Thanks everyone for all the input..
Well, I put a new fan clutch on it earlier today just so i new it was good and was a cheap thing to buy anyway. Drove it around for a few minutes to heat it up. It was above 100 degrees outside at the time I was driving it. It takes a while to heat up to norm range. Temp still climbs at lower speeds/stops and was about 210 when I shut it down. The only thing I havent done at this point is pull the radiator and have it gone through. This is the same rad that I drove the old motor on with no issues at all. everything is original as far as the shroud and the fan itself. The only thing I did when I had the motor rebuilt was to remove all the emissions crap. We dont require emissions out here so figured I would lighten the load ,,so to speak. The engine runs great..just gets to warm in my mind. I have the factory guage and a mechanical gauge that I installed (both work fine),so I know its not a guage problem. Next step I guess is to pull the radiator.

 

A thought just came to mind, and its with the radiator cap. If its gone bad it won't hold correct pressure, and will cause you to run hot because the pressure raises the boiling point. Maybe a pressure test on the cap, and system would help find your issue.

 

Yea i thought of that to. Swapped out the cap with my bronco as I know its good and still get the same results. not sure what the pressure rating is on either one of them so maybe i'll give it another look. I really like it when things are cut and dry Head scratchers like this kill me..which makes my wife want to kill me !!!! I guess its an attention thing on her part

 

My wife tells me I love my truck more than her lol After a bit of thinking I thought we might be focusing in the wrong area as far as how hot your truck runs. I don't know if you have the equipment to test the pressure (I think Autozone will do it free if you don't) that would be a great method to get a closer grip on the issue.

We know the fan, shroud, and clutch are good. That leaves the radiator, hoses, and possibly your water pump. I'm sure that was replaced, or inspected during the rebuild, and they tend to be noticable when they go bad. I think its safe to assume everything else is in working order.

So I'm thinking a pressure test would help determine whether its clogged hoses, or a clogged radiator. If your system holds pressure, and your cap hold pressure it has to be something clogged based on what we know.

One way you can usually tell if its a clogged radiator is if there is alot of rust color anti freeze draining from the bottom. Another side note to keep in mind which won't be an issue for you seeing as you had to flush the anti-freeze is the PH balance. Over time the coolant will become more acidic which is what causes the excessive build up rust in the radiator along with the neglect of a radiator flush from time to time.

I do have one question. Do you know if stop leak, or such brands have ever been used on that radiator?

 

The pressure cap is not going to determine if it overheats or not, just when the system releases coolant from the cap. Of course coolant spewing from the radiator cap overflow is usually a sign to most people that it's overheating, but that's not necessarily true. A bad cap will let the system spew out or go into the coolant reservoir earlier than it should, but it does not affect the temperature of the system. The pressure of the cap just determines how hot the system can get before it does release.

So if you are running no cap, the system can run to around 212 F (depends on your altitude) before it starts boiling over. A 7 lb cap will let it run a higher temp before it boils over, and 13 lb cap higher, and a 16 lb cap even higher. But like I said it just controls the point when the system boils and releases coolant from the radiator, it does not affect how cool the engine runs.

 

Oh. I'm sorry for the miss information then. I see where I made my mistake with that. Thank you Franklin2. Then perhaps its restricted flow is the only thing I think of.

 

Maybe not the cure all but..

%80 distilled water, %20 50/50 coolant, and a bottle of red line water wetter.

Be sure to up the coolant before winter.

 

When I rebuilt the radiator for the I6 in my 85 F150 it ran considerably cooler afterwards. I took it apart for a leaking inlet end tank gasket and while it was out I took the opportunity to clean everything as best I could using my garden hose. I was amazed how much of a difference it made without any proper tools and it being my first time working on a radiator. Definitely worth the effort in my mind considering how easy it was, in my case, to get it out.

 

Didnt get a chance to mess with it today as it was just to hot here..113...I know now what the witch in the wiz of oz felt like cuz i thought i was gonna melt .. as for the truck though, the only thing I didnt replace or havent replaced are the upper radiator hose and the radiator itself. At this point I'm willing to bet its somthing with the radiator. One thing i've noticed or at least I think i have is that the coolant jug fills a little more when its running. Doesnt overflow at all. Gets about 2 inches higher than the fill line and thats it. Is that normal because its something Ive never noticed before. I;m also thinking about swapping the radiator out with my bronco..it has a fairley new modine in it. It has a 351 W though some i'm guessing there's not to much difference in it and may work well enough to let me know if that's the problem. Im installing a new tranni cooelr with its own fan this week so i'm hoping that helps out a bit. It's nice to have other minds to bat this around with as it's making me nuts at this point The wife thinks i'm losing my mind..I just like things to work the way they were designed. I was a flight engineer in the air force (22 yrs) and have just gotten use to that approach. Maybe i'm expecting too much here Anyway, thanks again for everyone's input..I'll keep you all up to speed on how it goes ...Dave b

 

JB-1..i've never taken a radiator apart..are there any special tools I may need if I attept that?

 

Oh hey, Vertrees..In answer to your question about the stop leak..I have no idea if its been used or not in this radiator..It hasnt since I've owned it but don't know what the PO did.

 

I don't know about your case, but in my case it was three hoses and two bolts then the radiator slid right out the top. The radiator had a bazillion little tabs holding each end tank in place. I very carefully (emphasis on carefully) bent the tabs back so the end tank could be freed. There was dirt in the end tank which I cleaned out. I used the hose to wash as much of the dirt from the fins as possible, which seamed like a lot to me. Installed the new end tank gasket, then reassembled everything. The tabs had to bent back into place. I just happened to have a pair of pliers which were the same width as the tabs and that made things a bit easier. As for catching the coolant, I found a 2.5 gallon bucket was the perfect size and just fit beneath the drain plug. As I said, first time for me and I did this at my apartment while hiding it from them since they freak out if they see you working on cars. So it's not as challenging as it sounds, provided one is very careful with those tabs. Tools I needed, ratchet, socket, screwdriver, hose, bucket, pliers. But I'm no expert. I can say that it's easier than raising babies, lol, so if you can do that, the radiator is nothing.

 

Oh ok. I have seen people who have used it and their vehicles have suffered from it is why I asked. I am 100% against the use of it, but thats just me. I wish you luck on the radiator.

 

It probably is filling higher than before, just because it's running hotter than before.......so there's more expansion.

Personally, I wouldn't go to the trouble of swapping the radiator out of a vehicle that it's working fine in, unless it's going to be correct in the recipient vehicle.
Even then, that radiator might also be struggling for cooling capacity with the new engine.

113 degrees . I can't imagine that. We have 100% humidity at times, but 35*C (95*F) is as hot as I can remember locally.