cheesyxj

So as of late my 90 xj would get hot at random. Sometimes after a 30 min 65 mph freeway drive home, sometimes during a rainstorm doin 65,while it was 65..not all the time ,just every now and again. As soon as I would get off the freeway it would cool right back down, and be fine again(205-210) I could suit idle all day, temp fine. Wheel fro 2+ hrs no problem. Last night it pegged the red after 10 min drive from home. I pulled over within 10 mins cool, drove home didn't happen again.....
So this morning, New rad, hoses, water pump, thermo, heater valve...everything. burped it ,all is good 195-200.Life is good,wrong.
It keeps spewing water between the thermostat housing and gasket.it cracked the og one. Old part I thought,wrong it cracked a new one..I've burping the air out flushed the system ,heat on high...its not OVERHEATING but there seems to be a blockage or something. I am at a loss, I hate throwing money and just guessing ,but I honestly just wanted to spend some money and change all her parts, she deserved it!


So to recap...the water is flowing, both hoses are warm top and bottom, flush and fill. system wasn't that neglected, still had green antifreeze.
DID I JUST KILL MY ENGINE???!

DFlintstone

So, two t-stat housings cracked? I'm thinking the t-stat slipped down and got between the housing and the head? You do have the air bleed hole up at 12:00 and the spring facing the engine.... That's all I got....

Oh and the temp senders do go bad. You might verify the temp with an IR temp gun. They may loan you one at the auto parts, Idk there.

djb383

....and after the stat is properly seated in it's grove (and placed UNDER the gasket), the 2 bolts r just snugged down, not cranked down hard. Did u use a thin film of water pump RTV on both sides of the gasket?

cheesyxj

To clarify, and add to the mystery. The first time one cracked it was the old original, who knows how old one, by the lower bolt, probably my fault. the second was a replacement housing from azone in the webbing away from bolt holes all together, hairline cracking that got worse. Now a third WITHOUT a thermo installed started "gushing" from all over after it rose to 200.I'm leaning towards the flushing caused a blockage somewhere, or I'm an idiot ,just gonna sleep on it for a day.
thanks for the quick responses guys!

DFlintstone

MAN! How frustrating! Sheez....(well I dropped a washer from that lower left, that broke my belt and the whole deal was a weekend project).

Somehow the housing is not laying flat. Nothing completely clogged would make that leak. Can you snap a pic with the housing off? (and the housing). Djb has seen it all.......you will find the answer!

djb383

I'm puzzled why it would wait to 200 to start leaking?????......there's major coolant flow behind, around and to the side of the stat the moment the motor starts....cold/hot makes no difference. If motor is cold there's major flow by the stat, thru the bypass loop. If the motor is hot there's major flow by the stat, thru the rad. If there's no cracks, uneven surfaces on the head or the stat cover or both must be the problem....especially if the stat is in it's groove, under the gasket, both sides of the gasket have a thin film of water pump RTV and the bolts r just snugged down evenly.

freegdr

Pressure gets higher as temp goes up.

cheesyxj

Yeah just one of those things that has me puzzled. I've been wrenching on cars my whole life ,and still run into things I've never encountered before. I will snap a picture for you guys, guessing it is a pressure thing. I'm hoping starting fresh tomorrow will show me my mistake.
I have been budgeting/planning on an engine rebuild for 2 summers now, she just keeps running. I hope this little thing is'nt what pushes me into that ,the weathers just getting nice!

djb383

U r correct......but when the the OP says "gushing".........well maybe I misunderstood something.

cheesyxj

no, you didn't. It seemed fine at first, then a little turned into what looked like a thumb over a hose. I'm just hoping I didn't clean/prep it properly, and there"s no cracks, or irregular surface in head. it's why I guess I started thinking blockage, because it just seems so unlikely. Will update tomorrow

djb383

Nothing to do with a gushing coolant leak, but did the fan clutch get replaced during the cooling system overhaul?

cheesyxj

Yes it did. I should point out everything has been done in stages over a period of a couple weeks trying to eliminate the issue. Water pump ,hoses, t stat. Then fan clutch ,new belt(maybe slipping). Finally radiator, and new
t stat(thought it might be sticking). Flushed entire system several times, even though it had fresh green coolant from prior weeks of work.

djb383

T-stat can easily be tested in a pan of water, on top the stove, using a cooking thermoter. Do not toss stat into boiling water. U can determine open temp and how smoothly the stat opens/closes.

cheesyxj

The Cherokee is up and running again. I have done 2 days of work driving with it now, ran errands, and feel confident with making this post
I'm going to chalk this one up to too many long days at work. After installing said new radiator I followed the instructions and set the heater controls to hi. Do you know how often I use heat in Arizona?! I believe this is what released all the garbage into the system that kept building up and accumulating behind my brand new shiny t-stats! I have flushed the system several times and am looking at getting rid of that heater bypass valve. I think all the trouble with the housing not sealing was honestly due to my frustration with the situation. Thanks guys for all the input, looking forward to a weekend of wheeling with my son.

cruiser54

All the more reason to ditch the heater control valve. Allows stagnation to an extent in the heater core.