1G 0 compression in Cylinder 1...How can I be 1000% sure of the cause?

[4gfun]

On my 7 bolt 94 Laser Turbo, there is 0 compression on cylinder 1. I could of course pull the head to see the more than likely obvious cause.

HOWEVER.........the vehicle also has a bad transmission. While swapping the transmission, I'd also like to replace the clutch, pressure plate, and flywheel with new ones as to avoid dropping the tranny twice for no reason and since the reason that the old tranny died was likely due to clutch disengagement issues.

The problem is that I only have a certain amount of days on the used transmission that I am putting in, so I'd like to install it ASAP to verify that it is good.

I am concerned that the cause of 0 compression could be the piston. If that happens, then I'd more than likely grab my 6 bolt spare block and install it.

The thing is, I'd already have purchased a 7 bolt flywheel.

I have a built BogusSVO head ready to go, but I want to be absolutely sure that the piston is ok before pulling the head and making an investment in terms of time and money on a 7 bolt flywheel.

I have followed this link as a test:

http://www.dsmtuners.com/threads/compression-and-leak-down-testing.338152/

I removed the plug to cylinder 1 and applied compressed air directly to it when it was at TDC.

I left the other plugs in.

I could hear air rushing through the throttle body, but none through the oil cap or exhaust.

Is this definitive enough to CONCLUDE that only intake valves are bad? Do I need to rent a borescope to be sure?

I have GOT to get my order of operations just right.

Thanks for your help!

 

[pauleyman]

Definitively no but likely. You could crack a piston. This is the result of a broken tbelt?

 

[BogusSVO]

Remove the followers on #1 cyl and do the test again, if you still have air escaping thu the TB, then you can be pretty much sure the valves are bent in the head.

 

[4gfun]

Definitively no but likely. You could crack a piston. This is the result of a broken tbelt?

The cause is unknown....bought it that way...previous said it lumped like that because of the cams....partially true I guess.

 

[4gfun]

Remove the followers on #1 cyl and do the test again, if you still have air escaping thu the TB, then you can be pretty much sure the valves are bent in the head.

I'll try that and report back. Thanks

 

[edged1g]

On my 7 bolt 94 Laser Turbo, there is 0 compression on cylinder 1. I could of course pull the head to see the more than likely obvious cause.

HOWEVER.........the vehicle also has a bad transmission. While swapping the transmission, I'd also like to replace the clutch, pressure plate, and flywheel with new ones as to avoid dropping the tranny twice for no reason and since the reason that the old tranny died was likely due to clutch disengagement issues.

The problem is that I only have a certain amount of days on the used transmission that I am putting in, so I'd like to install it ASAP to verify that it is good.

I am concerned that the cause of 0 compression could be the piston. If that happens, then I'd more than likely grab my 6 bolt spare block and install it.

The thing is, I'd already have purchased a 7 bolt flywheel.

I have a built BogusSVO head ready to go, but I want to be absolutely sure that the piston is ok before pulling the head and making an investment in terms of time and money on a 7 bolt flywheel.

I'm not sure what I am missing here. The head has to come off one way or the other, right? Just pull the head. If you are pressed for time, you can cut some corners and have the head off in 2 hours. Then you can determine the status of the engine without question and proceed from there.

 

[92AWDHX40]

For now just do the test like mentioned above and go from there could be a number or reasons for the issues you stated, My issues have been a simple timing belt failure due to wear and timing components going bad.

 

[4gfun]

I'm not sure what I am missing here. The head has to come off one way or the other, right? Just pull the head. If you are pressed for time, you can cut some corners and have the head off in 2 hours. Then you can determine the status of the engine without question and proceed from there.

I'd have to find the time to pull the head and then get it back on. Then time the engine, fluids etc. I'd also have to shop for parts that I'd need during that process based upon what I find. Some of the parts may take time to get here if I can't get them locally when putting it back together especially if I'd like to use quality parts....or if the dealer doesn't have parts? Say I run into an obstacle (which I often do) and have to take pictures then come back here and post then wait for a response? Say I find a cracked piston? I won't be able to get the car back together very quickly. I have tons of other things to do, but that doesn't stop the time for the warranty on the transmission from ticking away. How can I start the car and verify transmission functionality without a working engine?

You are fast. It takes me 8 hours to pull the head comfortably. I make sure that I label everything so I don't have to hassle with it later.

Not arguing with you....if I had the answer for sure, I wouldn't be posting here.

 

[4gfun]

For now just do the test like mentioned above and go from there could be a number or reasons for the issues you stated, My issues have been a simple timing belt failure due to wear and timing components going bad.

Definitely going to go this route. How helpful would a scope be in this case though guys? Might save me some time. How well can you REALLY see what is going on with those things?

 

[1990TSIAWDTALON]

I have a scope that has a mirror on it that I can look into the bores and see back up at the valves which is very helpful. I don't know if you can rent them at parts stores or not but it is a good tool to have.

 

[edged1g]

I'd have to find the time to pull the head and then get it back on.

How can I start the car and verify transmission functionality without a working engine?

You are fast. It takes me 8 hours to pull the head comfortably. I make sure that I label everything so I don't have to hassle with it later.

SOMETHING is wrong with your engine. Regardless of what it is, the head HAS to come off. Either valves are bent or something more serious. The first step is pulling the head. You can't verify the transmission without starting the engine and driving it, and you can't do that in its current state. You are trying to diagnose engine internal issues form the outside and that can come back to bite you.

If you have a spare engine, why not just pull the current motor, install your new head on you spare engine, and drop it in. Then take the time to properly diagnose the current engine.

Definitely going to go this route. How helpful would a scope be in this case though guys? Might save me some time. How well can you REALLY see what is going on with those things?

Which route are you talking about? You can see some with a bore scope, but not everything. It's not the best way to do it.


I guess what I am saying is the engine CAN NOT run without the head coming off. Period. So, either start there, or just use your spare engine. Either way, while asking what you can see with a bore scope, the warranty on the transmission is ticking away.

 

[92AWDHX40]

Hey just do one thing at a time get to the head when you can, the head can take a bit to remove but take in in stride ive done it many times quite easy to do.

 

[4gfun]

SOMETHING is wrong with your engine. Regardless of what it is, the head HAS to come off. Either valves are bent or something more serious. The first step is pulling the head. You can't verify the transmission without starting the engine and driving it, and you can't do that in its current state. You are trying to diagnose engine internal issues form the outside and that can come back to bite you.

If you have a spare engine, why not just pull the current motor, install your new head on you spare engine, and drop it in. Then take the time to properly diagnose the current engine.



Which route are you talking about? You can see some with a bore scope, but not everything. It's not the best way to do it.


I guess what I am saying is the engine CAN NOT run without the head coming off. Period. So, either start there, or just use your spare engine. Either way, while asking what you can see with a bore scope, the warranty on the transmission is ticking away.

Lol, the engine does run on 3 cylinders though. Well enough to see if the tranny is grinding in any gear.

 

[Chumpaumpalumpa]

Remember to replace the TOB, ball, and fork while you're in there to avoid having to needlessly pull it again. Also the clutch feels awesome after you do that.

 

[bling5tatus]

It shouldn't take anyone that's worked on these cars a bit 2 hours to remove a head. It's a 30 minute affair from the time I take the key out of the ignition when I remove the cylinder head on my car. Done it several times.

The others are right, you cannot skimp on this. If your motor's f'd, which it sounds like it is, then you need to do this anyway. You have bigger fish to fry than finding the transmission. The other thing is, you could just take the case off the trans and inspect it (i think) to see if it has wear or not.

 

[4gfun]

It shouldn't take anyone that's worked on these cars a bit 2 hours to remove a head. It's a 30 minute affair from the time I take the key out of the ignition when I remove the cylinder head on my car. Done it several times.

The others are right, you cannot skimp on this. If your motor's f'd, which it sounds like it is, then you need to do this anyway. You have bigger fish to fry than finding the transmission. The other thing is, you could just take the case off the trans and inspect it (i think) to see if it has wear or not.

Thanks for posting, but I really disagree with your post. What do you mean "finding" the transmission? I already found a transmission and it wasn't easy at all.

I am sure that I can pull the head faster, but I disagree with your measurable that it should simply take "x" amount of time for anyone who has worked on these cars 2 hours to pull the head.

Some people work slower than others others. Some of us are very meticulous.

I never let speed define whether or not I can do a job. For some of us, these cars are hobbies.

What you mean about skimping? I don't recall implying that I was skimping.

Order of operations is very important.

 

[bmxfelon420]

If it's zero compression then it's almost assuredly bent valves. Usually bad rings would at least give you something, and a broken piston would be pretty obvious, like if you took the oil cap off you'd have smoke puffing like a locomotive probably from that.

 

[steelcurtaindsm]

Why not just take off valve cover and watch if valves are moving in sequence with all the other valves . maybe a lifter is stuck ...

 

[4gfun]

If it's zero compression then it's almost assuredly bent valves. Usually bad rings would at least give you something, and a broken piston would be pretty obvious, like if you took the oil cap off you'd have smoke puffing like a locomotive probably from that.

No symptoms like that. Thanks for the feedback.

 

[4gfun]

Why not just take off valve cover and watch if valves are moving in sequence with all the other valves . maybe a lifter is stuck ...

I might try that....thanks.

 

[4gfun]

I am not impressed with the piston at all...looks like it has hot spots and pre-detonation issues...but I can't see any holes strictly speaking.

All the valves look shut at TDC....but I did find something interesting. It looks like there is a piece of metal stuck under the valve. I can't see how that would stop the valve from closing or doing anything...I figure that it would have been taken away a long time ago if it were making contact or things would be rattling away.

Here are some pics, if you see a valve open, it is because the motor was at BTDC in an attempt to get pics of the entire piston area (which I could not do without showing spark plug threads instead).

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[BogusSVO]

That is an odd piece of metal to have in there, about the only thing I could guess it is, is part of the fire ring from the head gasket.

 

[4gfun]

That is an odd piece of metal to have in there, about the only thing I could guess it is, is part of the fire ring from the head gasket.

That makes sense Dale. What do you think about the top of the piston? I'll concede to what edged1g said about the bore scope. It is hard to see the whole thing....plus I can't tell if that is carbon or detonation.

Any thoughts as to whether or not that might just be carbon....or is that the result of detonation maybe?

Also, if the valves are closing all the way at TDC and the piston isn't holed then what could the problem be....oh yeah maybe stuck lifters, etc., like some of you and the others had mentioned....but checking that stuff out requires me to pull the cams and retime the car just to test....unless maybe I do what steelcurtaindsm had mentioned.....not sure if I should do that with the car running or not....don't want oil dropping on the exhaust manifold and causing a fire etc....I would also take me time to see what I am looking at while oil is spraying everywhere because I am not the FASTEST at figuring things out as you can see. I could do this with someone manually turning the crank I'd guess....but it's hard to find someone who will turn it so I can look and their arms will get tired by the time I figure things out.

I figure that if I so this any other way I won't be able to check the trans first.

Maybe the head gasket blew in a weird way....hence the fire ring possibility?

I don't think the fire ring is large enough to hold the valve stuck open...but I can't argue with the fact that it is THERE.

I know that I gotta pull the head guys....but I am planning to buy an XTD clutch kit with clutch, pressure plate, flywheel, etc. (Very happy with that setup on my GVR4).

Gotta make a choice between buying the 7 bolt kit and the 6 bolt kit!

It's almost to the point where I am thinking it would be best to:

1) Pull the tranny, put the used one I got in...use existing aftermarket (of unknown type) clutch, pressure plate, and flywheel.

2) Verify that the tranny is good by taking it on a brief spin around the yardd (Since the car still runs on 3 cylinders)

3) Pull the head....make a decision as to whether or not I just need a new head or I'd be better off pulling the 6 bolt of my parts car.

4) Then pull the tranny AGAIN and do the brand new XTD clutch/pp/flywheel swap if needed. (Still want to put my taller AWD 5th from my parts car in and pull a possible LSD from the old FWD tranny).

Thoughts?

Thanks

 

[pauleyman]

Cant hold the valve open my ass?
You have found you problem. Remove the head.

 

[4gfun]

Cant hold the valve open my ass?
You have found you problem. Remove the head.

Lol! 0 compression for that tiny amount of opening though?

Still would like to know about the piston tops.