Hi, I'm new here.

I recently purchased an '85 300D with a tired engine. I hoped that that it would get me by for a while. It didn't. Not being the sort of person to learn my lesson and cut my loses, I elected to double down. Now I have another '85 that was hit it the front end for parts.

The parts car supposedly has 200,000 miles on it. The radiator was busted and some parts already removed so I have not heard it run. I did a compression test with the following results.

#1 230 psi
#2 260
#3 310
#4 240
#5 270

I understand that these numbers are low and there is a large difference between the highest and lowest. This test was obviously done cold. The engine may not have been run in a couple years if that makes any difference.

The "good" car has zero rust (southern car), decent paint, fair but presentable interior and 240,000 miles on it. Everything works except the cruise control and power antenna, oh yeah... and that engine thingy.

I would like your opinions on the wisdom of doing and engine swap with this getting tired engine. Obviously there are no guarantees but how much life would you guess is left in it? If I thought it would last a couple years I would probably go that route rather than taking my chances on an $800 junk yard engine that may not be any better.

Any thoughts or suggestions would be appreciated.

I'm no expert but those compression numbers seem low and the $800 price seems high. I would keep looking for a different engine.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

then before giving up on that motor i would try to get a radiator on it and start up and run it for a while with fresh oil. rig it to drive around if you can. then after getting it good and hot and such do the compression test. cant tell much from an engine that has been sitting so long.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Below 300psi is suspect, but they will run with care far below that. I would probably look at some others, but keep that one in reserve.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

If those numbers were obtained by cranking the engine cold, which i assume they were, You might not be too bad off. Those low 200#s might show closer to 300 with a proper compression test with a warm engine.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I just bought a nice body 126 300SD with a junk motor & I had a parts car 123 with 320,000 miles on it & I thought the motor would be tired. After warming it up I found the compression to be 300 psi in every cylinder. Many people would be very gun shy about putting a engine with this many miles in but since Im doing it myself on slow days I did it & it runs GREAT!

If your doing the work yourself & you dont mind the work go for it. But I would not advise hiring out this work. Also dont get caught up in the trap of replaceing all these items just because "your in there anyways" If the motor mounts are still good leave them alone or take the better set from the 2 cars. Some like to buy $500-$1000 worth of new parts when doing this (ie oil cooler hoses, mounts, tranny lines, water pump,etc) Just replace what is bad if any. Although if the oil filter housing is leaking this is the time to do that.