172 turbo low compression

[scotty2hotty81]

Carried out compression test, results are.

Cyl1 140 psi
cyl2 135 psi
cyl3 65 psi
cyl4 130 psi

2 different testers carried out multiple times

F4r 2.0 turbo low compression engine

Now stripped with no visible damage seems very low to be just rings, it's covered 16k miles since rebuild

What are people's views on this?

 

[Fred@BTM]

want me to have a gander?

 

[scotty2hotty81]

want me to have a gander?

If you don't mind, sometime in your busy schedule, Bare in mind engine is out and on an engine stand, would appreciate you view. I'm only round the corner

 

[Fred@BTM]

give me a call then! i can come over tonight (working late )

 

[scotty2hotty81]

I will, il see when's best for both of us, I try and finish at a semi reasonable time unlike bionic Fred!

 

[Aydon182]

Did you find out what the problem was?

 

[scotty2hotty81]

Give me a chance lol

 

[Owen:s]

Valve stems carboned up stopping them from returning properly ?? Had 1 like this the other week

 

[scotty2hotty81]

On compression I pressurised the cylinder, it came out through breathers and dipstick tube, a friend of mine was on about all the piston rings lining up and pushing through that way? Can't see it myself.

 

[Struggler]

1 valves not seating properly due to carbon build up
2 headgasket (noticable)
3 piston rings.

surely it can only really be one of the above?!

 

[Dan519]

my money says it's had detonation, and the rings on that cylinder are seized into the mildly melted piston

 

[scotty2hotty81]

I'm thinking rings, not much else it can be, all rings move freely and I have removed them from the piston to check :S
Il be getting in touch with Fred to see what he thinks, it's Darren stones old one by the way.

 

[Dan519]

oh well that blows that theory out the water. Could still be rings though. What condition is the bore in on that pot?

 

[scotty2hotty81]

I'm hoping it is just that, just seemed like a lot of lost compression to be just rings, bore/bores are fine you can still see the honing marks, no scores or pitting.

 

[Dan519]

compression loss will only be down to 3 things. Ring sealing, valve seating, or headgasket breach.

As it's apart, I would hone the bores and fit new rings, strip the head down and clean up all the valves, maybe reface the valves and seats, fit new stem seals and check the lifters have some movement in them, and have the head checked to make sure it's perfectly flat, then skimmed if needed.