I have done just about everything that I have read hear and am still over heating. My 94 IDI has an ATS turbo on it and I am wondering if that is causing me the problem. I have just replace (all motorcraft parts) the thermostat and water pump the clutch fan runs and cycles. I have no problem driving around town it heats up to the N and the O on the temp meter and will go back down. But as I get into elevation the over heating begins. It hits the R and the M and it just jumps over off the scale meter. Could it be my sensors? I dont know if the turbo has cook a head gasket or what the problem is. When it does over heat the top radiator hose is really hard but there is no bubbles in the overfill and there was no oil in the coolant and vise versa in the oil. It will run hot for a couple minutes and when I shut it off and start it up again and squeeze the top radiator hose the pressure is gone and it will cool down again. That is leading me to the Head gasket but any thing would help!!

 

so what your saying is,that the only indicator that the engine is running hot,is the factory gauge but it's not actually triggered the over temp light on the dash and hasn't gone past the normal range of the gauge?
if so,it doesn't sound like its overheating at all.if your seeing the gauge fluctuate a lot,it could be a bad sender or the t-stat is starting to stick.
have you considered going with an aftermarket temp gauge to see what water temps really are? this is where i'd start.

 

It is triggering the engine light as well I should have included that info as well. Thanks for the info. and the thermostat is brand new just replaced it today.

 

sounds like she's running warm then.
oem radiator?
50/50 low silicate coolant with sca's?
what brand t-stat?
13 lb cap? is it new? how many miles are on it?
fan clutch work?
is the spring still in the bottom hose so it's not collapsing?

 

Thanks again! New radiator not sure on make will have to look again. the coolant is the 50/50 prestone. The thermostat is Motorcraft. the radiator cap i will have to look at again might just get one. Fan clutch does kick on and idles back down so I pretty sure its working. And I dont think that the bottom hose has the spring. My truck is down the mountain from me other wise I would just run out to see. Again thank you.

 

I second checking out the hose. Supposedly, what ends up happening is the suction on the hose gets strong enough when you put a load on it that the hose actually sucks closed, which could explain why you're only seeing these issues when you work it.

An aftermarket temp gauge is almost a must on these trucks since the dash unit is basically useless, but the fact that your dash warning light is popping on is a big indicator something isn't right. Just FYI, I believe that sensor is set somewhere in the 240s, so if its going off, you're getting HOT!!!

There's also speculation that some aftermarket radiators really are not up to the task of keeping the IDIs cool. Again, this is only what I have heard. My experience with my aftermarket one (Champion radiator off eBay) has been mostly positive.

Mike

 

Hears the update. The lower radiator hose does have its spring. Installed aftermarket temp gauge on the extra port of my water pump and tried it out with just over a ton in the back. It didnt send any overheating signal in town ran about 190 coolest and 210 at max thats in town. As I got in to the mountains I run up about 4000 feet to a final altitude of 8000 ft. and the truck ran from 200 coolest to 220 hottest. As the factory temp gauge hit the midway point it jumped off the scale and the engine light came on. looked down and the new temp gauge said 210 of some where in there. Is it just my factory sensors? Any thing else I may have missed?

 

The port you used isn't a super-common one to use to pick up the temp, so I'm not sure how those numbers stack up. They don't sound terrible, though.

Most folks either put the sensor for the aftermarket gauge in one of two locations. The first is the same location where the stock sensor is now, which means (of course) that your dash gauge would go from 'useless' to 'non-functional'. The other common location is where the sensor for the idiot light screws in. That's where I have mine.

Prior to replacing the thermostat, my truck cruised at 205°±5°F around town all day long (unloaded), but I would see temps as high as low 230s with about a ton of motorcycles and associated gear in the back and on my little Kendon trailer. With the new thermostat, I'm mostly running in the 190s around town but have seen as high as 203°F if I'm being silly with it, but it backs right off as soon as the thermostat fully opens and/or I back off a little. Haven't yet had a chance to put a load on it.

Normally I'd say you just have a bad sensor, but since BOTH the gauge and the idiot light came on, I'm not so sure. Perhaps they share a common ground that's giving you issues? Overall, though, I'd say if you're reasonably confident in your aftermarket gauge, forget the factory stuff.

Did your fan clutch kick in when the temps picked up?

Mike

 

Move the sensor. In the water pump, it's reading the temp right after the coolant comes back from the radiator: the coldest it gets. The other sensors are in the heads: the hottest the coolant gets...