Compression Numbers...

[AaronsSupraMKIII]

I did a compression check yesterday, and my numbers are
#1-160 lbs
#2-160 lbs
#3-160 lbs
#4-165 lbs
#5-125 lbs...I put a cap of oil in the cylinder and it went to 152 lbs. Rings shot?
#6-160 lbs

What can I do about cylinder #5 besides a rebuild? Could it be valve related, because I hear, what sounds like valve ticking in that area. May be an exhaust leak. I am really bummed.

 

[IJ.]

Aaron: Oil won't bring a dead valve back up like that unless you poured 1/2 a qt in

 

[AaronsSupraMKIII]

I put the oil in because a friend told me that if that makes the compression numbers go up, then your rings are probubly shot. I was just hoping that a valve might sticking, and not the rings bad....

Aaron: Oil won't bring a dead valve back up like that unless you poured 1/2 a qt in

 

[IJ.]

Your bud was correct!

It's a bit odd that it's only low in one cylinder though.
(ever detonated?)

 

[AaronsSupraMKIII]

Not on me, but might have with previous owner...
What are my options with it?

Your bud was correct!

It's a bit odd that it's only low in one cylinder though.
(ever detonated?)

 

[IJ.]

Worst case scenario is it's broken a ringland.

Best case is a set of rings and a hone.

Do a leakdown before you pull it down this will help you understand what's happened.

If you know anyone with a bore scope borrow it and scope the cylinder if it's mechanical damage you'll see signs on the walls.

 

[AaronsSupraMKIII]

Will it hurt it to drive like it is? I can't afford to tear down the engine right now. I work 7 days a week most of the time...and I am getting married next weekend, so I am really strapped for awhile. I don't know anyone with a bore scope. Can you rent them?

Worst case scenario is it's broken a ringland.

Best case is a set of rings and a hone.

Do a leakdown before you pull it down this will help you understand what's happened.

If you know anyone with a bore scope borrow it and scope the cylinder if it's mechanical damage you'll see signs on the walls.

 

[IJ.]

Aaron: Depends on what the damage is and this is why I suggested scoping it.

If it's mechanical ie: Broken ring or ringland yes driving it IS going to damage the block, if it's just a fried/worn ring then no it'll just cause some blowby and as long as you don't hammer it you won't hurt anything more.

Not really sure I'd grab the phone and yellow pages and ring some of the better race shops in your area and ask if they can scope it for you (Pity about the distance or you could borrow mine)

 

[AaronsSupraMKIII]

I have no idea how long it has been like this. I just happened to check my compression when I changed my cam covers, and painted some stuff. If it is the ringlands, then I have already screwed up my block. I did notice that it hasn't ran as good this last week or more. When I rev the motor and let off, it stumbles and almost dies, then idles back to normal. As for blow by, I have had pretty bad blow by since I bought it.

Aaron: Depends on what the damage is and this is why I suggested scoping it.

If it's mechanical ie: Broken ring or ringland yes driving it IS going to damage the block, if it's just a fried/worn ring then no it'll just cause some blowby and as long as you don't hammer it you won't hurt anything more.

Not really sure I'd grab the phone and yellow pages and ring some of the better race shops in your area and ask if they can scope it for you (Pity about the distance or you could borrow mine)

 

[IJ.]

Sounds like the damage is already done then

Get it scoped drive it gently to minimise any further damage.

 

[AaronsSupraMKIII]

I will, thanks! I hope it doesnt shit out on me. :cry:

Sounds like the damage is already done then

Get it scoped drive it gently to minimise any further damage.

 

[IJ.]

Drive it gently keep it out of boost and keep a close eye on the Oil level and it'll probably run forever.

 

[AaronsSupraMKIII]

I looked at a parts car a few days ago. It is an 87 turbo. The engine is tore down, and the head was ported and polished. The car had 70,XXX miles when it was tore down. I might try and buy it, and start building that engine, and hope my car lasts until I can build it and swap them out.

Drive it gently keep it out of boost and keep a close eye on the Oil level and it'll probably run forever.

 

[IJ.]

Good way of doing it but I'd shoot for an 89+ motor to get the better block and crank

 

[AaronsSupraMKIII]

I didn't know there was a difference. What did they change on the 89+ ones?

Good way of doing it but I'd shoot for an 89+ motor to get the better block and crank

 

[IJ.]

Blocks are much heaver castings and the cranks have full counterweights like a JZ crank.

 

[AaronsSupraMKIII]

Thanks for the info...I will look for an 89+. well I gotta get a nap before work. Have a good one!

Blocks are much heaver castings and the cranks have full counterweights like a JZ crank.

 

[IJ.]

No probs

I posted up pics of the 2 different castings outlining the differences to look for.

 

[AaronsSupraMKIII]

Wow thats a huge difference! Thanks for that! I am having some weird problems. I will post a new thread on it.

No probs

I posted up pics of the 2 different castings outlining the differences to look for.