Coolant under valve cover?

[ees]

I have another question...

When I pulled the valve covers off my engine to replace the head gaskets I spied what looked like coolant mixed with oil pooled near the bottom of each head. This seems quite strange. How would coolant get here? Is this a cracked head or block? Or is the up through a bad valve seal from the combustion chamber?

The one head I have off so far is quite dirty still so I have not fully studied it for cracks.

Any thoughts? I would prefer not to get into the block at this time. I was planning to get new valve guides/seals and general overhaul of each head however.

Is my engine in trouble?

Thanks
Eric

--
'94 2500 4x4 6.5TD Suburban 223k
Work in progress

[tom.mcinerney]

Head gaskets wear with miles&cycles, start leaking compression&coolant.
The 6.5L heads tend to crack with high hours/miles/heat, esp area between valves.
The cracks tend to propagate down into the water jacket.

More Power researched this issue and devised a solution that works pretty well. These are sleeves that can be inserted into a tubular channel beneath the valve-seats in the heads , sealing against further coolant leakage.

If you clean up the heads real well (preferably , but not necessarily, with glass-beader) you'll probably see some fine cracks between valves; some may even extend across/thru the valve seat(s). More Power found that the engines run fine with a small crack thru the seats. Mine had like 10 cracks on turbo side, 3 on other side.

Other wear issues with heads include valve seats that have been beat into submission (eroded) so that they are below (above) the specified level .

These heads demonstrate good dimensional stability, don't warp. But the seats are inductively hardened, setting up stresses which, in service temp/pressures, promote cracks.

Peninsular Engines sells OEM GEP 2004 heads at great prices; John Kennedy sells reman heads with new seat inserts. The '97-up heads have bigger cooling passages, new GEP stuff probably better castings....

Not to be a pain...but another issue with a hi- mile block is the condition of the block's firedeck, particularly the annular (circular , ring) area under the steel compression seal of the head gasket surrounding each cylinder bore.
In his TDP R&R Guide, More Power describes a procedure for resurfacing the firedeck. Very close inspection is in order here. On mine, there were grooves beneath the gaskets a few thousandths deep. I think it's difficult for new gaskets to seal properly if the grooves are significant.

[ees]

Will a local machine shop or diesel house know about the sleaving? I will be calling the one I machine shop I usually use this morning.

I will take special care inspecting the block before I put money into the heads.

Thanks for the input

-Eric

[Peter J. Bierman]

Engines that do not do a lot off long distance driving it might be water vapour condensated inside the engine.
Don't worry before you have the heads inspected.

peter

[tom.mcinerney]

Eric--If click on 'Members Area' toward top this page, then 'Reference Section' in the menu at that page, then ""6.2L/6.5L Diesel Cylinder Heads:" , i think the article explains, may have part # for the sleeve kit, or mention how works.

My local head/race engine shop wasn't aware of the procedure, wasn't interested in learning. They offered to provide reman heads from a source they felt reliable. And this shop's bread & butter is head reman--they don't do diesel. So it'll depend.

[ees]

Thanks for the link Tom. I had read some of those items a month or so ago and already forgot about them. I printed off the crack repair procedure.

I found a local shop that had heard of the repair, but not done it. They were willing to work with me on it. They said they had instructions. The shop I usually use (closer to home) was not interested.

I will take the print out with me and give it to them for reference.

Thanks
Eric