Compression Check Results

[Bigdough666]

Did a compression check on the Supra yesterday since Ive been getting some extra pressure in the crankcase (blowing off vacuum lines). Here are the results:

#1 - 155 , 160 w/oil

#2 - 160 , 165 w/oil

#3 - 160 , 175 w/oil

#4 - 150 , 160 w/oil

#5 - 150 , 160 w/oil

#6 - 170 , 180 w/oil

So how does it look? Not too bad I guess, I was expecting worse. But it does seem like the rings are worn out. I guess its not too bad considering Ive been beating the hell out of this engine since I last built it 3.5 years ago. I think its time to pull it out and freshen it up, new rings and bearings. While Im in there, get the head worked - cams, bigger valves, etc, etc. Non stop with these cars.

 

[Bigdough666]

Forgot to ask, whats the compression supposed to be at??

 

[jetjock]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=21

I'd leave it alone...

 

[Doward]

Range of 150-170psi = 20psi, which shows you with just over 10% difference. You're still 'OK' with the engine.

You say you are blowing off vacuum lines. Can we get more information on this? Is this while NOT under boost? How much boost pressure are you running? Which vacuum lines are blowing off?

 

[Bigdough666]

Range of 150-170psi = 20psi, which shows you with just over 10% difference. You're still 'OK' with the engine.

You say you are blowing off vacuum lines. Can we get more information on this? Is this while NOT under boost? How much boost pressure are you running? Which vacuum lines are blowing off?

Check this thread for more info on the vacuum lines.

http://www.supramania.com/forums/showthread.php?t=96210

 

[Poodles]

Technicly it's out of spec as it's supposed to be within 14PSI of eachother...

Leakdown check?

and #6 is the oddball...

 

[GrimJack]

There aren't any vac lines connected to the crankcase / valve covers. If you're blowing vac lines off, it's likely from boost, and you're going to need to clamp the vac lines.