How do this cylinder walls look?

[RickHaleParker]

When you drained the crankcase, was it chocolate milk or coolant that came out first?

[SuperHerman]

Well how much work do you want to do? I have repaired two worse one a 2.4T and the other a 2.9 NA.

The 2.4T I just cleaned and let it be - no issues.

The 2.9 NA was closer to what you had - I honed the one offending bore and replaced the piston rings. All was fine.

You can remove the pistons by dropping the oil pan. Then a light hone of all the bores, I would do one at a time. Take special care covering everything below so that you can clean up any metal.

Now the easier route would be to just hone the top of the offending bores and not remove the piston. To do this lower the piston as far as possible. Clean everything really well. Run some masking tape as far down as you can around the bore. Pack some paper towels for good measure. Just above this place a ring of grease around the bore, touching the paper towels (you could cut a circle about 1 inch larger than the bore). The grease will catch on the grease and paper towels. You don't want the honing debris getting into the piston rings. Then just lightly hone the top portion to clean it up. Once done, slowly remove the protective layers keeping in mind the piston rings.

It is possible the marks you see are the coolant boiling. One thing to remember or recognize is the piston rings are seated lower than the top of the piston - so the affected area may not even be in play. Maybe someone with a piston can take a measurement and this will give you an idea of whether you should be concerned or not.

[850T5Ritalia]

Thanks for all the insight and suggestions. I've got a little update on the head from the machineshop.

The head is warped by quite a bit. Also the valves/seats where in bad condtion. His advises was to find another head or preferably another egnine. He also said he never seen a Volvo with this kind of damage from overheating before and that the car was verly likely to been driven with an overheating engine for way too long. Chances of warped cylinder block and damaged piston rings. Im going to check the block for straightness first. If the block is straight I think I'll take my chances with another head.

[abscate]

I had my cylinder head reworked from 0.016” (0,4mm) out of true by thermal straightening.

They cook it, bolt it to a flat plate, and then slowly cool it, I believe it typically ends up within 0.002” (0.05mm)

Odessa in Clearwater FL did mine.

[850T5Ritalia]

I don’t think there is any option in my area for thermal straightening unfortunately. I can source a head for pretty cheap tho.

So I checked the block for warpage with a straight edge. What I found was a maximum of .004 inches. Would like to hear what you guys think about this. Thanks

[abscate]

It sounds crazy but Irememebr an old school guy telling me a block shouldbeas flat in “ mil” ( thousands of an inch)mas the number of cylinders.

That units problem is left to the student

[850T5Ritalia]

It sounds crazy but Irememebr an old school guy telling me a block shouldbeas flat in “ mil” ( thousands of an inch)mas the number of cylinders.

That units problem is left to the student

If I understand that right the maximum tolerance should be .005 of an inch or 0.12mm?

[SuperHerman]

I think you would be better off sourcing an used engine, assuming you can do the pull and replace. Too much risk that the pistons are cooked, not to mention damage to the bottom end.

Price wise it will be close plus you will have no worries.

On my 2.9 NA, it had a slow leak which apparently ran for 50-60k miles. I figure the head gasket was bad from the factory as the repair record had tons of warranty work and post warranty work for overheating. Everything but the head gasket was replaced by the dealer. When I got the car the thing was cooked good. When I pulled the head, what I noticed was small bb globs on the head and marks similar to yours on the head and in particular one bore wall. It appeared hot spots were created and caused considerable damage. The head cleaned up and milled flat in the end.

One thing to pay attention to - on the car the catalytic converter ended up being plugged. I think all the miles with coolant issues took it out. Engine ran fine, but after about 8k of miles it wouldn't start. It is entirely possible the rings were leaking oil and added to the issue - no way to know. My niece's husband swapped out the engine thinking that was the problem, in the end it was the plugged cat (or both). Something to think about.

[850T5Ritalia]

I have decided to give the block a chance with a good used head on it. The warpage on block looks to be okay. I dont think the warpage of the block is the biggest concern tho. Piston rings and bottom end might be more of gamble.. But I've had a handfull of people say these blocks are strong including the guy from the machine shop so im willing to take my chances. I can source the head and gaskets cheap so if it fails it isn't that big of a deal. Think I may the drop the pan and give everything a good clean and flush.

[RickHaleParker]

Think I may the drop the pan and give everything a good clean and flush.

That would be a good idea.

There is a reason I ask which came out first. The chocolate milk or Antifreeze? If it was Antifreeze of significant quantity. It means a lot of water got in the crankcase. If the bearings have been sitting in water they maybe rusting. Water is denser then Oil, it sinks to the bottom.

Look at the dipstick. Is the crankcase way over filled?

If I understand that right the maximum tolerance should be .005 of an inch or 0.12mm?

I am coming up with .004" maximum combined deflection (Block + Head ). .004" on the block is on the edge by your numbers or mine. It would be a high risk gamble.

DIY block surfacing is possible because you can cut Aluminum with sandpaper. You make a plane out of a flat surface faced with sandpaper and plane it true. Takes a bucket of elbow grease to do ... 2-3 of hours of back and forth.

It is looking like you would need to go all the way through that engine. Overhaul not repair.

Ignore the preaching. This guy is pretty creative when it come to DIY.
I would make the plane longer then the block. That way the plane would always be working the highest point.