Crankcase resurfacing

[bunni]

I looked around for some information on this but have been able to find none. So far that doesn't instill much confidence.

Can the crankcase be resurfaced? If so, what is the max that can be taken off, other gotchas, etc. My concern is that there are critical surfaces on 4 sides, with three of them being gasketed. The front and back have the timing cover and bell housing and I figure this is the more sensitive dimension. But is the block side of the crankcase completely flat all the way across or is there some weird depth offset because of the bearing caps?

If not, what are my options?




A number of years ago I went to a shop up the road and asked them to clean off the remaining gasket material. Figured it would be simple. Since before I moved out of state another shop did that to pretty much every other surface without hassle (didn't take the crankcase to them, wish I did). I got it back, still oily, still had bits of gasket material caked on, looked like it hadn't been touched. Asked them to do the job I paid them for, and when I got it back again it was completely sandblasted. Every surface. I stared at the guy before leaving without a word and then my engine sat for years.

I'm admittedly a bit embarrassed that all of that happened, but I'm back to working on this rebuild again. I also realized though this that I very poorly put the piston liners in place and am working on getting those seated with the correct nip.

[dn010]

Are you talking about the engine block or lower crankcase? Photos would help so we know what you're dealing with. If the surface isn't distorted then it should seal when you use the "sealing compound" between the block/lower crankcase.

[bunni]

Apologies for the confusion. I'm referring to part #102031 "Crankcase" I'd edit my original post to clarify this, but it appears I cannot. The block is fine.

The surface isn't warped (as far as I can tell with a straightedge) but all of the mating surfaces have been sandblasted and that's going to end up with uneven wear to a degree. The engine was partially assembled with this, and there was very clear oil ingress on the oil pan gasket. So I would suspect that if the surface is too uneven for a gasket, it would be too much for a metal-to-metal with anaerobic sealant.

I don't have a way to measure the surface finish, nor are there any tolerances specified in any of the manuals I have. If there are some specs, I can find someone to measure that and see if it will still work as-is. Easiest and most sure-fire at this point with be to get it refinished, if that's possible.

[bunni]

Let me back up and start over for clarity.

My crankcase/lower crankcase/102031 was sandblasted on every surface, including the mating surfaces. What needs to be done to get this to a point that it can be reinstalled and functional. I don't have all of the tools to measure, but I have people I trust to do them for me. Whats the easiest and fastest way to get this part back to a known, usable condition?

Evidence suggests that it probably won't perform well as-is. It was installed (after being thoroughly cleaned) and then left to sit for a period of time. Upon recent disassembly, there was oil ingress between the gasket and the crankcase surface on the oil pan side. With no pressure, oil creeped about 25% of the width of the gasket on one side.

[David T]

If necessary you can just run a file over the surfaces to smooth them. When you use a gasket, use some silicone or gasket sealer. Clean the surfaces well before installing and you should be OK. Most of the time what looks like a leaky pan gasket is the oil pressure sender unit on the rear left side of the motor leaking down onto the web, around the motor and over the seam looking like a pan gasket leak.

[Ethan Rode]

Hi Kris,

There shouldn't be any problem sealing up the lower crankcase to the upper crankcase, even if the surfaces have been blasted. As long as the surfaces are clean and flat, you'll be fine. I'd recommend ThreeBond 1211 as the sealant, but an anaerobic sealant works too.

For the lower crankcase to the oil pan, I'd suggest lightly dressing the gasket with ThreeBond, or Permatex gray.

With both of these parts, I'd suggest installing fasteners slightly snug, and letting the sealant cure for an hour. Then come back and torque to spec.

Were the head gasket sealing surfaces on the upper crankcase blasted too?

[bunni]

Were the head gasket sealing surfaces on the upper crankcase blasted too?

No, those were done right by a shop in PHX.

Once I get to re-assembly I'll give this all a try. Thanks for the feedback. If I have any issues in the future with assembly, will assess and ask again. The original lower crankcase to block seal looked good. Used permatex anaerobic gasket maker with activator (that was mentioned on another thread here somewhere). Will try permatex grey on the oil pan, since an off the shelf gasket doesn't appear to have held with the engine just sitting in place.