Rebuilt or Used Engine?
 

I'm about to put an engine in a 1986 560SL. Given the choice between spending $2700 on a good used engine (79K miles) or $6,000 on a rebuilt one, which would you rather do?

In other words, in your educated opinions, is a rebuilt engine worth twice the price of a good used engine?

I am assuming the new engine is a "longblock" (block and heads) versus a "shortblock" (block only), so the comparison would be a fair one.

MB bottom ends are virtually bulletproof, so the used bottom end should be solid (save for extremely poor basic maintenance).

The top end should be okay if only 79K, but eventually you may have to look at valve stem seals, and the timing chain at around 150K.

I don't remember when MB switched from the single-row to the double-row timing chain, so check both motors for the presence of that. I would assume the new motor would be converted to the double row. If the used motor has the single row, you will want to convert over to the double-row setup. Add $$$ for that.

I would save $$$ and go for the used motor. There may be some ancillary components on the used motor that may be in better shape than what is left of your current engine compartment.

New motors are generally only supplied with the basic motor and internals. You have to have the rest of the connections (hoses, harness, and other fittings).

The new motor would have a limited warranty versus the used motor. But considering the relatively low mileage on the used one, I think it's a better buy...

Used is the better deal.
The money you save would pay for several head jobs in the event you need one.
As G-benz said, the bonus ancillary components attached to the used engine can be an advantage as well. Stuff tends to break during transplant, so it helps to have redundant bits kicking around.

Go for used -- you know it works. With rebuilt, one always takes the chance that something wasn't put together correctly. AAA did a study once and found that one third of all rebuilt engines needed serious rework afterwards. Of course, this study didn't address how to determine the quality of the rebuilder.

Damn you guys are good!
Thanks. Used, it is.

The only way I would buy a rebuilt engine is, if I knew the rebuilder personally.
Have seen too many rebuilts over the years that were pure junk.
I believe you're doing the right thing by taking you chances on a used one, especially at the price difference. ;)

I agree with all the posts above.

I believe the dual row timing chains were introduced in 1984 in the 380. Would they have reverted back to a sigle row configuration in the 560? Please confirm this.