Thoughts on an overheated OM617A

[bratwurst]

A few months back I posted about the OM617A I managed to kill by running it without any water.

I still haven't pulled the head off as I'm now focusing on doing rust repair, but I did get a chance to spend a couple hours trying to get it to fire up.

I'm half convinced that I can get it to fire up if I try. I still expect to have to rebuild/replace the motor, but I still think it should start (and run horribly) based on what I've seen.

The motor itself sounded like it had 0 compression; it was basically free spinning when I ran the starter.

I took a look and the plastic bit that several vacuum tubes and the throttle linkage goes on to (not sure what it is exactly) on top of the valve cover was actually melted. There was serious heat involved. I unplugged the vacuum lines from this but I'm not sure if that would cause the IP not to pump any fuel into the cylinders.

I then checked the glow plugs; the wiring had melted near the block and there were numerous shorts. So I hacked together a quick wire-up of the plugs to the battery as a manual glow circuit. As part of this, I went and tested the plugs and they seemed to heat up OK. But, the weird thing is that all of the glow plugs were loose; I could turn them with my bare hands. Also, the number 4 plug was actually bent, maybe it was heat damage, maybe there was some sort of massive combustion event in the prechamber... not sure yet.

When I pulled the plugs I did the poor mans compression test, just turning the motor over and seeing if there was any compression, and also looking for diesel fuel. It seemed that there was at least some compression and I saw atomized fuel come out of each cylinder. Once I tightened the glow plugs the motor felt like it was compressing when I hit the starter, although there was a bit of an "air escaping" noise from the #5 cylinder.

The other symptom I had was a distinct smell in the overflow tank; like burning oil.

As I said earlier, I'm assuming I'll either rebuild or replace it, and I haven't pulled the head or oil pan yet to see what really needs to be done, but I just thought I'd send out a message to see what people thought about this; and if anyone had every seen glow plugs work themselves loose due to an overheat.

Cheers,

Michael

[turbobenz]

You could have blown out the head gasket. The noise of air escaping can be air escaping from the side of the block @ the head. Oil smell in coolant is probably also the head gasket.


617's respond well to overheating as nothing is aluminum.

[Stevo]

Originally Posted by bratwurst

The motor itself sounded like it had 0 compression; it was basically free spinning when I ran the starter.

If your timing chain was broken the engine would spin pretty easy, but you had the valve cover off, right?