HOT explorer... TOO HOT...

[SplashMan]

OK, here is the deal...
About two days ago on the way home from work I was doing my glance at the gages thing and noticed that the temp gage is pointing strait up and going higher(toward the red line). I imidiatly turn on my heater and the gage stops and then eventually goes down a little and stays there for the rest of the trip home(20min). When I get home and put it in park I notice it is ideling high(usually it idles just below 1 now it is just above 1 1/2). Well it was a VERY hot day(90+ with heat index about 105) so I figure it is the weather and only check the radiator overflow(right were it is supposed to be) and then forget about it. Next morning on the way to work I look at the gage and it is doing the same thing and it is only 75 out side. So I turn the heater on and get to work. When I get to work it ides high again and I check all the fluids and everything is good. After I get home last night (after driving 30min with the heater on full in 90+ temp) I grab the hose and spray the radiator off and get alot of dirt and crap off of it. Well this morning it does the same thing...??? The only engine mods I have are K/N drop in and a drilled air box. It is the 4.0 SOHC with just over 50K.
Anyone have any ideas??

 

[JDraper]

Could be a stuck or bad thermostat. It's not too hard to replace and it only costs a couple of bucks. I'd try that first.

 

[kps36]

jeffs right, that was about the time my TStat went out. May want to switch out the temp sending unit, easy too and not too pricy. Get a 195 TStat.
When it is HOT, is the upper Rad hose scorching too and obviously flowing fluid. My money says the TStat is stuck and heading south, just giving you some warning sign. You don't want a TStat to stick closed, very bad.

 

[SplashMan]

Hey guys thanks for the info and the quick response. I was hoping it was the thermostat, but I wasn't sure. Autozone has them for $14 and I am going to pick one up and put it in tonight. One last question... am I going to have to drain the radiator to do this? Its no big deal if I have to, but I want to know before had so I have two new jugs ready to refill it. Thanks again.

 

[Robert]

It is definately your thermostat getting stuck closed. My '97 SOHC did it last March. I noticed something was wrong about a week before my temperature gauge looked abnormal. My idle speed was running around 1200 RPM which was about 500-600 too high. A week later my temperature gauge ran a little above half way when sitting at a traffic light. As soon as I acceleratred, my gauge went all the way up to the red zone. It was only 60F at the time so I knew it had nothing to do with the outside temperature. Besides that, being in Arizona my Explorer has seen up to 120F without the temperature gauge ever going above half way.

If all you replace is the thermostat (and that is all you should need), all you will need to do is drain a little coolant out of the radiator (1/2 gallon should do it). Your thermostat is about the highest point in your coolant loop so even if you didn't drain it before removing the thermostat cover, you wouldn't loose much. If you remove about 1/2 gallon first you probably won't have any spill on the engine when you remove the cover.

 

[COMMOCOZY]

Brian! this is very easy to do, i did it right when i got my X. If you want come over tonight and we can do it. Also you will hardly lost any fluid, if i remember correctly. Give me a call if you have questions.

 

[irtySanchez]

I ran into the same problem also not that long ago. Changing the t-sata did the trick. Remember to install it with the relief valve pointing up.

As for the high idle, the truck was doing what it was supposed to. When it senses that the coolant temp is rising, it increases the idle to between 1000 to 1500. This helps to circulate more coolant through the engine. So if that does happen again, it is not a bad thing. My EX does it everyday.

 

[kps36]

VERY IMPORTANT !!
some Tstats do NOT come with the rubber O-Ring type 'gasket'. Make sure you get one ! do not reuse the old one.

 

[SplashMan]

Well, I just got back from lunch and I managed to get the T-stat, gasket and a bottle of antifreeze for $11.68 total. I went to AutoZone and they said they don't carry that any more (funny I looked it up on there web page and they carried it there). Next went to PepBoys and they said they could order it, but it would take 5-10 days... no good need it now. On my way out of PepBoys a old guy stopped me and told me to go to CarQuest... SCORE!! The guy at CarQuest walk two feet to a shelf pulled the part down and even grabbed the gasket on his way back saying "You will need this too", then grabbed a bottle of anti-freeze and said "Here this is on the house". Hope this fixes it... I will go home and let the engine cool and then tackle the T-stat. I'll let you guys know how it goes... and thanks for all the help.

 

[SplashMan]

I think that did it. I had to take the air cleaner hose and trottle body to get at it, but it seems to have fixed the problem. I drove around for about 20min last night with the AC on max and the gage never went past half way. I drove in this morning and it barely hit the half way mark. The real test will be the 4 1/2 hour drive to my dad's tonight. Wish me well...