New Thermostat?

[2good2btru]

Hey guys! I'm driving a '98 Explorer, 4.0L V6 SOHC.

Recently, since it's winter, I've been noticing that my cabin heat hasn't been all that superb. It takes a while for it to heat up. I recently installed a block heater and that has helped a little, but not like I was hoping.

A friend then suggested to me that my thermostat could possibly be stuck open? My engine temp. guage very rarely moves above the 'C' even after driving the truck for a fairly substantial amount of time. The only time it rises above the 'C' is when I've driven the truck on the highway for a good hour. And even then, it rarely meets 1/3 of the guage. My friend has told me that after a good 7-8 minutes, the guage should be in the middle between 'Hot' and 'Cold'. Is he correct or should I seek another solution?

How much is a new thermostat? Is it a fairly easy job for a weekend warrior like me? It would be great to knock this out today.

Thanks guys!!

 

[Anime]

It probably is the thermostat. Good thing for you it got stuck open rather than stuck closed.

You can get to it if you have all the wrenches and sockets. You can get an aftermarket 'stat for about $5, or a new Motorcraft one for about $20. I usually go with Motorcraft since the temperature they open at is the factory spec rather than the slightly higher/lower of aftermarket, but Stant has a good deal on an aftermarket 'stat for $5 with a lifetime replacement warranty. Be sure to get a new gasket/seal for the thermostat as well. You might want to keep the old one in the vehicle as a replacement in case you ever have one stick closed on you, rather than be stranded.

You should be able to knock it out in a few hours with the right tools.

Gas mileage and performance should increase greatly with the new 'stat since it will get up to the normal operating temp, and the heater will work a lot quicker, too.

 

[2000StreetRod]

Thermostat replacement step by step

Here's a link to a step by step procedure for replacing the thermostat:
How To Replace the Upper and
Lower Thermostat Housing on a
Ford 4.0L V6 SOHC Engine

 

[2good2btru]

Wow! Thanks for all the help guys! I went down to the store and grabbed the OEM replacement (192 degrees, I believe) for $15.99.

Honestly, it was a pain in the butt to find all the different bolt sizes. It probably took me an hour to get the three bolts off the top half of the housing because of all the obstructions in the way. Once those were out, it was tricky to figure out how to lift the housing open without removing part of the radiator house. But blah blah blah. Long story, I got it all replaced.

So for my first test drive, I started the car cold (outside temp was 26 degrees) and within 6 minutes, my truck was reading just a tad bit lower than halfway between hot and cold! You guys should have seen how excited I was. As long as i've
owned this rig, I have never seen the guage read that high. Rarely would it ever go above 'C'.

Also, the heat was almost scalding how hot it was. Never before have I has to turn the heat down before so that was a fun experience.

Curious, how much do you think gas mileage will increase because of this?

Thanks once again for all the help guys!!

 

[Anime]

Wow, that was pretty fast.

Gas mileage should return to at least normal, whatever that is depending on how you drive and whatever other mods you have on there. An engine that runs 'cold' and never gets up to operating temperature usually gets pretty poor mileage since none of the systems are working as efficiently as they can, especially those involving ignition, combustion, and exhaust.

Did you change out the old coolant for new, fresh fluid since you had to drain the system anyway? That should help keep the cooling system efficient and well lubed, too. Just be sure to check the level of the overflow tank over the next few days and keep it topped off at the fill line, and keep an eye out for any leaks as well.

 

[2good2btru]

About a week or two ago, I put in an engine block heater and just flushed and replaced the coolant then. Since the thermostat housing was so high up on the engine, I didn't even bother to drain it. When I removed the three bolts, a decent amount spilled out but I just didn't worry about it. After I finished, I topped off the radiator with some more distiller water.

During the summer, I usually get about 15.5 mpg. During the winter I average about 13.6. My highest so far is 14.3 and my low is about 12.6. The 14.3 was after getting the block heater though. Will this new thermostat bump that mileage up to my summer mileage you think?

I had a quick question though: The thermostat only affects the cabin heat, doesn't it? I know that can't be true, because my engine temperature guage is higher than it's ever been. But I thought all the thermostat did was allowed coolant to flow through the radiator (therefore creating cabin heat) as soon as the engine was sufficiently warm. How would that affect gas mileage?

Thanks!

 

[DLinkOZ]

The thermostat regulates the flow of coolant into the engine, which is why it effects your heater. With it running non-stop (yours was stuck open, never slowing the flow) your engine is never allowed to attain the proper temperature. The reason you could see increased fuel economy is due to proper efficiecies. An engine is designed to run at a certain temp, and lower or higher yields less-than-optimal performance. By allowing for proper metering of coolant into your engine, it will run as-designed.