A couple quick questions, about the cooling system?

[Jmac00]

1) where did my coolant go?
2) what the freak'n hell is this tube at the bottom of my reservoir {see pix}
3) checking the fan clutch?
(a) I have seen posts that say, "when the engine is cold, start the engine, let it run for a few seconds, turn it off. If the fan comes to a stop, the clutch is good. if it spins a couple times, replace it"
(b) when the engine is cold, gently spin the fan, if it turns more than five times, replace the clutch assy?
4) whats the best coolant for a TJ? Prestone 50/50? any other brand?
so what's the actual test, to see if the fan/clutch assy is working properly or not
I checked the oil, it needs changing, ( by 475 miles ) but its in good shape, does not have water in it?

 

[Jerry Bransford]

That tube is connected to the port on the radiator adjacent to the radiator cap, the overflow from the radiator. If you're not seeing any coolant leaking/dripping onto the floor there's a good chance it's disappearing through a blown head gasket and out the engine exhaust.

Coolants are not always compatible with each other so until you figure out the leak and replace all of the coolant I'd add nothing but distilled water which is available by the gallon at the local grocery store. For fresh coolant it's hard to beat Zerex G-05 mixed 50-50 with distilled water. Never add tap water which is usually too high in dissolved mineral/lime/calcium content which can clog a radiator.

 

[Jmac00]

if it was a head gasket, wouldn't there be water in the oil???

 

[KennethS]

No, the gasket could fail between the combustion chamber and a coolant passage. Had that happen before.

 

[Jmac00]

No, the gasket could fail between the combustion chamber and a coolant passage. Had that happen before.

soooo ~~~~ new head gasket?

 

[NashvilleTJ]

soooo ~~~~ new head gasket?

That is one possibility. Could also be a cracked head, or less likely a cracked block. Either way, first step is to pull the head and take a look at the gasket.

 

[Jmac00]

That is one possibility. Could also be a cracked head, or less likely a cracked block. Either way, first step is to pull the head and take a look at the gasket.

It can't be that hard to get the head of this thing. Does anyone have the procedure for that?? I should just order a new gasket and have at it

anyone have an idea of what that big tube is in the bottom of the reservoir?? I managed to pull it up and it fits very tightly into the reservoir filler neck? There is a rubber overflow tube from the radiator cap to the reservoir?

 

[Jmac00]

No, the gasket could fail between the combustion chamber and a coolant passage. Had that happen before.

and everyone said the 4.0 was a "bullet proof motor" LOL ~~~~this is the way 🤬

 

[Apparition]

and everyone said the 4.0 was a "bullet proof motor" LOL ~~~~this is the way 🤬

Fix it with a V8

 

[Jmac00]

Fix it with a V8

DD15 detroit diesel??? with a Allison 10 speed?

 

[TJ4Jim]

soooo ~~~~ new head gasket?

Pull each spark plug one at a time looking for a very clean plug, if one shows up that's the cylinder. Also check the tailpipe for any white smoke/vapor.

 

[g.hayduke]

BEFORE pulling the head, are you absolutely sure you don't just have a leak somewhere?

Look for antifreeze residue around all hose connections, underneath your water pump, engine side of radiator, etc. Do you smell antifreeze in the cabin? Heater core could be leaking.

Read this thread before pulling your head:
https://wranglertjforum.com/threads/how-can-i-tell-if-i-have-the-cylinder-head-that-is-prone-to-cracking.14604

Also, the procedures for all the stuff you're asking about are in the factory shop manual which is somewhere on this site. I have a hard copy so I'm not sure where the FSMs are but they are here.

 

[xXDavidCXx]

My head gasket symptoms were:

1. overheating at any speed
2. losing coolant slowly
3. lacking power at speed
4. random engine stumbling

I had low compression on 3 cylinders and all the exhaust valves were pitted.

The head was not cracked.

 

[BigFishIII]

1) where did my coolant go?
2) what the freak'n hell is this tube at the bottom of my reservoir {see pix}
3) checking the fan clutch?
(a) I have seen posts that say, "when the engine is cold, start the engine, let it run for a few seconds, turn it off. If the fan comes to a stop, the clutch is good. if it spins a couple times, replace it"
(b) when the engine is cold, gently spin the fan, if it turns more than five times, replace the clutch assy?
4) whats the best coolant for a TJ? Prestone 50/50? any other brand?
so what's the actual test, to see if the fan/clutch assy is working properly or not
I checked the oil, it needs changing, ( by 475 miles ) but its in good shape, does not have water in it?
View attachment 407788

View attachment 407789

The tube I believe is the tube that slides into your coolant cover. See photo below. I did a full coolant flush and deep dive into the system recently if you have any questions, pm me directly. My '04 required a specific coolant. Best off the shelf was G05 50/50. What year and engine? Not all places have it but my local auto advanced Auto had it. Autozone didnt. There is a sticky thread here with factory service manaual. Should have instructions you need for testing. For coolant, go to autozone free tool rental and get the pressure tester. Theres lots of youtube videos how to with UV leak detector etc. Mine had a breken "catch" on the top to keep it from sliding in.

 

[BigFishIII]

1) where did my coolant go?
2) what the freak'n hell is this tube at the bottom of my reservoir {see pix}
3) checking the fan clutch?
(a) I have seen posts that say, "when the engine is cold, start the engine, let it run for a few seconds, turn it off. If the fan comes to a stop, the clutch is good. if it spins a couple times, replace it"
(b) when the engine is cold, gently spin the fan, if it turns more than five times, replace the clutch assy?
4) whats the best coolant for a TJ? Prestone 50/50? any other brand?
so what's the actual test, to see if the fan/clutch assy is working properly or not
I checked the oil, it needs changing, ( by 475 miles ) but its in good shape, does not have water in it?
View attachment 407788

View attachment 407789

Also, depending on how much coolant youre loosing, could be a heater core. Do you have funky "sweet" smell inside or fog on your windshield with defrost? Run with heat on blast for a while and see if you are getting coolant dripping from port under the radiator heater hoses.

 

[Jmac00]

Pull each spark plug one at a time looking for a very clean plug, if one shows up that's the cylinder. Also check the tailpipe for any white smoke/vapor.

checked the tailpipe, perfectly clean at the start of a one hour trip of stop-n-go traffic, and clean after an hour drive? I have no pulled a spark plug yet.

 

[Jmac00]

My head gasket symptoms were:

1. overheating at any speed ~~~ nope, I added about a quart of distilled water last night and went for stop-n-go run through the middle of Phoenix. no over heating at all???
2. losing coolant slowly ~~~ probably, just have to find the seepage
3. lacking power at speed ~~~ nope, got P L E N T Y of power
4. random engine stumbling ~~~nope, running like a top

I had low compression on 3 cylinders and all the exhaust valves were pitted.

The head was not cracked.

 

[Jmac00]

The tube I believe is the tube that slides into your coolant cover. See photo below. I did a full coolant flush and deep dive into the system recently if you have any questions, pm me directly. My '04 required a specific coolant. Best off the shelf was G05 50/50. What year and engine? Not all places have it but my local auto advanced Auto had it. Autozone didnt. There is a sticky thread here with factory service manaual. Should have instructions you need for testing. For coolant, go to autozone free tool rental and get the pressure tester. Theres lots of youtube videos how to with UV leak detector etc. Mine had a breken "catch" on the top to keep it from sliding in.



View attachment 408071

View attachment 408070

THATS the tube? is that to control overflow??? Im going to the parts store tomorrow and start the flush/pressure test tomorrow. I lost the damn cap, I have no idea where that thing went. its not on the ground anywhere near where it should be???

this is a 2000 wrangler sport, automatic. it has 97/98,000 miles on it.

now I have a 'clunking sound coming from the rear end when I make a tight turn??? not sure what thats all about, the lugnuts seem to be tight, Im going to jack it up tomorrow and see if something is coming loose

 

[Jmac00]

THANKYOU VERY MUCH FOR THE HELP, I really appreciate all the knowledge on this site

 

[TJ4Jim]

checked the tailpipe, perfectly clean at the start of a one hour trip of stop-n-go traffic, and clean after an hour drive? I have no pulled a spark plug yet.

If there's anything going on within the cylinders the plug in the bad cylinder can look like it just came new out of the box.