This is a long story:

My current issue now is cooling............at high speeds. **I now have a mech temp gauge by the way(temp sender went out).**
That truck actually stays pretty cool unless it's 100º+ and I'm sitting still for a long while(normal). At 2000rpm(40mph) it stays cool no matter how hot it is, really quite amazing.

But as I get to higher rpm's, such as 2500+ for some unknown reason the temp starts to VERY SLOWLY climb, and just doesn't stop. Especially an issue when it is 100º+. I have never driven it long enough at high rpms to let it get very hot, but the thermostat is fully open at 180º and if 60mph doesn't cool it down......

(last week when it was 105º I just happened to be on the hiway and going 60--it got up to ~200+ before I arrive to my destination)

-Timing is not exactly factory, however it's only set at 7ºBTDC(compared to factory of 5º), that little increase shouldn't make a difference like this...
-All rad hoses are replaced and are the correct ones for the truck so there are no kinks.
-Radiator was "rodded out" in late May, still no difference.
-Coolant is always good and I have a correctly working overflow tank setup with fluid in it.

It's not really an issue because it really only happens at high speeds which I'm not at very often......

...but I now realize that this issue keeps me from going out of town or something that'd require me to sustain 55mph+ for hour(s)......the truck couldn't do that.


I have searched high an low, asked everyone I know, and still the problem persists(I first stumbled upon this problem in the winter time a few months ago, so I've had time to troubleshoot to no avail). I really don't worry about it, but I wonder about the first time I'm going to take it out for a long long drive at "high" speeds...
Thank you all very much.

 

Are you using the stock shape radiator, and not some Dodge replacement or something? My first thought would be to make sure all your baffling is in place, and that all of the air going into the grille cavity is being directed through the core, and not able to blow around the rad somehow.

Your timing comment is interesting. Something to consider; even though your initial is set at 7 degrees, that doesn't necessarily mean the full advance isn't too much. You may want to look at where the timing is at the high end. Perhaps a timing recurve inside the dist is in order.

 

There's nothing really wrong with 200 deg. operating temps when it's 105 outside and you're at any speed. Your system will be good up to about 230 deg if you are using 50-50 antifreeze mix and a 7 psi cap. Your engine is working its hardest to maintain 60+ mph.

If you think it can do better, you haven't said anything about the water pump. Cooling problems at higher speeds are usually a water-side problem. If the impeller is old and corroded, it may not be up to the task.

 

i tend to agree with ross on this. you said you first realised this in winter. is it possible that head gasket has small internal leak, pushing fluid only when at higher rpm,s and pressures?

 

I take it this is your 56 with the 223...

I'm more familiar with similar questions about flatheads, but in general an engine will run about 100 degs above ambient air temps during normal operation.

Also a block needs to be CLEAN to keep from getting too warm. Crud that has built up over the years is like you wearing a sweater in the summer.

 

Last year a customer had an overheating issue I could not figure out. He was overheating while at speeds...kinda like you are describing. It ended up being a blown head gasket between a coolant port and exhaust port...it was just enough to loose some pressure. His system would also over-pressurize at times.

Water pump is a great thought. I tend to agree, temp problems at speeds are typical water related issues.

I almost wonder if one of the hoses isn't partially collapsing causing a lack of flow. The real test would be a lazer thermometer to see where the heat buildup is.

 

what engine do you have, direct drive fan or viscous clutch fan? had an interesting one on a piece of equipemnt a few months ago,would overheat only at higher rpm`s,at higher rpm`s the fan belt would slip causing the water pump to stop turning but it would keep the altenator turning, no squeel or nothing, tightened the belt and never overheated again,

 

Yes, stock and original. Looks like some of the baffling might actually be missing. Just noticed this last week, but could it really make that kind of difference?

Timing recurve in the dist? way beyond me.

Water pump was replaced as a rebuilt unit when motor was rebuilt last year.
Not to mention my point of this thread is: It seems like if I drove it long enough, it would just keep going higher, 200-210-230-???. If it doesn't stop at 200º with 60mph windspeeds and a fully opened thermo, then what reason would it stop at 220-230?

Block is quite clean. Relatively.

223 I-6 Direct drive fan.
That's an interesting note, but I check it pretty often, it seems pretty taught.



Thank you all for the advice. I think the first thing I'll do is install some new baffling.

 

If the air seals are missing, and the air flow is not going through the core, it will make a big difference. I have to second some of the suggestions....possible head gasket (was it retorqued as directed by Ford, and most gasket manufacturers?), possible water pump not flowing what it should. Personally, you will likely need to check and see if it actually keeps going beyond the 200-210 range. It can easily climb, and make you think it's gonna keep going, when in fact, it could get to a point and not climb anymore. Pressure test the cooling system, and with the engine fully warmed, give the throttle a few quick snaps above 2K RPM, and see if the pressure gauge keeps climbing. That will indicate a head, or head gasket problem. As mentioned above, let it warm up, and use a laser thermometer to determine the hottest spots, and check for actual, not perceived temperature. Check the hoses while looking under the hood....crack the throttle a few times, and see if they suck shut. First, however, you'll need to see if it actually climbs above the safe temp range. Use the laser thermometer, and let it get hot, and keep checking it. If it doesn't actually go above 210-220, or somewhere near there, it's not actually overheating.