Crank Questions

[yachtsmanbill]

It looks like someone solvent washed the engine prior to a rebuild, hence the rust. If the gear cases are that dry and rusty inside then you need a total tear down. If its superficial, yes, pull the crank and get it polished (maybe) or cut (probably). Same for the cam(s). Once its all apart be prepared to clean EVERYTHING via PB Blaster and a wire toothbrush followed by a solvent
bath , probably several times including liberal usage of a good shop vac with a tubing pick up for nooks and crannies. Lots of scotchbrite for gasket surfaces and lots more cleaning. When your all done clean EVERYTHING 2-3 more times and you have a reasonable chance of success. When youre done, you will have gained intimate knowledge of your engines. Hopefully, the only rusty stuff is what shows from previous washing. Once the liners are out, youll have a better idea of the next step.
Ideally the engines should come out and be shop cleaned and built from there.
At that point, rebuilt long blocks may be the solution also. If you have Allison gears you are stuck with the Detroits, otherwise its a BIG repower job. If you have Twin Disc you may be able to convert to a different engine Mfgr. ws

[jim rosenthal]

What about if they stripped the engines to the long blocks and just replaced those, and the heads? Wouldn't it be easier to just use the old engines as cores? Just a thought.

[gottatanfl]

What kind of solvent wash?

[yachtsmanbill]

From the looks of it TRICHLOROETHANE 111. Its used to wash parts and also to degrease for painting. Makes stuff really dry. Usually cast iron will normally hold oil and not rust unless its been out in the weather for a considerable amount of time.
Could have been any other number of solvents, they all do the same thing basically; brake cleaner, acetone etc. just flammable. Thats why its crucial for a decent rebuild to get the film of oxidized iron off. It will contaminate everything.
I would pull the main caps off and see if there is ANY oil left on the journals. Those may not be rusty. Then you can decide if the crank is salvageable; either in place or out. You may get away with a CROCUS CLOTH polish job. The journals will need to be mic'd to see if there is too much gone or if its been cut before. Maybe the oil pump is still full of oil. If your lucky, the guy who washed it may have just sprayed stuff from above and anything underneath may not be as rusty. Look with a mirror and a BRITE light.
If youre desperate to save 50K, spray it down for several days with PB Blaster and then start wiping with lint free rags and a wire toothbrush. All the rust on the rags is the oxidized iron which needs to be removed. CLEAN CLEAN CLEAN !!! When you think youre done, you are half way there ! Wash from the top down! Put a bunch of elephant kotex's underneath to catch all the crud thats gonna come off. IDEALLY, you would turn the block upside down and get all the rust AWAY from the business end. The block and crank is probably 700lbs on a stripped 6-71. Is the trans still attached? If so, you know whats next! Are both engines stripped down that far? Are the air boxes that rusty as well? ws

[Genesis]

You can do this sort of thing in the boat BUT the key to success on a rebuild is cleanliness.

When you start flinging iron oxide around it gets EVERYWHERE and is damn near impossible to keep out of places it shouldn't be.

If there is any way to get these engines out of the boat I would pull them, stick them on a stand in your garage, and then see what you got. Yes, its more work, but you can get to a block minus accessories (blower, alternator, manifold, etc) and then reinstall it that way. If you find that they're toast you're doing this anyway...... and odds are, you're got a major problem.

[MikeP]

Just an added part re cleaning. The FINAL cleaning of an engine block/assemblies is with soap and water. Solvents will leave grime behind. Wash/scrub with soap and water using a white cloth. Repeat until a white cloth will not show ANY discoloration. Then dry and IMMEDIATELY coat with with something like WD 40. Cylinder bores will rust almost instantly if you delay. Then put a plastic bag over the entire engine block until you are ready to begin reassembly.

If you doubt the soap/water part, clean the engines with solvent with white cloths until the cloth won't discolor then clean it again with soap and water. I promise you that the first WHITE cloth with the soap/water won't stay that way.

[yachtsmanbill]

Yer right, there, old Poobah. I would even suggest as a DIY project to pressure wash the blocks and then immediately oil them-- out of the boat of course ! You HAFTA get rid of the abrasive crap or you are doomed ! Ive done boneyard motors like that. All the honing, tapping and cleaning and then a gunk job at the carwash wish reasonably good results. IDEALLY as we both know a good hot tanking is the way to start. It sounds like these guys would have a tough time pulling them out though, and I am just giving them the alternatives. In place in frames are a tuff nut to bust, dontcha think?? Even for seasoned veterans. I would absolutely dread doing the 12s that way, but on the ground, no sweat.
ws

[Genesis]

I won't do inframes personally.

That's just me.

A repair (e.g. change a bad jug), sure. But an inframe "overhaul"? No.

I know this means "but but but but" starts almost immediately, but you can't hottank a block in the boat, you have to do all sorts of wild things to flip one over so you can PROPERLY clearance mains, you wind up with crap everywhere it doesn't belong and maintaining cleanliness is basically impossible.

Add to that the number of inframes that I've seen go ONE HALF to ONE THIRD of the hours that a proper out-of-boat overhaul should go before they blow up, not to mention the VERY short-time failures, and I just see this path as a poor investment in basically ALL cases!

I've got a buddy of mine with top-end problems right now that we're putting back together. We don't know if he's got main bearing or cam damage to go along with the obvious top end issues (apparent lube trouble prompted this) and there's no way to know without tearing the engine apart. Everything above the pushrods is being replaced as a consequence of galling found in the rocker shafts (with one broken!) during a routine injector change job and tuneup. If there IS main or cam damage, and the engine blows up, as it may, I already told him that I'll help him either pull and replace it with a RTO or rebuild it in the garage, but I'm not doing an inframe - and that's on a boat with reasonable access.

I suspect this guy is hosed and if so the engine has to come out anyway. If not then it'll be a hell of a lot easier (and cheaper if you pay someone!) to do the rebuild with the engine OUT of the vessel.

Either way, this is one of those circumstances where I can't see the logic for NOT pulling it, and making provisions so you can do it again (easily) if necessary.