Jeep Wrangler Forum banner
1 - 20 of 51 Posts

·
Registered
Joined
·
59 Posts
Discussion Starter · #1 ·
Just looking to see if anyone else has had a similar experience.

01' Jeep TJ Sport, 4.0 with 88,000 miles on it.

Started losing coolant, actually a few years ago. A small amount, maybe an ounce or two every +/- 350 miles.

All along I've done pressure tests, block tests, pulled plugs (looked good) and did compression tests - nothing. Also sent oil and transmission fluid to Blackstone labs, no coolant in fluids.

It started using more, figuring I must be overlooking something took it to a shop, they did everything I've already done plus putting a scope down into the cylinders - no evidence of a leak.

The only thing left is pulling the head. I can't do something like that anymore - three failed back surgeries limit me.

The shop is hesitant, something is going on but they're a good shop, would rather have some proof. The conclusion is it is 'probably' leaking into exhaust however that should show itself in the block test or pressure test.

I live west of Phoenix, the going rate from a shop is somewhere between $120 and $140 an hour so pulling the head, sending it out to be pressure tested and surfaced is going to be in the neighborhood of $2500 minimum, that's if everything goes well, the head is good and it's a gasket leak that isn't showing itself through testing.
 

·
Registered
Joined
·
17,165 Posts
All 2000 and 2001 4.0 TJ had a crack prone head and tend to have coolant enter oil when head cracks

They revised the crack prone head design mid 2002 with TUPY head


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #3 ·
All 2000 and 2001 4.0 TJ had a crack prone head and tend to have coolant enter oil when head cracks

They revised the crack prone head design mid 2002 with TUPY head


Sent from my iPhone using Tapatalk
No evidence of coolant in oil, sent a sample to Blackstone Labs for testing, specifically for coolant and they found none, not even trace amounts.
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #5 ·
That was before you said loss increased at least that is how I read your original post


Sent from my iPhone using Tapatalk
Fair point, it was before the increase, it was tested in March 2021. There hasn't been an increase in volume in oil, no milkshake - nothing, plus passing the pressure test(s).

When I did the pressure test I'd leave it on for a couple hours, the shop has done at least 3 pressure tests, leaving it under pressure overnight with no negligible loss of pressure.

I'm not saying that it couldn't be but with the increase if it's going in the oil shouldn't there be some signs?
 

·
Registered
Joined
·
17,165 Posts
When was the last oil change and self inspection of that drained oil?

when (date) did the coolant loss increase?

Can you quantitatively the current amount (volume) of loss per 100 miles of driving?

Does the exhaust smell normal?


Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
14,041 Posts
Do you have a TUPY head?

What about a leaking intake manifold gasket, allowing coolant to be drawn into the combustion chamber and evaporated during combustion. Digger84 might be on to something when he mentions smelling the exhaust. The amount of coolant going through the combustion chambers might not be enough to smell in the exhaust. I don't know if the brake cleaner thing around the manifold would work if the leak is between the water jacket and an intake port. (Just brainstorming. What else could it be though?)

Good Luck, L.M.
 

·
Super Moderator
Joined
·
14,041 Posts
On an inline engine?
I don't know why not. If the 4.0 is anything like a 4.2, there is coolant circulating through the intake manifold. If not a gasket, then perhaps a porous casting allowing the coolant (under ~ 13lbs pressure) to be forced into the intake ducts (under negative pressure). Again, just brainstorming by a neophyte.

Good Luck, L.M.
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #12 · (Edited)
When was the last oil change and self inspection of that drained oil?

when (date) did the coolant loss increase?

Can you quantitatively the current amount (volume) of loss per 100 miles of driving?

Does the exhaust smell normal?


Sent from my iPhone using Tapatalk
I don't have an exact date when it started using more coolant but it was before the last oil change. I do it myself and transfer the oil from the drain pan to the fresh empties to take to autozone or wherever so I get a good look at it. Looked like it always does and filled the empties as usual, I didn't measure it to the ounce but it wasn't out of the norm. I also check oil level every few weeks and it is at the same spot on dipstick everytime.

As far as I can tell the exhaust smells normal, I use Zerex G-05 coolant and to me it has no smell so not sure I'd smell it if it was in the exhaust. I don't notice a white puff when I start it up but unless it was really bad, not sure I'd notice that either.

Here's the thing, it has to be head related, the hoses, t-stat housing and radiator are solid, those would show themselves in a pressure test. Either the gasket or a crack in the head itself but again with all the testing that has been done, you'd think something would be off. If I was able to do the work myself, I'd already have done it but since I can no longer do it and have to pay someone else, I'm with that shop in that I'd like to be sure or at least first hand confirmation that other jeep owners have had similar experiences.


Edit: added to last sentence
 

·
Los Angeles
1993 Wrangler YJ 4.0
Joined
·
2,436 Posts
Yes, it happened to me.

The front head bolt on the head goes through the water jacket on the 4.0.
Remove the nut, goop in some high heat and waterproof sealant, replace the nut and torque it to spec.

I chased this for about a year or more. It was not an emergency situation, only a small annoyance. I would need to top off maybe a few cups a month. The gauge would climb after a few months if I forgot to add coolant. This would remind me that I still had a problem to fix.
Automotive tire Motor vehicle Bicycle part Vehicle Rim
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #16 · (Edited)
Yes, it happened to me.

The front head bolt on the head goes through the water jacket on the 4.0.
Remove the nut, goop in some high heat and waterproof sealant, replace the nut and torque it to spec.

I chased this for about a year or more. It was not an emergency situation, only a small annoyance. I would need to top off maybe a few cups a month. The gauge would climb after a few months if I forgot to add coolant. This would remind me that I still had a problem to fix.
View attachment 4525925
Interesting. Were you getting any coolant around that bolt? How'd you find it not?

My Jeep is sitting in that shop at the moment, I won't have access to it until Monday, but if there is something to look for I might just call up there and have them look and have them apply the sealants.
What exactly did you use? High Performance Thread sealant & what else?
That would be #11 in tightening sequence, fsm says to use Loctite 592 sealant on that bolt.

Thanks!
 

·
Los Angeles
1993 Wrangler YJ 4.0
Joined
·
2,436 Posts
Interesting. Were you getting any coolant around that bolt? How'd you find it not?

My Jeep is sitting in that shop at the moment, I won't have access to it until Monday, but if there is something to look for I might just call up there and have them look and have them apply the sealants.
What exactly did you use? High Performance Thread sealant & what else?
That would be #11 in tightening sequence, fsm says to use Loctite 592 sealant on that bolt.

Thanks!
I would have used Loctite but it is filled with coolant already, so I opted for a non hardening sealant. I can't remember what. Maybe water pump sealant?
 

·
Registered
Joined
·
59 Posts
Discussion Starter · #19 ·
I would have used Loctite but it is filled with coolant already, so I opted for a non hardening sealant. I can't remember what. Maybe water pump sealant?
Was it visibly leaking?
 
1 - 20 of 51 Posts
Top