bubbling coolant in overflow

[Russ Chung]

A couple of years ago, my factory radiator started to seep from a hairline crack in the plastic header. At the time, I had over 200,000 miles on my Jeep, and it had never overheated whether I was on a highway or climbing a hill or rock crawling or in rush hour traffic or in the desert or had the a/c going. I decided that the OEM/Mopar radiator was good enough. I paid about $250 for it at the dealer.

So far, in ten years and 270,000 miles, here's what I've had to do to keep things cool:
1. Replaced the radiator cap
2. Replaced the fan clutch. (Fortunately, it failed in the engaged position; if it had failed in the disengaged position, I could have overheated)
3. Replaced the radiator and both radiator hoses. Tip: make sure the lower hose has a spring inside so it won't collapse from the suction.
4. Changed the coolant every 100,000 miles with the Mopar HOAT coolant and distilled water. I have an inexpensive antifreeze tester and I keep the coolant at 50% concentration.

[daniel_buck]

Yea, I guess I should just stick with the OEM. I found one. I'll make sure that it's the radiator that is leaking (it appears to be that way) and then I'll order it up.

I'm kinda wondering if I should just go ahead and replace the fan clutch right now, while I'm at it. That way pretty much everything cooling the engine is new. new pump, new hoses, new radiator, new cap, new thermostat... might as well do the fan clutch too? or is it not so common for them to fail? When I removed it, I made sure to keep it up right, I guess laying them on their side will cause them to leak or something? (read that somewhere)

[Lumpy Grits]

I would not fix what ain't broke--
I've seen new FC's go TU also.
Wonder if there is a real brass radiator made that will fit??
LG

[daniel_buck]

I made it home without over heating. And I found an OEM Mopar radiator, it's on it's way.

Here's the crack, pretty obvious once everything was dry.

[Lumpy Grits]

WOW!
What psi cap are you run'n?
LG

[daniel_buck]

I know right!? it's not a location where they normally crack, from what I'm seeing online. Looks like it just straight up BURST, haha.

Funny thing is though, I just got back from a road trip that was 4+ hours of driving this weekend, and nothing happened to it, it was only a few days later that it happened. Well, I did bust the idler pulley mid-trip, the bearing exploded, and what remained fused to the mounting shaft, which I cut off with a hack saw and found a junk yard part to bolt a new pulley onto. But by some miracle that belt never slipped off the pulley even though the pulley was wobbling all around like crazy, and the water pump kept on pumping for 80 miles before we repaired the idler pulley.

But anyway, I just put a new cap on there 2 weeks ago, I believe it's 18psi. Maybe I should test it, and/or replace it with another one? How do you test the PSI on a radiator cap?

[Lumpy Grits]

My local NAPA can test caps. Maybe your's can.
Is 18 psi the OEM spec?
Think'n my CJ's cap is 16 psi, IIRC.
LG

[daniel_buck]

I'm not sure what the spec for TJs is, whatever it was I ordered said it was compatible for my year and engine. I think my old willys CJ has a 4 psi cap

[Russ Chung]

According to the FSM,

[COLOR="#0000CD"]The cap contains a springloaded pressure relief valve. This valve opens when
system pressure reaches the release range of 124-145 kPa (18-21 psi).
If pressure cap fails to hold pressure of at least 110 kPa (16 psi) replace cap.
Refer to the following CAUTION.
The pressure cap may test properly while positioned on tool 7700 (or equivalent). It may not hold
pressure or vacuum when installed on radiator. If so, inspect radiator filler neck and cap’s top gasket for
damage. Also inspect for dirt or distortion that may prevent cap from sealing properly.[/COLOR]

[daniel_buck]

if it actually opens up after 18psi, then i's probably fine then. Now I need to find that actual PSI out

Thanks Russ

[mrchips]

Genright sells a HD radiator for a good price, dont know much about it, but the specs seem to be better than the OEm radiator and at a better price.
Ck under New Products on there site.http://www.genright.com/ProductInfo....5#.VH87sig77zs

[daniel_buck]

So, I'd like to flush the coolant system as I put the new radiator in. My plan was, when the old radiator is removed, just pop off the thermostat, and put a garden hose in there. Remove the serpentine belt so that the water pump can move freely, and then just turn on the hose and cover the gap around the garden hose with my hand, forcing the water through the system.

And then disconnect one end of the heater hose, and flush that as well.

Will that work? I'd kinda like to get it flushed before the new radiator is in place, any suggestions? Or should I just put the new radiator in, and do a normal flush through the top of the radiator?

[Lumpy Grits]

That won't remove the hard deposits.
Need a pro for that.
LG

[daniel_buck]

Better to just button it all up, fill it with water and drive it to the closest place that can do a good flush?

[Lumpy Grits]

Yup.
LG