I have a 1995 F150 - 5.0 5 speed 4x4. If I go faster than about 55-60, it overheats! If I am climbing even a small grade - it overheats! If I am stuck in traffic, it COOLS DOWN! I put a new thermostat in it, that did not help. What the heck? Anybody got anything for me?

 

check your rad hoses. One of them (probably upper) could be collapsing with the suction from the waterpump at these speeds




Jim

 

Feel all the radiator hoses, as in run your hand along and squeeze. If you encounter a soft or "soggy" spot in the hose that may be the problem, it collapses under the heat and suction.

Try this: Get a helper to start the truck while you watch the fan with the hood up. Have the person rev the motor a few times, then hold it at like 3000 RPM. Does the fan speed up accordingly to the motor? If not, the fan clutch may be going/gone. If you can't tell, get a piece of cardboard and lightly drag it on the fan blades. If the noise gets faster, the fan obviously is speeding up.

If the hoses and fan look fine, then get a decent non-contact thermometer, don't trust the goofy stock gauge(better yet replace it with a real temp gauge, as in it has numbers instead of "normal") Take it with you on a trip. When the gauge indicates it's overheating, pull over and just shoot the radiator with the thermometer. A reading around 200-220 is the max you should see.

Another basic test is to feel the plastic of the overflow bottle. If the bottle is HOT from boilover coolant, then there's likely a problem.

If you really do have a overheating problem first do the simplest thing, a radiator flush. Cost you maybe an hour or two of time and $10 of coolant. Still no luck? Then you'll have to dig into things, since the t-stat is likely bad.

 

Try this: Get a helper to start the truck while you watch the fan with the hood up. Have the person rev the motor a few times, then hold it at like 3000 RPM. Does the fan speed up accordingly to the motor? If not, the fan clutch may be going/gone. If you can't tell, get a piece of cardboard and lightly drag it on the fan blades. If the noise gets faster, the fan obviously is speeding up.

_____

Very unlikely. When you get to hiway speeds the fan is unused for cooling. It is ram effect then. the most likely cause is clogged cats, or lean fuel mixture. You do any work on your carborator lately? Timing could be off too. A T-stat wouldn't cause those symptoms either.

 

I just bought the pickup about 6 weeks ago, so I have not done any work to it. I drove it all the way across Oklahoma and into Amarillo with no problem at all. Then, on to the New Mexico mountains with no problems. Then, I made a trip back to Amarillo and that's when I encountered the problems. Driving even on flat land (near Amarillo), I could not go faster than about 60 mph. Then, when I hit the mountains - I couldn't even get above 60 going DOWNHILL! Then, going through Santa Fe, at the red lights, it would cool some. So, I am going to check the hoses first and go from there. Thanks all of you for your help. I'll try these options and see what we get. I'll let ya know! Thanks again.

 

sounds like a plugged cat more and more......

 

Hey Chris - I am NOT a mechanic, but I am trying to learn. So, I don't know what a "cat" is. I know it sounds like a really goofy question, but we girls ask goofy questions! ha ha

Thanks,
Jady

 

A cat is a Catalytic Converter used in the exhaust system, it's like a filter, so the emissions of the vehicle aren't as bad. They can get old and clogged up and keep the engine from having proper air flow.

 

OK - I get that. Now, is there a way to decide if that IS the problem, or do I just need to replace the converter or ?????? AND - if I need to replace the converter, is that something that a girl could handle, or do I need to find a mechanic?

Thanks

 

Go to a muffler shop and have them do a diagnostic. That should be free and an estimate included. Once you know what is wrong (if there is something wrong with the exhaust) then you can shop for a good price to have it done.

 

Hey guys! I just wanted to let you know that you all really helped me figure this out. I checked the "cat" and,........well, I don't have one! What they did was put in two mufflers with single pipe in each and took the "cat" off. So that ruled that out. Then, I checked out the fan clutch, just the way you said Chris1450 - I could hold the fan blade in my fingers while someone else started the pickup - with no trouble at all! Then, when I released the fan blade, it took a couple of seconds for it to turn. Now, I knew the clutch must not be working or else it would have taken that blade away from me as soon as we hit that starter! And....... I can fix it myself!

Thanks a ton for all your help!

Happy Trails!

Jady