Severe OM617 Overheat - Typical Result?
 

Hi,

Through my own stupidity I managed to severely overheat my OM617 that I swapped into my G-Wagen.

There was no heat coming from the heater, suggesting low coolant, and I thought I could get about 5km into town, but she blew up before I made it. The engine stopped running while I was cruising at highway speeds, its good I was in a remote area and there was plenty of space to stop as well as limited traffic.

I am relatively new to diesels so I'm wondering what approach to take; my options are find another engine to swap in and rebuild this one in parallel, or do a mini-overhaul and get this one running. A wrecker 617 can be had locally for $1500.

The engine turns over freely when I try to start it, but it doesn't seem to have any compression. While the engine doesn't seem to be seized, the throttle linkages are - I can't move them at all.

So my question is, what are the normal failure modes of this engine when overheated? I am guessing the head gasket blew, oil was everywhere. But what other items can I expect to go? Is it typical that I would crack the head or block due to an overheat? The engine got hot enough that there is now flash rust on the outside of the block...

Thanks in advance for your help!

Cheers,

Michael

617's don't typically 'blow up' when overheated. But, the fact that it quit running is an indication of something serious going on. I'd try to determine the source of the oil. An overheated engine does not typically spew oil. Did an oil cooler hose break?

if you overheated it to the point that it scored the cylinder walls then you are either overhauling the engine or swapping it out for a new one. mostly if you didnt extremely overheat it the cylinder walls will be fine, and you just need to install a new headgasket / mill the head if its warped. Other than that, there isnt much else that can go wrong.

OM616/617 with their cast iron head are among the most resilitent engines when it comes to overheating however in this case, it looks like you have totally ruined it.

Find a used engine. If you overheated it to the point that it blew an oil line and died from oil starvation, it will take waaaaaaaaaaaaaaaaaay more than a "mini-overhaul" and $1500 to get it going. Expect pistons, cylinder sleeves, bearings, probably some valves and an injection pump rebuild too by the sound of it (PLUS core charge if the pump is not rebuildable). Parts cost of the pistons, rings and sleeves alone will easily pass $1500, not counting shipping and installation labor.

I love that you've gotten a 617 into a G (please post some pictures of it!) but you screwed the pooch not stopping at the first sign of problems. :(

removing the head may be the only true answer other than a compression test.

A compression test is essential to know what happened. If it has no compression though you will be albe to tell it by the engine spinning freely without any lumpiness caused by the compression of the individual compression events.

Not to keep beating you but running on after an engine is overheated is one of the surest ways to really ruin it.

I'd diagnose before trashing the motor. Overheating is bad AND every problem that I've had has turned out to be minor. I like leak down tests in conjunction with compression tests for gassers but haven't had to run one on a diesel. IF you determine that the engine needs to be rebuilt, buy a parts car with a running engine. They show up on craigs list for less than the $1500 you quoted. Salvage yards think they're gold. I try to buy non-running junk that people want to get rid of. Eye of beholder comes to mind.

He didn't just overheat his engine, he ran it out of oil.

Thanks for the help guys. My plan of attack right now is to buy a wrecker motor and then rebuild this one over a one year period... that way I'll have a 100% reliable motor for next winter.

The strange thing is that while there was oil everywhere, it didn't look like I blew an oil line. To me, it looked like oil was spewing from the head... mind you that was in the dark and few weeks ago, the only thing that will tell me for sure what happened is pulling the motor apart.

I did have one additional question; the motor turned over but there was no feeling of compression whatsoever. On another forum that point was brought up as a symptom, but the potential reasons for it weren't discussed. Does anyone know what that lack of compression would suggest?

Cheers,

Michael

Overheat and run out of oil? Probably seized....doesn't sound fun.

Lack of compression could be from lack of seal of the rings or the valves. A leakdown test will reveal where the leak is located. You put air in the cylinder and listen in the intake and pan for hissing. If its in the intake or exhaust manifolds you have valves leaking, if its in the pan you have ring seal failure.