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2G No compression, Valves are Good.

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breaksdaily

Proven Member
97
16
Nov 4, 2014
Colombus, Georgia
Ive built a few of these motors and never had any issues like this, rebuilt the bottom end of a project car and used the stock head, everything was disassembled and inspected and head components/valves looked good. This car was not running when purchased and the only thing I saw that was an immediate problem upon teardown was the piston rings, which were all replaced...Yes it is timed correctly this is not my first rodeo with these motors but I usually use all new components in a rebuild like this.

Compression results were 60, 0, 0, 60.
Lifters? idk..
 
Yea supposedly they "cleaned up" the valves, block is straight, it doesn't leak in B/w cylinders anymore like I said.
 
Figured a machine shop that fully disassembled the head would of maybe noticed some seat issues, probably not easily seen by the eye however... Back to them for a valve job.
 
Completely finished with this POS, got head back from machine shop with fresh valve job and it still blows air out the exhaust ports on a leakdown just as bad as before. Somebody come get this junk
 
You need to take the head to another shop, or get another head because it sounds like what ever you do the issue keeps repeating...unless your doing something wrong, or something is worn out really bad, Id wager the shop is missing something here.

I know it's hard to stay objective with the results your seeing but don't let this car beat you man, figure it out and fix it, and then thats when you will see the rewards.
 
I'm lost here, I have over $250 in machine work on this head, been completely disassembled twice at the machine shop everything inspected cleaned, a valve job and "vacuum" test and it literally still leaks out the exhaust side like the day I bought it. This thing is killing me and im starting to give up on it, never seen some BS like this.
 
are you testing the head bolted up to the engine? did you get the timing belt on and try starting it?

if the head is off the car, try filling up the exhaust ports with water to test the valve to seat seal. make sure the cams are not in the head for this test. if it leaks on the bench, it will leak on the engine. if no water leaks out the valves, its gotta be something else.
 
Not sure how I can remotely still have problems with the valves sealing here....head is back on the car.

I didn't do any test to the valves with the head off, why? Because I just paid for all that to be right and seal... apparently not.
 
Welcome to the wonderful world of dsms love hate I just would have double checked while head was off just to ass lure yourself after all the hassle.
 
Found the problem boys

Install height was wrong, machine shop didn't take enough off tops of valve stems, ground lifters down and she makes compression! Thought this was my problem initially but there was in fact warped seats and 4 slightly bent valves all which was fixed at the machine shop. Should be running I'm a few hours.
 
Last edited by a moderator:
Glad you found the problem. It makes sense too when you are getting a consistent leak across all the cylinders like that it would have to be a pretty horrible valve job for them not to get at least a few of them to seal.
 
Well spoke to soon once again, it was making 150psi across now #4 has 0 and the car runs like dog shit, extreme lifter noise happening even after running for 2-3 minutes, can't figure out why I lost #4 compression.
 
Cylinders 1&2 had 0 on initial install with cams In, that told me the lifters were holding the valves open, removed about .025 on those intake and exhaust side and reinstalled cam. Boom 150psi, 3&4 did not need lifter grinding as they made 150 as well, but now after running for about a minute like ass #4 has 0... and some how depending on orientation of the crank air will be heard coming out of #2 plug hole when putting air in #4... completely blowing my mind here, remember this head had a fresh surface deck and valve job.
 
Install height was wrong, machine shop didn't take enough off tops of valve stems

how does a machine shop grind down valve stems and hope to change valve length without addressing the keeper groove location? the keeper groove sets the valve height based on shims and spring height. you might need some spring shims to get your valves to seal.
 
Been down this road also. As EGLTAWLN said you will need to add spring shims. I also ground off some material off the lifters also to just get a temporary fix, but it only worked for a few minutes than the lifters pump up and didn't let the valve rest on the seat again. I would pull the head and let your machine shop know whats going on. Keep the cams installed and show them. Then make them fix it right and pay for some of your time and a new head gasket.
 
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