My 87 300D is running hot. The pavement temps here in Atlanta on the connector are hitting 130F, and at times after spirited driving with AC on, then hitting a traffic jam the needle sometimes goes over 110C. Its even peaked at 120C briefly. I know this is very bad, and Im not sure really what causes this. It usually runs right at 90C, but if I get on it and run 90mph with AC blasting it seems the cooling system just cant keep up.

So all this heat may be causing the diesel fuel to become too hot - what is the upper limit ? Im running a frybrid system that heats the veg oil with coolant, and the wvo side of this works like a charm in this heat. But when I try to switch back over to diesel at these temps, it usually looses prime and stalls.

Ive double checked all the diesel lines for vac leaks, from lift pump to hard line, there arent any leaks. But Im wondering if the hot VO (what I would assume to be same as coolant temp, 110C) is actually heating the solenoid valve that dispenses the diesel fuel (since both fuels run to the solenoid valve). And this heat causes the diesel to bubble up and loose prime.

How can I make this thing run cooler? 3 seasons out of the year it runs at 90C or less, but when it gets extremely hot outside the engine just runs too hot. Perhaps a new rad is in order. Its the original at 275k miles. I took it out a year ago and flushed it, seemed to be OK (same flow rate coming out as in). But maybe some of the passages are blocked and coolant isnt flowing thru entire rad (dont know if thats even possible).

I wonder if the diesel fuel in the lines esp right at the solenoid valve that is stagnent during wvo use is just getting too heat soaked. How hot can you get diesel before you run into problems, and is loosing prime a common result of overheated diesel?

Dam its going to be 100 here for next week so this problem is getting worse. Once I do purge back to diesel (by revving motor excessively), it runs just fine on diesel. Its just the 1st 15 sec or so that it stumbles or dies when over 100C coolant temp unless Im at 3500 rpm.

__________________
Paul
Benz-less
I need an SDL !