Hi guys,

This is my first post on this forum. I recently put a deposit down on an Evo VIII MR and got a pre-purchase inspection done. Everything on the car seemed to check out apart from the compression test.

The mechanic tested it 3 times because he couldn't figure out why the results were so low (he test drove it and it seems to boost fine). The results are as follows: No 1) 150, No 2) 170, No 3) 170, No 4) 150.

I'm wondering what your thoughts are as to what could be causing this and whether it's likely the motor is going to go on me and need a rebuild. Not sure whether I should go through and buy this thing.

Thanks in advance,

George

 

Have him do a wet test. That will give you an idea if its pistons rings going out. If the compression doesn't go up in cyl 1&4 then I would venture to say that valves Aren't sealing. He should do a leak down test as well. Specially if you paid him

 

^^^ I was probably beat to death and then traded in

 

Thanks for the replies guys.

Just to give you some background, the car is stock apart from a Fujitsubo 3.5" catback exhaust. The mechanic went through it and confirmed all the parts are stock OEM. However, he told me that the zip tie on the suction pipe had been cut which could be a sign that the car has been returned to stock.

I don't know all that much about cars so was just wondering how bad those results were and if it was for example a faulty valve or a glazed bore and whether it would be a serious/expensive issue to fix. Thanks!

 

RED Flags all the way and your own risk!

 

Thats not bad compression most range from 150 to 160! From factory it should be in the 145's

 

Every Compression tester is different. Your not really supposed to go off the actual numbers as much as the consistency of the numbers. Which in this case seems to be an issue.

 

By consistancy you mean 10% of leakdown..rt? Depending on how you look at it he is within 12% or so--no perfect, but consistant as this related to 2 of the 4 cylinders-- Not perfect, but not sure I would get crazy over it.. and yes the actual numbers matter, there is a range he should be in.. if he had a motor with all 4 cylinders at 120, I would walk away. Do a wet test. Finally, an old saying.. "buyer beware"--there are no inexpensive, " stock" evos anymore.

 

If it makes you feel better here's my.
1st cylinder 140,2nd 120,3rd 145,4th 135.

 

^^ you guys are both correct.

it really is depending on the year make/ amount of ks' on the are etc.
my evos compression done a few months ago was inbetween 150-160. as said before, consistency between the numbers are more important ! ie. as close as possible is best !

 

Do a leak down test that should tell you everything, no more than 18% - 20%.

 

18-20% seems like a lot. I start to worry when I see over 15%

 

Standard pressure 163
Mininum pressure 138
Max difference between cylinders 14

You mechanic is a number rounder. I suggest doing the test over with real numbers, not numbers rounded to 10.

 

Thanks guys, really appreciate all the feedback. I will call the mechanic this week to check whether he did a leak down test (wasn't on the report he sent me) and if not get him to do that and a wet test.

Car has done 57,000 km (they seem pretty genuine given the immaculate condition of the exterior, interior and stock parts but I guess you never really know for sure with imports). I'll let you know how the results go. Hopefully it's nothing dire because I really want to buy this car!

 

Under Mitsubishi its 18% - 20%.