Hi everyone I'm having some issues with my turbo b18c1 with 6k miles on the rebuild. I was told by the previous owner that it had a valve problem because he floated a valve, But I'm not sure.

The issues Im having:
1. Cylinder 4 has low compression. came to around 60psi, all other cylinders are good. Did a leak down test and air came out through the oil cap.

2. Has a rough idle. Sometimes idle sticks around 2k rpm then randomly drops back down.

3. Smokes out of oil breather and the dipstick hole when i remove it.

The car still starts up and runs fine, but the car is not running right when i get into boost.

If anyone could please help give input on these problems that would be great.
I dont know what it could be and trying to get an idea of what I'm up against.

Thanks in advance.

 

wouldn't a blown headgasket cause the leak down to go thru the coolant system, seeming's how it has to pass the coolant passages to get to the oil passages.

 

Could bad piston rings cause any of this? i hope its nothing in the block.

 

I would more go toward the rings. There is no other way the leak down would get into the oil area ( coming from oil cap) besides the rings.

 

alright thanks for the input man, but could that cause all the problems im having like the rough idle and the low compression?

 

the rough idle your having is due to low compression in that one cylinder. do yourself a favor and stop driving it till its fixed

 

Yea the car has been parked since i got it. Im just trying to get an idea what the problem is before i take it apart.

 

And will replacing piston rings need a rebuild? or can i just replace them.

 

The head's coming off regardless. Start wrenching. Leakdown tests should tell you exactly where it's happening.

 

Already started lol

 

Oh whelp. Too late for a leakdown.

 

I already did a leakdown test. The air blew out of the oil cap hole.

 

Drop the oil pan and windage tray and take a look at the underside of the pistons. I broke a ring land on my ls and I seen it from underneath after I looked at the tops with a scope

 

Derp. Saw that right in the first post.
What have you found?

 

bad pistonring or brake the stage between ring 1 and ring 2

had the same problem on cyl 4. and smoke out of breather. oem pistons or aftermarket?

 

Yea mine was cylinder 4 also. I have JE pistons in it.

Just got it all apart and checked the stuff out. The pistons are melted and the bottom side of head in cylinder 4 is beat up from melting. Must have been running too lean. All the valves were fine. thanks for all the input though guys!