Since my car has been burning oil (1 L every 1,000km or so), and I wanted a leg up on the dealer before I bring it in for testing, I went to a mechanic buddy's house today and had a Compression test and a Leakdown test done.

Results:

Compression Test
Cylinder / PSI
1 / 215
2 / 220
3 / 220
4 / 225

Leakdown Test
Cylinder / Leakdown %
1 / 7%
2 / 7%
3 / 6%
4 / 6%


So... all looks good. Why am I burning oil? All test were done with the engine still very warm from driving 50k to get there, and throttle was wide open (injectors unplugged as per standard test procedures) for the compression test.

Does anyone know what the stock "fresh engine" compression numbers are supposed to be? JTso says 165 -- if so, then I have LOADS of carbon buildup, but to me, 165 seems way low for an engine with 10.5:1 compression. Any Acura mechanics here that can verify this with the shop manual?

Thanks, and if anyone knows how else I might be burning/losing that much oil with this good of compression numbers, please feel free to let me know!

~Eric

 

I went to look at the service manual again and it says the compression should be "above" 135psi with a max variation of 28psi. I must have misread it being normal at 135psi. So you should be fine.

 

The thing with those manuals is that it isn't showing "normal" levels, it's showing "minimum before your engine is toast" levels. Which is why I wanted to know if anyone knew the "fresh" (non-carbon build-up) numbers.

To me 220ish sounds good but it might be 30psi worth of carbon caked on there.

 

If there was that much carbon on there, you'd probably be able to see it. You probably don't want to pull the head yourself, but if they do it when you take it to the dealer ask them if you can take a peek.

Also there'd be some indication of it on the spark plug itself, too. If that's not black, then it might be something else. Maybe just a bad oil control ring(s)?

 

My numbers are probably pretty "fresh" as the engine only has around 8K miles. I don't believe it has much carbon build-up if any. It is currently producing decent performance and no performance drop even after the mis-shift according to the dyno. 165 might seem low but I think sauceman has the similar numbers... Then again, sauceman's engine is using oil.

 

The plugs were a light grey/tan color -- seems normal. No apparent oil residue on them.

How can I check the oil control rings specifically? Wouldn't it be captured in the leakdown test?

Also, where else could the oil be going? If its not getting burned in the engine, and there are no puddles at all on the ground where I park every night, where else could it possibly go?

 

How did you do your compression test? Engine still quite warm, throttle open, injectors disabled? If you didn't do these three things, then our numbers cannot be compared.

 

Yup, did all that, except I disabled the fuel pump. Did you also remove all the plugs?

 

Yeah, all plugs out.
Unclipped the injectors - really simple.

If the oil control rings were the culprit, but the compression rings were fine, would that make the leakdown test appear "normal" as the compressed air is being blocked by the compression rings? How can I test the oil rings?

 

Yes. The compression rings are the "top" ones and they keep the compressed air/fuel from going down into the crankcase. The oil control ring is the "bottom" one, and it keeps too much oil from going UP into the combustion chamber. Its two separate processes--so one could be fine while the other is bad.

Unfortunately checking/changing piston rings usually involves pulling the block off the crankcase which is a HUGE job. This should be one of the very last things you or the dealer check for, but it sounds like it could be it if you're consuming that much oil and your compression is still fine.

 

165 was what I had at around 100,000km. It wasn't using oil then, at least not that I was aware of then.

I'll be doing a full compression and leak-down test as well pretty soon and see what come out of it. I might try a few things before actually deciding to open it up. Hopefully by then I could salvage an 06 engine.

 

Hey sauceman - you used the exact same method as myself and JTso did, is this right? I know having the engine cool as opposed to warm can make HUGe differences w/ the test.

I called Acura - they wouldn't tell me the stock fresh numbers.

 

Actaully, it was the Acura dealership who did it. I would assume they did it with the engine relatively cold and only cranking with the starter.

 

UPDATE

Down 1 liter of oil in 1,300km. Not a good sign, as I was driving like an old-man, only VTEC'd a few times in that span, shifts below 3500 nearly every time.

IMPORTANT NOTE: On startup, no real smoke, but if I give it gas within the first 30 seconds or so after starting it, I see lots of grey/blueish smoke come from both exhaust pipes. Smells partially like oil, partially like gas.

MY GUESS: Since the leakdown test was done with the engine still fairly warm (sitting for 30 minutes), it wasn't tested on a "cold" engine (although it's supposed to be done on a warm engine). Since when I checked the tail pipes today, after the car had been sitting for a few days, and saw smoke, I assume it's a problem where the oil is getting in through COLD valve seals, as they haven't expanded due to heat by then at all.

Does this make sense? Also, since I see soot on the bumper (PWP bodykit), this would lead me to believe that the oil is being burned when the car is sitting still or travelling SLOWLY, as otherwise the exhaust wouldn't go straight up onto the bodykit. Does this also make sense?

I'm going to Acura tomorrow (after Thanksgiving holiday today) for my 1000 km checkup after the oil change, but obviously the car will be warm at that time. I'd have to leave it there all day to get the "cold" test to work properly. I know I'm going to get a hard stance from them as always.

Any opinions and/or help appreciated!
Thanks,
Eric

 

If you can get someone to follow you, smoke on acceleration
is through the rings, smoke on engine braking is through the
valve stems ( high vacuum ).

 

Soot on the bumper is normal for the TSX, I know I accumulate a lot on my PWP as do some other PWP owners. Within 3 days of a wash it'll be dirty again

 

I think drag would cause soot/buildup on the bumper, so it doesn't necessarily happen at stand still/idle.

 

Do you burn oil? If so... rings, valve seals, or ???

 

nope, when I first got the car it ate oil like all TSXs do, but I checked before my last oil change last week and didn't lose any oil between changes.