Help with compression test results

[Saleen313]

I've been having smoking issues with the car. It's fine at idle, cruising, and revs under 3500. If I rev the car past 4000 or high rpm 1-2/ 2-3 shifts I get lots of white smoke from the tailpipes. Yesterday the smoke seemed darker than normal but its back too white/gray today. Tailpipes and bumper are covered in oil. I also have black crap in my overflow tank but no coolant in the oil. Figured it was time for a compression test to see what was going on. Here are the results. I"m not sure if there is an issue with cylinders 1,6,and 8. I will be doing a leakdown test tomorrow but wanted to get some input from you guys in the mean time.

If anyone needs picture of anything or vid let me know and I'll see what I can do. Hoping I wont have to have the motor torn apart to replace rings and can get away with replacing a gasket(unlikely) or getting the valves replaced.

Update: Did a cold leakdown test today. Tried to do it when the motor was still warm but I had to take my tester back and exchange it for a new one. I'm going to do a warm test when the rain stops. Numbers might drop but the difference in Cylinders 4,7 and 8 will more than like remain. Looks like I will be doing a rebuilt and installing a head cooling kit this fall/winter.

1. 180-D 180-W 20%
2. 175-D 190-W 23%
3. 168-D 171-W 20%
4. 170-D 186-W 60%
5. 171-D 190-W 20%
6. 169-D 175-W 23%
7. 168-D 175-W 40%
8. 170-D 175-W 75%

 

[Wynn]

Numbers are good. 4 Valves smoke a little. I had the same problem and found out my shifter was actually loose, and leaked oil onto my X pipe in 3rd gear causing a major smoke-show

 

[Saleen313]

I wouldn't be worried if it smoked a little but it smokes more than a little. Didnt start until my evac pump thats being used to pull pressure from the cylinder heads stopped working. There is also the fact that my coolant is contaminated. I guess I'll know more tomorrow after the leakdown test. I'll also see if I can get a video of it so people can tell me if this would be considered excessive smoking.

 

[Saleen313]

ttt

 

[Double"O"]

white/grey smoke is usually a sign of a headgasket issue

the Compression numbers look good so don't go assuming you need to rebuild the motor

 

[Saleen313]

Well I did another leakdown test with the car at op temp. It just made me more confused. When I did the test cold cylinders 4,7,and 8 were high and I could hear the air coming from the valve cover and dip stick hole. Today I could still hear slight air out of all Cylinder but not as much as yesterday from the suspect ones. Never heard any air from the exhaust, intake or no bubbles from the coolant. Could I just be suffering from a bunch of blow-by when in boost?

Here are a few pics of my coolant res. The soot is oily to the touch so Im assuming its oil. Also the results of my warm leakdown test.

1. 20
2. 24
3. 23
4. 10
5. 18
6. 9
7. 20
8. 15

 

[006]

Try routing your intake and vacuum lines back to normal and bypass your catch can system.

I suspect that you've got pressure building up somewhere that's causing this leak.

Also check to make sure your PCV valve is operational.

 

[Saleen313]

PCV valve was deleted by the previous owners shop(Lamotta Performance). It just has 90 elbows coming from the VC's to a tee. From there it goes to a evac pump and to a catch can. I bought another stock pcv valve before I started these test but never put it in. Im going to get another one from a 03/04 or a turbo thunderbird. Dont care for the evac system setup anyway.

 

[Double"O"]

Try routing your intake and vacuum lines back to normal and bypass your catch can system.

I suspect that you've got pressure building up somewhere that's causing this leak.

Also check to make sure your PCV valve is operational.

indeed

 

[Quadcammer]

dbl

 

[Quadcammer]

20%+ leakdown is still very bad.

Loose ring gaps is one thing, but that seems pretty excessive.

hows the car run?

 

[Saleen313]

Car seems too run strong. Doesnt seem to be down on power unless power was down since I bought it. That was two years ago and it wasnt smoking then. Only thing is the smoking at high rpm/boost, residue in the coolant and exhaust pipes, and burning oil. Im trying to avoid pulling the motor out. Even if its just a head gasket, with the head studs I dont think it will be possible in the car.

Quad, Anything else u can think of that will show compression lose across all the cylinder. I thought anything over 30% is when you should start to get worried.

 

[Quadcammer]

You hit on all the big ones.

To me, even a fairly heavily boosted street engine should not leak down more than 15% when healthy. You may have a "loose" motor, but that sort of leakdown is hurting power as well.

Did you focus on where the leaks were on the hot leakdown test?

 

[Saleen313]

When i did the hot test the only place I could hear any air leaking was from the oil cap and dip stick tube. I unhooked the tester and hooked my compressor directly to each cylinder with about 80psi. It wasnt rushing out like it was when I did the cold test with 60% loss but you can clearly hear it.

I may take it somewhere to have the test done again or do it myself again to verify the numbers but Im sure I did everything right. Even if I didnt get all the cylinder exactly at tdc, pistons 1 and 6 should have been since I was using the mark off the crank. You do rotate 90 degrees for the next piston to test right?