87 300TDT Overheating issues
 

My Wagon has been having issues with running a little warm, but my mechanic swears it should be running at around 90. When I put a load on it, particularily uphills, the temperature would go up to about 100. If the uphill is long, then the temp even higher, sometimes even reaching 110. I changed the fan clutch and the radiator, and it still runs a little hot, about 90 on the freeway, I was going about 80mph and outside temp was about 80 farenheit. This was driving from SF to Los Angeles. about 400 miles.

Tonight, my wife was driving in about 65-69 f outside temperature and the car really did overheat, went to almost 120, I hope she didn't crack the head... I verified with my mechanic that he replaced coolant from the hose and the reservoir. Thermostat? Water pump? Advice? How do I check the water pump?

I have a 84 300 TD and had a similar problem, and I was able to fix it with a new cap to the radiator expansion tank

The cap is only a 5 dollar part that can contribute to the problem

Forced is right, over heating comes from poor circulation ( stuck t-stat, worn out water pump, plugged radiator, or low coolant level) All the cap does is raise the boiling point of the coolant by holding pressure on the system.

^^^^^Yep!

To adderess the overheating issue first posted, I would look first at the thermostat. When it goes up suddenly, it is usually the thermostat not opening all the way up, since you didn't mention coolant all over the engine bay I wouldn't think it was a burst hose causing sudden loss of coolant. If it didn't over heat any before the problem started, then it probably isn't a blown out head gasket, or a cracked head.

OK, still trying to diagnose the problem. The tricky thing is when I bought the car, it came with a WVO system, which I bypassed the fuel from going through. Meaning, coolant is still running through the system. Could this be contributing to the high temp issues?

I think the only thing I did not change out is the electric fan and water pump. How does the electric fan work? I have not seen it turn on yet, so I suspect that may be the problem.

When I go up the grapevine, which is a pretty steep grade where 18 wheelers trudge along at 30mph, my car gets pretty high in temp, even getting up to about 115 C. Way too high? Could my temp guage be off? Engine doesn't struggle though.

Any suggestions on how to diagnose this would be helpful. Could air be in the system? How to bleed air in the system? Sorry for the random thoughts, just thinking it through with the forums.

Getting hot under a load is an indication that the fuel supply is too lean, or the cylinder compression is falling off. Run a compression check and maybe a cylinder leakdown check, also check injector pump output. It still could be the water pump as well. You can check your temp. sender by putting it in water on a hot plate with a thermometer and watching the change in resistance with an ohm meter. The only way I know to get the proper ohm reading is to heat up a known good one with it.