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Do I Need A Engine Rebuild?

firefox
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firefox Contributor

firefox

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Posted

Hi

My car had been using oil. I was not happy with my mechanic so I took it to another shop and they done a compression test:

Here are the results 1 - 150psi, 2 -160psi, 3 - 160psi, 4 - 155psi, 5 - 160psi, 6 - 145psi

They said the Oil rings in the engine need replacing. And it could have been caused by a bad tune or bad engine build (yes i already had it rebuit once and it has forged pistions).

They also quoted me between $4,500 - $6,000 for the build, depending on how much work needed to be done once they pull it apart.

Also they said I should not be driving it the way it is.

What do you guys think of these compression reading?

What you you think of the rebuild quote? (is there anywhere I can go to get a good rebuild for cheaper?)

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DAN00H Mentor

DAN00H

Posted
Posted

have you spoken to the original builder about it usign oil? that would be the first thing to do.

discuss the result of the compression test with them.

Also

1. I would not be paying 4.5 - 6k for them to replace oil rings

2. oil rings do nothing for compression, so I don't know where they get that idea

3. not a place I would go back to.

does the car blow any blue smoke on acceleration / deacceleration/ initial startup?

Better off getting a LEAK DOWN TEST, more useful than the compression test.

unless the engine is pinging heaps/ burning LOADS of oil or making a lot of noise, I can't see any reason from what you describe why you couldn't drive the car...

firefox Contributor

firefox

Posted
  • Author
Posted
have you spoken to the original builder about it usign oil? that would be the first thing to do.

discuss the result of the compression test with them.

Also

1. I would not be paying 4.5 - 6k for them to replace oil rings

2. oil rings do nothing for compression, so I don't know where they get that idea

3. not a place I would go back to.

does the car blow any blue smoke on acceleration / deacceleration/ initial startup?

Better off getting a LEAK DOWN TEST, more useful than the compression test.

unless the engine is pinging heaps/ burning LOADS of oil or making a lot of noise, I can't see any reason from what you describe why you couldn't drive the car...

the original builder is out of business to the best of my knowledge. (probably a good think for other skyline owners) PET modification

it used a lot of oil since the last service probably about 5L

when i boost it hard through 1st and 2nd it puffs black smoke.

I think they done a Leak down test too and said it had blow by. there was also a small exhaust leak from one of the pipes near the rocket cover.

DAN00H Mentor

DAN00H

Posted
Posted
the original builder is out of business to the best of my knowledge. (probably a good think for other skyline owners) PET modification

it used a lot of oil since the last service probably about 5L

when i boost it hard through 1st and 2nd it puffs black smoke.

I think they done a Leak down test too and said it had blow by. there was also a small exhaust leak from one of the pipes near the rocket cover.

Fox

Is it leaking oil? (check where you park) as a car burning oil is very noticable! blue smoke :) how many km's since the last service to use 5l of oil?

black smoke is a rich mixture, not particually worrysome.

can't have blowby when it is returning good PSI readings.

exhaust leak near the cam cover can only be the exhaust manifold - not an engine threating condition...

PM me who you are dealing with.

firefox Contributor

firefox

Posted
  • Author
Posted
Fox

Is it leaking oil? (check where you park) as a car burning oil is very noticable! blue smoke :) how many km's since the last service to use 5l of oil?

black smoke is a rich mixture, not particually worrysome.

can't have blowby when it is returning good PSI readings.

exhaust leak near the cam cover can only be the exhaust manifold - not an engine threating condition...

PM me who you are dealing with.

It's not leaking oil.

about 6-6.5K between services

yea I think the guy said its the exhaust manifold with a slight leak

I think i was running a bit rich.

Also cold start it pretty bad.

its running a mirco tech ltx12

I got it retunned and the dynoed and they said it was runnig pretty bad only making about 140rwkw now they retunned it to 170rwkw. Feels much better to drive.

firefox Contributor

firefox

Posted
  • Author
Posted
Hi

My car had been using oil. I was not happy with my mechanic so I took it to another shop and they done a compression test:

Here are the results 1 - 150psi, 2 -160psi, 3 - 160psi, 4 - 155psi, 5 - 160psi, 6 - 145psi

They said the Oil rings in the engine need replacing. And it could have been caused by a bad tune or bad engine build (yes i already had it rebuit once and it has forged pistions).

They also quoted me between $4,500 - $6,000 for the build, depending on how much work needed to be done once they pull it apart.

Also they said I should not be driving it the way it is.

What do you guys think of these compression reading?

What you you think of the rebuild quote? (is there anywhere I can go to get a good rebuild for cheaper?)

What do you guys think of these compression test results?

kx2fity Collaborator

kx2fity

Posted
Posted

Gasoline engines only need moderate compression - 140 to 160 pounds per square inch (psi)

The nissan manual states the maximum acceptable variation between cylinders is 14psi (1kg), So you are basically on the boarderline!

If you were to continue driving it would be important not to lean on this engine for big power increases given it's pretty tired.

Low compression in cylinders could mean that problem of fuel washed cylinders exists. Meaning that the engine has had too much fuel introduced into it and all of the oil has been washed off the cylinder walls. Oil creates a sealing effect between the piston and ring assemblies and the cylinder walls of the engine block. Without thi thin layer of oil, the engine compression is allowed to escape into the crankcase. 'flooding' problem

If the engine seems to run normally but is weak and puffs a small amount of bluish smoke, it can be an indication of worn piston rings and cylinder walls.

If the compression is found to be too high in one or more cylinders (not neccessarily your case), this would be an indication of excessive carbon buildup in the engine.

(I used to have a 94 R33 GTS-t with a lot worse compression varience (from day one): 150 145 140 140 135 125, It was running around 280bhp and I had that for 2 years and by no means drove it softly and had never a problem!)

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