Help, coolant problem with my Jeep

[JPL]

I know this is a Charger web site and you guys have been really good to me and my '71 SE  but I am lost, and so is everybody that's tried to help me with this problem. I have a 2002 Grand Cherokee 4.0l 90K and I've been having a coolant issue for about 2 months, seems I go from "full" to "add" in 2 weeks in the reservoir. I brought it to a mechanic; he did a pressure test and found nothing. I have no spots on the driveway, dry block, good hoses, good heater, runs fine idles good no other issues. I asked if it could be a cracked head or head gasket, he said no because I would see a lot of white smoke through the exhaust or water in the oil. He says it's related to my electric fan not working, and because it's overheating, I told him I didn't think so because I mostly commute on the highway and never let the gauge go past 210. So we changed the electric fan and still have the same problem.  I'm going nuts, oh btw oil looks fine, like honey, but maybe a little pressure drop. Any ideas? I'm at a loss, and just driving around adding Prestone every two weeks.

Thanks all, I really do appreciate it!!

[RECHRGD]

It's got to be going somewhere.  Have you smelled the oil?  Any coolant odor?  Bob

[JPL]

It's got to be going somewhere.  Have you smelled the oil?  Any coolant odor?  Bob

Oil is in great shape, no signs of water/coolant, oil level is the same after about 1.5 gallons of coolant added over time.....

[RECHRGD]

Any indication that it may actually be overheating and going out the overflow tube?  The gauge may not necessarily be right.   Bob

[JPL]

Any indication that it may actually be overheating and going out the overflow tube?  The gauge may not necessarily be right.   Bob

Nope, cool as a clam & dry overflow tube, and dry area around where the discharge would be from that overflow tube.....

[firefighter3931]

Check the sparkplugs so see if any of them show signs of water. With a pressure test and the engine cold... a cracked head won't be obvious but as the engine warms up and begins to expand the crack will become larger. If you have a small crack in the combustion chamber then coolant will leak out and be slowly burned off.

If the coolant isn't leaking externally and not mixing with the oil it is going somewhere like Bob said. 


Ron


Ps. I've used Bars Leak rad sealer in the past with excellent results...it might be worth a try. 

[JPL]

I did notice this today, not sure if it matters, in the morning the reservoir was empty, I get to work, it's half full, I'm leaving work and it's empty, I get home it's half full?.............

[RECHRGD]

Isn't that the normal scenario?  There should be a higher level in the tank when the engine is at temp. (me thinks).  I don't think you should be empty when cold though.  Bob

[elacruze]

I don't know the 4.0 specifically, but check to see if you have a bleeder point somewhere besides the radiator. Sometimes if you have trapped air in the system it will superheat at that point and boil & evaporate your coolant a little at a time without any obvious wet places. Was there a time recently when you know the radiator was low enough to draw air into the system?

[Dans 68]

Sounds normal. There are normally fluctuations with the coolant level...I have the same "problem" with my 4.0 liter Cherokee. If the level doesn't change day to day, given the same engine operating condition (i.e., cold before you start it up or hot when you get home) then I wouldn't worry. The reservoir has cold and hot levels marked, so it does change.

Dan

[acelondon]

Bad radiator cap?

[Rayzor]

You may have air trapped in the head. On the right rear top of the head there is a temp sender.  Try jacking the back of the jeep up or point the nose of it down a steep driveway, then loosen the sender until  coolant comes out. Then fill the radiator and the resevor up to the full mark and try that. if there is air trapped it may be displacing the coolant when it heats up.

[bordin34]

Check your coolant reservoir and make sure it isn't cracked.