overheating while driving?

[forcefed]

Ok I know my clutch fan is bad and I'm goinig to pin it soon as I can get it off the waterpump. (PITA) When I'm driving empty and just going 55mph my truck starts to get warmer and warmer untill i have to eventually turn my heater on to help cool it down. I usually turn my heater on around 215 but the truck will cool down and idle all day at 195 degrees. My question is am I going to need a radiator too or is this just the clutch fan. I think just driving 55 and the wind from driving would be enough to cool down the radiator to keep the temp down. If I hit a decent grade i have to feather the throttle to keep it from shooting over 220, and this is not towing anything. Maybe water pump too? I just want to fix it all at once and not be under the hood 3 different times if I can. I have to leave next week and tow a 25' camper with me and need to resolve this in a couple days.

 

[MIDNIGHT RIDER]

Contrary to popular belief, a vehicle pushes a wall ahead of it that does not allow nearly so much air through the grille as one would believe.

Even at speed, one still needs some fan to pull a stream of air through that big shield that the vehicle is pushing ahead of it.

Make sense ??

 

[Rot Box]

Look through some of my recent threads about radiators... They can be a pain! I would check to see if you have a 3 or 4 row in your truck. This might be controversial but I don't think that most parts store 3 rows are enough to cool a 7.3 (6.9 maybe but not a 7.3) and finding a true 4 core replacement is somewhat difficult and/or very expensive. Typically a fan should not kick on while cruising down the highway unloaded under normal circumstances nor should the engine continue to heat up to the point of needing to turn on the heater. I'd be worried that your fan will be on the entire time you are pulling your trailer.

i would drain a little coolant out and look to see how many rows you have. Then if everything looks good and there isn't a ton of corrosion I would take a garden hose and flush out the fins to make sure there is no debris in the way--these big radiators can harbor a ton of crap in there! Good luck! Let us know what you find out

 

[The Warden]

You didn't say anything about the thermostat....do you know the history of it?

Unless you replaced it recently and you know it works properly, I would go ahead and replace it...just make sure you get one from either IH or Ford, and I would test it in a pot of boiling water with a candy thermometer to make sure it opens fully at the proper temperature, before installing it...

Beyond that, pulling the radiator and back-flushing it's never a bad idea, and if you don't know when it was last done, flushing out the engine itself would be a good idea also...

 

[forcefed]

Thanks, I'll try the garden hose and wash out the radiator fins. There is not any corrosion that I can see at all on the top the radiator. Its a original radiator but looks to be in great condition. Antifreeze looks great and nitrates are fine too. Thermostat is original but I can watch my guage and it opens at 190 and my temp will drop to about 180 then slowly level off at 190-195 till I start driving. Then from there it just slowly climbs till I sit and idle for awhile or turn on my heater while driving.

 

[The Warden]

Thanks, I'll try the garden hose and wash out the radiator fins. There is not any corrosion that I can see at all on the top the radiator. Its a original radiator but looks to be in great condition. Antifreeze looks great and nitrates are fine too. Thermostat is original but I can watch my guage and it opens at 190 and my temp will drop to about 180 then slowly level off at 190-195 till I start driving. Then from there it just slowly climbs till I sit and idle for awhile or turn on my heater while driving.

It may not be opening all the way...it's supposed to open a little bit at 190 F and IIRC it's supposed to be completely open by 210 F. At that point, if the thermostat's opening all the way, the system SHOULD be able to keep up with the engine's output and then some.

If you look at the heater lines, they go from the cylinder head to the core, and then back to the water pump, bypassing the thermostat. So, if the system can maintain a temperature once you turn the heater on, that tells me that it's either a thermostat issue or a SEVERELY clogged radiator, or maybe both.

What do you know about the history of your truck in general and the cooling system in particular? If you don't know when it was last done, I would recommend thoroughly flushing the system (including pulling the block drains, and possibly even running a flush compound) and replacing the thermostat. For that matter, what shape are your hoses in?

 

[forcefed]

Hoses are in good shape and I do not know when the last flush was done on it. I have had for 3 years and I have never done a flush on it. Never had a issue with it until now. I changed the antifreeze when I bought it and everything has been fine since. Maybe its time just to go through everything and refresh it all.

 

[MUDKICKR]

could also be a radiator cap holding to much pressure, since you do relieve some pressure by turning the heater on.

 

[vegas39]

If your thermostat is good, then I'm going to say bad fan clutch.
I can be haulin down the freeway here and the wind isnt enough. As soon as the clutch hits in full force, about 205 degrees, the thing drops fast back to 195.

My radiator is plugged a little bit and even at that, with a good fan clutch my truck never goes over 210, even at 110 degrees outside.

I bought my fan clutch at napa, about 150 bucks and was really easy to change.

 

[forcefed]

Update. I got my fan clutch off and decided to pin it to see if it helped any before going any other routes. Re-installed the pinned clutch and took it for a drive. Now mind you it is late evening now and not 90 degrees out but I turned my ac on and got the egts to 1000 and I could not get the truck to run past 200. So tomorrow when it is hot and sunny out again I will take it on a trip and hook a trailer up and see what she does. So far it seems like the fan clutch is to blame for overheating.

 

[Cincinnati Guy]

How can you test a fan clutch?

 

[franklin2]

How can you test a fan clutch?

I have tried playing with the fan while putting a heat gun on the bimetal spring in front, but I never came to any conclusion, basically since both clutches I had were bad. I could see the spring move though, but the fan clutch may have to spin at a high rpm for the fluid inside to work correctly.

Someone else can chime in, but most of the good clutches I have had on other vehicles were locked after they sit overnight, and the fan made a loud roaring noise when you first cranked the engine. After it ran a couple of seconds, the fluid would settle out and it would start free-wheeling. I have never had a broken clutch do this.

 

[forcefed]

I know you can check the fan to see if is locked in by driving down the road and when your truck starts to get warm you can pull over and pop the hood and rev your engine to see if your fan speed increses with you rpms. Mine didn't so I assumed my clutch was bad and it was. Now since I have mine pinned, wow I can tell you my fan has never been fully locked in when the clutch was good. Big difference.

 

[Agnem]

I doubt the fan is your problem. Those of us who have converted to electric will point out that you should be able to get away without having a fan at road speed on level terrain with no load.

 

[forcefed]

Well I don't know but I pulled a trailer full of wood and my truck was loaded with wood too and never seen it go past 210 today. Soon as I was on level road it cooled right back down to around 200 and stayed there. I don't know but pinning the clutch seem to work so far. I know that I want to buy a new clutch though because like said 2000 rpms seems like a train under my hood and it can't be good on the water pump bearings.