Jeep TJ disappearing coolant

[sergioemz]

Hello all,

My Jeep Wrangler Sahara 2001 4.0L, has been loosing coolant for quite some time now and I'm sure there is no external leak. I loose about 28oz of coolant from the reservoir once the engine is cold every 3/4 of gas tank (about 180 miles) here's what I've done so far.

1.- put 15psi to the radiator and there isn't any pressure loss or coolant leak, same to the radiator cap
2.- my oil doesn't look milky and the level has maintained
3.- Sparkplugs look fine, no signs of coolant burn
4.- I'm not getting any white smoke (sign of coolant burn)
5.- no sweet smell coming out from exhaust

the only thing that I'm missing is to replace the head gasket, but do you think that could be it even when having clean oil and no white smoke?

Thank you!

 

[Link]

Just guessing here but maybe heater core leak? That’s a pretty fast leak so there should be something visible somewhere. Also would be a good idea to test your coolant for exhaust gases.

 

[GaTechTJ]

It may be a cracked head.

The 00-01 4.0L with the 0331 head casting has some history of being prone to crack.

Look under the Oil Fill Cap and see if you have a creamy yellow/brown emulsion inside.

 

[lBasket]

Is it leaking out the weep hole of the water pump? Mine was loosing small amounts of coolant regularly, that ended up being the problem. Needed to replace water pump.

 

[sergioemz]

It may be a cracked head.

The 00-01 4.0L with the 0331 head casting has some history of being prone to crack.

Look under the Oil Fill Cap and see if you have a creamy yellow/brown emulsion inside.

Yes, I do have some yellow/brown under the cap, but read that also happens from normal condensation. is that right?

 

[sergioemz]

Just guessing here but maybe heater core leak? That’s a pretty fast leak so there should be something visible somewhere. Also would be a good idea to test your coolant for exhaust gases.

I heard I should have a wet passenger carpet if it was the heater core, but I will double check on that. thank you.

 

[lBasket]

Yes, I do have some yellow/brown under the cap, but read that also happens from normal condensation. is that right?

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mine don't look like that lmao.

that looks pretty bad

 

[sergioemz]

nevermind, It is a cracked head. I just turned the jeep on and coolant comes up from there. can that be fixed with J-B Weld? or need to replace the head?

 

[Duck Doctor]

Yes, I do have some yellow/brown under the cap, but read that also happens from normal condensation. is that right?

View attachment 421703

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That sludge is not a by product of normal condensation.

 

[GaTechTJ]

Yes, I do have some yellow/brown under the cap, but read that also happens from normal condensation. is that right?

View attachment 421703

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Some can happen from normal condensation, especially if the jeep is driven a lot of short trips.
With the amount showing in the pictures, my next step would be to pull the valve cover and see if a crack was visible.
The symptom described with the loss of coolant fits. Antifreeze comes up through the crack in the head and boils off and escapes through the valve cover vents.

 

[sergioemz]

Some can happen from normal condensation, especially if the jeep is driven a lot of short trips.
With the amount showing in the pictures, my next step would be to pull the valve cover and see if a crack was visible.
The symptom described with the loss of coolant fits. Antifreeze comes up through the crack in the head and boils off and escapes through the valve cover vents.

I think this is it, I can see my pink coolant through the oil cap hole..

 

[sergioemz]

Some can happen from normal condensation, especially if the jeep is driven a lot of short trips.
With the amount showing in the pictures, my next step would be to pull the valve cover and see if a crack was visible.
The symptom described with the loss of coolant fits. Antifreeze comes up through the crack in the head and boils off and escapes through the valve cover vents.

Do you know if a crack can be fixed with J-B weld? or would need to replace the entire head?

 

[lBasket]

Do you know if a crack can be fixed with J-B weld? or would need to replace the entire head?

I wouldn't bother trying that, personally

 

[B1Toad]

I once fixed a cracked piston on an old Renault with JB Weld and it lasted about 2 hours. Where abouts are you at down there?

 

[txbemis69]

looks like it’s time for a new head.

 

[B1Toad]

A Clearwater head is $625 and not too hard of a job. New bolt kit, gaskets and a few oil changes to flush out the contamination. It will be better than new.

 

[4BY4ADV]

Good luck! Inspect the block before you put too much time/effort into the head.

My Jeep is at the mechanic right now for what was supposed to be head work... but I just got a call that there's piston slap and the engine needs to be replaced. :/

Hopefully your day isn't going as bad as mine!

 

[Link]

Ouch definitely the head. Replace it

 

[sergioemz]

thank you all, will start looking for a new head. here's a clear video

 

[JKP]

Either get a new clearwater head, or if you get a rebuilt it needs to have the letters TUPY about where your crack is. TUPY marked heads are the improved OEM ones.