I think I burnt up some valves:(

[BIGGSIE]

My gf and I went to the Custom Compact show in Harrisburg PA, It was about a 4 hour drive. On the way down the 1G was running good, trims were normal and coolant temp was good. On the way home things started to change. My trims went higher and higher untill they were all maxed out at 118.7%. At this time I pulled over to check things out. I was expecting to find my intake pipe loose or a vaccum hose off but no problems were found. Well we made it home OK but right before I shut her off for the night I noticed a misfire at idle. Yesterday I did some testing and found that I have a misfire on cyl. # 3. I've got good spark and my injectors and fuel pump are brand new. Today I'm going to do a compression test and see what that says. It seems to me that I may have burned up a valve or two from running her at 75mph for hours on end. Anyone have any suggestions as to what else I should replace if I have the head off ?

I was thinking :
- Timing belt
- Remove balance shaft
- Water pump
- Oil seals

 

[BIGGSIE]

Cyl. #1 = 80psi

Cyl. #2 = 80psi

Cyl. #3 = 85psi

Cyl. #4 = 75psi

My misfire is only on Cyl. #3 By looking at my results does anyone know why I would only have a misfire on that one cyl. ?? I will be doing a cyl. leak-down test tomarrow so hopefully that will explain more.

 

[doodie]

um... maybe its just me. But it looks like your compression is insanly low.

 

[eclipse90gsxt]

Did you beat the sit out of your car? Your compression readings are very low, the service limit is 120. From the factory its 165.


Probably valves, its highly unlikly all piston rings at once, but it could happen.

Are you sure your compression gauge is right? I would try another one, those readins are very low. I would try a different or new compression gauge and then come back with the readings.

Also do a wet test, where by you do the normal test, then add a cap full of oil to each cylinder, then take the reading again. If it raise' a lot its the rings, if it doesn't probably valves.

 

[BIGGSIE]

I have not beat the shit out of my car but I know it has had a hard life from it's previous owners. It had a big leak at the intake manifold gasket for a while but I replaced it and it ran good for a couple weeks untill now. I have done the compression test several times using different guages, wet AND dry, hot AND cold, all at WOT. My readings do not change more than 1-5psi. I have been told that if my cam timing jumps a tooth or two this could cause low compression across all 4 cyl's. BUT wouldn't it run like shit or possibly bend some valves? I will be doing a leak-down test and checking my timing marks today and I will post my results here. If anyone has any input let me know.

 

[BIGGSIE]

My cams are both off by 1 tooth! I hope no valves were hit, I also noticed my water pump is leaking so now is the time to replace it. I think I have been driving with my cam timing off for months now, but the engine felt strong. I wonder how it will feel with all the marks lined up. I will let yall know what happens.

 

[Crazy-MC]

Anybody hear the one about the low compression due to stuck lifters? It increases the duration your valves are open

 

[DSMJim]

Cyl. #1 = 80psi

Cyl. #2 = 80psi

Cyl. #3 = 85psi

Cyl. #4 = 75psi

My misfire is only on Cyl. #3 By looking at my results does anyone know why I would only have a misfire on that one cyl. ?? I will be doing a cyl. leak-down test tomarrow so hopefully that will explain more.

If you bent a valve even a little bit its gonna have a lot less compression then that. When you did this test did you have the car warmed up or what? You can't compression test a cold car because metal expands when hot and your pistons will not seal properly if the engine is cold. Take it out for a drive to normal operating temp and re-do your compression test.

 

[philipkrotch]

If you bent a valve even a little bit its gonna have a lot less compression then that. When you did this test did you have the car warmed up or what? You can't compression test a cold car because metal expands when hot and your pistons will not seal properly if the engine is cold. Take it out for a drive to normal operating temp and re-do your compression test.

i compression tested my car when it was cold and was 160 across the board, and 150 when warm.

 

[philipkrotch]

i doubt u burnt that many valves, i burnt 4 valves running 16 psi, on shitty ass gas, 6es plugs, and it was like 5 degrees outside. i had no compression in 2 cylinders.

 

[BIGGSIE]

Well it turns out that my timing was NOT off, I replaced my water pump and reset the timing and checked compression again and it was still low :thumbdown . So I pulled the head off expecting to find somthing obvious causing my low compression but everything looks good. I am thinking maybe lifters (lash adjusters) are sticking and causing my valves to not fully close. Anyone have any other ideas as to what would cause low compression across all 4 cyl's? Also now that I have the head off I was thinking either re-ring my 1G pistons or go to a used set of 2G pistons. Anyone have any input on getting into replacing my pistons? My goals are 300-350 WHP eventually.

 

[DSMJim]

i compression tested my car when it was cold and was 160 across the board, and 150 when warm.

First time I have ever heard of one being high cold and lower hot. Ever find the cause?

 

[Crazy-MC]

Before you go and start moding the crap out of your car, get it running stock first! It's important to have a good base to build from. If you just mod whats already broken, your just wasting your time and money. And you will never find what is actually wrong! Do the lifters and valve seals first, put it together, and see what you get. If you get 165 across the board, start building away Don't forget to make a map of where everything goes! Don't mix valves and springs! Best of luck and let us know how it goes

 

[philipkrotch]

First time I have ever heard of one being high cold and lower hot. Ever find the cause?

???? i had a lot of excess fuel in my cylinders..maybe that was teh cause. thats why i compression checked it, my car isnt running and wont stary running because im getting too much fuel. i just checked the motor to make sur eit wasnt something internally.

 

[BIGGSIE]

Before you go and start moding the crap out of your car, get it running stock first! It's important to have a good base to build from. If you just mod whats already broken, your just wasting your time and money. And you will never find what is actually wrong! Do the lifters and valve seals first, put it together, and see what you get. If you get 165 across the board, start building away Don't forget to make a map of where everything goes! Don't mix valves and springs! Best of luck and let us know how it goes

 

[BIGGSIE]

It went very smooth and only took about 4 hours, I can only hope it goes together as easy.

 

[BIGGSIE]

These are the only problems I have found so far. I had a misterious oil leak it could have been the HG I guess, but thats not near an oil port. The turbo to manifold gasket was brand new 2 weeks ago, but I got it off e-bay so it's probably not a decent gasket.

 

[philipkrotch]

o ya..those intake valves are burnt

 

[BIGGSIE]

o ya..those intake valves are burnt

No they aren't, thats what they all look like DSM or not. If they were burnt they would be missing pieces or melted. I don't think they are seating properly due to carbon build-up from the shitty gas it's had it's entire life before me. Either way I'm rebuilding the head with new valves, seals and lifters. I haven't decided if I'm going to the 2G pistons yet though.

 

[Lancer14]

Yikes! Let me know what you decide to do with the motor. I'll gladly lend a hand.
I dunno if you've seen the thread about inexpensive revised lifters over at dsmtalk.com, but that is the place I got mine from last year.

Chris

 

[BIGGSIE]

Today I stripped down my head so it can go to the machine shop. I took off the cams, removed the rockers and lash adjusters. Everything but the valves, springs and retianers. I sprayed some brake cleaner in the ports and it ran right out of the valve! This tells me that they definatly are not sealing properly. I'm hoping to get away without buying new valves. I also have a "spare" 130K long block from a 91', I took that head off and it was just as bad, and it had some leaks too but not as much. I know that valves do not seal totally even on a brand new motor, but this was bad. I guess it just proves the effects of carbon build-up on your compression. I'm wondering if it could have been fixed with a simple intake system cleaner chemical?
Either way I don't care I wanted to get elbows deep in a 4G63 . I'm going to sell my 2G to pay off my debt, then I will slowly build a kick ass race motor out of the "spare" . Does anyone know of any long block differencees between a 90' and a 91' ?

 

[DevilSperm]

when i swapped from a 90 to a 91 i had to use my 91 throttle body, CAS, TPS, Coil and Power Transistor, i think thats all...and i guess the timing mark on the 90's are a little different

 

[Crazy-MC]

You still have one option left! They do sell remanufactured cylinderheads out there. I picked mine up for 400. It'll least get you going! Sorry to hear about the valve seals Gotta love these 4G63T's :laugh:

 

[BIGGSIE]

I figured that the machine work would only be like $200-$300. Anyone know if my guess is correct?

 

[philipkrotch]

No they aren't, thats what they all look like DSM or not. If they were burnt they would be missing pieces or melted. I don't think they are seating properly due to carbon build-up from the shitty gas it's had it's entire life before me. Either way I'm rebuilding the head with new valves, seals and lifters. I haven't decided if I'm going to the 2G pistons yet though.

look at the the intake valves in the 1st 2 cylinders genius...1 intake valve in each of the 2 cylinders have pieces missing from the top of them.