Engine temp Hhgh on acceleration

[Al (noisebeam)]

Vehicle: 2001 Ford Explorer 4.0L 4x4.
Symptom: Engine temp guage moves high with high speed driving (>70mph) and during acceleration. Gauge will return to normal temp below ~60mph and with no acceleration. Ambient temp is currently 65-70degF. If heater is put on full this helps control temp back to normal.
What has been checked: Radiator is full of proper fluids. No leakage in cooling, no seaps or drips. Oil is full. No objects (plastic bags) are blocking radiator intake.
What I suspect is the cooling fan clutch - I noticed that the fan freewheels (with some resistance) even when engine is hot - same as when engine is cool. Is that normal?

Thanks,
Al

 

[ve4ron]

Welcome to the site.

My 92 does this also when passing or under heavy acceleration . :thumbdwn:

I'm not to worried about it yet, but spring is comming .

 

[Al (noisebeam)]

Welcome to the site.

My 92 does this also when passing or under heavy acceleration . :thumbdwn:

I'm not to worried about it yet, but spring is comming .

Well spring temps are closer here in AZ
On normal acceleration say from stop to 40mph my temp gauge goes perhaps to 3/4. (vs. 1/2 which is normal) But if I accelerate harder like to get up to highway speed on an onramp the gauge will move to full hot and the check gauges lite goes on. As soon as I let up on acceration (or put on heat full blast) the gauge will move back toward normal. I only once had gauge read full hot as now I am careful to turn on heat before accelerating to get on freeways.
As another example if I cruise on highway at 70mph the gauge will read just a bit over normal, but if I put on heat it bring it back to normal.

My main question is can one tell if the fan clutch is bad without removing it. That is when engine is cold I'd expect it to freewheel, but when hot I'd expect it to be locked. I notice that hot or not it freewheels with some friction. Or perhaps this is normal?

Al

 

[Doug]

Sounds like your thermostat might be bad or your fan clutch. fan clutch is easy to check. When the engine is cold the fan should be fairly easy to turn when the engine is at temp. it will be alot more difficult to turn. Thats generally how a fan clutch goes bad, never heard of a fan stop turning. Check the coolant level and replace the t-stat and see what that does.
Also is your coolant nice and green or is it nasty lookin? if it's nasty looking you're going to want to have it flushed and changed.

 

[ve4ron]

Thanks I'll check it out when it warms up a little .

 

[Al (noisebeam)]

Sounds like your thermostat might be bad or your fan clutch. fan clutch is easy to check. When the engine is cold the fan should be fairly easy to turn when the engine is at temp. it will be alot more difficult to turn. Thats generally how a fan clutch goes bad, never heard of a fan stop turning. Check the coolant level and replace the t-stat and see what that does.
Also is your coolant nice and green or is it nasty lookin? if it's nasty looking you're going to want to have it flushed and changed.

Well what I meant by not turning was that the clutch is fully locked it to the shaft, but perhaps what you are saying it that it never fully locks up, but just gets a good amount of resistance.
I wouldn't call the fan currently difficult to turn at temp, just some mild resistance, i.e. I can turn it with one finger and it will spin several revolutions when hot engine is turned off.
T-stat not checked or replaced, but woudn't this cause more severe overheating issues and not the rapid rise and fall of temp gauge in response to engine load and unload?
Coolant was flushed perhaps a year ago, engine has 60k miles on it. Its not new coolant green, but not nasty either. It is full, I took off radiator cap when engine was overnight cold and it was as full as one could get it (and overflow resevoir had some to spare)

As a side note, my previous Explorer was a 1992 standard trans sport 4x4 and I liked it much more (I can go into details why some other time). I had >200k miles on it before I got the 2001 (and I never flushed the radiator, luck I guess )

Al

 

[Doug]

T-stats can do weird things when they go bad. I had one that would intermittant get stuck closed, mostly when driving up hill it seems. Temp would shoot way up then drop back down then shoot up again at random. I say replace the t-stat because they're 5 dollars and take all of 10 minutes to replace.

 

[blue xlt]

If water pump age is not known or is original you may want to swap out since old worn out pumps cannot move enough coolent at higher rpm's.Also new coolent ,192F thermostat and 16lb radiator cap.Pressure wash radiator from back to front.check acc. belt for glazing which is caused from slippage and tensioner pressure on belt.You may also have high rpm pinging which will cause temporary rapid rise in temp.regardless.Weak fuel pump may be leaning out mixture at high rpm.In any case,fan does not contribute to cooling at speeds over 30mph.Good luck.

 

[Al (noisebeam)]

Good news and BAD

So I decided to replace the thermostat since its relatively easy. Pulled out the old one. Went to Checker and looked up the right one for a Ford Exp. 2001 4x4 Sport 4.0L SOHC. The one they gave me was half the size! Checked for other years and engines, none matched -all too small. Checked AutoZone, same problem.
Went back to Checker and finally found one that looked the right size but had two valves instead of one like one I pulled. Strange I thought - more below.

Now the bad news. I went back to the 'cup' that holds the t-stat and put my fingers in the green fluid and found loose bits of spring and metal and a flat disk, then I ooops, accidentallly bumped the spring into a hole towards teh back of the 'cup' and the bit of metal cylinder fell down the tube. How I am ever gonna get these parts out? Well that explains why the t-stat I pulled out looked different than this 'double' one - I only had pulled half of it out.

Well the good news is that I know the problem is the t-stat as it is obviously broken. Has any one else seen a t-stat break like this?

I am curious to know why this t-stat has two valves? Why two? Also what was that hole in the back side of the cup I pushed the spring into for - it looks like there is a sensor in it - does it go anywhere else?

My friend is coming over with a magnet device to try and fish the spring out, but the shaft that fell down is non-magentic I think.

Al

 

[TPLYNCH]

Easiest way to get the pieces out is to just try and flush it out I would think.

 

[Al (noisebeam)]

Easiest way to get the pieces out is to just try and flush it out I would think.

I was considering that too. In fact if I turned over the engine, wouldn't it blow everything up and out (and make huge mess) Flushing would be a more controlled and sensible way of course.

Has anyone ever heard of a tstat busting like this?

Al

 

[Al (noisebeam)]

Just wanted to let y'all know that my Explorer works great now.
I was able to fish out the spring with a magnet, but not the small brass shaft. I left that in there. I also tried flushing with pressue, but not luck in pushing it out.
Chaning the t-stat is harder than it looks, very tight in there.
Coolant runs cooler than before and stays steady.
Engine idle is back at 5-600rpm, before is was 1500 or so.

Al