Okay, so I've been avoiding having to post something for months, because I'm trying to go by the "Somebody's had this problem and has posted about it" rule, but apparently they haven't?? So I'm finally at my wits end. So here it is:

The gauge has lately been reading in the "higher" end of normal for quite some time, now. What it does is, while driving, it will get up to "normal" (around the "O") for around 5 minutes max, then it starts creeping up into the " R," then the "M," and occasionally it will drift into the "A" of "NORMAL." It normally used to stay on the "O" and never went above.

The things I've done: Started with a new radiator, from Murray. It's never fed the reservoir tank, nor taken from it, and I've bought 2 new caps, one an 8lb just to see if it made a difference. None. Nevertheless, next we replaced the water pump with a high flow one from Summit. Nope. Still getting hot. Then, we replaced all hoses, just to ensure no leaks are present. Nope. The thermostat in it is only about 9 months to a year old, so I wouldn't suspect that to be it. (I really don't want to replace that though, because the bolts both snapped off into the intake, so we had to re-tap and die the whole thing, and it takes a new silicone gasket to seal now, as the mating surface is not quite perfect, anymore.) Nonetheless, if you guys think I should try a new one, I will if I must. I really started noticing overheating a couple of weeks after the smog pump was disconnected. It was making racket so we discontinued its use (no smog checks in Florida.) If that makes any difference??

Things we haven't done: The fan (attached to the water pump) is starting to go a bit, but it still spins sufficiently enough to cause a breeze under the hood. Thus it hasn't been replaced yet. Thermostat hasn't been replaced yet.

Do you think we need a new radiator, despite this one being new? Since getting this one, the res tank doesn't fill or empty anymore. Maybe a thermostat? It's not that old, just don't want to do it because it's such a pain on mine particularly. do you think the smog stuff might have anything to do with it?? I'm at a loss. Any suggestions are greatly appreciated. Thanks guys.

 

One more thing: I did replace the gauge Sender, but alas, the new one does the same thing the old one does. We used a "point and shoot" thermometer while the thing reads hot, and the hottest reading we can pull anywhere is 189.

 

The way to test the fan behind your radiator would be get out on an open road where you can maintain a speed of say at least 50 MPH. If doing that you maintain a cooler steady temperature, you fan clutch is probably bad. By maintaining a reasonably fast speed, you are essentially taking the fan out of the equation, as the forward speed of the vehicle is blowing the air through the radiator.

It's strange you aren't filling and retrieving coolant from the reservoir tank. Are you sure the hose isn't plugged? If the hose was too soft it would at least deposit water in the tank.

 

You should put ALL the truck's details into your signature so we can see them with each of your posts. Right now, we don't even know which engine it has, but that's NOT all we need to know. Click this & read the caption:


(phone app link)

This caption explains exactly how to test the fan clutch:


(phone app link)

The link in the caption explains how the system works, what goes wrong with it (including the overflow tank), and how to test the radiator for blockage. The place to shoot temperature is the fronts of the heads, or the front crossover of the intake manifold on a V engine.

 

I apologize about skipping a few details. The truck is a 5.8L Windsor with an E4OD. 2wd. SB. SuperCab. 3.08 non-locking diff.

The fan clutch, as tested, is "weak," however, I do not believe that this is the final source for the problem, as it seems to run cooler when sitting. It heats up with more engine load, so O/D runs the hottest. Also, if I tow anything (including a mere jet-ski trailer, we get even hotter. Overdrive canceled, and all. I figured too at first, that enough speed would help, as my assumption was that the fan wasn't good enough to cool it adequately, but I can drive at 70 mph, and it stays warmer than when I drive at 20 mph. This doesn't make sense to me. Would this be symptomatic of radiator, or perhaps a partly stuck thermostat? Or do you guys have another suggestion? Thank you for your prompt responses so far.

EDIT: I also have shot temperature at the location you described. That's where we got the temp described in my original post. I'm going to re-read the second link and see if I can come up with any other deductions of my own.

 

If it's not in your signature, we won't know where to look for it as this thread (or any future ones you ask questions in) progresses.
https://www.f150forum.com/profile.php?do=editsignature
And you need to put ALL its details in there - not just what you've mentioned so far. Its YEAR is also important, and some years have several distinct options for each engine (MAP/MAF, sonic/PFEGR/DPFEGR, etc.), so be thorough. Your avatar makes it look like a '94-96, but that's when the most variations appeared.

The cooling system article in the caption of that 2nd thumbnail above explains how to test the radiator for internal blockage. This shows how to check for external blockage:


(phone app link)

This shows how to fix minor leaks:


(phone app link)

 

Thank you for the replies so far. Somehow my signature got deleted, so I reinstalled a signature. This should hopefully show said signature.

 

So is your avatar your truck? Why does it have a '94-96 front bumper? Was the original bumper damaged, and you got the later-style replacement? If so, how was it damaged - collision? Was anything else damaged?

Where did this hi-flow pump come from, and when/why was it installed? Got a link to the source?

Why is the smog pump disconnected? How exactly are the dual mufflers hooked up - as true duals? If so, what happened to the oxygen sensor & catalytic converters?

How long have you been running 12° advance? Have you tried setting it back to 10° since this problem appeared?

 

Doesn't really seem to be a problem here. It's not overheating. That's why changing the cap had no effect.

 

Honestly, the problem appeared shortly after installing the new radiator. This new radiator has NEVER vented into the overflow tank. Ever. I've got three different caps I've had on it, one of which was an 8lb cap, and none of them allowed it to work properly. The water pump was replaced because upon opening the radiator at operating temp, there was hardly any coolant flow. You could open the cap and there'd be no pressure build up, nor would there be any flow. Since water pump replacement, we have flow again. The timing bump was for a bit of additional power for when towing a larger load (like our boat). Some folks on this forum have talked about going to 14°, but I didn't want to take any chances. I have not reduced the timing back down since this issue. The dual is a one in, two out system. I've had it for years. Nothing is changed in front of the muffler, just behind it. The smog pump was disconnected by my uncle at the same time the water pump was installed (he also did the water pump). I don't know why I allowed that. Can't reverse it now, a lot of parts were lost on that one.

This is the link to the new water pump:
https://www.summitracing.com/parts/g...670p/overview/

The 94-96 bumper was installed for aesthetics. I preferred the slotted look of this one vs the other one. I am still running everything else fairly stock, minus lights. I don't have a chmsl, I have an R12 system that has been converted to R-134. And I do not have the airbag. I'm running a MAP system, not MAS. But that isn't related to my cooling issue. Lol.

Could the lack of venting be causing my overheating? The system at least does not have a leak (that I notice). It is usually full again when I look and see.

EDIT: The radiator is made by Murray, if that's any bit important.