Hemi Coolant Leak Mystery

654 Views 14 Replies 5 Participants Last post by nvrdone1, 6 d ago

Mainsail

Discussion Starter · 14 d ago

Found a 'wetness' under the jeep, less than a puddle and more than a drip.

Pulled off the skids up front, not much there. There are visible droplets of coolant on the rear of the oil pan and dripping on the cat. Nothing above the oil pan dripping down.

I know there's a very slight seep up by the waterpump connections, but barely enough to form a drop, so I don't think that's the problem I'm seeing.

Is there a freeze-plug in the bellhousing area? Other than that I'm stumped. It's wet all around the lower aft part of the oil pan at the transmission-engine point.

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Mainsail

Discussion Starter · #2 · 14 d ago

Also, this is just laying by the coolant reservoir- what is it and should it be connected to anything?

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GRAND420

· #3 · 14 d ago (Edited)

The heater lines run behind the motor so it could be that. The second picture is the differential breather, It snaps on top of the strut stud.

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nwoods

· #4 · 14 d ago

Mainsail said:
Also, this is just laying by the coolant reservoir- what is it and should it be connected to anything?

View attachment 4187296

That is the end of the vent that comes up out of your differential. The round star shaped end fitting slips on over the top of one the shock strut nuts that is directly under that coolant tank. Its not broken and is quite easy to slip back on over one of those three nuts.

You can just barely see mine in the bottom left of this photo:

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Mainsail

Discussion Starter · #5 · 14 d ago

GRAND420 said:
The heater lines run behind the motor so it could be that. The second picture is the differential breather, It snaps on top of the strut stud.

I'm not seeing any coolant higher than the top of the oil pan, so nothing on the block dripping down.

I wiped everything down and ran it until it was up to temp - no sign of a leak or drip anywhere.

GRAND420

· #6 · 14 d ago

Maybe something is leaking when there is more pressure at higher RPMs. It could also be running down the front and then blowing towards the back when you're driving. Is your reservoir loosing anything?

Mainsail

Discussion Starter · #7 · 14 d ago

I guess anything is possible. I ran it until it was hot up on the ramps, crawled under and don't see anything. It's still on the rams and I'll look again in the morning.

mastertech64

· #8 · 12 d ago

The coolant can splash around everywhere. The 1st place to check is the top of the radiator, the plastic cracks or separates from the metal in the radiator. See if any fins are wet or sides of radiator are wet. If it is the radiator, tough job.

Mainsail

Discussion Starter · #9 · 12 d ago

After wiping everything down I left it up on the ramps and it looked dry for a day, then this morning there's a puddle forming again.

I was able to trace it up the front of the engine to the waterpump area (still not sure which of the two things up front there is the pump), but I don't see any weep-hole from which fluid would leak. So is the pump itself going bad? I want to be sure it's the pump before I start tearing into it because one I start pulling lines off there'll be coolant everywhere and tracing a leak will be much harder.

GRAND420

· #10 · 12 d ago

Maybe check the thermostat area and both radiator hoses. I believe the weep hole is behind the pully so it's hard to see. Try to find a small mirror to see behind the pulley.

Mainsail

Discussion Starter · #11 · 12 d ago

I put a breaker bar on the tensionor and took the load off the waterpump and it doesn't have any wiggle, so it's not like some of the videos where the pump is wasted.

As near as I can tell it's coming from the pump or the thermostat housing. I'll try to get a look behind the pulley.

nvrdone1

· #12 · 11 d ago

I had coolant seepage on my 07 5.7. Wasnt enough to leave a puddle - just a few drops when parked with engine hot with a loss of coolant in the overflow tank and a foul smell. Finally replaced the t'stat, gasket and housing. That was about 4 years ago and no more problems. I think it was because I used aftermarket parts. Replaced with OEM.

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Mainsail

Discussion Starter · #13 · 10 d ago

Thanks, I think I will start with a new thermostat and gasket since (1) it's a lot less work, (2) less expensive, and (3) I'd need those anyway if I change the water pump.

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Mainsail

Discussion Starter · #14 · 6 d ago

NAPA said there's a thermostat housing gasket, even though I didn't notice anyone changing one in the videos. Bought it anyway. Got the new t-stat and a gallon of coolant.

I pulled the housing off and think (hope) I found the smoking gun that says I get out of this cheap. The gasket around the t-stat is deteriorated and the housing shows evidence that coolant has been getting by it.

Even though there wasn't one under the t-stat housing, I did install the paper gasket NAPA sold me.

It'll take a couple days to be sure, but I may be out of this for around $50.

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nvrdone1

· #15 · 6 d ago

I know Napa shows a paper gasket for the t'stat housing on our 5.7's. But I'm not sure its needed. If I remember correctly there is only the o ring. Anyway, good luck. Hopefully this solves the problem.

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