96 850t burning or leaking coolant after head gasket

[rspi]

I don't know. I do believe it's a white block thing. I thought it was there for coolant to pass through.

[northernlights]

I'd say that is exactly what it is there for. But usually either the cylinders are fully siamesed, or there is a giant space between them, not a small machined slit.

[futureboycolin]

Took out the plugs, getting ready to crank it over and see if coolant sprays out of any of the cylinders. Looked down in there at the piston tops, but they're all still dark and grimy (glad I didn't go whole hog and clean them!), no steam cleaning was evident, but I could only see the very center of them.

Just ran the internal coolant leak test, and I watched each cylinder crank over at least 10 time. No coolant was pressurized into any of the cylinders, as far as I could see, during the test. I'm hoping this means that the leak is not internal.

[erikv11]

I agree, mtd has a good suggestion there.

It is easy for a head swap to go awry. This is what I was talking about in my earlier posts, it is the most technical DIY job I've done IMHO. I'd much rather swap the engine any day of the week, except it is so hard to find a used engine you can trust etc. Even if the head seems to go on fine, there can be problems 50k later (far too early). I feel for you, hope this gets figured out without substantial additional investment.

You need to be super careful about the cleaning so that you both remove all residue and do not mar the aluminum. If no external leak shows up then I would most suspect a high (or low) spot on the block at the sealing surface with the head. Can't see why the block would be cracked. The symptoms OP describes are classic head gasket leak, where the breach is only between cooling and combustion chambers.

You'll need to decide on reusing the gaskets. I can tell you, I have reused the spark plug tube seals just clean them off. But any paper gaskets will probably be ruined if you used a sticky spray. Cleaning the anaerobic sealant off the top of the head will be a hassle, think about getting a machine shop to do it. Then clean the block meticulously. Intake and exhaust manifold gaskets you could re-use. Head bolts up to you. Personally a Volvo brand head bolt I will use twice, an aftermarket one I would never re-use. Yes, I said I re-use head bolts, when they all come out nice and clean. This tip came from someone who has done literally several dozen head pulls on these white blocks and has never broken one head bolt going back on. But given that you had one break on the way out, I would be uneasy re-using them in this case. You need to figure out what you are comfortable with.

If the head gasket is indeed what is leaking, then it is likely because the block surface was either (a) not clean enough or (b) marred somehow. What I mean is, just taking it apart and putting on a new head gasket may not fix it. Before you put it back together you are going to want to be very sure about what the problem is and that you've fixed it, this may be harder to pinpoint than the burnt valve which was trivial. If the block was damaged in the cleaning process then the next one will leak just the same.

Do you have many pictures of the block surface after you cleaned it?

Not sure what you hope to gain by changing the water pipe and t-stat housing gaskets? If they are leaking you will see it, if you don't see it then they aren't.

Pay attention to any tips you can get from JD, he runs a shop and has done a lot of these.

[erikv11]

Where was the burnt valve, #2? I don't remember.

In the pic, it looks like there is a different style valve in #2, and in #5. That's why I asked.

No, that's 1 and 4, I didn't catch that. Looks like this car has burnt a valve before unless they replaced 2 valves this time.

Yeah, that is weird, by the pic it seems almost for sure two valves have been replaced now. I guess they didn't replace the valve stem seals last time. But who knows. Not the best news, but maybe not important.

I never use the copper spray.

The visual check for a leak is a good idea I definitely would have tried it but I don't think a negative result helps very much here. A leak could easily only occur when the engine is hot.

[futureboycolin]

I just did MTD240's test, and no coolant was evident in the cylinders at all. How reliable is this test?

I rechecked the water pipe, and the gasket is behind the flange nicely, and the bolts are torqued down.

I've come to terms with the fact that I'm going to have to do this all over again. Already ordered the parts. What do I do if it's a low spot on the block?

[futureboycolin]

Should I run the car for a little bit to warm it up and then try this test again?

[erikv11]

Yeah that seems like a good idea but to be honest I still not sure I would trust a negative result. It is so much hotter in there when there is combustion. If you do watch out for hot plugs!

[futureboycolin]

I think deep down in my gut I know it's the head gasket. I just watched the exhaust, and I'm fairly sure. I smelled the Zerex bottle, and then the exhaust, and they are very similar. The vapor isn't billowing out at idle, but in the closed garage with a flashlight shining on it, when I rev the engine, it definitely steams out more.

Just going to have to face facts, and decide that I have to tear this thing down again. Will be doing that on Monday...putting parts on order now. I'm guessing I'll know which cylinder didn't seal properly, or where the leaks are, and then whether or not I'll need to take the cylinder head in to the machine shop to be planed.

The thing that kills me is I just don't know where I went wrong...what do I do if the block has a low spot? The pictures are from before I cleaned the block.

[rspi]

You did NOT have a head gasket issue when you started so I doubt you need to have any leveling done. I really would look real hard for an external leak before I go pulling the head. I'm puzzled though.