Small antifreeze leak

[War9661]

Hi everyone,

My Jeep (98 4.0) just started dropping antifreeze. We had a water pump replaced last summer. We don’t drive it much, maybe 2,000 miles a year. I was going over my fluids and saw my antifreeze was below the min line. I filled it. We drove it 3-4 times. Maybe 20ish minutes. Since then, the fluid builds pressure when hot but as it cools it drops a slight amount. I’m now about 1/2 inch below the mark I filled to. Nothing is dripping. I can’t see anything obvious. Thermostat may have some color change on it but I can’t remember if that was there before. Color isn’t white like they say is left from dried antifreeze. No smoke. No exhaust smell in the reservoir. Replaced the radiator cap with a new one. Oil looks fresh and new. Pressure test was done for 2 hours and nothing changed. No sweet smell in that I can find. Motor isn’t getting high temp readings on the gauge. Any ideas or suggestions on where to look?

 

[TJ Jim]

Maybe they didn’t get all the air out of the system after the pump replacement and you are now getting it back full. The weather has warmed up so your getting more fluid exchange between the radiator and expansion bottle.

 

[CJ with a TJ]

I was thinking along the same lines, that they didn't get all of the air out.

 

[TheBoogieman]

Wishful thinking.

 

[War9661]

Maybe they didn’t get all the air out of the system after the pump replacement and you are now getting it back full. The weather has warmed up so your getting more fluid exchange between the radiator and expansion bottle.

How long do you think it would take to circulate out air pockets? Is that something that takes 1,0000 miles or should it be sorted out after one good run? Just trying to figure out how long I should monitor before I decide it needs a mechanic to check for leaks

 

[TJ Jim]

Depends on the style of thermostat installed. Mine has the 1/8” air bleeder hole at the 12 o’clock position. Just sitting there running after a flush all the air pockets were gone.
With a cold engine take off the radiator cap and check the level. Start up your Jeep and run it till she’s hot and the thermostat opens. If it’s low fill it up. Be aware it may spit a bit of antifreeze out while heating up. Clean up any spills, it’s toxic to you pets. Once all the gurgling and air escape top off the radiator and put the cap back on. Max fill your bottle and you should be good to go.

 

[KennethS]

I would remove the cap when the engine is cold to verify the level in the radiator is up to the top. If so, fill the overflow reservoir and just monitor the level over time. If it goes down, there is likely a leak. If it doesn't change, then it was likely all the air wasn't purged after the water pump replacement.

 

[DuckNut]

it’s toxic to you pets.

FYI...15 years ago they added a chemical to make it taste horrible to pets so they wont drink it. Cant even use it to get rid of rodents anymore.

 

[TJ Jim]

FYI...15 years ago they added a chemical to make it taste horrible to pets so they wont drink it. Cant even use it to get rid of rodents anymore.

Well dang I’m glad to hear that. I lost one dog years ago from drinking antifreeze. I was paranoid as the devil doing the flush for my present dog. Guess now you can’t get rid of your cheating spouse as easy!

 

[DuckNut]

Well dang I’m glad to hear that. I lost one dog years ago from drinking antifreeze. I was paranoid as the devil doing the flush for my present dog. Guess now you can’t get rid of your cheating spouse as easy!

I know farmers used to use their drained fuid for rat control. Now they have cats peeing all over the place.

 

[Cooper Smith]

How long do you think it would take to circulate out air pockets? Is that something that takes 1,0000 miles or should it be sorted out after one good run? Just trying to figure out how long I should monitor before I decide it needs a mechanic to check for leaks

Every time I've bled a cooling system after coolant flushes/rad replacements, I've only had to top off once after about 100-200 or so miles. After that the air was pretty much bled out. This was on both my 2.4 TJ and several 350's.

 

[War9661]

I think I finally found it! See. Little dried green dried up on one side of the radiator. Little staining of liquid being at the bottom of the radiator on the passenger side. Driver side I guess could be a splash from topping off the reservoir but I think it is a small pin hole in the radiator now and not something worse!

 

[Feralkid]

The seals between the plastic and the aluminum of the radiator will wear out with age and coolant can seep out from the mating area, especially when cold and then seal up and stop leaking when at operating temperature. It's nothing to worry about of course unless the leak becomes to big or if leaks when the engine is warm. Best fix is to replace the radiator as oppose to using stop leak.