Hi,

I'm new to the forum here.

I have been having an engine running hot problem with my 87 300TDT for a while now but it has recently gotten worse.

The car runs great, however, under load, going uphill especially, the temperature will climb, albeit not all the time. This is especially true for the long highway hills. The temp normally runs at around 85c. Going up a hill it will climb to 110. In extreme circumstances, 120. I try not to let it get to that though.

I have replaced all the hoses, thermostats (twice) radiator, fan clutch, fan blade, pretty much the whole system except the water pump, which is not leaking, and the electric fan, which works.

The tricky thing is the previous owner put in a vegetable oil system and messed with the cooling hoses to heat vegetable oil. It is a lovecraft Biofuels system. I had it removed last week, and now a new problem has come about.

The car now runs hot on the freeway, and especially under load, but it will not run hot in local driving, no matter how many hills I do. Very small incline and the temp shoots straight up.

I don't think it is the gauge because it gets hot only under load, and now with light load under freeway driving.


Can someone please help me with a suggestion?