My 1997 f-150 is overheating. The temperature climbs even when parked and the a/c off. Then when the needle gets to the red, the coolant starts pouring out from the coolant reservoir cap becuase the reservoir got full on it's own. The thermostat was changed on it a couple of months ago, the coolant IS green but seems to have rusty looking oil in it (not a lot). The engine oil is black. The radiator has bugs and so forth but nothing major and the fan clutch seems to be just fine. Does anyone know the cause of this? Could I have a head leak? Help.....

 

I'd check the t-stat to see if it opens, but check the water pump and change the coolant/ oil etc. If your head was leaking, white smoke would be out the tail pipe. Can't really say, all overheating I have ever had was bad water pumps and insufficent rads on old Model A's with 302's.

 

You can definitely have a head gasket leak into the waterjacket and force exhaust gas into the water but not have white smoke out the exhaust for a while. At first it will heat the water fast and create pressure blowing the water past the radiator cap and over flowing the reservoir. There is a radiator test that will tell if there is exhaust gas in the water. It uses a chemical that changes color when exposed to exhaust gas, sometimes called a "sniffer test". It won't be long before the white smoke starts and the oil turns sorta like chocolate milk. Better get it tested.

 

Well it definatley sounds like a head gasket leak. I am going to buy the dye or chemical today to test it. Thanks so far for the info but if anyone as any more suggestions, please let me know.

 

You might be able to test it without the special equipment, I don't know. I have only seen it done with an adapter that replaces the radiator cap that connects a hose into a glass jar that contains the chemical. Hope it's not the head gaskets cause they can get real expensive.

 

Okay, I did the chemical and nothin. the blue dye stayed blue. I did notice that when the coolant started to rise in the res. tank and I ran to shut the engine off, the coolant stopped rising. So I hooked up my snap on microscan and let the truck idle. At about a temp of 200 the thermostat opened I guess and the coolant began to rise again. To me this means that the thermostat is working but somehow the coolant is going thru the top hose into the radiator, thru the radiator and when the coolant exits thru lower hose, it is not traveling into the block but imstead it is traveling into the reservoir hose thru the bottom of the reservoir and pushing the coolant out thru the cap. Could this be a problem with the water pump? First time with this kind of problem. Need some help!!!!

 

Okay, I took the thermostat out and ran it like that. Same problem except this time it just takes longer to over heat. Thinkin maybe the radiator is plugged up or the waterpump aint workin hard enough. Any suggestions????????

 

I would test the chemical you have by putting some in a jar and put the jar right in the flow of exhaust at the tailpipe and shake the mixture. It only reacts to exhaust gas.

 

I would check the radiator for adequate flow/cooling. This truck is 9 years old. How many miles? Has the coolant been changed before? AntiFreeze is good for about 3 years, and then starts to ferment. It goes sour, and can lead to clogged radiator tubes.

How are the hoses? Is the lower hose collapsing by chance?

 

ESOXSHEP: The truck has 163,000 miles. it runs really good. Nice response, and nice power but just overheats and pours the coolant out of the cap once it gets past the 200 degree mark. The coolant has been changed but way more than 3 years I think. The cooolant still looks green. When it overheats and pushes the coolant through the cap both the top and lower hoses feel like they are filled with pressure. No collapsed hoses.

 

Pereirajr1,
Have you tested the radiator cap. Or is it the overflow cap that is pressurized? Anyway no pressure build up in system means lower boiling point for anti-freeze. Usually the system will just boil the coolant off. Not familiar with Failsafe coolant system. Rad caps are relatively cheap and I think you already know how to change. Cap testers are hand pumps with gages attached by hose to a cap, there is an adapter to test cap to cap.

Good Luck
David

 

Thanks David but I had already changed the radiator cap. It still did the same thing. So I am going to go ahead and chage the radiator and see what happens. I really want to say that I am new to this forum and it is great. Everyone is very knowledgable and helpful. I will change out the radiator let everyone know the outcome or I may have more questions.

 

If it was my money, before I bought a new rad and not need it I would just take it to a mechanic and let them diagnose it. Might be the best $100.00 you ever spent. Blown head gaskets are becoming an epidemic these days so the professional wrench turners have all kinds of neat equipment to track this stuff down.

I'm on my 2nd set of head gaskets on my '99 5.4. Luckily' it was under extended warranty. Weird thing was, with a cold engine the coolant system was airtight. But once it warmed up to normal op temps the gasket would leak. Its called aluminum heads bolted to a cast iron block.

 

Alright i just want to thank everyone for their input and suggestions. Now it is my turn to give something back. If your truck overheats and at about 200-220 the coolant starts to rise in the coolant reservoir and pours out thru the reservoir cap then you might have to replace your radiator becuase it might be clogged and it is not letting the coolant flow thru. I found this out after replacing the cap and the thermostat and performing the block leak test with the dye to check for head gasket leaks. If these 3 things check out okay then you might have a clogged radiator. I replaced the radiator, flushed the system and ran the truck for an hour and a half at idle and driving with the a/c on and the temp never went past the 210 mark. I hope that my experience helps someone else now or in the near future if this happens to you. Once again thanks everyone. This is an awsome forum.

Rogelio

 

Rogelio,
For those of us who have not had to change the Rad yet. Can you tell us how much that Rad set you back.

David