I've had my '97 TJ (125,000 miles) for almost two years now. It runs fine and never overheats but it always smells hot after driving it. Temp gauge looks normal; radiator is always full, but the overflow bottle is always empty. Hose look good. No apparent leaks - ever. Radiator looks good - no leaks. It just smells hot, the overflow bottle is always empty, and I hear gurgling noises when I stop; but the radiator is always full.

Any thoughts? I thought maybe the thermostat but seems like that would cause more obvious problems.

I guess I could drain and refill the radiator but it really does look fine when I look inside; nice and green.

I took the overflow bottle and tube apart, cleaned them up, checked for leaks, and reattached them.

I guess it's not hurting anything but I grew up in the desert and learned to dread that hot radiator smell. It's like an instinct ...

Is this a sour kinda smell that's unfortunately rather difficult to describe in words?!

Do you get this in summer only, or winter too? My presumption is winter, since most people only raise issues when they're hot topics, if you'll pardon the expression.

My TJ is around the same as yours in terms of age/mileage. I get gurgling after long drives, but the temperature gauge sits on the ubiquitous 210 mark like everyone else's. You mention that the overflow bottle is empty. Shouldn't there be some in there, about 1/3 to 1/2? I though there was a 'full' indicator on there around 1/2 way down to allow for expansion, though that's just from memory. That's the only thing that draws my attention.

Otherwise, as you say, there's no damage being done. If everything's apparently fine, temperature gauge is okay, thermostat's fine etc etc, then it might be nothing more than an ageing radiator burning up 125,000 miles worth of bugs.

OTOH, no sign of a perished hose that might be spraying onto the block/manifold/any other hot engine part? Other than that, I'm truly out of ideas....

To expand on Incenerators answer, yes, there should be some anti-freeze in that bottle. If there is none at all, its gone someplace, probably out on the ground thru a tiny leak. Go buy a bottle and fill it to the add full mark when the engine is cold. Then pull off the pressure cap (again when its cold) and make sure thats filled, too. If the radiator has a small leak, sometimes it won't be able to draw the fluid out of the bottle as is cools and contracts.

My guess is that you were smelling anti-freeze, not "hot". Heat generally doesn't smell, its the heat that cooks off antifreeze or paint. If you've had the jeep for any period, it shouldn't be paint burning off.

My bet is your plastic tanks on your radiator are seeping (yes mabel your radiaotr is plastic)... The seals between the platic tanks and the metal core begins to harden over time... when that happens under pressure that is generated it seeps out - the evaporation of the water causes the odor :-) ie - it smells hot but because your still building pressure the system still cools.

Sooner or later the seam will bust apart and water will pour out. Most likely it is the top seem between the top tank and the core.

This is from personnal experience and having seen this very thing happen on multiple TJ's.

I posted this before, not saying its the answer, but has happened to me.

Had hot smell + empty overflow bottle. Found that the hose that fills the overflow bottle had worked its way loose. Spayed antifreeze everywhere in a fine mist. Shoved the hose back on, problem solved.

Thanks for all the feedback folks!
I appeciate you "checkin my six".
Yeah, this happens all the time, and no, I wouldn't call it a sour smell. It could be antifreeze I'm smellin' but it's the smell that used to tip me off (in the desert) that either my radiator was overflowing or my hose about to burst. But it's neither of thise things - I've smelled it for at least a year now.

Yeah, the overflow bottle should have something in it and the first thing I checked was the hose that goes to it. That's not it. But the thing is, if the water/antifreeze is going somewhere, I would expect to eventually find some missing from inside the radiator; but it's always full. (I check it cold)

I'm thinking it's most likely the "ageing radiator burning up 125,000 miles worth of bugs" or " plastic tanks on your radiator are seeping". Guess I'll do a flush 'n' fill in a few weeks and see what happens. And I'll keep my eye open for another radiator on E-bay; there's an outfit in Portland, OR called Jeep Recyclers that has lots of new and used TJ parts. E-bay Store
Anybody ever heard of them? I'm also watching for a heater box; they seem to have every year except 1997. (I would have though they were pretty much the same from '97 to '99 at least)

[Just reread my post: No, the heater isn't the problem; I just need to replace the heater box because the door that opens/closes for the defroster is broken.]

This may be a function of me being old and lazy, but I would refrain from using recycled cooling system parts on a TJ. As this thread has pretty well pointed out, the factory radiator isn't the most robust when new. As they age they just fail. You have absolutely no way of determining the prior owner, how many miles and under what condtions, or preventive maintenance. I hate guarantees if I'm the guy that will need to do the replacement and have my jeep out of service waiting for the brown truck.

The simple answer is to install a better quality new radiator. We had some postings a while back concerning new, soldered seam radiators. You can also get them with added cooling capacity. It does't take rocket science to buy and install a better quality part. It just takes money. DC puts the cheapest thing they can find in your shiney new jeep. All they really care about is that it lives thru the warranty period, or that the majority of them do. They can absorb some warranty expense because its cheaper. Then they make it back replacing them after warranty expires. I'm certain there is a formuala to define that, and its dollar driven.

You can probably buy a much better radiator for less than the dealer charges. DC and the dealers put in a terrible profit margin.

Look for the old fashioned radiators, the ones that don't use plastic tanks. Look for one that uses an extra row of tubes to help with cooling. Fins allow cooling, more is better.
If you replace the current radiator prior to its death, you've got a spare. You can even re-install it when you sell the jeep, harvesting the better one to use on your new TJ.

Cooling systems and drivelines aren't the place to go 'cheap'. If you want to save money, don't bother with a sound system. Sell off the back seat. Forget custom paint. Don't bother with high $ lights, anything chrome or Stainless. Just concentrate on function.