Hello everyone,

Long story short, I bought an Evo in rough shape with 85,000 miles on it about 4 months ago and have been rebuilding it. Yesterday, I picked it up from a local shop after having a new clutch/flywheel and Bushwacker installed. Since I can support power now, I had them also do a compression and leakdown test since the motor is what is next on my list. I'm new to this testing, but I've done a lot of searching and my results seem off.

Current miles : 87,500
The car was warmed up prior to the test:

Cyl 1 - 130psi w/ 52% leakdown
Cyl 2 - 125psi w/ 63% leakdown
Cyl 3 - 130psi w/ 47% leakdown
Cyl 4 - 150psi w/ 35% leakdown

I'm currently ready to buy a built shortblock or head, and am looking for some advice on what you guys think I should do based on these results. Any input is much appreciated.

Stay safe out there,
-Jon

 

those PSI numbers seem decent, they're all around the same compression. Im not sure about the leakdown though.

 

If somebody gave me those numbers I would do my own test to confirm, then do a teaspoon of oil in each cylinder and repeat the test to see if they come way up. That would tell me if the rings are going bad.

 

your compression numbers should not change that much between cylinders

 

you're talking about the compression numbers?

also, what are healthy compression numbers for an EVO 8 and EVO 9?

 

From what I've read it varies, but should be consistent... like within 5 psi from each other or so.

A couple people have guessed valve seats or head gasket which makes me lean more towards getting a built head.

 

In my opinion those numbers are very low. I am not sure what compression evo suppouse to have but on 1G the service limit i beliave was 145psi or something like that and 160 when its good. 2G normal i beliave was like 175. So I would make a wild geuss here that those numbers are low and I would first check where its leaking. Rings? Head Geasket? Valves? Dont just get a rebuild, maybe you can still save this one. God Luck.

 

In the service manual the minimum acceptable compression is something like 138, and all cylinders should be within 15% of each other.

 

those leakdown numbers would scare me more than the compression numbers


anything more than 15% leakdown and i start to get worried

did they say where it was leaking from

 

definitely double check those leak down numbers if they are confirmed I would be rebuilding right away.

 

The leakdown numbers are crazy. 15-20% is deemed acceptable.

I would say you also have bad compression numbers,too low.

If you wanted to, have them do a leakdown with the valvecover off.
While looking at the gauge at over 20% leakdown, have them tap the valve.
If the number decreases, you have a valve seat problem,possibly a guide or even carbon buildup.

Good Luck.

 

No, they weren't really sure. Just gave me ideas like the valve seats, head gasket, rings, etc.

Yeah everything just seems low and inconsistent. I don't mind buying a new head/block (in fact I kind of expected it).

I guess what I'm asking now, since we've agreed there is damage somewhere, is what would you guys do first? Head or block? Leaning towards BR stage 3 & MAP 2.4 L. Again, any input is appreciated.

 

To me it makes more sense to do it all at once. Why go through labor twice when you can do it all at once? I like to piece my own kits together but that is all money dependent on you. I just came back from the PRI show and Winberg Crankshafts had a really nice crank but at 3k just for the crank. Then piece together a nice rod and piston set up but doing that along with the head is going to be a lot more down time/money than buying a short block/head from a shop that has them already built.

 

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any competent shop doing a leakdown test would try and diagnose where its leaking from... otherwise whats the point of doing it?

bring it to a competent shop who knows how to use the leakdown tester for what it was designed to do

 

Yeah, that does makes sense. I guess it's just hard to sit and save.

Yeah, trust me I know this shop isn't the greatest, however my only options are this shop (5 minute drive) AMS (5 1/2 hour drive) Mellon (5 1/2 hour drive) and a good one in Kansas City (5 hour drive) so I'm kind of stuck.

Any other opinions?