Ever since i have owned this truck it has had a over heating problem. When i got the truck it was completely stock it over heated. I have since rebuilt the motor and when i had it out i cleaned all the water passages and got lots of junk out i thought then i had it fixed. I put the motor back together with new radiator, water pump, fan and fan clutch. Every thing in this cooling system is new and still has the same problem. I have tried every thing i know to do i'm in need of some ideas.

 

T-stat in good working order? How about the shroud and fan clutch, I know its new, but does it function correctly?

 

Two things I can think of, a bad fan clutch or is your shroud sealed to the radiator. OK one more, a collapsing hose. A bottom hose without the spring in it can collapse at high rpm/temps..

 

What is your AFR rate at? Does it change when under harder acceleration? What T-Stat are you running? I am going to a 180 in my truck, which is somewhat similar to yours.

 

i prepped my van for a vacation and pulled the stock t-stat (it looked like the old robertshaw style) and replaced it with a stant brand. same temp rating but different construction. drove on vacation for a couple of days and all seemed fine. went to reno and headed to sacramento about 1 am in oct and found i had no heat - it was about 40 deg out. went to the first ford dealer i found and bought a factory t-stat, installed it in the parking lot and all returned to normal. i have turned wrenches for a living for and have never seen this happen.

just tossing it out there...
neil

 

I have changed t-stats to no end so i now its not that. I have swaped the new and old fan clutch out made no difference. The fan shroud has a good seal and the air conditioer condensor is good and clean. The AFR never go's over 14.7 and will go as low as 13.0. I have a 195 t-stat in it now i guess i can try a 180 again?

 

Make sure the water pump is in good condition, also make sure it is the correct one for your engine and the pulley is the correct size. Some can have eroded blades which will cavitate, make bubbles, which don't cool very well.

Like the other guy said check your main hoses to see if they collapse at higher RPM. It may take almost a minute to see this happen. If the hoses do not have the spring in them or some reinforcing ridges, the hoses can collapse. This is a common problem.

When you rebuilt, I assume the correct gaskets for your model year were used and you did not block any coolant holes?

The block and head were hot tanked and then cleaned out with brushes etc? Block checked for cracks?

Are you sure the engine overheats or maybe the guage or sender is bad? Use a thermometer to check the real water temp.

Ignition timing and advance are correct?

A very long shot, but it happened to me once long ago...

Did you check the crank and bearing clearances. I am not sure if they still sell it, but plastiguage is great for this kind of measurement. I had an old Dodge that had one piston rod with an undersize bearing clearance. Caused me years of fiddling around with cooling before I discovered this problem when I did a rebuild. Requires a tear down so this would be my last resort.

Just some ideas,

Jim Henderson

 

Are you sure its not just a bad guage???

Put a candy thermometer in the radiator, and match it to your temp guage...

Is it puking antifreeze out all over? or the guage just reading hot??

 

Ok the water pump is good hell i don't think any thing was wrong with the one i took off. The lower hose is good no colapse all the gaskets are fel pro and the head gaskets are on right. i checked the water pump rpm looks to be doing 900rpm at 700rpm idle. The block and heads are good no problems and the timing is perfect. the sending unit looks to be good. but i put a mech gauge on it so i could watch it.
what i guess i didn't mension is just driving down the road is good even on the hotest days runs about 205. Stop and go traffic kills me on 100 degree days with a/c on. if i'm not moving at least 30mph the temp gauge will keep climbing. Idleing is good if i pop the hood on a hot day with the a/c off runs 210-215 with the a/c on it can't cool its self. Now once the cooler weather get here these problem will go a way but i want them to stay gone.
I have the standard size radiator for my truck maybe i need a bigger one? As you can see i am running out of options.

 

I never let it get to the point where it spits out a lot of antifreeze. When it starts getting around 220 i shut it down or get it moving.

 

You shut it down, or get it moving??? That tells me, 1 your water pump isnt operating efficiently, either the pullies are spinning it to slow, or something is causing restriction. OR 2 Your not moving air past the radiator fast enough...

The question I have as far as the water pump, is it new, from the old motor?? (prerebuild) or did you throw that one a way and get one from the parts store fresh? If it is from the old motor... They may have given you one that spins the wrong way??

Either way... it is either, 1 bad guage..2 Water flow issue,..3 airflow issue. based on your quote

 

If the vehicle moves and the temps come down its probably safe to assume that the fan is not pulling enough air. Do you know at which point the fan clutch pulls in? Sounds to me that there is just insufficient drive to cool the engine. This is typical of clutch style systems when oil leaks out and the variable side of the clutch does not work like it should.
Slower speeds and hotter engine temps leads me to believe that the fan clutch may be frewheeling a little too much and not tightening up enough to produce adequate air flow when engine speeds are low. Red lights can be torture if this is the case.
Since the truck cools down once it is rolling then the heat exchange seems to be fine, so the radiator is sized properly. The rest is left to low speed problems, which leads me to believe that the fan is not doing its job when it should.
I know it is now, but is it the correct one, and is it any good? Heavier duty option available for this? I see some difference between A/c and non A/c trucks. Perhaps you have had a non A/c unit the entire time? Just thinking out loud here.

 

I changed all the cooling system stuff before the rebuild and it is the right one. I checked the speed the water pump is moving and it is turning 892rpm with the crank pulley running at 720rpm. I also think there is not enough air being pulled through the radiator via the fan. That is why i have to get it moving to cool it but i have changed the fan and clutch. The fan i have is a 5 bladed fan is that right? I seen on summit they sell a 6 bladed replacement is that what i need. When this truck gets hot shouldn't i hear the fan roaring pulling lots of air? Because it never does. Thanks for all the help

 

I think you just hit on the problem. No fan roar. I doubt that you would mount the fan backward. I would be more inclined to think the fan clutch might be the wrong one. Did you check the arrow on the front of the clutch to make sure the clutch is designed for the correct rotation?

Richard

 

My 5.0 Cougar had a bad fan clutch and it did EXACTLY what you describe. I lived with it for a few years and as described Red lights along with running the AC would kill you on a hot day. There’s nuthin' funner than running the Heat full-blast on a hot/humid day to get the engine temperature back under control.

Now when I leave a light after idling with the AC on, I can hear the fan roar for the next 30 seconds or so... Overheating issue solved. I bought my OEM Ford Fan Clutch from RockAuto. Added bonus: AC blows colder at idle!

My AC'd F250 has a good (loud) fan clutch and it never runs hot. Inspect your clutch closely for any signs of oil leakage. Who Mfg'd the new clutch? (please don’t say made in China! )