Temp Guage Goes up and Down

Ok i just bought a 1993 Ford Explorer.It runs Great, 183,000 miles..4 wheel drive.No noises,Drives Perfect.But i have one problem i just wanna get Help on where to Start.it seems that when im driving (never really looked at it while sitting or idling)But my temp gauges goes up about half way to the normal Level and then Drops back down and it will just keep doing this.it never Overheats i just wanna solve this problem.Sometimes the smaller problems Turn into Bigger problems.Should i start by Changing my thermostat?Do i got Air in the Line?I am just looking For suggestions.Thanks guys!!...

By the way I love the site I see myself becoming an active member here helping out other members as best as i can along the way.I am currently a very active member at gixxer.com Because i own a Streetbike (Gsxr) And always put my 2 cents in..<<Just alittle about me!..

yep, you nailed it on the head. Change that thermostat, those are classic signals it is going to outright die on you.

ive also got a 93 4x4 with 70,000 miles and mine is doing the same thing. its always running at a normal temp but when i come to a stop it drops down to cold. and much like yours, it never overheats.

Could also be an airlock in the cooling system... just check to see if your levels are correct; an airlock in the system should work it's way out after a few heat ups and run downs. Just pop the cap and see if there is a good level and temperature range for your climate and keep the reservoir filled up!

Mine has been doing the same thing for over a year now since I bought it... I tried and tried to fix it.. I don't look at it anymore. I put a manual gauge in,, It fluctuates SOME but not near as much as the factory gauge does.

Yea i just checked levels All Seem Good..My MAIN concern is that this explorer has a possiable Blown Head gasket But i kinda ruled that out.I just wanted to make sure..So im gonna go ahead and put a new thermostat in whenever i get a min..weather it fixes it or not idk but either way its not seeming to be a problem so i may just leave it??..it seems others are having this same Issue..Hmmm idk!

My 94 does the same thing but never hits mid-way...temp needle goes up a bit then drops way down...just did a 4,000 mile trip with it...Other than the 4x4 taking a dump all was well..

I would say it IS the thermostat, but it might not be a problem, at least not yet.

I ran a cheap Autozone t-stat for a quick replacement one time, and noticed it had a very thin spring and flimsy construction, compared to the thicker Motorcraft and Stant stats, although Stant does make a cheap, flimsy replacement as well. The thinner 'stats with the weaker springs seem to be the cause. They open easier under less pressure, and apparently the 'stat opens different amounts depending on the coolant pressure and flow. While I had the Autozone stat installed, the needle went up and down with starting, normal driving, idling in traffic, highway driving, etc. I finally ditched it and went with a Motorcraft 'stat. This one still moved the needle some, high at idle or low on the highway. My current Motocraft 'stat keeps the needle just about pegged dead center on 'NORMAL', but still goes up and down just a bit. The original factory 'stat never moved from dead-on center except when warming up.

So, it might just be a cheap aftermarket t-stat is installed. Whether or not you want to change it out is up to you. If it never gets about halfway, it's probably fine. If it EVER goes up higher than the L on NORMAL, replace it ASAP.

i get great heat out of my X but the temp needle never gets above the N...so I'm hoping eveything is okay..

ok i believe i have this problem Pin pointed Down..Please look for my other Thread..Sudden Stalls!

Yeah it seems to me that explorers and rangers put out a great amount of heat. Never leave it on high :

My temp gauge was jumping up and down recently on my ride home from Indy to Bedford. I took 31 south which was out of my way but it was the first road trip my explorer had with me driving. Minus the roll back ride to my fathers when I first traded for it

It's something I will change out once spring hits along with many other things that I'm not sure about since I've not owned mine long. But it does seem the gauges jump around a lot on explorers from what you'll hear here.

my money is on your thermostat. as far as thinking you may have a blown head gasket, do a compression check.

My temp guage (I just noticed it tonight) will go up a little higher than halfway as im idling. Then as I speed up the temp guage goes almost all the way down. I have a 94 Navajo with a little over 205,000 miles i just replaced the a/c compressor yesterday and im wondering if the mechanic messed up or something but also it just got extremely cold in the last two days in south florida so I dont know if the temperature outside is messing with it too. Any help???

I am having a similar problem. The temperature gauge goes up very slowly from about 20% to just over 50% in about 3 minutes or so. Then it drops down much faster (in about 10-15 secs), back to about 20%, and repeats. It started doing this after I had the radiator replaced. I then replaced the thermostat thinking it was the culprit but the same thing still happens. At first I thought the temperature increased when stopped and decreased when accelerating but not true. It seems to be a a fixed cycle as if on a 3 minute or so timer.

The engine seems to run fine and has plenty of power. In fact, engine power was noticeably better right after replacing the radiator. The temperature fluctuations do not have any effect on engine performance, just the darn needle going up and down.

You might want to replace the temp sending unit. My gauge would go from N to L constantly while driving. The entire cycle would take about one minute. It is cheap to replace and took care of my problem!

Thanks, surf. I did find other threads pointing to the same solution. Will try that in a week or so.

SAME ISSUE FIXED

I have had this issue son my son's 94. I found that there was air trapped in the hose. I raised the frontend and burped the air out by lifting on the low area of the hose to work the air pocket out. This solved my issue till I had to replace the radiator a year later and ended up with the same thing.... re-burped it and has been fine for last 18 months.

"The sender (to the guage), to the left of the manifold, was the culprit when my guage was doing that. The sensor is the one on the right. (and don't tap the boot to make it fit on, thats why I had to replace the new one because the boot was too small on the first one I bought.)

Coolant Temperature Sender:

http://www.rockauto.com/catalog/moreinfo.php?pk=40556

Coolant Temperature Sensor:

http://www.rockauto.com/catalog/moreinfo.php?pk=1983986 "

From:

http://www.explorerforum.com/forums/showthread.php?p=2450740

I just look through the responses real quick. But I had a similar problem a few years ago. It turned out to be the clutch in the fan. No one mentioned the possibility of a bad clutch in the fan. You should be able to hear the roar of the fan if it operating properly. Any way that was my problem slipping clutch the fan wasn't keeping up to speed with the engine.

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