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#%!&$!! Mystery Coolant Leak

Mighty.Mighty_XJ

NAXJA Forum User
OK, I'm truly baffled.

I serviced the cooling system on my '99. It wasn't overheating, just "new" vehicle preventive maintenance. :repair: Full flush, all new hoses, thermostat, water pump, radiator. I'm using screw clamps & I put the coiled spring from an old hose into the new one. When I add coolant and before even running the Jeep, there's seepage from the base of the lower hose connection to the radiator. I swapped hoses. Same thing. I took the radiator back & bought a different one, different store, different brand. Same seeping. Disconnected the hose & reconnected. Still seeping! :banghead: What am I doing wrong?!?

This is driving me nuts - it's been 2 weeks, haven't driven the Jeep, and of course I waste coolant every time I disconnect the hose. Any ideas?
 
Just a shot in the dark...

The last new set of hoses I bought had their part numbers on a plastic tag that was pierced and looped through one end of the hose - leaving a tiny nearly invisible pinhole
on one end of each new hose. If this is your case, be sure that the hose is pushed on
the connection fully, and that the hose clamp is above the pin hole - or cut off that end
of the hose where it was pierced by the part number tag.

In the past, the part numbers on rad hoses were simply taped on, or printed on the hose
itself. I do not understand why using a plastic punch tag that would leave a tiny pin hole on the hose is such a great idea. Kids these days ...
 
Clamp too close to the Nipple rib at the end? Clamp not tight yet? Are you using a socket and wrench or a screwdriver?

I had a batch of super hard bad heater hose I had to send back recently, the entire lot has hard as a rock.

I hate plastic Radiator nipples.

Is it the right size hose?
 
I used 2 different hoses. One was a spare hose that I used to carry in my '92 for emergencies. The other is a brand new one from Rock Auto. No hole punched in it, PN taped on. I checked ... I placed the clamp as close to the radiator body as I could get it, then backed it off a quarter inch or so, then tightened it.
 
The 2 hoses were bought years apart, the latest one is from Rock Auto, no pinholes. Clamp has about quarter inch of room on each end. I used a screwdriver. My socket thingie is too short to get down there.

Right size hose? Pretty sure it is.
 
You need to locate the clamp in the middle of the radiator hose nipple, not at or near either end.

Also a screw drive does not cut it. Just does not tighten the clamp enough.

Move the clamp and get a proper tool, problem solved.

I always tighten clamps up to the point where I see the rubber starting to poke out of the clamp groves. Not too much, not too little. It is easy to under and over torque radiator hose clamps!!!

The 2 hoses were bought years apart, the latest one is from Rock Auto, no pinholes. Clamp has about quarter inch of room on each end. I used a screwdriver. My socket thingie is too short to get down there.

Right size hose? Pretty sure it is.
 
I always tighten clamps up to the point where I see the rubber starting to poke out of the clamp groves. Not too much, not too little. It is easy to under and over torque radiator hose clamps!!!
This part of your reply got me to thinking. So I took the hose off again and replaced the clamp with a factory clamp (which I hate). But the seepage stopped. It seems that the loose edge of the other clamp might have been butting up against something under the hose that I couldn't see, causing it to stop turning and made me think it was fully tightened. That's the only explanation I can think of because when I tightened it, it had completely stopped turning to the point of starting to strip the screw.

Anyway, problem solved. Thanks guys.
 
The factory clamps are a pain to R&R, but they tend to work best because, since they're spring-loaded, they keep constant tension regardless of temperature, swelling/contracting, etc.
 
The factory clamps are a pain to R&R, but they tend to work best because, since they're spring-loaded, they keep constant tension regardless of temperature, swelling/contracting, etc.


That's a very good point. I tend to avoid over tightening mine new, then snug them up 2-3 years later, and I make sure I place them so they are easy to reach with a 1/4 socket drive wrench.

The second best clamps are the ones with an inner sleeve, not sure what they call them, hard to find them. But the bolt on them is off set up off the surface of the hose.

Congrats to the OP on figuring it out.
 
Fuel injection clamp is what I know them as.
 
Fuel injection clamp is what I know them as.

These work well too:

https://www.z1motorsports.com/images/Z32HeaterHoseClamp.jpg
Z32HeaterHoseClamp.jpg


These are the ones I was mentioning, They have an odd name IIRC.

$_3.JPG
 
I use the factory spring type clamps and convert vehicles that didn't come with them to use the spring clamps. They are never too loose or too tight. They just work.

MOPAR SPRING HOSE CLAMP AT T/STAT HOUSING 50MM 55037990AA
MOPAR SPRING HOSE CLAMP AT RAD/LOWER 50MM 55307990AA
MOPAR SPRING HOSE CLAMP AT UPPER RADIATOR 42MM 04809146AA
MOPAR SPRING HOSE CLAMP AT WATER PUMP 55MM 55037660AA
 
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