Thread: 2.6l 6-pot oil in cylinder #6 - Where is it likely coming from?!?!?!?

Emailed the guys are Turner Engineering about the piston rings. They said that my compression problem is coming from somewhere else since they do not clock the piston rings in any particular order and to not bother with setting the ring gaps at 120 degrees from each other. So now I'm scratching my head again wondering if I have more than one issue. I keep going back to how well the engine ran. Yes, I still had oil getting into the cylinder and I clearly had a compression issue on #6 based on leak down and compression test. But based on what I've seen on the condition of the head gasket, the fact that there were no apparent leaks on the outside of the head gasket and the valve seats looked fine...I'm not sure where to go from here.

I'm trying to get my hands on new head bolts (assuming they're stretch bolts) and piston rings since I have the head off. I will at least change out the rings on #6 and #1 since they had the lowest compression.

So, gentlemen, any other suggestions that I might be able to follow while the head and sump have been removed???


Again, any advice is appreciated!!

You were correct in staggering the ring gaps it has been standard practice since day dot. I cannot believe Turners don’t do that, below are excerpts from Detroit Diesel Series 60 and Cummins NT855 engine manuals showing the position of the rings during assembly.
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Originally Posted by Gippslander

You were correct in staggering the ring gaps it has been standard practice since day dot. I cannot believe Turners don’t do that, below are excerpts from Detroit Diesel Series 60 and Cummins NT855 engine manuals showing the position of the rings during assembly.
.image.jpgimage.jpg

You are correct about staggering the ring gaps. As an apprentice I was taught at Automotive Collage & by the tradesmen I worked under to do this & top compression ring gap 180deg to the exhaust valve. Have no idea why Turners would not do this.

From the workshop manual (Actually the S2a manual, but same engine)

"1. Position the piston rings so that the piston ring end gaps do not align with each other or with the gudgeon pin bore in the piston."

G'day All,

According to the manual the valve stem O rings fit in an internal grove inside the valve guide bore NOT externally and there is a procedure to fit them. I would use Viton rubber O rings. Something to check.

I would use a copper head gasket on these older engines installed with a sealer.

Because you have smoke in cylinder 1 and 5 when you put smoke in 6 my thinking is the gasket you used was not sealing well. Check block for straightness as well. ( I note you had the head decked).

You will get there in the end so keep on going with it!.

Chris

Originally Posted by Busted Syncro

According to the manual the valve stem O rings fit in an internal grove inside the valve guide bore NOT externally and there is a procedure to fit them. I would use Viton rubber O rings. Something to check.

That's what I was hinting at earlier, on the valve stem the O-rings will do nothing and would probably be the main cause of oil burning.
Not quite sure why there would be a 'procedure' just a simple case of installing as you would any O-ring, well that's what I did without issue.

I wouldn't be changing to Viton.
Viton will withstand higher temperatures but is a harder material so has less 'give'. The standard O-rings in the VRS are OK but will ultimately harden & fail with age but we are talking many years.

The composite head gasket seems best, there's also a metal 'shim' type but I've heard that these are less successful. Mind you, a mate with a Rover 3 litre car swears by the shim gasket so who knows.....
Problem is locating the old composite gaskets.

I put a dab of sealant around the oil drain holes but otherwise the gasket was installed dry.

I had to install new rings in mine as the previous owner had run without oil in the air cleaner.
Hand scraped the wear ridge and honed the bores in situ.

FFR Refurb


Colin


Colin

The o-rings are installed inside the valve guides? I mean that would make more sense but I’ve never seen anything that shows that.

Are there grooves in the guides the hold the o-rings?

Originally Posted by gromit

Just to confirm what you're describing......the O-rings are installed inside the valve guides.

Colin

Thanks to you Busted Synchro and Gromit I am now understanding what you're saying. Clearly I'm not experienced rebuilding this particular engine. Getting the o-rings in the guides shouldn't be that much of an issue with the head off. Now the exhaust side is a different animal. I'll have to remove the valve springs and in order to do that I'll have to remove the rocker arms and rocker shafts. I can't remember if that shaft is one piece or two piece like the intake valve rocker shaft?!?!? either way, I'll have to go from the front with the engine in situ which means I'll have to remove water pump and probably the radiator to get enough clearance to pull the shaft out. AND then I'll have to rig a bracket for my spring compressor so that it will work on the engine in situ. I haven't yet checked the manual to see if the rocker arms can be removed as stated above but I'll do that now.

Thank you both. I have a new sense of confidence that I can stop the oil now!!! And I do agree with you that I must have had unsealed passageways in the head gasket for smoke to come out of random places. Now, if staggering the rings takes care of the compression, along with a secure head gasket, I'll be in business.

Originally Posted by Busted Syncro

G'day All,

According to the manual the valve stem O rings fit in an internal grove inside the valve guide bore NOT externally and there is a procedure to fit them. I would use Viton rubber O rings. Something to check.

I would use a copper head gasket on these older engines installed with a sealer.

Because you have smoke in cylinder 1 and 5 when you put smoke in 6 my thinking is the gasket you used was not sealing well. Check block for straightness as well. ( I note you had the head decked).

You will get there in the end so keep on going with it!.

Chris