BMW Blog

Hi 258 gurus (yeah...I have a YJ but I hang out here more cause there's more 259 knowledge floating around).

I had my rear main seal replaced last March by a trusted mechanic (the dad of a good friend of mine - he really is an honest guy). He told me after the replacement that there's a "heck of a groove" on the crankshaft, that the rear main will likely leak again in time, and that when it does he can replace the crankshaft. At the time he said (off the top of his head) probably $250 or $300 for the part, plus labor (which he usually cuts my wife and I a deal on).

So...the rear main is leaking again (go figure). I really hate it.

I believe him that the crank is scored - that's not the issue. My questions are:

-Will a new/re-manufactured crank solve the leaking problem?

-Does replacing the crank shaft (and do the kits) usually include new bearings?

-Is this basically like rebuilding the bottom end?

-How long (hours) would you guess off the top of your head it takes to replace a crank for a professional, skilled mechanic?

I have no idea...and although I'd love to try, I don't have the facilities (or knowledge...yet) to tackle this one myself.

Thanks!
Tim
It really depends on if you are replacing the whole thing or if you are going to have the original machined.

If he takes it out the bottom (has a lift to do it would be a lot easier), he can swap a new one in in no time, but if he has to have it machined, install new bearings and put it all back together, it would take the time of the machining I suppose. And before anyone gets on my for the no time comment, I just meant that it was possible for arguement sake, pulling the motor and ripping it down would probably be a better way to handle it, but then again, rebuilding the top end would probably be a better way to handle it as well...

I guess the question I would ask is how many miles does the rig have on it? If it is up there, would a full rebuild be worth it? Also, if you go that route, I am in the middle of doing that irght now and it is costing me about what it would have cost to buy a newly remanufactured one, so it is pretty much all personal preference
It just rolled over 110,000.

I briefly thought about a full rebuild or remanufactured engine, but truthfully it runs great now, and of course money is tight.

He has a shop and a lift, so he'd definitely take it out of the bottom I would guess. When I talked to him last year he didn't make it sound like a very big deal, actually. It just sounds intimidating to me. I wouldn't get it machined - you can get a remanufactured crank with new bearings for anywhere between 250 and 300 bones after the core charge.
I went through the same thing, but my crank wasn't grooved too badly so I ended up keeping it. So far no leak but I am still breaking it in. It is hard to find a (new, not reground) replacement crank for a old engine, when you do please let us know where you got it.

If I was you then I'd just go ahead and pull the engine and do a compleat overhaul on it. The crankshaft and bearings are the heart of the engine and if your gonna replace them you might as well do the rest of the stuff.
I went through the same thing, but my crank wasn't grooved too badly so I ended up keeping it. So far no leak but I am still breaking it in. It is hard to find a (new, not reground) replacement crank for a old engine, when you do please let us know where you got it.

If I was you then I'd just go ahead and pull the engine and do a compleat overhaul on it. The crankshaft and bearings are the heart of the engine and if your gonna replace them you might as well do the rest of the stuff.

I agree, but head jobs and overhauls are $$$ and as a graduate student money is, unfortunately, an issue that I can't overcome. Can't do it myself since it's my DD and I don't have a garage. For the time being, I'd like to stick with just the crank if I can get away with it.

The crank seems to be easy to find...I found a couple of places online that sells them for less than 300.

Edit: The ones I found are re-manufactured, not spanking new.
Pulling the crank out the bottom is just as much work as just pulling the motor and doing the rebuild. sounds like a lot of work for just the crank. You are probably about due for a rebuild anyway. You can do just the crank but then in a little while you'll just have to do it all again when you rebuild the engine. I like to keep the original and don't like the whole re-manuafactured engine route. With some advice (and a garage) you can do the whole thing yourself (except for the machine work that is). Cranks are no problem, there are probably a few crankshaft shops in your town. You take your crank to them, they weld up any low areas and then turn it back down to the original specs. The last one I did was only 150.00. That was a chevy 350. If you need to drive it more until you can afford it I would just put up with the leak, unless it's really bad.