Rebuilding Bottom End - Good Value?
 

Ok so I'm heavily involved in a complete top end rebuild. Rebuilt heads, new pistons and cylinders, steel head studs the whole nine yards as far as the top end is concerned.

My question is whats the value of splitting the case? The engine has 184k miles on it. A DIY top end is approx $4,000....what would the bottom end cost me? What could I expect to pay if I just dropped the bare case off at a Porsche shop and said rebuild it please and seal it back up? Is this money well spent whether I do it myself or have a shop do it? Or is the top end really the only area of concern for most of you guys?

The low end takes very little time. Can't imagine not going the whole way.

Only you can make the call, but I would consider the condition of the rod bearings in my decision. Were they still in spec or did they have have significant wear? Also, it is typical to find significant wear on the intermediate shaft bearings at that mileage, so if the rod bearings showed wear, the intermediate shaft bearings are likely even more so. I can't give you guidance on shop charges for rebuilding your bottom end, but I think the peace of mind that a rebuild bottom end will give you is worth quite a bit.

I understand that it takes very little time in comparison to the top end. If someone could post numbers for a basic rebuild and reseal job for a 3.0 that would help my decision. If it's something a shop would do for $500-$700 than it's a no brainer. If it's over $1000 I'll probably have to do it myself.

Buy "the book" and do it yourself... not hard at all. When I rebuilt mine, I had a good friend helping me. And with the two of us, it only took us a weekend to asemble the entire engine. (that was of course, after all the machine work was done... and all parts were surgically cleaned)....

To me, the hardest part about assembling these engines is timing the cams....

What year is the engine? It's one thing if all you need is some main bearings. But you can easily spend $2k on an early magnesium case that needs blueprinting, line boring, an oil pump mod, etc. (Ah, I see, it's a 3.0. You'll probably do better.)

It's a 1982 3.0. What all would I need to do to perform a "complete" bottom end rebuild?

Go for it. You shouldn't replace the pistons without sizing the rods (new pins, new fit) and you're gonna find substantial wear on the countershaft bearings. Replacing the mains (except #8) and a reseal using the proper sealants is a good idea, and the time and parts cost are relatively low. There's a little sealing trick with the o-ring on the #8 MB, BTW. With the bearing clean and the seal oiled and installed, carefully fit the bearing to the crankshaft (mind the lip of the seal!), push the o-ring toward the nose of the crank, and fill the space behind the o-ring with green Kuril (Kuril T).

Have fun! The Cap'n