o.K guys I have a 1995, F-350, with a 351 Windsor. This started happening a few weeks ago my truck usally ran between the "NO" in NORMAL all of the time no matter what other than when I had my plow on when it was kinda hot outside. It now jumps between the "NOR" in "NORMAL" in the city. Now when I get on the highway that truck starts to warm up it comes all the way up to the "AL" in "NORMAL", when getting up to highway speeds and then it takes a little while fo it to cool down too, I have to trun the heat on HI to cool it a little. I have replaced the thermostat and it is working. Also Today I put in a brand new sever duty fan clutch which is working. All of the hoses are new and they all check out fine. There are no leaks coming from anywhere either. My next guess is the radator my be its plug or its one its way out. Any way guys I really need help on this I have to pull a 35 foot boat at the end of the month on a 360 mile long trip. I dont think my truck and handle it if my truck is heating up with out even working it hard. THANKS for the help.
Shane

 

Check your water pump to make sure the bearings are still good. If so I would go with a radiator that is getting pluged up.

 

If you can reach it, feel around on the radiator with your hand after you warm it up and shut it down. You are looking for spots that are not as hot as others. If they are big you may have to have it roded out, but you can try a good flush and see if that helps. Fix any leaks even little drips will cause it to overheat.

 

i also pull a 32ft boat with my truck and if i were you i would get a new radiator, a new rad. cap also make sure the fan is pulling air towards the back of the engine, not pushing it towards the radiator, you really have to flush your radiator yearly or else you will get deposts in it and it will slowly clog up the radiator, i know when it flushed my radiator it was full of crap, also try a 60/40 mix of water/ coolant, you can also switch to a 180degree thermostat, i would first replace the radiator and the radiator cap

 

O.k guys hear his something werid to chew on. After I posted early today I took the truck back out on the highway and it Was staying between the "NO" in "NORMAL". And I wasn't taking it easy on the gas pedal either I was going about 75 to 80 mph and the truck stayed cool the highest the gauge would come up was the "R" in NORMAL. And then it would go back to the "NO" in NORMAL and It stayed there too. I drove around town and it was fine then too. I still am going to have the radiator flushed tomarrow I know it wont make things worse. Now I really confused on how the truck ran hotter earlyer and now it going good, also the outside temp has stayed the same too. The waterpump also checked out to be running good too. So like I said I'll get a good flush and blow out an crap in the radiator, and go from there. THANKS guys for the help gotta love this web site.

Shane

 

O.k Thats It I can't take it anymore.I flushed out the system topped it off and I just had the truck up on the highway and it started to do the samething again. I bought this truck at the end of febuary, and the temp has always stayed near the NO in NORMAL. But up untill a few weeks ago it has been heating up around town and on the highway. In the in middle of june the bypass hose on the water pump blew and I replaced it and I was good to go. A little while after that I noticed the truck starting to warm up. Right now it is about 60 degrees outside so its fairly cool out. when I am speeding up on the highway is when the truck will start to heat up. this is weired you would think that the truck would stay cooler because there is more airflow on the highway, not in my case I get hotter on the highway and cooler in the city, Also there is no obstruction in front of the radiator either. The only 2 things that are part of the cooling system that I havent replaced are the water pump and the radiator. Guys I really need some help here I am open to anything at this point. THANKS
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Just a few days ago another member had the same issues.....he replaced the radiator and now it's all good. Yours is probly partially clogged and a backflush might not get all of the rust and crap out.

Welcome to FTE by the way
Good Luck
Bob

 

Shane, have you tried reading other posts on the issue and doing searches ??

Someone last week ws posting that he found that he had the wrong fan on his truck that blew air back through the radiator rather than the proper one that pulls it through and back over the engine. He was heating up the faster he went because of the fan fighting with air coming in through the grill.

 

chek your fanclutch.. if its heating up.. when driving up the highway. then the wind isnt letting the fanclutch move

 

I replaced the fan clutch the other day and it is working good. To day I did a back flush on the system hopeing that it would clear it out. Also the fan is pulling air into the radiator it can feel the flow going in. Like you guys said either radiator or water pump is next to be replaced. Also when I am looking down in too the radiator how much of a flow should I see. Right now it is moving kinda of slow. But it is moving I am not sure how fast it should be flowing. THANKS for the help I'm going to start pricing out radiators.