Rering/resleve, or not to bother?

[MT_Merc]

So, a couple months back we picked up a wrecked but running '85 300D-TD showing 215K miles on the odometer for an engine/transmission swap, and since then I've managed to get it pulled and partially disassembled. I ran it several times before pulling it, and it started and ran well except for some knocking noise that I suspect was injector nailing based on what I've read. I wouldn't say that it had a lot of blowby as far as I could tell; some, as I remember, but nothing terrible. I didn't get around to a compression check. Anyway, after getting the oil pan off, I got a look at the bearings and cylinder walls. The bearings looked pretty nice, just a few minimal scoring marks on the ones that I looked at (nothing like the ones I pulled out of my old 302 with who knows how many miles, they were original, said FoMoCo 68 on the bottom). The thrust checked out well on the rods (within normal tolerances according to the Haynes manual), the thrust on the crank was well out, so I suppose new bearings would be a good precaution no matter what. The cylinder walls, inspection-wise, were a mixed bag. On a couple cylinders I could still see the honing marks, but on others there was some scoring; the number one cylinder looked the most worn.

I would like to get this motor ready to go for the long haul before I throw it in. The motor seems to start, run, and rev out nice enough, but I'm seeing more wear on the cylinder walls than I'd like, and I'd hate to drop it in only to find that it burns oil. I'm leaning towards getting new rings and sleeves and maybe having the machine shop do the assembly on the short block in addition to the sleeves and honing. Rings, sleeves, and related machining will probably double the price of the engine work (I am replacing all the seals, it's had its share of leaks, and I'm sure I'll run into other little things), but I don't think the cost is too big a deal if I don't run into any serious issues. The pistons I'm planning on reusing, I do need to get the head off to look at the crowns, but the skirts look good. Top end work I plan on leaving for later; I'll pull the head apart and have it hot tanked to clear out all the accumulated sludge, but unless that looks pretty worn I'm not going to worry about it.

So, does all this sound reasonable? I know I need to find a good machine shop, I don't know how much good new rings and sleeves would do if I were doing it all myself. Also, I'm not expecting to come out with a like-new bottom end. As long as it's good to go for another 200K or so I'll be happy. I basically want to do as much as possible to ensure that we'll get good service out of it--it'll be a daily commuter--without blowing the whole wad on a rebuild that it's not really in need of.

[t walgamuth]

it is pretty hard to say anything from your description. i would have an experienced machinist look at it and take measurements to see how much taper there is in the bores. he will have books to see how much is allowed before work is needed.

it really would have been a good idea to take compression and leak down tests before tearing the engine apart.

the bottom end s are really robust and it is not uncommon for them to show vitrually no wear at 250k.

since it is apart i would do a valve job probably at least. and seals. and valves for those that are too worn.

the job of knocking out the sleeves and reinstalling new ones is a lot of time and work. the sleeves arent much but after installing the new ones you have to bore them to match your pistons and mill the tops off. it is also not a bad idea to deck the block to remove the twist it will have after 250k miles.

no idea of the cost until the needs are assessed.

tom w

[MT_Merc]

I'm afraid things just took an unexpected and unwelcome twist on the project. I finally got the pistons out, and the top ring land on number five piston is pretty badly busted up. Of course, I have no way of knowing what might have caused it, up to this point things have looked fairly good. The other pistons look ok, and actually the crown of the number five piston looks just fine as well. Sucks that this happened, but I am glad I didn't just put new seals in and drop it in the other car. Now I really wish I'd had a compression tester, I'm sure it would have shown way lower than the others as bad as it, and no way was it worth what was paid for it given this. Live and learn I guess, ya pays your money, ya takes yer chances.

Anyway, I'm going to be taking it down to the machine shop next week, and I'll see what they say, but are there any opinions as to what I'm looking at here? How often is a serious ring land failure an isolated thing? I'm hoping I can just replace the one piston, is that likely to work out if the other pistons check out ok? Does it affect the balance? I don't know if it's important, but one piston has 90.85 and the others (including the busted one) have 90.86 stamped on the crown.

[engatwork]

I've got a couple of good spare pistons if you need one. PM or email me.
The different numbered piston should have come out of the #1 cylinder.

[mplafleur]

You can find deals on sleeves if you look hard enough. I just bought a set for my SDL for $19 a piece. Now I need to make sure my machine shop can do diesels. Maybe I can drop off the block next Friday with the sleeves and new pistons.

[t walgamuth]

can measure the pistons including the ring lands and determine if they are good to reuse.

reusing them is no problem if they measure out.

sorry it isnt going the best.

tom w

[the tenor man]

I went through all of this on a 240D...my advice is that unless this car is a real beauty...(no rust anywhere, great interior...you really love the car more than a few thousand bucks), stop now and cut your losses....I'm sure that you can find a better example out there for $3000-$4000.

When my car was finished (I did all of the grunt work) it ran a bit better. It's hard to tell on a 240D...there are already SLOOOOW!.

I don't think it was all worth it....just my opinion.

Jim Schaffner