running cold
 

I have a 1990 7.3 that is not getting up to operating temp. I have put a new thermostat and did a flush and fill with a mix of 50/50. It wont get above 175/180 at highway speeds pulling a 2200 lbs car trailer with a 5000lbs junk SUV on it. Any ideas would help. Thanks.

I hope you are using a motorcraft or international t-stat, the chinese just can't seem to make a good IDI version. Lot's of people complaining about the aftermarket units. What kind of outside temps are you seeing? I know when it's in the single digits out here, I can have my truck plugged in all night, let it idle for 20 minutes and then drive another 40 minutes to work and it's still not very warm. These trucks have a large cooling system, and sometimes a winter front cover is necessary to get these things up to temp.

running cold
 

Just switched from stant to a gates brand t-stat. Outside temps have been running in the mid 30's to the high 40s. I will have to go to the Ford dealer and get one from them. I know last winter when we had that porlar vortex super cold i had no problems at all with it. No grill cover needed. I live in North West Ohio. Thanks.

For some reason, the aftermarket units either don't let the motor heat up enough or don't open far enough and cause it to overheat. I was just searching on my other IDI forum about this issue and several people with the same problem as you, cured it by putting in a motor craft thermostat.

running cold
 

Ok. Thanks. I will let ya know what happens after I put the new one in.

running cold
 

Ok. Just put a new motocraft thermostat in and i put a new water pump and fan clutch on it let it idle in the driveway for 15 minutes or so then drove 20 minutes to work and still not getting above 175 degrees and the outside temp is 34. Not sure what to do next but any and all ideas would help. Thanks.

I am assuming you have a mechanical temp gauge?

running cold
 

Yea I have a sunpro after market. I even purchased a laser temp gun to make sure the Gauge did not go bad,when I take a temp reading at the thermocouple for the gauge at the block it is with in 3 to 5 degrees of what the gauge is reading in side the truck.. I have been reading some other sites and a couple of guys have said something about the little ball inside the t-stat housing,I just ddon't think that there would be enough coolant flow that small passage to cause this much trouble. Thanks.