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?

__________________
1991 560SEL (254K miles)
1980 Lincoln Mark VI - Givenchy
1979 Lincoln Mark V Collector's Series
1979 Lincoln Town Car Collector's Series
1979 Ford "Effie" Pickup (in gradual transformation to a show/street truck)
1969 Lincoln Mark III (waiting for "Overhaulin" to call)
1989 Lincoln Towncar
2001 Lexus GS300 (spousal unit's daily driver)

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...

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

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.

__________________
1986 300E 5-Speed 240k mi.

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.

__________________
95 E320 Cabriolet, 159K

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

__________________
1991 560SEL (254K miles)
1980 Lincoln Mark VI - Givenchy
1979 Lincoln Mark V Collector's Series
1979 Lincoln Town Car Collector's Series
1979 Ford "Effie" Pickup (in gradual transformation to a show/street truck)
1969 Lincoln Mark III (waiting for "Overhaulin" to call)
1989 Lincoln Towncar
2001 Lexus GS300 (spousal unit's daily driver)

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.

__________________
2007 C 230 Sport.

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.

__________________
Rick

'85 380 SL (sold)
'85 Carrera Flatnose
'71 280 SL Signal Red/Cognac