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Ideas for chronic leaking upper radiator hose at thermostat housing

lobo411

Well-Known Member
Joined
September 14, 2011
Messages
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Year, Model & Trim Level
1996 Explorer 4.0 OHV
Hi all,
I have a 1996 explorer XLT w/ 4.0. I've experienced mysterious signs of leaking for several years (puddles of coolant on top of the lower intake manifold, dripping coolant from the heater valve, even drops of coolant on the ignition coils). I finally tracked the leaks down to three sources: the front timing cover gasket (replaced, fixed), the heater hose on the radiator side of the heater valve (as opposed to the heater core side of the valve, which has never leaked...just put in a new hose and hope that fixes it), and the upper radiator hose where it meets the thermostat housing.

The upper radiator to thermostat housing is the problem hose. It has always leaked--that's where the puddles came from, and the coolant on the ignition coils (fan blew the coolant droplets onto the coil pack).

I put in a new upper radiator hose last year, and while I was at it I painted the rusty thermostat housing with rustoleum barbeque paint (believe it or not, I repainted the rusty tail pipe with this stuff 10 years ago and it still looks like it hasn't aged a day). That fixed the upper radiator hose leak. Then I removed the hose to replace the valve cover gaskets, and now it's leaking again. I'm guessing the paint may have helped it to seal originally.

Now, is this hose connection area a constant headache for anyone else? The same hose connects at the radiator and has never leaked a drop. Also, what to do about it? When I got home just now and popped the hood, I saw a pretty good trickle of water streaming down the thermostat housing, down the water pump, and to the ground. I touched the hose and it immediately spurted coolant, so I grabbed an 8mm socket on a 1/4" ratchet and tightened the hell out of it. All hoses use made in USA worm drive clamps.

I figure I'll see if that works, but if not, should I put on a second hose clamp? Am I putting the hose clamp in the wrong place (I have it occupying the 5/8" closest to the edge of the hose. Should I move it back some?)? Should I RTV the dang thing in?
 




radman

Elite Explorer
Joined
December 27, 2006
Messages
207
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Location
Indiana
City, State
Camby
Year, Model & Trim Level
99 Eddie 5.0
It may not be the hose but a badly pitted thermostat housing. You might want to remove it and inspect it closely. Over tightening the clamp can cut into the hose causing leakage. After 17 years it is not uncommon to need to replace these housings.
Mike
 




lobo411

Well-Known Member
Joined
September 14, 2011
Messages
921
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Year, Model & Trim Level
1996 Explorer 4.0 OHV
It may not be the hose but a badly pitted thermostat housing. You might want to remove it and inspect it closely. Over tightening the clamp can cut into the hose causing leakage. After 17 years it is not uncommon to need to replace these housings.
Mike

That's a good idea...I'm going to leave it on as long as it's not leaking ("Do no harm" principle), but frankly, without even taking it off I know it's deteriorating (that's why I keep repainting it). Rockauto has them for $15/$25, with the difference being that one is a "35 mm" and the other is a "40 mm." I have no idea what that really means...the diameter of the thermostat or something? I went to the manufacturer catalog and got no additional info. I'll email them, but anyone know what this is all about? I'd like to order one and just have it on hand so I can swap them out the next time an opportunity presents itself.
 




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