jeroensikma

Hi all,

I have a 99 Cherokee XJ and my coolant is disappearing. I’ve read a lot of threads about this and all the potential solutions. After about 1000 miles on the highway I need to fill with about a gallon of coolant. It overheated once on 12k ft in Colorado, and spiked for 5 sec to 260 but then didn’t show any other problems. I’ve brought it to 2 different mechanics, 1 did a fluid test and said there might be some fumes getting into the coolant. The other did a pressure test, but did not see any problems. So before me driving too long with whatever problem and preliminary changing the head gasket, I wanna cross off anything that might cause this. The previous owner said someone had backed into her front bumper. There is a good dent in it, but she didn’t think it was worth fixing. The radiator is def loose because of the bumper. Could this be the cause of the problem? Worth fixing the bumper/radiator before anything else?

Thanks!

Kap

Cracked head. Coolant is flowing out with exhaust gases.

BlueRidgeMark

1. Accept reality. You have a cracked head or blown head gasket.
2. If your 'mechanics' didn't already tell you that, find different mechanics.

jeroensikma

Thanks both. I just needed to hear it from the Jeep owners!

agreen

Hold on a second. The number one cause of a mysterious coolant leak is the radiator cap.

jeroensikma

If it is indeed coming out of the radiator cap, would it be visible anywhere around the area? Or does it just straight evaporate? The coolant overflow tank seems to not change or loose anything. And looks clean. Oil seems clean to me as well.

BlueRidgeMark

Radiator caps don't put exhaust gasse in the coolant.

jeroensikma

Yea, that makes sense.

agreen

Ok, I get that. It's been to 2 different mechanics and one said "there might be combustion gases in the coolant. I'm not ready to condemn it based on that.

You won't see anything if the radiator cap has a slight leak to it. It'll barely steam off over time and you'll lose coolant slowly. Just try replacing the cap first. Fill it back up, drive around some more, and see if it loses coolant.

I mean, 1000 miles and a gallon of coolant doesn't quite sound like a head gasket. At least not yet.

BlueRidgeMark

That is a very cheap test/fix. Makes sense to give it a shot.

jeroensikma

Thanks everyone for sending your thoughts!

Mechanic said the blue fluid test turned light blue.. I’ve read many stories that those fluid tests are not super reliable? The other mechanic said If an engine pressure tests doesn’t show any loss of pressure, there is no need to do another fluid test. Both are reputable mechanics here in NYC. Both handle multiple Cherokees.

ill try the radiator cap and see how much coolant it loses!

agreen

So one of them is mostly correct. (This reminds me of the ASE tests lol)

The fluid test can be inaccurate if there's exhaust gases already in the air. Say, for instance, a cracked exhaust manifold is near.

The other one is mostly wrong. I have done cooling system pressure tests and it passes with flying colors, then overheats on the highway. When a head gasket juuuust starts to fail it can seal when cold. Can. Not always, but it can. So if it passes the pressure test, it could still have a problem.

jeroensikma

Could coolant leak out from a cracked exhaust manifold? I just read up on that, and I did seem I had to press the gas pedal a bit more for power. Initially I thought that was because I had a little transmission oil cap leak (which has been fixed), or because it didn’t have enough coolant in. I’ll go look and check the manifold tomorrow. I did get a new cap and filled her up.

agreen

What? No. The blue fluid test sniffs for exhaust gasses in the coolant (exposing a blown head gasket). If it sniffs exhaust gasses from another source (not from the coolant, but from a possibly cracked exhaust manifold) then the test is inconclusive.

jeroensikma

That makes sense. So what if my acceleration feels sluggish, little ticking sound and sometimes weird noises when engine is idle. Is that a potential intake manifold gasket leak that then also causes coolant to seep out?