I am replacing an engine in a 300sdl.
 

What should I look for in the new (used) engine. My wife blew the original engine when the temp. sensor blew out. I have several sources for the engine, just need some tips on which one to get. Any help is much appreciated. I look forward to learning from you guys! My car has about 150,000 miles on it. Engines I have found were quoted with anything from 40k to 150k. Thanks again for any help.

If you are getting it from a bone yard, see if they will do a compression check. Mid to high 300 and up would be a minimum I would want. Also check the engine compartment of "rust" stains. This is a good indication if a hose ever broke while driving and may lead to overheating.

Thanks DM, most junkyards said they would start and compression check. Current engine has a compression of 50. :eek:

I like to see 350psi and up for many more miles of use. Low 300 will work if nothing else is available.

That is great to know, I have about five places I am looking at. Range in price from $1800-$2900 including shipping. There is one local (in Mobile) that I plan on looking at first.

Metric Motors has a good repution for their Mercedes rebuilt engines.

www.mercedesengines.net

the compression numbers
 

stated above are for a warm engine. cold will be considerably less.

tom w

Check to see if it's just the head. The bottom end may still be OK if it was only overheated.

Any idea what a cold pressure would be?

How would I do that, remove it and have it checked by a mechanic?

It's almost certain that the head will be bad since they hate to be overheated. They crack. I'm sure a head rebuilder can check it to be sure.

cold compression
 

is more close to 300. 320 is as new i think. and 220 min for starting.

good luck.

tom w

Thanks for the help!:D

Pull the cylinder head, yes, and the bores will speak for themselves. Also examine the cyl head for warps and cracks, probably run a straight edge over the shortblock too.

I agree with lietuviai, you are crazy to jump to wild conclusions on a completely destroyed engine when typical overheating never touches the crankshaft and frequently leaves the pistons, bores, camshaft and even the valves intact depending on how long the car was driven. Hell you might just have a blown head gasket and/or cracked warped head.

Then if its just the head figure you've saved yourself beaucoup dollar$. 2nd hand cyl head is helluva lot cheaper than an entire engine. And figure your original 150k shortblock might be good for another couple hundred thousand miles, assuming its properly maintained and whoever drives it pays attention to the guages. And another easy trick that any talented mechanic can do is hook up an audible overheating alarm if you fear this might happen again.

The car is on the family farm, I will see if my father-n-law will pull the head to check the cylander etc. Again, thanks for all the info.