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Unexplained coolant loss, but mechanics thinks the head is fine. ???

Chemical test came back negative. I got my Blackstone kit in the mail today, so I'll send that off and we'll see what happens.

In the event that I do have to replace the head, what's the board consensus on which replacement head to use? I've already spoken to one member via PM who gave me a good recommendation on an eBay option, but I've also read enough from members who went the '03-'04 Grand Cherokee junkyard route to know that that's a viable option, as well.

Pros on the new/refurb: should be problem-free.
Pros on the junkyard: cheap.

I'd like to save money, but I'm not a competent mechanic by any stretch of the imagination. I think I could unbolt enough stuff at a Pull-A-Part to get my cylinder head that way, just because that motor wouldn't be mine and I wouldn't have to worry about the consequences of screwing something else up, but swapping it onto my motor is a completely different story. Yes, I could probably YouTube, message board, and Haynes my way through it with enough time and effort, but I'm a college prof, classes start soon, my wife's working on her dissertation and working full time, and we have a one-year-old. Point being, I don't have a lot of free time to fumble and bumble my way through a big job like a head swap.

So, assuming I can get my hands on a TUPY from a Grand Cherokee, do you all recommend that route or a new (or refurb)? head?

Thanks for all the feedback, everyone.
 
I did that a while back. No leaks from that area.

Exactly what type of chemical test did you have done? An oil test? Did you test the coolant for hydrocarbons?

You won't see any external leak because there won't be one. What happens is that a small amount of fluid/steam is slowly vented into the overflow and that heat in the overflow allows the moisture to evaporate. Any excess is sucked back in when the engine cools, but if you loose a couple of tablespoons every heat/run cycle, it adds up over time.

It is recommended that you replace your radiator cap every two years and make sure and use a 16lb cap. Many references call out a 14lb cap and it will do the same thing over time. You lose coolant with out ever seeing any evidence of where it is going. Most people then think the worst and blame a cracked head. If that is the case, there is a simple tester that can be used to sniff the coolant for hydrocarbons. You pop the radiator cap after things cool down and then put it over the radiator inlet and pump the fumes through a liquid that changes color in the presence of hydrocarbons. You can score these at NAPA for around $40. If you have a cracked head, it should tell you.

If you are burning the coolant, you should be able to see evidence of that doing a spark plug reading.
 
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Exactly what type of chemical test did you have done? An oil test? Did you test the coolant for hydrocarbons?

You won't see any external leak because there won't be one. What happens is that a small amount of fluid/steam is slowly vented into the overflow and that heat in the overflow allows the moisture to evaporate. Any excess is sucked back in when the engine cools, but if you loose a couple of tablespoons every heat/run cycle, it adds up over time.

It is recommended that you replace your radiator cap every two years and make sure and use a 16lb cap. Many references call out a 14lb cap and it will do the same thing over time. You lose coolant with out ever seeing any evidence of where it is going. Most people then think the worst and blame a cracked head. If that is the case, there is a simple tester that can be used to sniff the coolant for hydrocarbons. You pop the radiator cap after things cool down and then put it over the radiator inlet and pump the fumes through a liquid that changes color in the presence of hydrocarbons. You can score these at NAPA for around $40. If you have a cracked head, it should tell you.

If you are burning the coolant, you should be able to see evidence of that doing a spark plug reading.

Good stuff. Thanks very much.

I had the coolant tested and didn't find any problems. I also replaced the radiator cap shortly before all this started. My next step is to send some oil to Blackstone, but I'll check the spark plugs, too. I appreciate the suggestion.
 
I bought a Clearwater cylinder head back for my 2000 in '16 and sent it to Russ. It was the newer modified design.
P1080516_zpsybaiiwn0.jpg
 
Good stuff. Thanks very much.

I had the coolant tested and didn't find any problems. I also replaced the radiator cap shortly before all this started. My next step is to send some oil to Blackstone, but I'll check the spark plugs, too. I appreciate the suggestion.
Radiator caps have a high failure rate right out of the box. If you changed it just prior to the problem showing up, I would spend the $5 and try another. It is a drop in the bucket compared to a new head.
 
Numerous times I've had coolant loss in multiple XJ's. Many of the leaks and seeps have been hard to find. I mean I had to really look, multiple excursions over, under, around and through my motor area to spot the seep. The obvious ones dripped onto the driveway, most weren't that easy.
I had a pinhole leak on the top radiator hose that sprayed a fine mist over the motor that wasn't that easy to spot. The end tanks on the radiator, usually the passenger's side, front and rear of the radiator. Water pump seeping out of the bearing seep hole, I used bits of white paper towel on a stick to trace that to the source. Various clamps that relaxed with age. Heater core seeping, that I found by smell. Surge tank hose seeping and even a bad cap on the surge tank that let coolant slosh out of the canister when dirt roading. There were others that I forget at the moment.

I eventually started using a coolant with UV dye and a powerful UV light. I was actually using the coolant for a while before I actually read the destructions and discovered it had a UV dye in it, I borrowed my son's commercial type UV lamp.
 
I did the pick and pull I got a 2004 grand cherokee head and got the head for about $50. it was cheap then I re seated the valves and changed the valve seals I also chanced the lifters because they were making noise , it's been running now with the 2004 tupy head for about 2 weeks and no problems and it smooth . been checking coolant and oil not losing any coolant or oil , it would gain oil before because of the coolant going into the oil .
 
Strawberry milkshake transmission fluid. Sunday I wrapped up replacing the radiator, bypassing the oil cooler in the radiator and flushing out the trans fluid due to coolant leaking into the trans through the cooler. Noticed the coolant level going down for a while before I checked the trans fluid as part of a usual underhood check-up and there it was. Doesn't seem to have done much damage to mine but if you wait too long, it's a surefire way to kill a transmission.
 
So, an unfortunate update: after driving it around a bit, I looked through the oil fill port and could see antifreeze green specks clear as day.

As far as auto repairs go, the most I've successfully completed is your basic bolt-on stuff: fan clutch and shroud, water pump, thermostat, belts, and hoses here and there. So, let's say I do manage to get everything cleared away to a point where I can unbolt and remove the head. I've learned that the crank bearings would be the first thing I'd need to check as far as additional damage goes. Can any of you think of anything else I should check or do right off the bat? Does a good thread for that (or any other resource) already exist?

Thanks for all the feedback, everyone.
 
All the bearings are subject to damage, specially the cam bearings.
 
It sits between 40-50 at start-up, then settles down to 12-15ish while idling. Tbh, I've never known what's typical for an XJ.


That's okay if its a hot idle. Basically minimum spec. But if you're getting that at cold idle and it goes below that, you probably have bearing damage.
 
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