Whole List of Problems...

Hey Guys!
Have had a good couple months of a well running '90 XJ 4.0L until this weekend.

So before heading to the snow this winter I decided to flush my cooling system and when I did this I took off the t-stat housing and RTV'd it back on. It dripped a little water but i kept an eye on it.

Few weeks later my alt went out, this is a napa alt moved up were the a/c compressor used to be. Replaced the alt, and at the same time put on a t-stat gasket from napa. After all was bolted back up, poured water in the overflow tank and the water just poured right back out by the t-stat housing and the belt squealed profusely.

Didn't drive it at all until this weekend when I had to drive home from school. The volt gauge went all the way up, I took a break on the road put more water in. Continued on my way and it felt like volts were rev dependent. Now it died completely.

So overall:
-Leaky t-stat housing
-Non working alternator
-Squealing Belt

So my real question is, Is my water pump dead? I have considered a new belt, new water pump and t-stat housing.
Do i need a new water pump?

1. Your t-stat housing could be cracked or improperly installed. I have installed a t-stat with the lip slightly off center, making it not seal correctly. When you look at it from up top, it looks fine, but it'll leak like crazy. Or it's also possible to crank down in the housing mounting bolts too hard and crack the sucker. Check your installation. Coolant should not "pour right back out". If cracked, new stat housing from junkyard for next to nothing.

2. Squealing - Either your is belt is old, not tight enough or it's soaked with slimy coolant or related to the alternator. When installing an alternator you should have a fully charged battery or your new alternator tries to work like crazy to charge the sucker back up. Another possibility is your idler pulley. Sounds like a belt

3. If your leaking from the weep hole at the bottom of the water pump it usually indicates that your pump is either going or gone. I didn't see any reference to water pump problems other than possibly a squealing belt.

4. Alternator - I dunno squat about electrics. It's possible to get a bad alternator right out of the box, I never have, but some have. Of course if you have coolant pouring all over it, or the belt routed wrong, that could cause problems.

I vote cracked t-stat housing.
I had one that had obviously been cracked a long time (rust in the crack), but it never leaked until I reinstalled it as part of a complete cooling system changeover (91+ rad/overflow bottle)

Anyway, check it carefully, especially by the ears. If in doubt, you can get a new one at the parts store for about $25. They call it a water outlet. I replaced mine with an HO unit, and put a brass plug in the sender hole, just so I could eventually move my fan control there.

ParadiseXJ said:

4. Alternator - I dunno squat about electrics. It's possible to get a bad alternator right out of the box, I never have, but some have. Of course if you have coolant pouring all over it, or the belt routed wrong, that could cause problems.

Click to expand...

I've seen more than my fair share of dead product come out of refurb boxes from the parts store. Someone returns one for a core and it accidentally gets put back on the shelf and Whammo, you get someone else's dead Alt.

There should be testing procedures though somewhere on here or in a FSM/haynes manual before you go tearing it back out

and X2 on the t-stat housing leak. dry gasket, no RTV is what i've seen create the best seal.

good luck.

My bet is also on thermostat housing. I've had small leaks actually solve themselves, when I replaced the thermostat on my MJ it had a pinhole leak through/along the gasket in one spot, I gave it a little throttle a few times to see if it was actually leaking or just residual coolant from installation. It spurted out a couple of times and then abruptly stopped and hasn't leaked a drop since then :dunno:

hightime81 said:

I've seen more than my fair share of dead product come out of refurb boxes from the parts store. Someone returns one for a core and it accidentally gets put back on the shelf and Whammo, you get someone else's dead Alt.

There should be testing procedures though somewhere on here or in a FSM/haynes manual before you go tearing it back out

and X2 on the t-stat housing leak. dry gasket, no RTV is what i've seen create the best seal.

good luck.

Click to expand...

sometimes it isn't accidental :smsoap:

Wow you don't know how relieved i am to hear that! I'll have a look at the weep hole just to be sure the pump hasn't died on me. My battery wasn't quite fully charged but now it is and it'll get a new one.
So on my shopping list at napa:
warrantied Alt
new belt
new t-stat housing
dry gasket for it

Thanks guys!

flyingbrick said:

Wow you don't know how relieved i am to hear that! I'll have a look at the weep hole just to be sure the pump hasn't died on me. My battery wasn't quite fully charged but now it is and it'll get a new one.
So on my shopping list at napa:
warrantied Alt
new belt
new t-stat housing
dry gasket for it

Thanks guys!

Click to expand...

Yeah, that will help- the t-stat housing is like $12 at autozone.

Be careful with the t-stat housing, they are usually aluminum and CANNOT be torqued with retard stregnth. If you do happen to use retard strength, you can crack one.....or two. Use water pump/t-stat RTV and let it sit overnight, if you can, before you pour coolant back into it.

Best results on tstat gasket would be from cleaning both surfaces off extremely well with razer scraper and scotchbrite. Then use gasket cement only to glue gasket to tstat housing. This will hold the gasket in place. Next time will be easier cleaning because you take the housing off the engine where it is easier to clean than the part on the engine. If it's not on there that long, it might even not need a new gasket next time.