erratic temp gauge/coolant thump | Ford Explorer Forums - Serious Explorations

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erratic temp gauge/coolant thump

1dantheman

New Member
Joined
January 15, 2010
Messages
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City, State
crown point, indiana
Year, Model & Trim Level
96 sport 4.0
hello all, I've been having some trouble with my explorer, 96 4.0 pushrod engine 130k. I've owned the truck since 50k and have always maintained it. I had a leak in my radiator(cracked side tank), so I replaced it. I am currently having trouble with the temp gauge moving erratically, and the coolant thump sound. I recently replaced the thermostat, rad cap, and the coolant sensor. The gauge isn't as erratic now, but the temp still gets very hot, and then jumps down to very cool, I'm assuming, when the thermostat opens. I've read a bunch of threads on here, but don't know what to try next. The temp gauge was getting erratic this past summer before the rad went out. I burped the system a couple times, but it hasn't helped. the cooling system is clean. I usually do a flush every couple of years, so i don't think sludge is the culprit. Has anyone had problems with aftermarket radiators, flow pattern, etc? I'm going to change the upper and lower hoses tomorrow to see if a collapsing hose might be causing the thump sound. The upper hose did collapse when I was burping it a couple of days ago, before I discovered this site. I'm ruling out the water pump because the only failure i've seen with them is leaking. Do the explorer waterpump fins break down over time? Could a cracked head or blown head-gasket cause this? No smoke or coolant in oil, or any signs of head failure. the truck runs fine. I could be getting cylinder gasses in my coolant with no obvious signs. if i did a coolant pressure test with the engine running, an erratic gauge on the tester would indicate some type of head failure? ex: pressure going up and down. i've never experimented with any tests for checking for blown head gaskets/cracked head. Any help or advice would be appreciated. i work on cars all the time, but this problem is irritating me. thanks, Dan
 



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Sounds like air trapped in the system. That would account for the raising and dropping temp level. Also what brand and temperature thermo did you use, and are you certain your replaced it facing the correct way?
 






hello all, I've been having some trouble with my explorer, 96 4.0 pushrod engine 130k. I've owned the truck since 50k and have always maintained it. I had a leak in my radiator(cracked side tank), so I replaced it. I am currently having trouble with the temp gauge moving erratically, and the coolant thump sound. I recently replaced the thermostat, rad cap, and the coolant sensor. The gauge isn't as erratic now, but the temp still gets very hot, and then jumps down to very cool, I'm assuming, when the thermostat opens. I've read a bunch of threads on here, but don't know what to try next. The temp gauge was getting erratic this past summer before the rad went out. I burped the system a couple times, but it hasn't helped. the cooling system is clean. I usually do a flush every couple of years, so i don't think sludge is the culprit. Has anyone had problems with aftermarket radiators, flow pattern, etc? I'm going to change the upper and lower hoses tomorrow to see if a collapsing hose might be causing the thump sound. The upper hose did collapse when I was burping it a couple of days ago, before I discovered this site. I'm ruling out the water pump because the only failure i've seen with them is leaking. Do the explorer waterpump fins break down over time? Could a cracked head or blown head-gasket cause this? No smoke or coolant in oil, or any signs of head failure. the truck runs fine. I could be getting cylinder gasses in my coolant with no obvious signs. if i did a coolant pressure test with the engine running, an erratic gauge on the tester would indicate some type of head failure? ex: pressure going up and down. i've never experimented with any tests for checking for blown head gaskets/cracked head. Any help or advice would be appreciated. i work on cars all the time, but this problem is irritating me. thanks, Dan

There is a Ford TSB and special kit to address this problem(thumping and gauge variations). I believe there is a revised water pump too. It has to do with steam formation in the system. It could be your water pump is failing too.

I would definately pressure test the system.
 






1dantheman

Hi, i put in a napa thermostat, the spring is facing the engine, trickle hole on top. I think it was a 195. I also bought one from autozone, which was a 198, but the napa one seemed to be better quality. I already have the part # for the purge kit. I saw the TSB online F8PZ-8522-BA. The truck hasn't made this sound for 130k, so, I'm kind of wondering why it is doing it now. Are these trucks particular to a certain brand of antifreeze?
 






If the water pump was failing, what would indicate this, or what tests could I do to find out. Dan
 






I only use the motorcraft stat with this engine, as I was told to do so by an experienced Ford tech. It was subtly revised a few times and has a modern part number. I'm not saying that is causing your issue though, especially if two stats don't help it.

The other thing could be the thermostatic fan clutch.

I don't know how to test a water pump, but after all this time the impeller blades could be worn down. If the coolant was neglected in the past that is very likely. I did replace my pump, but it was because the shaft had play in it. The blades did have some wear on them.

These engines do hold some air but nothing to cause what you describe.
 






Are the waster pump blades steel, or are they a plastic composite? if they are plastic, I might try a new water pump. I'm almost certain the water pump is orignal. I bought the truck when it had 50k miles on it, and i haven't changed the pump since. i'm assuming a weak water pump might have problems purging air out of the system. Dan
 






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