Sudden overheating problem
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Sudden overheating problem
2004 F250 6.0 L. New head gaskets, ARP studs, new oil cooler, new water pump, all new hoses, new thermostat, 4" exhaust, EGR delete, new coolant bottle, radiator and cooling system flush, new injector seals and oil rail plugs all done at 98,000 miles. The truck is at 119,000 now and has been doing great since all the work. I have been frequently hauling very heavy loads and pulling cars on trailers and no problems. EOT has been staying about 7 degrees above ECT except on hill climbs. No coolant loss at all. Today suddenly while driving on the freeway (unloaded) the temps spiked. I pulled over when the ECT hit 240. Once cooled down I checked coolant level, hoses etc and since all was fine I took off again. Overheated again after about 5 miles. My understanding was that the Ford thermostat fails open if it fails. Do I have that wrong? Do I have a stuck thermostat? Some other problem? Any advice?
Lead Driver
Joined: Feb 2011
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From: L.A. (Lower Alabama)
Coolant level, belt slipping, impeller slipping on the shaft inside the water pump, blocked radiator (plastic bag or something) could be a possible reason. What are you monitoring temps with? Is it possible the sensor is failing? Oil temp climbing with coolant temp?
Normally the thermostat fails open just because of the way it's designed and how they fail but I don't know of any that can force it's self open if it happens bind up in the closed position.
Did you hear the coolant boiling in the system? If it overheats again, I reccommend not shutting it down right away, temp and pressure often spike even higher if you shut it down, let it idle a couple minutes and see if the temp drops.
Normally the thermostat fails open just because of the way it's designed and how they fail but I don't know of any that can force it's self open if it happens bind up in the closed position.
Did you hear the coolant boiling in the system? If it overheats again, I reccommend not shutting it down right away, temp and pressure often spike even higher if you shut it down, let it idle a couple minutes and see if the temp drops.
Last edited by Rusty Axlerod; Jul 13, 2015 at 09:41 PM. Reason: Add
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Coolant level, belt slipping, impeller slipping on the shaft inside the water pump, blocked radiator (plastic bag or something) could be a possible reason. What are you monitoring temps with? Is it possible the sensor is failing? Oil temp climbing with coolant temp?
Lead Driver
Joined: Feb 2011
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From: L.A. (Lower Alabama)
You're on it 
. Lots of good observations there. The water pump impeller is plastic and although I haven't seen one personally, there are quite a few posts on the subject of it slipping. The plastic impeller was on the factory part and many of the aftermarket replacements but I think I remember a couple people buying pumps with metal ones. Seems like it was just luck of the draw. I don't know if there is a specific part number that ensures you get metal but maybe someone else can post up a number if they have one.
There are two size water pumps, I believe the change happened mid year 2004, but it may have been 2005 that got a larger one.
. Lots of good observations there. The water pump impeller is plastic and although I haven't seen one personally, there are quite a few posts on the subject of it slipping. The plastic impeller was on the factory part and many of the aftermarket replacements but I think I remember a couple people buying pumps with metal ones. Seems like it was just luck of the draw. I don't know if there is a specific part number that ensures you get metal but maybe someone else can post up a number if they have one.There are two size water pumps, I believe the change happened mid year 2004, but it may have been 2005 that got a larger one.
Tuned
Joined: Nov 2005
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From: Double Oak, TX
A similar situation happened to us when we were down at South Padre Island. Suddenly, the temps went up for both coolant and oil. We limped back to the trailer park stopping a few times to let everything cool down. The engine cooled down over night and everything seemed to be OK in the morning. As I had a long trip home through the back roads of Texas, I opted to replace the water pump and thermostat and had them sent in from Rock Auto. Upon examination, the thermostat was dirty and apparently stuck closed, the water pump looked like new and the truck had 94K on it. I replaced the thermostat with a Stant and the water pump with a Gates. Later, I found out that the Ford thermostats can stick closed. I'd recommend you check/replace your thermostat first before anything else.
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A similar situation happened to us when we were down at South Padre Island. Suddenly, the temps went up for both coolant and oil. We limped back to the trailer park stopping a few times to let everything cool down. The engine cooled down over night and everything seemed to be OK in the morning. As I had a long trip home through the back roads of Texas, I opted to replace the water pump and thermostat and had them sent in from Rock Auto. Upon examination, the thermostat was dirty and apparently stuck closed, the water pump looked like new and the truck had 94K on it. I replaced the thermostat with a Stant and the water pump with a Gates. Later, I found out that the Ford thermostats can stick closed. I'd recommend you check/replace your thermostat first before anything else.
Maxi
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Yes the fan did come on strong as the temp passed about 235 or so.
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Tuned
Joined: Nov 2005
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From: Double Oak, TX
Since nobody has replied, I'll give you my cost for replacement of the water pump and thermostat. Parts delivered from Rock Auto-$69. Labor at a local shop in Port Isabel (a small bayside town), $173. Normally I would have done it myself but we were 600 miles from home. I would figure at least 2x at a Ford dealer or around $500. Good luck.
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Thanks for the reply. It must be the thermostat or the water pump. Drove it 5 miles today and the coolant temp climbed to 238 degrees and the oil temp went to 212. But using a pyrometer showed the upper radiator hose at 162 F and the top of the radiator at 155 F. The bottom of the radiator was 114. The oil pan showed 206. The front of the water pump housing read 219. Grrrrr. The water pump and thermostat are brand new.
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New thermostat this morning. Drove 5 miles to my shop. Coolant went to 237 and oil was still climbing at 223 when I idled it down to try to cool it off. Idled for a bit but coolant wouldn't of below 220. In researching on here and elsewhere I see there was a 90mm pump and a 100mm pump. My old pump measures 100 mm. I wonder if NAPA sold me the wrong size impeller/pump? It is part #43541. I called them but they said they couldn't tell me what size impeller that part number has.
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So any other ideas for me to check before I tear the stupid pump off? The radiator is not blocked with debris. I assume that since the oil temp and the coolant temp both rise to high levels the sender is OK. All hoses, belts, tensioner, idlers etc are new less than 10,000 miles ago.