Compression Results, HG?

[Bluefire16]

Hey guys, ive done this 2 times now and just like it says on the VFAQ.

Checked the compression, WOT with the injector fuse pulled.

Numbers came back (from left to right on top of the head) 150, 145, 130, 130

I have had some heating issues recently and i think i am burning VERY little coolant, because it seems the level is going down. I am NOT SMOKING however, no white exhaust.

So think a bad HG is the problem here? And whats the service limit? I have read 121 and 131. I have had like 8 sources for each so im unaware of which one.

 

[Tyeler18]

131 is the service limit for 1g's I know. Can't imagine it's much different for 2g's.

 

[Bluefire16]

^^ I find that hard to believe, 1gs have even lower compression

 

[Tyeler18]

So your service limit should be higher than 131 if your logic is correct.

 

[9!'clipseDOHC]

131 is the service limit for 1g's I know. Can't imagine it's much different for 2g's.

From the VFAQ:

1G (90-94) T/E/L 1.8L NT engine
Compression ratio 9.0:1
Standard compression 185 psi
Service limit 131 psi

1G (90-94) T/E/L 2.0L NT engine
Compression ratio 9.0:1
Standard compression 192 psi
Service limit 145 psi

1G (90-94) T/E/L 2.0L Turbo engine
Compression ratio 7.8:1
Standard compression 164 psi
Service limit 121 psi

2G (95-99) T/E 2.0L NT 420A engine
Compression ratio 9.8:1
Standard compression 170-225 psi
Service limit 100 psi

2G (95-99) T/E 2.0L 4G63 Turbo engine
Compression ratio 8.5:1
Standard compression 178 psi
Service limit 133 psi

2G (95-99) T/E 2.4L NT Spyder engine
Compression ratio 9.5:1
Standard compression 192 psi
Service limit 146 psi

Hope this helps!

 

[19Eclipse90]

There is also a service limit for maximum allowable pressure difference (MAPD) between any two cylinders. For all engines except the 420A, the MAPD between any two cylinders is 14 psi. The 420A is allowed a 25% difference between cylinders.

 

[Bluefire16]

Alright i thought 131 was for ours, and 121 was for 1gs with turbo. Like stated above, thanks for confirming.

So do you think the headgasket could be the reason for heating? I think its the reason why my compression is bad as well

 

[FLASH1970]

A leakdown test will show where the compression is going. Or put compressed air into the cylinder when it's at TDC and listen and feel for where the air is going.

 

[broken_eclipse]

I just had a similar problem in my 2g's 6-bolt. It used very little water and I had compression right around 115-116 across the cylinders. It ended up being a supposedly "MLS" headgasket installed from a well known shop.

 

[tweakgod117]

Headgasket likley culprit

 

[blueboost68]

What do the plugs look like? Check to see if one or two are cleaner than the rest
If so the head gasket is leaking steam cleans the hell out of plugs.

 

[Bluefire16]

Well, needless to say im going to pull the head after the winter. Im buying all the parts now, and getting ready for the big day.

Im slowly burning coolant, so im sure its the HG because of the low compression in the 2 cylinders and the burning.

 

[Clinical]

Well, needless to say im going to pull the head after the winter. Im buying all the parts now, and getting ready for the big day.

Im slowly burning coolant, so im sure its the HG because of the low compression in the 2 cylinders and the burning.

Going to cast my vote for the blown headgasket

 

[navyvr4]

yup hg

 

[zanderson]

Definitely headgasket, glad to hear you've figured it out. Figure out which one you're going with yet?

 

[Bluefire16]

Nope ... the HG isnt going to be replaced till Spring (or at least once it warms up here in Michigan) but i still havent decided. I think i will end up with a OEM gasket.

 

[zanderson]

I'v been reading up on which one to go with and people have been suggesting either the mitsubishi composit or MLS, but I havent decided yet either.

 

[Bluefire16]

I have read enough from other threads in the past to say that a stock OEM Mitsubishi gasket from the dealership with ARPs is fine up to like 450hp. Im looking for 350-400 in the long run.

And pro only looking at like 20-24psi on my 20g

 

[zanderson]

I have read enough from other threads in the past to say that a stock OEM Mitsubishi gasket from the dealership with ARPs is fine up to like 450hp. Im looking for 350-400 in the long run.

And pro only looking at like 20-24psi on my 20g

In that case the OEM MLS and ARP's would put you right where you want to be with plenty room for error.

My car's being setup for autox, so I'm looking for a similiar power goal and everyone's recommended the OEM MLS.

 

[Bluefire16]

MLS requires machining...which i hope i dont need, if i dont im going with a STOCK OEM which is composite.

There is some good info in this thread i found.

http://www.dsmtuners.com/forums/maintenance-repairs/373022-whats-best-headgasket.html

 

[GIRman67]

now I have a question I live in Montana where the elevation is a lot higher than most people on this forum should I still be seeing 178psi in my cylinders? I was told that up here normal 8.5:1 Compression would show around 150ish psi. Are our cars the exception to that? I know my HG is done for. I'm just wondering should I still be seeing 178psi up here or is 150 going to be regular dur to the thinner air?

 

[Bluefire16]

178? Thats like brand new perfect comp.....

131 is the service limit when you need to rebuild, and brand new is supposed to be like 180 er maybe 170.

But yours is not bad...i wish i had that