Anthonyb

1996 Sport 4.0

The coolant level in my overflow bottle seems to be getting lower over time. There is no smoke, there are no wet spots under the Jeep, there is no residue on the dipstick or on the oil cap. The engine runs and sounds exactly the same as when I bought it almost three years ago. There are no telltale white spots in the engine bay anywhere to show a potential leak. After 2 1/2 years of owning this Jeep I have seen and fixed my fair share of those. So I am at a loss as to what is going on.

The level has dropped maybe a half inch to three quarters of an inch over the course of a couple of months. So am I being over concerned or is there a potential issue? Is it simply contraction due to the colder winter temps incurred over the last couple of months? (Minnesota) I have noticed just after shutting it off at normal temp, the coolant in the overflow bottle seems to be ats the normal level.

Additionally my A/C doesn't work, all the R134 just leaks out after a week or two, so it never runs. Well, earlier in the summer, I had to replace the Prestone flush plug that the PO had installed as it was leaking coolant. I just replaced it with a new hose completely, problem solved. Elevated the front end let it warm up, and burped it as best as I could. Is there a possibility there is still some air in there as the A/C does not work and this is causing some coolant burn off? Admittedly I know very little about A/C sytems in relation to the cooling system.

Thanks for any ideas help or suggestions. Sorry for the lengthy post, but I wanted to give as much info as possible for a more accurate answer. Thanks!

bloddy mud

The AC has nothing to do with the coolant. I think it getting cold out. Keep an eye on it

Anthonyb

Cool, thanks for the reply, I just thought that since everything I had read prior to burping it said to have the A/C on max that it had something to do with it, but I feel better you saying it doesn't!

Northwoods Snowman

You might try doing a compression check. A common cause for mysterious coolant loss is a cracked head or a blown head gasket. The compression check should help rule out or confirm a blown head gasket. You don't have the 0331 head on a 96 so the cracked head is less likely. You'll loose SOME coolant over time due to evaporation, but I don't know how much. I'm loosing some slowly even after redoing my head, but I think I have a pinhole leak in my heater core as I get the sweet coolant smell from the vents when I turn the fan on high after being on low for a while.

JJCIII

Have you noticed the carpet being wet? Specifically on the passenger side under the dash. But definitely do a compression check. Some small leaks only occur while driving due to higher pressure which is probably why you dont have a wetspot on the driveway. But judging from thecoolant smell id put my money on a bad heater core or hoses running to it

Anthonyb

Nope, carpet is dry. And there is no smell, not sure where that came from, but everything is perfectly normal except it seems to be losing a tiny amount of coolant over time. I'm talking like a half inch over two months or so in the bottle. And the heater blows heat directly from hell so no problems with the heater core.

Anthonyb

Ahh, I see that was in reference to the previous poster!

Kalali

I wouldn't worry about that much coolant loss over that time period. Just check it regularly.

tjwalker

How old is your radiator?

It is not at all uncommon to have a small amount of coolant loss with a radiator that is beginning to fail at one of the plastic seams (if so equipped). I've seen it more times than I can remember. And I had it happen to me personally on my 99. Eventually the leak got large enough for me to find it.

I'd take a very close look at the seams on the radiator.

Anthonyb

Radiator is less than 2 years old. Since I bought it in march 2010, I've replaced the water pump, radiator, t-stat, and most of the hoses. Radiator went in summer of 2011 I think?

tjwalker

Do NOT rule a leaking radiator out, no matter how new it is. I've seen them leak right out of the box.

Inspect your radiator.

kansas-klx

Mine's kind of the same way. Once colder temps came around the level in the overflow dropped a bit when cold but once the engine is operated at normal temps, it goes to the level I'm used to seeing it at. It doesn't concern me too much since I'm always snooping around under the hood to make sure nothing is leaking, loose, or smells funny. Zero tolerance here for coolant and fuel leaks...

Northwoods Snowman

If you want to rule out the engine there's two things you can do, well I guess three.

1) One would be to do a pressure test on the cooling system. If you're not familiar with it it basically entails pressurizing the system and then monitoring if/how the pressure drops. You can usually borrow a tester from Autozone or O'Reilly's or Advance Auto. If the pressure drops too fast there's a leak somewhere; if you can't see anything dripping it's likely internal to the engine

2) As mentioned before, do a compression check with the engine at operating temp. If one cylinder or a pair of cylinders next to each other are low the head gasket might be blown.

3) Have an oil analysis done to check for coolant in the oil. I didn't do this when I found I had a blow head gasket, I found my issue because i changed my rear main seal and when the oil pan was off I had water in the bottom and a water film on everything in the lower end of the engine!

4) OK, so one more thing to look for would be oily goop build up in the coolant overflow bottle. If coolant is getting into the engine then it's likely that oil is getting in the coolant and it will show up in the bottle.

If these things all check out then I would think you can be confident nothing with wrong with the head/gasket and the coolant loss is just due to evaporation unless you can find a weaping radiator or something like that that is so slow it dries up before you can find it. If that's the case, you might try some of the fluorescent dye that you put in the coolant and then use a black light to make it fluoresce.

The Rooster

make sure all the clamps are tight on the hoses... check all your hoses... you could have a pin hole leak.... older hoses swell which could cause a not to noticeable leak.. and as tj said check your radiator... did the new radiator come with a new rad cap?

Me personally being a 96 I do not think you you have a head gasket problem... unless you overheated it before.... that is a very little amount for such a long period of time.... just double check your coolant system...

The Rooster

i just saw that... coolant dye eh? that is a great idea as well...