Amethyst643

Well... now my car needs a new thermostat. When started, the antifreeze isn't leaving the radiator. When stopped, most of the antifreeze in the radiator tries to fill up the coolant reserve tank, overflowing it.

So now I need a replacement, but I'm not sure which one to go with. Here's a list of the ones available at the local Autozone and O'Reilly's:

Duralast [160, 180, 192]
Failsafe [160, 180, 195]
Valucraft [160, 180, 195]
Hypertech [Low, 160, 180]
Mr. Gasket [160, 180]
Mr. Gasket High Performance Race Only [195]
Murray Ultrastat [160, 180, 195]
Murray Economy [160, 180, 195]
Murray Standard [160, 180, 195]
Murray Fail-Safe [160, 180, 195]
Gates Regular [195]
Gates Premium [195]
Gates Economy [195]

They all range from $4 - $18. Not too bad. Any suggestions on which one I should get??

Amethyst643

It's an '87 by the way.

hooked073

owners manual says 195.

Amethyst643

Any idea which brands are better?

hooked073

they are all about the same, I like the gates preimum, or the murry std.

Amethyst643

Thanks for the info!!

ZBRA

I have always had the best luck with the ones that look like this:



A few different companies offer them. Auto Zone used to sell them, don't know if they still do.

Amethyst643

Here's what happened :

One day I changed the antifreeze. I didn't start it that day, or drive it. A few days later I let it idle for maybe 5 minutes, but didn't drive it. I noticed that the radiator was steaming / smoking a little.

A few days later (today), I drove it for 10 minutes. In the last 2 minutes of driving I noticed that the COOLANT TEMP (on the speedometer display) was high (250ish). It was slowly creeping up to 290, but when it got there, it went back down to about 250, then slowly creeped up again - then back down. Then, it went up to 299 and stayed there for 30sec-1min till I arrived back at my house and turned it off.

I then opened up the hood. The radiator was steaming like before. I pulled the red handle up on the radior cap to relieve pressure. It steamed / shot out a bit of antifreeze for a few minutes.

When it stopped steaming, I added a gallon of distilled water, started the car, and pulled it into the garage. The COOLANT TEMP was lower than before. I opened the hood, then turned off the car. Almost immediately, all of the water I had just put in the radiator was being pushed out of the coolant reservoir (under the passenger headlight assy). Even with the lid screwed on, a mix of the antifreeze that was in the reserve and the water that was in the radiator gushed out onto the floor.

It stopped a minute later. I drained the radiator from the valve at the bottom, and siphened out what was in the reserve. I then detached the hose that runs from the engine to the radiator to drain it, but there was nothing in it.

And.. that's how it remains until tomorrow morning at least. I don't know FOR SURE that it's the thermostat, but that's my best guess right now. And, I really HOPE that's what it is because it's a cheap and easy fix.

If you think it sounds like something else, I'd love to hear input!

93 ragtop

IMO its probably not your t-stat thats the problem. You have an air pocket in the system.
When refilling the system, dont fill it completely. Leave about 2 inches or so below the neck in the radiator. Leave the cap off, start it up and let it idle. After it warms up, the t-stat will open, and you will notice the antifreeze drop in the radiator. Again, start adding antifreeze or water to the system. to fill it back up. When its full, the upper hose should be getting hot as well. Put the cap on it, top off your over flow tank, and take it for a drive, but monitor the tempature. It shouldnt go above 230 or so.
Assuming everything is ok now, let it set overnight, and recheck the overflow tank to make sure its still up to level.

kimmer

How old is your cap. A cap that is not working correctly can cause this, by not letting the fluid from the overflow tank in fast enough or not at all. This would cause extreme and quick temp. changes. Also if your hoses are old it can cause them to collapse.

lt4obsesses

I would go ahead and replace the t-stat, it's cheap, and sometimes when there are issues such as yours, the t-stat never seems to fully recover and operate properly.

Then, follow the proceedure outlined by 93Ragtop. You really need to bring the car up to operating temp with the cap off in order to bleed the air out of the system. It's a pretty essential step.

As far as the type and brand, it's not really a big deal. Just go to a place you trust. I've had good results with Autozone, Napa, or even go to a Chevy dealer. Either way, just tell them your make,model and year and they can find the factory replacement.

powerpigz-51

I suggest avoiding the "failsafe" type of thermostat. These have small clips that lock the thermostat all the way open, instead of all the way closed (which overheats your car). My failsafe was constantly getting stuck all the way open, especially after topping off the coolant. I may have just had a bad one, but I ended up cutting the clips off. Another way to remove air is to add coolant to the radiator, while revving up the engine (thermostat opened, pressure in upper radiator hose). You will notice the level drop as you rev. Tighten cap when full and revved up. This is called "packing" the radiator and should help remove air pockets. Drill two small 1/8" holes in the rim of the thermostat helps fight air bubbles, also. You can tell if your thermostat is working if there is pressure in the top hose when warmed all the way up.

Amethyst643

Thanks for the info! I will try this in the morning. The Gates Premium 195 was only $8, so I went with that one.

samsonb

If you get a stat with a jiggle valve. You don't have to drill an air hole.

Amethyst643

Ended up having a radiator leak and an air bubble in the engine - on top of needing a new thermostat (which was stuck shut by the way). Got it all fixed, though. She runs again!