Sinking Creek 4WD Association

My Jeep's been running well for a while, seemingly without any issues. But over the past week that I've been home, the radiator fluid overflow bottle has been filled back up to the full mark (from about empty), yet today it is down and nearly empty. I realize that with the engine running, the overflow bottle may be more full than if the engine hadn't been running for a while. After parking the Jeep outside last night, I noticed two spots where radiator fluid had apparently been dripping. They weren't big, maybe 4-6 inches in diameter. At the bottom of the radiator, drips were forming on the petcock and another area or two from the same corner. It was not actually dripping.

Several months ago, I had the radiator flushed, and replaced the thermostat myself. There does not appear to be any leakage of coolant around the thermostat housing, though I need to check more closely. The coolant is collecting (in drops) on and around the petcock, I can see that the actual radiator fins in that lower corner look moist as if fluid had dripped down it.

Any suggestions of what may be the issue? I have no idea how I could lose a decent amount of coolant (say a liter or so from the overflow bottle) and not notice puddles under the Jeep. The Jeep has been in the garage, been driven daily the past few months, and there's no evidence of a major leak on the floor.

I am guessing that it must be leaking when I am driving, but don't know why. I have a feeling that a new radiator may be in order, but would like to narrow down the problem.

A possible culprit is the water pump, though that typically means coolant leaking down to the front of the oilpan and dripping from there. Not the case.

I checked all of the tubes going into the radiator, and all are tight and dry. The radiator itself is topped off with fluid, just the reservoir/overflow bottle that is low.

Bump for any 4.0L guys....

Keep checking the oil as well as the coolant. Make sure that they aren't mixing as this would be a tell tale sign of a blown head gasket. Granted this is worst case scenario, but very possible.

Another thing to check is your radiator cap. Sometimes, they can fail and that would be an inexpensive and quick fix.

Check on those two things and see what you find out.

Fonger wrote:Keep checking the oil as well as the coolant. Make sure that they aren't mixing as this would be a tell tale sign of a blown head gasket. Granted this is worst case scenario, but very possible.

Another thing to check is your radiator cap. Sometimes, they can fail and that would be an inexpensive and quick fix.

Check on those two things and see what you find out.

Oil is good, checked that.

Radiator cap is fine from what I can tell, seals nice and tight. Fluid level in the radiator itself is nice and full, reservoir at the "ADD" mark.

From what I've read up on, 4.0L TJ's radiators are comprised of a metal core, but plastic top/bottom, which are crimped onto the core. The seal can fail over time, and though it seems more common for the top seal to fail, in my case it seems to be the lower seal, since it appears that fluid is seeping around the joint of the metal/plastic.

I got the Jeep up to running temp, and let it idle while I checked things out, to see if having it warm and running would reveal signs of leaking. I couldn't find anything though. I also turned the heat on full blast for several minutes to determine if the heat running had anything to do with the coolant loss, but didn't seem to do anything.

As for a new radiator, where have you guys gotten them from? I've been recommended radiator warehouse, and have also read about radiator barn. Any other suggestions?

97JEEPTJ wrote:As for a new radiator, where have you guys gotten them from? I've been recommended radiator warehouse, and have also read about radiator barn. Any other suggestions?

I forget where but I got mine from one of those two

Jwlman wrote:

97JEEPTJ wrote:As for a new radiator, where have you guys gotten them from? I've been recommended radiator warehouse, and have also read about radiator barn. Any other suggestions?

I forget where but I got mine from one of those two

You get a 2-row? Pretty good quality/happy with it?

1800radiator in roanoke

ford150 wrote:1800radiator in roanoke

Well the Jeep's back home in MD Probably going to order one online to have ready for me to install when I get home for break. I'll keep it in mind though.

x2 for www.radiatorbarn.com

One of the last places you can get all metal replacement radiators.

97JEEPTJ wrote:
From what I've read up on, 4.0L TJ's radiators are comprised of a metal core, but plastic top/bottom, which are crimped onto the core. The seal can fail over time, and though it seems more common for the top seal to fail, in my case it seems to be the lower seal, since it appears that fluid is seeping around the joint of the metal/plastic.

this is an problem with all of the crimped radiators in the TJs ... mine leaks around the top and bottom .... not enough to notice a heavy drop in fluid level day to day ... but i add about a quart a month or so ...

if you get a replacement rad, get a good one without crimped caps. for a full metal one, they can be found.

from what i have read when i diagnosed my leak ... those rads last a few years, maybe 50k, and then start to leak at the crimp.

also, dont rule out cold water leaks. spend $20 and get new band clamps (not the crappy spring clamps) and a new rad cap ... if that doesnt fix the problem ... then reuse them on your new radiator (and keep the new rad cap that comes with your rad as a spare, it is not uncommon for them to go bad). cold water leaks are worse in the winter (obviously).

new clamps, new rad cap = $20 or so

new rad = a lot more.

its worth it to put new clamps and a new cap on it and see where it goes from there ... if it still leaks, you pinpointed your problem for $20 instead of paying a shop $100 to tell you your rad is bad.

if the fluid is on the bottom of the rad, you can pretty much rule out anything from the engine side ...

Thanks Jonesy.

It is the lower passenger side corner of the radiator, around the metal/plastic crimp that has been damp/wet and been dripping fluid from. Everything on the front of the engine (waterpump) has been dry.

When it was parked overnight, or as it sits at home in the garage now, it does not drip a lot, just enough for a small spot on the ground. So it must be worse when driving if the overflow bottle went from full to ADD in a week with no signs of puddles.

I'd like to try all of these things to pinpoint the problem (start of break), but I'm trying to decide whether I want to go ahead and order a radiator so it's there for me when I get back in case the one in now totally fails. Hmm...

I guess I will try these things as soon as I get home, and then decide on a new radiator or not. My dad will be driving it around this weekend, so we'll see if the leak progresses.

97JEEPTJ wrote:Thanks Jonesy.

It is the lower passenger side corner of the radiator, around the metal/plastic crimp that has been damp/wet and been dripping fluid from. Everything on the front of the engine (waterpump) has been dry.

When it was parked overnight, or as it sits at home in the garage now, it does not drip a lot, just enough for a small spot on the ground. So it must be worse when driving if the overflow bottle went from full to ADD in a week with no signs of puddles.

I'd like to try all of these things to pinpoint the problem (start of break), but I'm trying to decide whether I want to go ahead and order a radiator so it's there for me when I get back in case the one in now totally fails. Hmm...

I guess I will try these things as soon as I get home, and then decide on a new radiator or not. My dad will be driving it around this weekend, so we'll see if the leak progresses.

the crimps are common leak points, like i mentioned earlier. how many miles are on the jeep??

if you do put a new rad in ... do the whole job. rad, hoses, band / screw clamps (not the spring clamps, they leak like a sieve over time and you cant really tighten them), thermostat, and if you are up for it ... go ahead and flush the block.

if you have the cooling system apart already and are paying $200 or so for a new rad (that is a completely random number ... i have no idea what jeep rads cost) you might as well put in another $50 -75 for those nasty little parts that always seem to go bad as soon as you put the system back together.

if its in your budget, replace the common stuff and be done with it. but buy quality stuff for sure ... sont skimp ... it will probably come back 10 fold to haunt you ...

jonesy wrote: the crimps are common leak points, like i mentioned earlier. how many miles are on the jeep??

if you do put a new rad in ... do the whole job. rad, hoses, band / screw clamps (not the spring clamps, they leak like a sieve over time and you cant really tighten them), thermostat, and if you are up for it ... go ahead and flush the block.

if you have the cooling system apart already and are paying $200 or so for a new rad (that is a completely random number ... i have no idea what jeep rads cost) you might as well put in another $50 -75 for those nasty little parts that always seem to go bad as soon as you put the system back together.

if its in your budget, replace the common stuff and be done with it. but buy quality stuff for sure ... sont skimp ... it will probably come back 10 fold to haunt you ...

Close to 72k miles on the Jeep. I just replaced the thermostat a few months ago, so that should be good. A new radiator is lookin to be around $160-$180, pretty reasonable I suppose.

As for new hoses, are they standard, or are they specific parts per vehicle? Should an Advance Auto have them? I get what you mean about the real hose clamps and not the spring clamps, sounds like a good idea to me.

97JEEPTJ wrote:
Close to 72k miles on the Jeep. I just replaced the thermostat a few months ago, so that should be good. A new radiator is lookin to be around $160-$180, pretty reasonable I suppose.

As for new hoses, are they standard, or are they specific parts per vehicle? Should an Advance Auto have them? I get what you mean about the real hose clamps and not the spring clamps, sounds like a good idea to me.

yeah ... 72k is pretty typical to have the rad issue ...

you can get universal flex hoses ... but DONT. they are pretty worthless and they put some stress on the connections to the pump, thermostat housing, and radiator .... i put these in the "only as a last resort" category.

they do offer formed hoses which are application specific ... sometimes they take a few days to get in, but any auto parts store should be able to get them and might have them in stock ... get these ... they are easy to work with and usually not too expensive ...

upper and lower rad hoses from advance are going to run you about $25 for the lower and $15 for the upper ...

hose clamps should be $10 or so for 4 of them to fit your application ...