Quick thermostat question

[CJ7inNH]

Read through everything thermostat related, but didn't see this specifically addressed.

Just installed a new t-stat (after draining rad) because AMC 258 i6 / 4.2l was running hot and I didn't think there was any coolant flowing.

I thought I read that I could leave the rad cap off, run the jeep, then watch the fluid level drop when the t-stat opened. Well, I ran it for a few minutes with the cap off and the water just started to bubble out - a lot. Didn't seem like the water itself was real hot.

Am I making up this whole thing about leaving the cap off?

Is there a way for me to tell if coolant is passing through? There did seem to be a difference in temp between upper and lower rad hoses.

Thanks.

 

[csuengr]

Read through everything thermostat related, but didn't see this specifically addressed.

Just installed a new t-stat (after draining rad) because AMC 258 i6 / 4.2l was running hot and I didn't think there was any coolant flowing.

I thought I read that I could leave the rad cap off, run the jeep, then watch the fluid level drop when the t-stat opened. Well, I ran it for a few minutes with the cap off and the water just started to bubble out - a lot. Didn't seem like the water itself was real hot.

Am I making up this whole thing about leaving the cap off?

Is there a way for me to tell if coolant is passing through? There did seem to be a difference in temp between upper and lower rad hoses.

Thanks.

The coolant coming out indicates the thermostat opened. I put the cap on just as it starts to do this. You will have to let if heat up and cool off again before you do the final level check.

 

[CJ7inNH]

Well that's some positive news. I'll let her cool and take a look.

Thanks for the quick reply.

 

[CJ7inNH]

Fluid dropped a little. Not as much or nearly as dirty as I would have expected. Now I'm thinking that the old t-stat was good.

Does the gurgling water sound when turning her off indicate anything?

The temp gauge never moves up into hot at all, so I need to address that first. Even on a cool night, if I take a real short cruise, come back and the hood and around is crazy hot.

Also noticed that the heater hose that comes out of the t-stat house for heat (looks like it goes into the manafold) was real hot almost right away.

The blower motor for heat doesn't come on, so that's another one to work through. Get's power up to that point though.

Always something.

As usual. Thanks for all the help. Love this site!

 

[hole]

I've never noticed a drop in coolant while observing with the cap off, but you should see the coolant start moving while giving it some RPM's. If you aren't seeing the coolant move (kinda like a stream does) after the engine is warm, then something is wrong. Maybe T-stat is in backwards, wrong rotation water pump, blockage somewhere.

 

[robert421960]

yea are you sure the tstat in not in backwards?

 

[CJ7inNH]

Thanks for the feedback.

Still not sure why the water bubbled out with the cap off, but with it on there is a drop in the level when I run it for a while then check it.

Flushed it all twice with straight water, then refilled with 50/50 mix.

Then the big DOH! Two jugs of distilled water sitting there. I forgot to use it and just went with water from the hose. Oh well, what's one more flush at this point.

Also replaced the lower rad hose while I was at it. The replacement from the store didn't have the spring thing in it. I took the one out of the old one and fed it into the new one.

What does that spring do? Just help keep the shape?

Forcast tommorow is 93 degrees. I'll cruise around and see how it goes.

Thanks again.

 

[thiswontbetooexpensive]

The spring is to keep the hose from collapsing under negative pressure if I'm not mistaken.

 

[DHugg]

Put your T-Stat un question into a saucepan of water over a stove burner. Use a cooking thermometer to monitor the water temperature. You can see the thermostat open when it reaches target temperature - check the cooking thermometer and you'll nail the T-Stat temp.