Causes for 99 Mountaineer 5.0 overheating? | Ford Explorer Forums - Serious Explorations

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Causes for 99 Mountaineer 5.0 overheating?

jremington59

Explorer Addict
Joined
October 28, 2009
Messages
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City, State
Watertown, NY
Year, Model & Trim Level
1997, 99 and 2000 5.0's
I stopped and looked at a 99 Mountaineer today. The guy told me a garage told him it needed a water pump. I started it, and looked and the pump wasn't leaking, but it did get hotter than it was supposed to be so I shut it down. I've never seen a water pump go bad that wasn't leaking. The garage stated they changed the thermostat prior to diagnosing the water pump issue. My question is, if it's not leaking water, how the hell do you diagnose a bad water pump. And what else could cause the overheating issue?
 



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Ah---

Overheating can be several things--
Weak lower hose collapsing and not letting coolant back to the radiator-
Clogged radiator( coolant sealer)
Bad radiator cap
Clogged thermostat housing ( coolant sealer?)
Blown head gasket?

I suppose the water pump blades "could" have corroded off, or the impeller"could" be slipping on the shaft. Usually though, they just leak.

Ask him which shop told him this, then go ask if they remember--I think he could be pulling one on you. If the engine warms up and hot coolant gets to the heater core, coolant is being pumped--
 






I'm going back here in an hour or so and take a closer look. The sellers wife was home and she showed me the estimate for the water pump from the shop. I didn't want to overstep my mouth and say "I don't see how they knew that without tearing it down" without knowing if there was a way I didn't know of for checking the fins.

So would you check the oil for water and vice versa? I didn't see any "puffing" from the exhaust, and it heated up quickly, so there's not much if any water circulation going on. Wouldn't it be a surprise if the shop lied and never changed the thermostat, lol?
 






Cooling systems that have not been serviced as they should can and will turn coolant into a caustic slurry that can over time attack and actually mill the inpeller off of the water pump shaft. I have seen this where there was only a disc remaining on the shaft with all the blades gone. Some water pumps can also have the inpeller come off and the pump will not leak a drop.

Several years ago a gentelman came into my shop wanting to have a new radiator installed in his S-10 pick-up. His problem was that the truck could set and idel all day and never overheat but on the hiway the temp gauge would race the speedo. I checked his fan, also did an exaust gas test on the coolant system, negative gases and the flow of his radiator and assured him that they were working properly, and ask him if it might be the water pump. He said he had just put on a rebuilt one from a discount auto part store and it could not be bad it was new. He insisted he needed a new radiator. After the radiator replacement the same problem excisted. He insisted the new radiator was also the problem. So I replaced it with another new unit knowing the first one flowed properly.
The problem still existed and I told him that I had done everything but change the pump to no avail but he told me he was planing to take it to a GM dealer and let them check it over. Now it gets fun.
He was adviced it was a sensor, that did not fix it.

Then they told him his instument cluster was the problem and it needed to be changed, that did not fix it.

Lastly they decided it must be leaking head gaskets, and you guessed it, that did not fix it. Now $2000 later he returns to my shop almost in tears wanting me to advice him.
I told him the same thing I had told him before. Change the water pump and the problem was fixed.

Bottom line many cheap auto parts are not bargins even with lifetime warranties, how many times do you want to change them? Listen with both ears when a service shop has proven that all componants in the system check good and only one has a question mark hanging over its performance.
 






it could be the water pump, i've seen impeller blades get wore down due to rust in the cooling system. i've also seen impellers become loose on their shafts. these problems will not cause the w/p to leak. however, as Turtle mentioned there are many other reasons for overheating. some can be easily/inexpensively fixed, some can get very expensive. the 5.0 isn't known for blowing head gaskets, but if the cooling system has been neglected for 13 years (as many have been) and if the engine has been severely overheated, you could be looking at expensive repairs. i sure wouldn't take the word of the person selling the vehicle as to what the real problem is. if he's a dealer, make him change the water pump, thermostat and flush the cooling system. i'd also pull the plastic cover from the bottom of the radiator and check for signs of leaks. if after that it doesn't overheat, consider buying it, but there will no doubt need to be more maintenance/PM things needed. if you also have to replace the radiator, rad cap, hoses and serpentine belt, that's no big deal.

as far as radman's comments... all true, and i'll add one that took weeks to figure out on a '54 Corvette. the problem turned out to be a baffle, in the bottom of a resently re-cored radiator, had come loose and was blocking the coolant flow. the engine could idle all day w/out overheating, but if you brought the RPM up a little it would immediately overheat. let it idle again and it was fine.
 






Silly question, but is there coolant in the radiator? As a side note, don't depend on the gauge, use an infrared thermometer on the upper hose to determine radiator coolant temp. I bought my 5.0 Exploder from a woman who told me it needed a water pump or head gaskets because it always overheated at the drive-through. Right off the bat I noticed the lower valance was missing as well as all the plastic shrouding that directs the air through the radiator (she had earlier mentioned the missing valance due to hitting a snowbank). Replacement valance and duct work from a donor vehicle and (knock knock) has yet to overheat.

Bill
 






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