I have an '01 supercrew 4.6 4x2 w/70.000 miles on motor. Today i towed my boat for service. Ambient about 80deg, speed at 60mph, rad. flush 2yrs ago. No trans cooler, (just orderd one today) A/C runnig, and with a slight grade, The temp. climbed very high almost to red. Shut down A/C, slowed to 50mph. and ran heater, temp. started to drop some, however, not much. Exit fwy. while driving the streets the temp. dropped to almost normal operating range. I thought it was due to the extra load, while on the fwy. When i dropped off the boat and was on the fwy with the A/C running it was doing the samething. So I again exited the fwy. and had lunch, after aprox 90min. I checked under the hood and found the overflow tank was at mid level, and there was pressure when I removed the cap some steam escaped, along with a fishy like smell, I took the streets home and again the temp. was at almost at normal range. I never had any issue's with overheating before while towing. I checked the fan clutch tonight by spinning the fan and I felt some resistence. Any suggestions, Thanks.

 

Go to Autozone and rent a coolant pressure tester. When testing look for external leaks. If no external leaks check your oil level to make sure its not elevated. This could be the beginning of a headgasket leak.

 

Did you change your thermostat when you did the coolant flush two years ago?

Regards

Jean Marc Chartier

 

The thermostat has not been replaced since purchasing the truck.
If it was to be the head gaskets, what I'm I looking at to repair this issue and how difficult of a job is it. I looked at the engine and I did not noticed anything leaking, the motor is clean and dry. When I run the engine it is smooth, I did noticed that the fan clutch is winding up and down, however, the RPM's are at 700 and steady.

 

Time for a new thermostat.......

Regards

Jean Marc Chartier

 

JMC, from your opinion it's the stat. OK, I'm on my way to the dealer to purchase it. I will let you know whay the results are after completing the job.

 

OK, I changed out the thermostat and I also replaced the upper rad. hose. I went for a test drive with the A/C on. Drove up some near by hills and back home, all in all a total of 10 miles. I did not noticed any signs of overheating, seems to be normal, however, when i raised the hood to check for leaks I touched the new rad. upper hose and it was hard to compress, I opened the rad. cap and the pressure released. Is this normal to have the upper hose acting this way? And do I have to bleed out any air that may have enterd the system? Thanks for the help.....

 

Normal.. system is pressurized when its hot.. one thing the lower hose is the one that will be more likely to fail if you were going to replace one that would be the one to do first. Its a bugger though. 4-5 hoses in one. Real drag to replace plus it costs about $150-200..