2G low compression problem

[JakesSweetTalon]

I'm having really really low compression 30psi across the board at the highest compression tested and leak down tested and everything checks out on both its just really really really low me and my mechanic are baffled because we have no idea where to look next its a fresh rebuilt motor with almost all new parts, the only things that i believe are still stock is the crank block and head everything else has been replaced with performance or manufacturer parts the timing is dead on and we are completely lost beyond reason so any help would be awesome

 

[3kgt2nv]

Was the test done hott or cold? Did you try a wet test to see if it improved? Also double check the timing and do a leak down test to see if your loseing compression anywhere.

 

[95gst16g]

Also make sure you hold the throttle wide open is the gauge bad?

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[dsmrollerz90]

You said a new motor. How many miles are on it?

 

[JakesSweetTalon]

test was done cold and it was wet and dry tested and we got no change between wet and dry so we are lost

the motor had 103,000 something on it when it was rebuilt its got absolutely no miles on it since the rebuild this is our first time trying to start since the build and thats why we dont understand we checked everything we could think of

 

[dsmrollerz90]

If you replaced the rings, then its because you havnt seated them yet.

 

[JakesSweetTalon]

if the rings werent seated wouldnt it leak? and if not then i'll try that next. I'm at my house right now i'm getting ready to head back tgo the shop and i will keep the computer on to let you guys know as i try stuff to check the problem thanks guys

 

[3kgt2nv]

If its got 0 miles the rings haven't seated. but even if you get no compression during a wet test like that i would say your timing is off or you have a major leak. If all it was is the rings a wet test should have put it to spec since the oil is sealing it.

And i have to say if your builder is stumped by this i would get the thing away from him as he doesn't know what he is doing. Only so many issues lead to low compression and if he doesn't know what to check I would have to question his ability to build a motor from scratch.

 

[dsmrollerz90]

And i have to say if your builder is stumped by this i would get the thing away from him as he doesn't know what he is doing. Only so many issues lead to low compression and if he doesn't know what to check I would have to question his ability to build a motor from scratch.

+1

 

[JakesSweetTalon]

HAHAHAHA well guys i guess we had an idiot attack kinda....my intake cam was off because of the dual marks on the cam gears we luckily have spare engines sitting around and we looked at one and realized it, but i do still have one question, Whats the difference in the cam's that are stamped "G" and the ones that have a "K" stamp on them just curious

 

[3kgt2nv]

If you tried to crank it you might want to inspect the head to make sure nothing got fubared. How close are the timeing marks? If they are more than 3 teeth you may have damaged valves if you cranked it

 

[JakesSweetTalon]

As for my mechanic he does know what he's doing he was just stumped because we knew what to check but everything was working from what we thought and it wasnt until we saw the head of his engine and noticed the camshaft positions on both cams he's not an idiot by any means he was just lost when we thought the timing was ok all tests checked out and the block and head were fine so thats what we mean theres only so many things that cause that and we had checked all of them multiple times which brought us to scratching our heads

 

[3kgt2nv]

Im in no way a auto mechanic but after I set timing on any motor i always recheck it to make sure the belt didn't move. I also make sure i'm aware of any important marks or torque specs. If he knew what he was doing he should have known the correct mark to use.

If you had gone to a dealership and they caused your valve train to be mangled would you still take your car there for service?

I understand mistakes happened but did you guys use a fsm to do the build or did you shoot from the hip with the assembly? If any kind of fsm or walk thru instructions were used that was total neglect and inattention that allowed this to happen.

I know this is harsh but I have been around cars long enough to see this kind of stuff ruin peoples investments and desire to own the car.

 

[JakesSweetTalon]

No he's been a mechanic for 27 years and he's damn good at it, was un-noticeable unless you took the valve cover back off and then you could see that the cams were not sitting even so it wasnt until we saw one with the valve cover pulled that that happened also he teaches an automotive class and a student couldve moved the timing but as far as we knew it was still where he placed it, now i understand what you're saying but i dont think you understand what i'm saying, he's not an idiot and we just checked all of them today and thats when we tested was today so that being said our double check of the timing components is when we caught it, because we only tried compression testing this one time, and in all honesty i dont think there are many people who have an open mind enough to understand that this was not a careless mistake but a miscalculation on mitsubishi's part because there shouldnt be multiple timing notches on one gear, its really redundant to have both

 

[3kgt2nv]

Are both the dowels at 12 oclock position with all four cam gear timing marks lined up with a flat edge thru the bolts?

was the tensioner replaced or the old one reused? there are many issues that could have caused a timing slip of a half a tooth but a movement of several teeth is a major issue.

And if other students were allowed access to the motor all the more reason to use things like cam lockers and painting timing marks to make sure things are where they should be

I am open minded enough to understand your frustration, but if your building a motor everything should be double and triple checked prior to anything else being done.

Like i said not trying to be negative but if it was my motor i would rip it all apart and recheck everything in case any other small issue was missed.

And also if the cams were out of alignment when you cranked it for the compression test you may have damaged the valves so if it was my engine i would inspect it before I went any further with the build.

 

[KRRZ350]

What's done is done, if you bent the valves you'll know it soon. Situate your timing & fire it up.