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2G Weird oil consumption

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DSM_delinquency

Proven Member
34
5
Feb 24, 2020
riorancho, New_Mexico
So I noticed that my spark plugs had some oil in the the spark plug boot area but when I removed them they had oil on the threads . all this with the oil consumption I have all points to bad piston rings but here where it gets interesting the car runs perfectly and has no smoke or very little .which is the part that I don't get if it was bad rings or valve guides shouldn't it be fouling the plugs and smoking like a train.
Any other ideas on what's going on?
 
If you have oil on top of the spark plugs then that is either coming from the oil cap or the valve cover seals. Oil on the threads isn't coming from the combustion chamber. it's coming from the spark plug wells and gets on the threads when you remove them.

Oil from the oil cap is from high pressure in the crankcase. Either the PCV system is clogged or otherwise failing to vent pressure, or you have lots of blow-by from worn piston rings. But I admit I am not familiar with the specifics of the 420a engine at all.

What does the spark plug tip actually look like? Is it covered in buildup? Worn? White or orange? That is what will tell you whether oil is burning in the cylinders or not.

the spyder NT has a 4g64 2.4l sohc

Yup, I missed that it was Spyder. I just saw N/T and thought RS/GS. In that case, it's unlikely to be coming from the oil cap and if it were it would be pretty obvious. I don't know how the spark plug tubes seal to the head and valve cover on the SOHC head but oil still isn't going to be getting on the spark plug threads from inside the combustion chamber.
 
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FSM shows nominal as 192 psi and service limit minimum as 145 psi. Compression tests will be lower at higher altitudes too. When correcting for RR you'r probably around 185 psi.

Altitude Correction Factor Table for Compression Testing
Expected compression tests are always specified at sea level unless specified otherwise in the service manual.

Altitude has an effect on readings obtained and a correction factor must be applied to expected readings taken at other than sea level.

For example: Specified compression = 150psi, Altitude = 2000ft, (150 x .943 = 141.5psi expected@2000ft)
Altitude(ft) Correction Factor
500 .987
1000 .971
1500 .960
2000 .943
2500 .933
3000 .915
3500 .907
4000 .888
4500 .880
5000 .862
5500 .853
6000 .836
 
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