Hey there, just seeking some advice for for my terrifying mystery of "where's my coolant going?"

The low down:
Just purchased a 99 xj 2.5L, she has 199k, recently replaced head gaskets, valve cover gaskets, thermostat, water pump, just had the timing done, etc. She's clean and runs great!

The problem:
I've noticed that pretty much daily after my work commute (60 highway miles a day) my coolant reservoir is near empty. Ive put 2 gallons in over the last 3 days, yet there is ZERO sign of leaks, nilch nada nothing... the car runs great, idles fine, no coolant smell, no white smoke out of the tailpipe, no overheating, no power loss, no chocolate milk on my dipstick that I can see. I'm at a loss...

My question is, can the HG be leaky/block or cylinder cracked and still show zero symptoms besides missing coolant? Any ideas on where this coolant is going or places I should start looking?

I'm hoping this jeep can last me a while, I don't want to lose her just yet! Thanks guys!

 

Let's try the easy thing first: Have you checked to see if the reservoir itself is leaking?

I would then try getting your oil tested for water. I think blackstone labs has a test.

I believe a HG or a cracked head can show zero symptoms other than missing coolant. Someone should verify that though.

 

Hmm I'm quite positive I don't have anot external leak anywhere, I don't see it pooling in the engine bay anywhere and there's definitely no pools on the ground in the morning/after she's been parked.

If there's hydrocarbons in the coolant is that pretty conclusive?

Thanks for the reply!

 

Check Radiator Cap or screw it for the price buy a new one. But get a good OEM one. I was also having to fill a little bit of water in reservoir every 2-3 days. After long drives I could visibly see the level went down. I purchased a new Radiator Cap and sure enough I'm going on 2 days and my coolant level has remained consistent.

 

I'm going to try this tonight, did you notice any leakage around the old, bad radiator cap though?

 

Good idea, can't hurt to give this a try.

 

Cracked head or block can lead to burning coolant.

So can an improperly installed or blown (again) head gasket.

If it was the radiator cap, coolant would be blowing all over the engine compartment at speed.

Pull the plugs one by one and see if any look like they have been steam cleaned.

 

Was actually going to look at these tonight as well, just to make sure I'm understanding correctly: a squeaky clean plug=leaky or blown gasket?

 

It might be an indication that that cylinder or cylinders may be burning coolant.

It gives you a clue as to what diagnosis you should perform next, and where you should concentrate on first.

 

Gotchya, thank you for the insight I'll check on those tonight. If I do find a clean plug, what would you suggest doing next?

 

Yes. That would mean you have exhaust leaking through a blown head gasket or a crack in the head or block. However, the absence of combustion gases would not rule out a head issue. You could have a leak into the oil instead.

Was that a rhetorical question, or did you detect combustion gases in your coolant?

 

I've yet to check, I was planning on checking my plugs, as well as draining my oil to check for coolant in it before moving on to spending money on having my coolant sniffed or pressure testing my engine.

I'm hoping that the guy who did the head gaskets a month back just simply didn't install them properly... 😑

On a sidenote, should I cease driving this vehicle entirely until I can ficome her? Or is it somewhat ok to make short trips here and there?

 

There's only one head, and one head gasket, on an inline 4 cylinder engine.

I would not drive it until diagnosis is complete. If coolant is getting to the bearings, even a little of it, it is ruining them.

You would not be able to see coolant contamination in modern oils with the naked eye unless it is REALLY bad.

You say you plan to do this, that, and the other. Go get it done, then report back your results. Be methodical. Don't grasp at straws or jump to conclusions.

 

That's understood, just a typo/typing habit from my old boxer in my sti.

To be clear, you're referring to the rod bearings yes? I'm tearing into this project this weekend and will report back to you guys asap, with pictures hopefully.

Appreciate the input though, I wasn't aware coolant wasn't visible in modern oil unless it's a bad leak, must've only dealt with bad leaks in the past!

 

Step 1 pressure check cooling system and cap also inspect coolant bottle.