Burning coolant
 

Hello all, I wanted to ask to see if you guys had any ideas of what could be causing my car to burn coolant. It is not burning it super fast, but fast enough that I need to fill it up periodically. I havent noticed a leak recently, and I know that it is burning because I can smell it after I park and get out of the car. My car has also decreased in gas mileage by about 4 mpg over the last few months (now standing at 12mpg), I think that it is related. It is a stock Cherokee 4.0L 1998. Any suggestions or tips would be most welcome.

Thank you

The radiator frequently splits at a corner. Check there first. Then check all hoses and track that leak. Pretty sure radiator fluid doesnt "burn" it just smells strongly because it is hot fluid. Check your oil and see how that looks. Your main seal may be bad if theres issues in the oil.

x2. I had a "leak" that only had the sound of air hissing on the top right corner tank on my radiator. Use a pressure test.

This year has a head that was prone to cracking if overheated too much I would suggest checking your oil if there's coolant let us know

Unexplained coolant loss is often a sign of a blown head gasket, and/or a cracked head.

This year is no more prone to cracking the head than others, excepting the 2000-01 0331 heads.

Any head can crack and any gasket can blow. Period.

You may not find coolant in the oil if the leak is not into an oil passage.

His is a 1998. It does NOT have the 0331 head.

If you can smell coolant when you get out and walk past the hood, I'd check the radiator first. Then all the hoses, water pump, etc. If its coming out the exhaust then you have a blown head gasket or cracked head. 1998 had the 0630 head, not the 0331 head, but as others have said, any head can crack and any head gasket can blow.

Exactly!


If not look for a hose with a pin hole leaking onto the exhaust that is burning.

Hello All,

Thanks so much for your replys. I looked at my oil, and concerning what it looks like, I am not totally sure what to look for, but it looked pretty normal to me other than being slightly darker than expected. I think that it is just due time for a change... I also looked for leaks and small pin holes without taking anything apart, and I didnt see anything out of the ordinary. I think that there may be merit to the idea that radiator is cracked in the corner because I do sometimes see a little puff of steam or smoke coming out of the driver side corner only right were the radiator would leak while sitting at a red light.

Would a leak in the radiator explain the loss of coolant, not seeing spots on the ground when you would expect to see a leak, and the decrease in gas mileage?

Thanks all

Yes, a crack in the cooling system anywhere would loose coolant, but a cracked radiator will definately leak. It leaks when under pressure, not when your engine is off, which would explain why you dont see much when shes parked. The water pump is turned by the engine's rotation of the belt, which turns a small turbine inside of the water pump moving the coolant throughout the engine and up into the radiator. The coolant is under pressure and if there is a failure within the housing (a crack) then the liquid will take the path of least resistance: out of the radiator. Depending on the crack size your fluid loss could be slow, or drastic.

Unfortunately our jeeps run on a series of sensors and mostly anything can cause bad mileage when they go bad or get strange readings. Unless youre pulling a house or suddenly god huge tires a sudden drop in mpgs can be really anything. Bad O2 sensors, bad sensors anywhere really lol. Im not much if an mpg diagnostician so someone else will hafta chime in for that one.

Thanks gunmetal, and everybody else, your information is excellent. I am thinking that I will take the thing apart and see if the radiator has a leak. Do you think that I should replace the water pump at the same time just to be safe?

Also another quick question, I was looking further into the gas mileage deal, and I realized that a couple of my tires were looking a little low. I pumped them up and I left it around 6 psi below max pressure, what are your opinion on this? Should I go with what the door panel says (with aftermarket tires) or just shoot for 3-6 psi below max rating on tire wall?

Lastly, some of you mentioned that I should look for a leak of coolant in the oil of the engine, what specifically would it look like?

Thanks

A chocolate milky look to it. Google it, you'll see plenty of pictures.

You might be able to see the leak without taking things apart right way. Poke around, maybe youll find it without doing all the extra work (youll have to anyway of you have a bad enough leak). Honestly its up to you to replace the pump. Does it look new? If you do take it off, check the insides. Also would be a good time to replace the thermostat. Lots of write ups on that. Preventative maintenence is nice, but it always costs money for new parts.

The tire pressure on the door is for stock tires. If you have anything not stock, you should go by the sidewall of the tire. Find what pressure works for you. Performance varies on type of tire, size, what load you have in the rig, wind, tire wear, YOU, etc.

Not always. Mine did not look milky when the head went. It was just a slightly lighter shade than normal. Newer oils do not react to water the way older oils did because of the improved detergent packages.

The only reliable way to determine whether there is coolant in your oil is to send a sample for analysis. Blackstone charges $25 and will send you the test kit for collecting the sample for free. They send you the oil report via email.

As long as you take the sample hot, the oil report will tell you for certain whether your oil is contaminated. I have an analysis done at every oil change just to see what's going on in the engine. It's cheap early-warning insurance.

If your tires are load range C, use 35-50 PSI.

If they are load range B, use 30-35 PSI.

The actual size doesn't matter.

Don't take anything apart until you verify for sure if you have an external leak or not.