Unexplained Coolant loss

I have a 2001 Jeep Cherokee with a total of 29.5K miles with only 5 weeks
to go on the warranty. I have taken the XJ back for a 2nd time(this year)
now for coolant loss. There are no traces on the ground or in the engine
compartment. I do not see excessive smoke out the tailpipe or any wetness on
the hoses or smell it anytime .The bottle was checked by the dealer and
found nothing wrong with it or the system. Both times the dealer had
pressure checked the system to 18 psi and left it sit for 40+ minutes with
no pressure loss. I have asked as of this week that THEY will add coolant
when I see the bottle go empty. This is my attempt at as much documentation
before warranty expires. The consumption rate in the last 3 months or
approximately 3000 miles was 2 gallons!.

Anyone with similar? How was it resolved?

Brian

 

Probably a leak either at the head gasket or small crack or hole between the
cooling system and a cylinder. Have them pressurize each cylinder with a
leakdown tester (engine hot and cold) A leak will be indicated with a rise
of coolant in the recovery bottle. The reason I say perform it hot and cold
is that the leak may only occur at either hot or cold but not both.

Bill

 

Good advise to perform it hot. If this is a hair line crack in the block or
head casting, the crack may not open up enough to pass coolant or air until
it's hot.

 

May be the water pump or cap. My T&C was doing some coolant loss and the
system pressure checked ok but the cap was not holding. Additionally I had a
miniscule leak in the water pump. Did not show any leak but it would "burp"
a tiny bit at the weep hole but not enough to show up on the floor.
Larry

 

Well, I took it in Monday afternoon with less than a week since the last
time in. The reservoir bottle was empty and the mechanic topped it off. A
discussion with the service manager and his boss has resulted in an
agreement that the next time I come in to re-top the bottle, that I would
leave it with them to have another look see. I myself did not find any leaks
on the water pump or hoses anywhere. They didn't see anything either... So I
think this time around they will pull the head and check for cracks and
flatness.

Brian

 

If it were me, I would have the engine oil analyzed for coolant. It is a
cheap test (about $15) and would indicate if the coolant is entering the
crankcase somehow. Coolant in the oil will cause a lot of problems.

 

Hi Mike,

The dealer has been reluctant to do anything but a pressure test. I guess he
follows the standard procedures Jeep has set forth. I got the "99% of all
problems are found with the pressure test" from the service manager. I told
him that just maybe I could be the 1% since you haven't solved anything yet!

The jeep goes back Monday again with 100 miles and 1 week since last time
they filled the recovery bottle. They will keep it this time and look deeper
into the problem.

I'd hate to have them destory another shortblock, because they haven't
looked at the head yet.

Brian

 

Thanks, to all who responded. Got my XJ back on Friday and dealer had
replaced the head. They did not see anything wrong visually, but the dealer
sent it out to a machine shop and they found a crack.

Brian