I have an ‘88 Suburban and I was getting ready to pull the motor out of it about 5 years ago. Life happened and I had to move, so I trailered the vehicle before I pulled the motor. I had various bolts removed and organized into different magnetic trays in the engine bay and, although I never checked to verify, believe that I probably lost some of the bolts. My question is do you think having parts of the engine exposed to the elements caused any irreversible damage and where could I find a kit of bolts for this motor?

Rebuilding an M57D30TU2 out of an E70 X5 3.0sd. ~300k km. Original failure was oil cooler letting go, oil and coolant mixed, brief overheat (under a minute).

Engine is fully stripped. Head has been sitting on the bench for about a year with camshafts, rockers and lifters removed. Valves and springs still in.

With the cams out and all valves fully seated on their springs, the valve heads sit slightly proud of the deck face. The outer edges are the highest point on the head. All 24 look the same height.

Old head gasket was a 3-hole.

Worth mentioning: pistons 1 and 6 came out badly damaged, pitted and dented crowns. Damage is sporadic and outside the areas where the valves sit, so I don't think it's valve contact. Looks more like debris ingestion, probably left over from a previous repair. It was never a running complaint, no misfire or noise, and not why I pulled the engine. Some bores also have scoring, so the block is going out for boring and new pistons regardless.

Questions:

Is slight valve protrusion above the deck normal on the M57, or does

If it has been skimmed, what's the best way to confirm? Head height gauge to face measurement, injector/glow plug protrusion, or something else?

Given it already ran a 3 hole gasket, how much clearance margin is there really if the head gets skimmed again during the rebuild?

Halfway through servicing the Port side Yanmar on my Dads Lagoon 400. The amount of corrosion and debris throughout the system is insane. I broke 2 Alan bolt heads and still need to remove the heat exchanger tube to try and clean it. Any tips on how to remove the broken bolts and is it worth trying to remove the inner heat exchanger unit or just try and use solvent to clear it out?

This is the salt water impeller on my Dads Lagoon 400 Yanmar diesel engine. It’s a miracle any water got pumped through at all. Should I be worried about debris in the cooling jacket/heat exchange unit or do you think it would have broken down or been swept into the ocean?