*%$&! Overheated my 300SD
 

I drained my coolant tonight and switched to Zerex, but in the process managed to overheat my engine. :( I parked the car on a steep hill to fill it, then took it for a test drive. I drove around in L a bit with the heat on full blast and watched as the temperature gauge went higher and higher waiting for it to "burp" but it never did. It finally reached the top and after a minute or two I stopped and checked the coolant level which was still high in the expansion tank. My poor engine was smoking :bigcry:. I let it cool off for a bit then pulled the upper radiator hose (using a key to loosen the hose clamp :rolleyes:), filled the engine and it cooled off.

I hope I didn't do any lasting damage...:o

that sucks.. is this on the new beast?

pouring cold water in there may have been a bad idea. You shold have let it cool on its own first.

Luckily, that reading only comes from what is happening at the head, probably no reason to worry about cylinder scoring or other moving parts in the block.


I did the same thing when I switched over also.. why doesn't it burp? I was on a steep hill as well w/ heat on??

I would call you a DF..........but, that language is not allowed on the forum.;)

:D

:o :o

These engines have the most confusing coolant path. Do you think this was a case of being filled without the thermostat opening or does this bizarre coolant path work around that???
Keep it close to home on that first drive after work like this.....
Hope it's OK. It should be. :)

I still don't know how people get this problem. I have flushed and refilled my MB diesels numerous time without ever having an overheating problem afterwards. Fill it slowly through the upper radiator hose and top off the overflow tank if it has one. Drive it to bring it up to temperature. Next day, top it off if needed. Works every time.

I do.


Fill it slowly via the expansion tank.............

That could do it, of course, but people seem to get air bubbles even on 240D's. :confused:

I haven't seen the radiator on a 240D, but, I'll hazard a guess that the top hose is very high on top of the radiator, similar to the 300D. If the radiator is filled quickly, the coolant will not allow the air to flow out from the head, and, therefore, the coolant won't flow to the head. It's a bit dicey to accomplish and requires patience if the hose is not removed and filled.

Old age and skill trumps youth and impatience. :D

Touché;)

I've done this 4 or 5 times, this is the first one that has not burped after a short drive.

dont know why you guys have such issues lol. When im doing a coolant flush i usually keep the thermostat in, then remove the radiator, start the car and jam a hose down the lower radiator hose. since the water flows from the lower radiator hose into the engine and out the top hose it will flush out whatevers left in the engine. Then i throw the hoses back on fill it 3/4 way with tap water, put in the 1/4 with coolant and then add 4 drops of dawn dish soap. and i havent had an issue since.

That sounds messy, foamy and mineraly. :D

And bad for the environment when you let all that cr*p run into the yard or drain.

But it works the best. On vehicles where the thermostat is easily reached I tried to always pull it and remove the hoses when doing a flush when I used to do this myself. Nowadays the shops charge so little for this job that I'd just as soon let someone else deal with it, though I will watch to make sure that they do not screw up and overheat the engine.