A friend and I changed the thermostat housing gasket on my '91 XJ last night because the first time we did it, he refused to use the gasket sealer that I bought and the bare gasket started leaking coolant.

So, basically we replaced, and I went out to start her just 10 minutes ago, and I pulled the rad cap before she warmed up and topped off the coolant (I know this isn't all I need to do.) I let her warm to operating temp, except she didn't stop warming. She easily got to the last white mark when I turned her off. Went up front, and upper rad house didn't feel hardly warm at all, and had only a medium amount of pressure to it.

My question is this. While I was scraping old gasket from the housing and cylinder head, my friend dropped the thermostat on the gravel ground. He picked it up and shook it, and we heard a slight jingle like something was loose. He said no worries and we stuck it back in because we were almost out of daylight. Did the thermostat break? How could a small fall have broken it?

 

certainly could have - if it dislodged the spring from the valve. I guess you'll be buying a new one.

 

Wow, talk about crap luck. I was so happy I got that t-stat housing sealed, and now I gotta take it off again because my dumba** friend has butter-fingers. Would that cause a little rattle from the t-stat? A dislodged spring? It just amazes me that it woulda broken from a mere 5 ft drop.

 

It may have jingled before. Some t stats come with a tiny hole in them and they put a little almost rivit peice in witch makes a jingly sound. The hole is to help when filling the system to have less air .

 

sure you didnt put the thermostat in backwards the second time?

 

Im pretty sure that I didn't. Because that was one of the major things that I checked before I reinstalled it. I put the spring-end towards the engine, the dome end in the t-stat housing. I don't think it woulda fit the otherway around. Could it possible be that the first time I didn't leave the rad cap off and let all that air burp out? Im gonna go back outside and start her up and see if she does any better.

 

The ones that have that, they actually call it a "jiggle valve" and serves a purpose. It lets a little air thru it, and suposed to be mounted close to 12 oclock as possible. if my memory is right

 

UPDATE: So I just went outside after letting the truck cool off for about 5-10 minutes, and I went to pull off the radiator cap again, and all of a sudden a large gush of coolant squirted on out. It wasn't hot or anything, but it just gushed. Could this be a massive air bubble that was causing this, even though my '91 has an open-system?

 

I didnt know they called it a jingle valve but I know you can drill a 1/16th hole in one with out to get the same affect.

 

Also, if I left the cap off this time until it reached operating temp, would hot coolant just suddenly blow out and burn me to death? I am thinking that if I leave it off and the t-stat opens, all the air will burp itself out, and then I just refill with coolant.

 

It has to be something wrong with the thermostat. The second time I started it, I left the cap off to burp any air, and only some little burps came out. When it hit 210, it started spilling over and steaming. It went a little over 210, and even then the upper rad hose had nearly zero pressure and wasn't warm at all. I turned her off... guess im replacing the t-stat again.

 

OK, so i dont know if you fixed it yet but im pretty sure you got air in the system.The top hose sounds like its airlocked.Grab ahold of the top hose and squeeze it a few good times.also try to squeeze the lower hose and see if it helps.Mine did the same thing two weeks ago.

 

nah he has the open system (different than yours) - it can't get airlocked

 

thermostat in backwards

 

oh god please tell me he didn't do that...they are marked "outside" for a reason. You did install it spring side in right?

edit: never mind he said in post#6 he installed it the correct way, so that's not it