jbdpayne

hey everyone...just as the title says my coolant has been disappearing from the reservoir. i came home from work where i was in the field for a month so my jeep sat in the shop...checked the fluids and it was below the fill mark. I just went to visit my parents and decided to leave the jeep home...once again its beginning to get low. I crawled under it but cant seem to find any leaks as far as freeze plugs hoses ect. no dried up coolant. I also checked my oil being that its prone to cracking but oil level is perfect and nothing that i can see under the cap. Any ideas where it could be going? I mean if it lost that much over the course of a month without actually running it could it be the radiator?

djb383

Time for a cooling system pressure test.

jbdpayne

did a quick search on that, basically tests to see if it holds pressure? im no mechanic, and it's also getting pretty cold here so im not sure if that would affect it as well

Pelican

It would have to get really, really cold for it to cause a substantial coolant loss while just sitting for a month.


Djb383 told you what to do. Anything else you're just playing a fun guessing game.

jbdpayne

yea id rather not do that considering I'll be back out in less than a week working. I will check it out asap tomorrow and see if its losing it internally...hoping for the best

gw204

Slow leak in the heater core is my guess. My 2000 does the same exact thing.

tjwalker

Pressure test is a good idea. There are a number of ways that it can lose coolant that are tricky to diagnosis. One is the "seams" on the radiator; they are a weak link with plasticized radiators.

So let's say that pressure holds and you can't find any reason for losing coolant. Then it's time to switch gears and consider the possibility that you are "burning" it, because of a crack on your OEM 0331 head. This is a very real possibility.

Troubleshooting that can also be tricky. I always start by removing the oil filler cap and with the best light you can get your mitts on, look inside with a hot, fully pressurized cooling system. Sometimes (not always) with a cracked 0331 head, you can actually see the green coolant seeping through a crack in the cylinder 3-4 area, which is where virtually all 0331 heads will crack, if they do.

Other tests include a cylinder leakdown test and a block test, where you sniff the coolant for the presence of hydrocarbons (oil).

You have some sleuthing to do. Good luck and godspeed. Keep us updated.

jbdpayne

thank you, ill keep everyone updated...i was hoping to look into it today but hadnt gotten time to. My buddy is going to give me a hand tomorrow for the pressure test and I will also take a look to see if i notice any seeping through the top. If I cant I will have to go from there, but ill keep everyone updated!

djb383

^^^^This is easy to check by yourself. Pull the carpet back, passenger side floor board.

md21722

The coolant has to be going somewhere. Its either leaking externally, leaking out the exhaust/engine is burning it, etc. 2000-2001 models have 0331 heads that are known to crack between the rockers of cylinder 3-4. Take the oil fill hole cap off and at it. Is there a milk residue? Next look straight down through the oil fill hole between the rockers for any signs of cracking - oil mixing with coolant, "tan lines", etc. If the coolant loss is significant you risk washing your bearings and then rebuilding or replacing. If caught soon enough, you can just change the head if this is in fact your problem.

jbdpayne

sorry for the late reply everyone, brother and i had a look yesterday and did a pressure test. turns out it was slowly leaking from the pump. replaced that and the thermostat housing and everything went well no signs of head gasket or crack (knock on wood). It must have just been drying up on the side before I could see it. Appreciate the help everyone!

djb383

How old is coolant....old/weak coolant will evaporate quicker and give much less corrosion protection than fresh/good coolant.

jbdpayne

it was flushed in august so it was new, but i almost wonder that the previous owner had put stop leak in and when it got flushed flushed it out. I will be keeping an eye on it just to make sure its ok though and not leaking or escaping elsewhere

djb383

Keep in mind that the rad cap is the key to a "open coolant recovery" type system. The rad cap contains 2 valves and 3 sealing surfaces and any of those failing can cause a false coolant level reading in the bottle. When the motor is COLD is when coolant level should be checked by removing the rad cap. Coolant level in the rad should always be at the very top, motor COLD.