I had a large puff of white smoke come out of my wagon on startup and was about 2 miles from home. I got home and the temp was a little high most of the way and the reserve(filler) tank looked very low.

I let the car sit for about 3 hours and went to the auto parts store. The temp got to just below about 105 on the way there. I added fluid (almost a gallon) and it was topped up.

I drove about 4 miles to a friends house. At about 2 miles the temp started to really climb. It sat at 80 and then started to really shoot up.

About 1 mile from my friends house it hit the 120 mark and kept going.

I made it to their house and let the car sit. We went to a movie and I called a tow truck to get me home.

There is no coolant in there again. I did not see any draining out. When I go to my friends it was all steaming out.

Is the water pump dead?
I cant think of any other reason that there is no coolant and no obvious leaks. I did not see any coolant on the dip stick and it did not look foamy or small of coolant.

It really seems like it just superheated and boiled all away. Although the smell was not super strong.

I will fill the tank in the morning again and see if I can see any leaks.

Could the radiator be plugged?

Any diagnostic should start with a cooling system pressure test.

If you are lucky it will be a simple leak.
.

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head...

If you have a leak, it'll be pretty obvious where the leak is to dump that amount of coolant that quickly. Look for wet/greasy spots. Specifically look at hoses and fittings (don't forget about the aux fitting coming out of the back side of the head under the intake manifold!).

If you don't have an obvious leak (a leak that large will be obvious), go look at the exhaust. If you see white smoke or steam, you have a blown head gasket or a cracked head, both are fairly common on the OM603.

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The puff of white smoke is a huge clue that it's likely a head and/or head gasket. Coolant will slowly leak into the effected cylinder when the engine is shut off but still under pressure (as it will be until it cools down to ambient temp). When you start it up the errant coolant will, of course, burn off leading to the white plume that you saw. If you're losing enough coolant to be down as much as observed it's probably a significant leak.

As Whunter said, the place to start is with a pressure check. There are also kits to check for products of combustion in the coolant and/or coolant in the engine oil - probably worth looking online for one of those kits. I haven't needed to look into this for many years but the last I knew the "kit" was a strip that you immersed in the fluid in question and it gave some indication of the issue. Depending on how much coolant has gotten to where it doesn't belong you may also have creamy-looking engine oil if the coolant has gotten that far.

Sometimes the failure is only between the coolant and the combustion chamber and usually that will show up in the chemical analysis of the coolant though I have had one where the coolant only flowed one way - into the combustion chamber. Pulling the head showed a bad head gasket (you can see the trace of the coolant from a coolant passage to a cylinder bore).

Dan

Dan

The 1987 300 OM603 motor came with the weakest design head... because of this it is unwise to run the motor AT ALL if coolant loss or temp rise is noted... and it is EXTREMELY critical to keep the ENTIRE cooling system in tip top shape.

Your head is ruined. For sure. You got a warning with the temp rise and climbing temp. That was the sign to shut down the motor and get a tow truck to take it somewhere for service... the further driving destroyed it. You now need a new headgasket, AND a new head. Plus whatever caused the coolant loss and temp rise... probably the fan clutch and bugs in the radiator...

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I think you are dead on.

I have 2 other heads and a complete OM603 that has just under 200k on it. I will probably just try and swap that one in later this summer/early fall.

I'd vote for the head too.

Just went through a similar experience with a #14 Head SDL. Drove the vehicle for years showing a very steady temperature gauge value. No sign of overheating. Suddenly the gauge starting doing the rapid rise/drop action and heat in the cabin was intermittent. Got it back home and parked it.

When I went to start it the next day the engine was hydro locked. Coolant was low in the overflow tank. When I finally was able to start it, the SDL was billowing steam and there were bubbles in the overflow tank.

Postmortem on the head showed several cracks.