent, and low. Mechanic said the head seemed to be in good shape from what he saw during the valve adjustment. I guess its the bottom end then, perhaps it really is worn out rings. Yet the car runs very strong and no signs of bad rings or other. This isn't looking good