94 explorer tempature problem

[KobeJ05]

i have a 94 explorer sometimes when im driving the temp gauge reads all they way to the L on normal then goes right back down right away happens when im taking off from a stop and going onto the free way. i noticed to in hot weather driving it down from wa to ca the gauge was up pretty high then cools off when your actually driving it but the temp is higher then ever. but mainly right around here its only in the 60's or 70's seems when im goin in the city here it gets like that going through town getting on to the freeway flies up to L on normal then goes back down to the normal temp right away. could this be my sensor doesnt seem like its over heating i could be wrong though. i just had the head gasket replaced few months ago up in wa. it doesnt do this all the time. anyway hope this makes sense thanks for looking

 

[33exploder]

temp problems

inspect the water pump's weep holes for leakage, wetness, water/coolant stains. but most likely your fan clutch has worn out. to check it you can't be faint of heart. start the engine and try to stop the fan's rotation with you hand (use a leather glove). the fan is make of plastic if you can stop it the clutch is bad. good luck

 

[doonze]

Could also be air in your system, sometimes air can get trapped in the channels, seems to happen right behind the thermostat the most. When this happens the thermostat closes because there is no water to warm it and it closes, then once the bubble passes the theromstat it opens back up.

However this mostly just happens once, mainly the first time the truck is getting up to operating temp when starting out driving, sometimes 2x in a row. But then for me it never comes back once the bubble has passed the thermostat. If your getting this after driving for awhile, it would have to be air escaping the gaskets/heads and getting into your water channel. I have the same problem if I don't burp my system after draining the coolant. Try doing a really good burp on the system and see if you get any bubbles, if you do it may fix your issue, if it still happens burp it several times, if you still get bubbles you've got a issue with air getting into the system.

 

[KobeJ05]

i do smell that sweet smell better not be a damn head gasket i just got the rings replaced out of state sorry not takeing it out on you just had the damn thing fixed.

 

[KobeJ05]

Could also be air in your system, sometimes air can get trapped in the channels, seems to happen right behind the thermostat the most. When this happens the thermostat closes because there is no water to warm it and it closes, then once the bubble passes the theromstat it opens back up.

However this mostly just happens once, mainly the first time the truck is getting up to operating temp when starting out driving, sometimes 2x in a row. But then for me it never comes back once the bubble has passed the thermostat. If your getting this after driving for awhile, it would have to be air escaping the gaskets/heads and getting into your water channel. I have the same problem if I don't burp my system after draining the coolant. Try doing a really good burp on the system and see if you get any bubbles, if you do it may fix your issue, if it still happens burp it several times, if you still get bubbles you've got a issue with air getting into the system.

how do you burp it? i ran it with the radiator cap open for alittle still it started comming out.

 

[doonze]

Ok, I'm going to write this up in my flush How to, but I'm not quite ready for that write up yet so here ya go.

When I did my first burping I was doing about the same thing as you, but it always seemed I had air in the system after. So I read a post on here about a different way to do it, it was written by a guy who used to work at a radiator shop and I tried out his idea and haven't had a problem with it since.

So first you get a funnel, Wal-mart sells a yellow one in automotive that's called a "radiator funnel" the works great, it's the perfect size. The bottom of it "fits" right inside the lip on the fill tube of the radiator with a little pressure and seals it up perfect. You fill the radiator up like normal then put the funnel into the neck and fill it up at least 1/2 way. This will get you a water level several inches above the highest part of the cooling system. You then let the engine run, I rev it every so often, just in short little burst. Fill the funnel up again when the bubbles finally get out and leave room for more water. And I just keep doing that, making sure that it gets up to a temp that the thermostat will open (around the O in NORMAL). Then I keep revving it and letting it run until I can get to about a count of 20 without a bubble coming up the funnel. Can take awhile sometimes, 10-15 minutes or so. I have the plastic "shield" thingie removed off my throttle cable so I can rev it by hand and once I get to my 20 count I rev it until the water level falls back into the neck, pull the funnel, and screw on the cap. Then I let it return to idle. No more problems of the needle swinging to L then falling back to O.

Most people just kinda let it burp itself, but for some reason mine won't, even if I give it a couple of weeks, so I came up this this process and it's worked very well. It might be a little more time consuming then some would want to mess with, but I like it to be right, and I like things to behave like they are supposed to, and that includes my gauges.