How can you tell the difference between...

[AIM:c0nniver]

How can u tell the difference between bad valve seals and turbo burning oil. (please only answer if u have had experience with this problem... If you *THINK* you know, dont answer.)

I rebuilt my 7m but i might have punctured a valve seal upon installation. My turbo, as far as i know, hasn't been rebuilt.

It blows blue smoke on startup and stops after 7mins but does it on hard accelerations too. When starting up, I accelerate a bit and no blue smoke until about 2mins into the "engine warmup" process. Then it does it at idle and will blow blue smoke for 7mins then stop and only do it a little bit (barely noticeable) on hard accelerations. The barely noticeable part could be due to how spread out the blue fumes are down the road.

Please help, Thx in advance,
Brad

 

[PynkEye]

I so wanna know the answer to this. Mine does the same, start up is usually valve seals, and when boosting its usually turbo. But mine does both.
I dont see valve seals burning oil on hard accelleration...its not logical
anyways...ill wait for the answer also

 

[AIM:c0nniver]

PynkEye, how long has it been since you replaced your valve seals? (if ever)
and when was the last time the turbo was rebuilt? (if ever)

 

[PynkEye]

Never, im gonna change the seals when I do my MHG, as soon as i get the money.
Just got the car last year, havent had time to play in the motor much.
Ill let you know what changes when I do so..might take a while tho. Ill ask around..im also interested in knowing the answer... either its just the turbo seal thats fucked, or both. But I doubt that only the valve seals would do that.

 

[outofstep]

Compression test will give you the answer. A blown turbo (as long as that's all that is wrong) won't effect the test at all. Leaking valves will give you a low comp number.

 

[AIM:c0nniver]

Were not talking about leaky valves (air). We're talking about leaky valve seals (oil).
So, a compression test wont work. The valve stem inlet in the head is on the other side of the valve.

Say we cranked this to the compression stroke (with both valves closed) with a compresstion tester where the spark plug should be. Its only going to tell us if the rings, head gasket, or valves are bad. (The valve seals are under the springs.)

 

[Johnny Dangerously]

at startup: most likely valve stem seals

at boost: most likely turbo

all the fuckin time: most likely rings

 

[TONY!]

^^Yep. a compression test or leak down test will indeed indicate bad valve to seat contact, but not seals.

 

[AIM:c0nniver]

man! how can my new seals be bad. that drives me nuts!... Is there anyway of tellin which cylinder might be the cause? (surely not all of them)