Are people replacing T-stats and Water pumps

Well guys my 2000 xj is passing 110000 miles and I am starting to get concerned about the 0331 head problem. Are you guys replacing your t-stat and water pumps before they fail or just going until there is a problem? I am an overly careful jeep owner/lover and I love to do preventative maintenance. Is there anything else I should be replacing before they go "bad" at this point that isnt common knowledge maintenance (like fluids, shocks, plugs, air filters ect.)?

Thank you guys for all your help,
Keep on jeepin.

I think you are worrying too much.

There is no way to know if the head on your Jeep will fail. Also, there is no preventitve measure to me taken except to replace the head before it cracks; and even then there is no guarantee that the new one won't crack.

Relax, stop worrying, enjoy your Jeep, and monitor the oil at regular intervals for level/discoloration.

With the potential damage to head and engine that just ONE overheat can do to an engine with the infamous 0331 head, I don't think your concern is unreasonable.

None of the cooling system parts are expensive. I change thermostats every 60k regardless.

IF you plan on keeping the vehicle, and if you want to ensure the rest of your system is up to snuff, and if you can do the labor yourself, a new water pump, hoses and radiator cap (often overlooked) and a new radiator while you have things torn apart isn't going to break the bank.

If the waterpump isn't squeaking or weeping, I wouldn't worry.

Simple check: Remove the belt and grab water pump and test how much play the bearings have.

Recently, replaced the jeep's water pump, thermostat, and coolant. Cost $70.00
Very easy project when compared to rebuilding drum brakes.
96 4.0 @115k


The water pump failure story:
My jeep had an engine squeak. Never knew the cause. Didnt leak a drop of antifreeze. After a long road trip, I smelled antifreeze when i slowed down while getting close to home. After I pulled up to my apt and turned engine off, the water pump bearings let go. Antifreeze started pouring past the bearings. All of the fluid drained out. I noticed the aux fan never kicked in. Not even sure the jeep overheated. But...

Worst Case:
Waterpump bearings go at speed and all fluid drains out. If all the fluid drains out, the sensors wont read the high temps. The jeep's coolant temp gauge won't read hot. If you continue to run your engine, it will blow a piston rod. A good friend verified this theory. (I really think he was getting anxious to build his stroker.)

birchlakeXJ said:

With the potential damage to head and engine that just ONE overheat can do to an engine with the infamous 0331 head, I don't think your concern is unreasonable.

None of the cooling system parts are expensive. I change thermostats every 60k regardless.

IF you plan on keeping the vehicle, and if you want to ensure the rest of your system is up to snuff, and if you can do the labor yourself, a new water pump, hoses and radiator cap (often overlooked) and a new radiator while you have things torn apart isn't going to break the bank.

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X 2

Any issues with the 0331 will be caused by a poorly functioning cooling system.

Keep the cooling system in good condition ...
Keep the vehicle operating temp at that imaginery "designed" op temp of 210' ....
and the head should survive fine.

If it was my vehicle At 110,000 miles .... It would already be wearing out its second waterpump, fanclutch, thermostat, fanbelt & hoses ... and I'd be considering a new radiator depending on the originals condition / usefulness.

... as Ive got better things to do than stop in the middle of an 8hr highway drive to replace something .... because someone told me .... " If it aint broke - dont fix it" is a good preventative maintenance procedure

Upgrading to a heavier duty fanclutch and more efficient radiator when maintenance time comes around is always a good move ... no matter what brand of vehicle.

Careful consideration / applicaton of the "coolant" mix ratios and the thermostat temp rating / actual running temp .... will also get you gains in engine component longetivity.

smiley, T-stats are cheap and super easy on the 4.0L. If it is the original on a 2000 thats 10 years of operation. I'd replace it to be on the safe side.
The water pump is up to you, but again, relatively cheap and pretty easy on a 4.0L.

clean96XJ said:

If the waterpump isn't squeaking or weeping, I wouldn't worry.

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Not always...

The lower pump didn't leak, weap, or squeak and the bearings felt good but it obviously wasn't anywhere near something that you'd want to use.

RCman said:

smiley, T-stats are cheap and super easy on the 4.0L. If it is the original on a 2000 thats 10 years of operation. I'd replace it to be on the safe side.
The water pump is up to you, but again, relatively cheap and pretty easy on a 4.0L.


Not always...

The lower pump didn't leak, weap, or squeak and the bearings felt good but it obviously wasn't anywhere near something that you'd want to use.

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Flush much? Any application of "swamp water" into the coolant system is bad !

clean96XJ said:

Flush much? Any application of "swamp water" into the coolant system is bad !

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Wasn't me. I bought a XJ with an overheating problem and a bad headgasket awhile back. I think that might have been the cause. :laugh3:

That entire cooling system has since been replaced.

smiley said:

Well guys my 2000 xj is passing 110000 miles and I am starting to get concerned about the 0331 head problem. Are you guys replacing your t-stat and water pumps before they fail or just going until there is a problem? I am an overly careful jeep owner/lover and I love to do preventative maintenance. Is there anything else I should be replacing before they go "bad" at this point that isnt common knowledge maintenance (like fluids, shocks, plugs, air filters ect.)?

Thank you guys for all your help,
Keep on jeepin.

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smiley,

I have a '99 XJ with a 0360 head so I'm not that worried about cracking (or should I...); however, being 11 years old and with 129,500 miles on it without changing anything in the cooling system since new (except the antifreeze) I figured it was time to inspect the system and do some preventive maintenance before my Michigan winter sets in. I found the upper radiator hose nearly chafed through on one of the A/C compressor mount bolts and the lower hose chafed on the power steering pump return line tube. I flushed the system and changed out all the hoses, pump, thermostst and housing, coolant temp sensor, clutch, and the tensioner pulley (found the bearing shot). The drive belt was starting to deteriorate so I changed it as well.

The pump and thermostat didn't look too bad when I got them off and they looked as though they would last a little longer. The radiator hoses and the tensioner pulley would have failed fairly soon though.

As for other things to change, look at how long the component has been in service, whether it is a 'simply' to change, and the $ involved. If your oxygen sensors have never been changed, you may want to consider changing those (I didn't and the front one bit me on the a$$).

I also replaced the alternator (never been changed) since I was in the area but I did fix a small problem in the process. The alternator was working as designed but I noticed the voltmeter needle would occilate a little (almost impersepatable) at all times. The new (rebuilt) alternator fixed that. Was the needle occilation an indication of an impending failure...I'll never know.

I spent 42 years as an aircraft mechanic (now retired) so preventive maintenance is in my blood. Although it may seem foolish to spend money on replacing parts that work fine, it is worth it if you plan on driving your XJ for a long time to come...like me. My XJ has served me well over the years even though I've beat her like a rented mule; now I think it's time that I pay attention to her needs.

I think it will be a toss-up if my XJ will outlive me or not...it will be a close race I think.

At some point though, you have to say "Is this reasonable".

Everyone has their own style.

I've also worked on aircraft. Most XJs do not get the attention your average aircraft gets. How many people tear down their XJ once a year, completely inspect the frame, engine, tires, brakes, and instrumentation and completely reassemble it; then document it? My guess would be zero.

The basic premise is. Check the questioned component for wear. If it fails, clean, repair, rebuild, or replace the component.

In the case of the OP, there is not a way to check a head while it is on the vehicle. Replacing a perfectly sevicable water pump or thermostat could simply result in another repair ( I have had both fail out of box ).

Also, if we are going to play the "Aircraft Mechanic" game, the FAA's way of dealing with possible failures like this, is to issue manditory compliance bulletin that makes any Aircraft Mechanic replace, on sight, a noted offending component with one that is not prone to failure. So, if we play by those rules, the OP should have the head replaced before any failure "may" occure.

haha ... my water pump is being replaced right now, this is pump #2... the 3rd one total. I told them to go ahead and change the S-belt, heater hoses and mix valve while its torn apart... I was hesitant to do that because the orginal heater hoses have never been disturbed... I was told I should because they could burst at any time.

Its going on 175K miles...

.

you guys actually flush your coolant? why are you having so many water pumps go bad? When you guys have had pumps fail out of the box have they been "quality" pumps or chinese makes? (its ridiculous they have us do their quality control, its cheaper to have us do all the work installing and uninstalling a bad part than for them to just be sure they are all good parts in the first place) I have never had a problem with anything, but I am anal about changing fluids and lubing everything at the EXACT interval required.

I have the mentality of drive the snot out of it till it breaks and when it does, you know for sure what is broken. Then again i had to replace my head and entire cooling system when i bought my $500 heap cause the PO overheated it that bad. Ive turned pretty much every bolt, nut and screw on my jeep doing the 4x4 conversion, lift and locker install in the last year and a half so i know what is going to be needed soon. Like my front pinion bearing is going out cause the front yoke was hitting my exhaust collected, which ruined my APN header, when i went offroading before my lift. I just disconnected my front axle vac disco until i have the motivation to swap the front end again. Ive just gotten tired of working on it and want to enjoy driving it

So is everyone having to replace a t-stat, waterpump, or radiator before 100k or just the guys who havnt been flushing? My jeep is running great so far and I havnt had a single problem with any of them. In fact I still have the original break pads on my car (i am at 110,000) miles and yes they are still in good condition. Maybe I am just a pussy driver, but my jeep has been amazing other than 1 o2 sensor going bad.

Also if I was going to replace everything what should i replace? Radiator, t-stat, t-stat housing, radiator cap, water pump, hoses, fan, fan clutch? Anything else? Anything less?

smiley said:

So is everyone having to replace a t-stat, waterpump, or radiator before 100k or just the guys who havnt been flushing?

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Other than the heater core, my water pump is the last remaining piece of original equipment in my cooling system at 160,000 miles. It's not making noise or weeping, and my XJ has never overheated. What does this prove? Nothing.

I flush and change the coolant annually. The radiator gave way a few months ago and got replaced; same with the fan clutch. Thermostat and radiator cap are new. Hoses (heater and radiator) are two years old at most. This on a 2000 with the 0331 head, by the way.

As relates to the water pump, I'll probably replace it before Winter hits just to be on the safe side. Given its age and mileage, it's just time to do it as preventative maintenance.

My jeep is running great so far and I havnt had a single problem with any of them.

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Let me ask: would you rather have scheduled maintenance on your XJ at a time that's convenient for you to undertake it, or would you rather have it happen at a time when it isn't?

In fact I still have the original break pads on my car (i am at 110,000) miles and yes they are still in good condition.

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If not for your sake, please replace your brake pads for the safety of those around you. 10 years and 110,000 miles on them means that they're anything but NIB-fresh regardless of how much material may be showing.

Also if I was going to replace everything what should i replace? Radiator, t-stat, t-stat housing, radiator cap, water pump, hoses, fan, fan clutch? Anything else? Anything less?

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You can skip the thermostat housing unless it's actually cracked and/or weeping; I'd be inclined to go the same way with the radiator. Other than that, at this age and mileage, that's a pretty accurate list.

casm,

My thermostat housing hose connection fitting was badly pitted when I changed it, so was my water pump hose connection fitting. Neither was leaking but I was glad I found it during my Preventative Maintenance, and before they puked their guts out in the middle of February.

Now I'm pondering my starter. It works fine but it's 11 years old (has the original Chrysler logo paper sticker on the side of it). This, like my battery that died in the parking lot of Advance Auto Parts at 10:30 PM one night, can make you wish you changed them at an opportune time. They sure can make you talk to Jesus when they crap out.

My water pump is dying this week 2000 Cherokee with 105k miles.

Cooling system maintenance is important on all vehicles.

It is "extremely important" on the 00-01 XJs with the infamous 0331 head, as one overheat can leave you in a big pile of trouble, including head/engine replacement.

whats your plan of action djrjr?

Also do you guys have any recommendations for the water pumps and t-stats? I am hearing that DPG makes a great radiator.