Weird rare problem, atleast i've never heard of anything like it

[SHOemup]

As you may or may not know, my car was running hot and i thought it was because the fan wasn't turning on. Well, i was wrong. The fan turns on but not til the gauge gets past the "N" in normal. It only stays on for about 10 seconds and knocks the gauge down to the "R" and it's back up again in no time. I can usually keep it at the " R" when i'm moving but if i'm in traffic, it likes to hang around the "N" and the "O". I thought maybe the fan wans't turning on because the Thermostat wasn't opening up so i changed the Thermostat along with the sending unit. I still have the same problem and I don't know what it could be. Is my gauge screwed up? Any ideas? Thank in advance.

By the way, There are no coolant leaks, the waterpump is brand new, the radiator is brand new and the top radiator hose is brand new...Althugh I'm pretty sure it doesnt have anything to do with that anyway.

<small>[ June 12, 2002, 01:34 AM: Message edited by: SHOemup ]</small>

 

[olympic]

There a re 2 temp sensors. One sends info to the ECM for it to know when to turn on the fan, and the other is for the temp gauge. Are you sure you replaced the right one? It's the one with only one wire attached to it.

 

[SHOemup]

olympic:
There a re 2 temp sensors. One sends info to the ECM for it to know when to turn on the fan, and the other is for the temp gauge. Are you sure you replaced the right one? It's the one with only one wire attached to it.

Im almost positive, I chanded the temparature sending unit. Only one wire attached. Kinda diagnolly/down and to the left of the thermostat if i remember correctly

 

[Random]

if it was the sending unit, you wouldnt get any reading off the gauge. Mine used to do exactly the same thing. I replaced the thermostat with a 4 dollar one from NAPA. Now it hangs right were it should, and doesnt budge. Unless I let it idle in hot weather for an hour. then it may rise a bit. it usually hangs right around the AL. It used to hover above the R.

 

[ghostrider]

Mine has always ran around the NO at the top of the gauge. I've heard that, that isn't that big a deal. As long as it doesn't get up into the red at the very top then your fine. Many trustworthy mechanincs have told me this. I don't know. I feel the same way you do though. You feel since it is that high something is wrong. I don't know.

 

[twr]

I chased an overheating problem for a month. I finally broke down and bought a cooling system pressure tester (not cheap) 1 radiator and four different hose later it was fixed. It doesn't take much of a leak to for the system to get hot - esp. sice the SHO has a relativly high pressure system.
Terry

 

[SHOemup]

twrsho:
I chased an overheating problem for a month. I finally broke down and bought a cooling system pressure tester (not cheap) 1 radiator and four different hose later it was fixed. It doesn't take much of a leak to for the system to get hot - esp. sice the SHO has a relativly high pressure system.
Terry

I tested for leaks. None at all. It used to hang around the AL but now it seems to like the NOR area. It just seems like the fan isn't coming on when it should. It seems like it's coming on late and when it does come on, it's only on for about 10 seconds. I just dont want to have to replace a head gasket anytime soon.

 

[twr]

What about replacing the temp. sending unit for the PCM?? Maybe the dash one is reading correctly and the pcm one is *****.
Terry

 

[Axianator]

Let us know what you find, Chris. I had the exact same thing happen to me today. Since adding my LPM a few months ago, my fan would sometimes kick on a little later then it should, but the temperature would come back down where it should (any other time it would kick on at a lower temperature than stock). Today, however, I was in slow-moving traffic and it didn't kick on until it reached the top of the NORMAL area (a notch below the red mark), and I almost starting crapping bricks! Praying that I wasn't overheating, I thought I was going to have to pull over, but I blipped the A/C and the fan kicked on. I don't know if it's my sending unit or just the LPM. I'll try to post about it once I find the cause of the problem.

 

[SHOemup]

The problem started monday. I didn't think the fan was kicking on at all. I tested everthying Tuesday morning. Fuses, fan motor etc. were fine. i just let it run and thought maybe it's coming on too late and thats what happened. I thought maybe it was because the t-stat wasn't opening up letting to let the fan know the water is coming out. I then changed the T-stat and temerature sending unit. I don't know what else to change. I'm lost now.

 

[snowwind1990]

I have been working at this problem for a month now on Snowwind........so first of all, it is not unusual!
I am going to replace the rad. cap and see if there is even a slight difference...and check all the connections carefully at the throttle, the air charge package near the maf...I found one thing that led to the problem..a hair line crack at the bottom of the reservoir, filled it with hot glue(outside) and tape. Now the temp. doesn't go to N, but O.
Make sure you don't have an air pocket! Like while it is pretty cold after just starting up, say 2 mins. stomp on the gas and push the air out! That may be your only problem. A faulty ECT could be it too. Just keep eyes open for any leak whatsoever.
Does running the A/C at max/cold help at all?
Ma Ma M

 

[pjtoledo]

twrsho:
What about replacing the temp. sending unit for the PCM?? Maybe the dash one is reading correctly and the pcm one is *****.
Terry

Ok, now we are getting close to what really happens in our cooling systems. The 2 wire sender sends the temp reading to the PCM, the PCM decides if it hot enough to turn the fan on, The PCM tells the CCRM (black box) to close the relay for low fan power. If The engine gets even hotter, the PCM tells the CCRM to close the HI speed fan relay. Turning the cabin fan all the way to hi should tell the PCM to put the engine fan on hi speed. The AC also forces it to run, not sure if it's hi or low. A short, or very low resistance (15 ohms) across the 2 sender wires should be sufficiant to turn the fan on hi speed.

Perry Toledo,Ohio

 

[Hambony]

I too have encountered this. After replacing the T-stat, ETC, Radiator fan (needed it done anyway), and radiator it would still register high. I finally ended up bringing it to a dealer hoping they could figure it out. Turns out the gauge (or sensor behind the gauge) is bad. The fan kicks on at the right temp so the only thing that I had to do in the first place was replace the dash gauge/sensor, 99 bones from fordpartsnetwork.com and a little elbow grease. You might want to check that route out.

 

[SHOMA]

This is just a thought, but here goes: There is a module called the Constant control module, which mounts right under the plastic piece telling the belt routing etc...... It has an l shaped bracket, and also has a sticker on it, (my 93 MTX said "M" on it...." Supposedly, that constant control module tells the engine and fan when to go on, as well as some other functions... It is just a thought, but if you have another one around, or one available, try it.. If the fani s only coming on for 10 seconds, something is wrong! Im just trrying to help you out, as i know that module is called the "Constant Control" Module, and controls such things as the cooling fan, etc.. GOOD LUCK, let me know how it works out!
Kevin
[email protected]

 

[jcostantino]

If you don't know how old your radiator cap is (or if it's a year old or older) buy a new one for $7 and replace it. Mine was probably the same one the car left the factory with and it held 6 lbs of pressure (13 lbs is normal). It might help out and certainly can't hurt.

Jeff

 

[Hubes]

i am buying a new radiator because i have some small leaks. shall i replace the hoses too? also how much do radiator hoses cost?

chris, if all else fails, install another fan so you ahve 2 and hook one up to a switch that goes inside your car. erik tremblay aka sho91mtx ran a second fan to cool everything down. he can tell you how and why he did it too.