Strange problem...When driving about four hours straight I noticed that when pulling through a parking lot slowly that my radiator fan was increasing and decreasing in speed relative to throttle position. This is a 93 es with no leaks. As this sounded weird I pulled over and popped the hood, the overflow tank was overflowing a little bit. I check the temperature gauge on the dash and it was half way like always. I then pulled the throttle cable and sure enough the fan was moving in relation to the throttle. Weird. Is there a sensor that controls this that could be out? I have already had it checked for a blown headgasket and it is fine. It has a new thermostat, radiator caps, all the hoses, and the radiator. The power steering pump and high pressure line is new as well. Also, I can short the terminal and the fan goes from low to high just fine. Please someone help!!! What else should I check?? Normal around town trips it has no problems. After cooling off it ceases this weird behavior.

 

That cooling fan behavior is normal... When your engine is hot the fan must increase speed to keep your engine cool under acceleration...

 

The fan is powered by the poewrsteering pump. The faster the engine turns over the more fluid the powersteering pump circulates.




Burp the cooling system (change the coolant by the book) and check the radiator super careful like.

 

Ok, I must not understand this system like I thought I did. Please explain this to me if I have it wrong. I thought the fan was hydraulically controlled by a mechanical valve on the power steering pump activated by a temperature sensor. When the sensor says it is to a heat threshold it triggers the valve on the powersteering pump that allows more fluid through causing the fan to speed up to the high setting, when sufficiently cooled the valve closes allowing a minimal amount of fluid through making the fan go to low speed. Normally the fan is always in the low speed setting right, it should never be fully off?

After I got back from a trip today I noticed when letting it idle, that the fan seemed to be on high continuously. It was not even switching from low to high for the air conditioner, and the temperature was cool on the gauge. I moved the throttle and the fan took off roaring from the high speed even higher with the throttle. I would think that with the valve in the open (high) position that all the fluid possible would already be going through the system, and that the fan could not go any faster. Does anyone else notice their car doing this? It just seems odd. Also, odd is the fact that when I stopped the overflow tank was all the way up and slightly dripping from the tube.

Also, would anyone happen to know how long the tube inside the overflow bottle should be? I replaced mine with one I made when it mysteriously disappeared after a mechanic worked on the car one day. If someone could measure theirs I would appreaciate it.

 

my tube goes all the way down below the lower line almost to the bottom... also if your tube is missing your not replenishing the system with coolant when it cools off

 

The pump does not have a continuously varriable belt drive system on it. The fluid it pumps increases as the rpm of the pump increases. Regardless of high / low being activated, high @ 750rpm is not the same as high @ 6850rpm. There's like, more than 100psi differance in operational range of the system itself.








The tube should extend most of the way down into the tank, ya.

 

Yeah I have already replaced the tube in the reservoir, I just wanted to make sure I had it the right length, which it sounds like I do. Thanks for the replies. So I guess it looks like the condition where the fan is running at the throttle speed is normal. At this point I am not sure what to do next. I am tempted to replace the temp sensor and see if that helps my overflowing problem as I have already replaced everything else that I can think of and checked for leaks. Any thoughts?

 

Warm the engine & do a compression / leakdown test noting the info for all cylinders.
Change the water pump, the car could have had coolant in there long enough for it to become corrosive & eat the water pump's fins away. Deminishing it's pumping capacity.


Sounds like the fan is fine, but you shouldn't be boiling over. Ever.

 

Well, this all started after I had the timing belt and water pump changed a few months ago. I guess all that is left to do is have a compression check done on the system. What poundage should the radiator caps be? I had replaced them with 16 pounders.

 

I just had my timing belt and water pump changed and my ac system has a super high pitched sound now, from quiet as a mouse prior to the work.

Oh yeah...my mechanic jacked up my valves and had to do a complete head job. the car is running like a piece of junk. No power and I didn't drive it a mile, before I turned around and took it back.

 

Yeah same here. Car was running excellent with no noise or vibration or overheating problems. Since the timing belt and water pump replacement it has never run correctly. I have found many things the mechanic did that were not right. I took it back to him after he first did the work as it was running so poorly and came to find out he had mixed up some vacuum lines. It then ran better but still not like it was when I took it to him. After taking it back repeatedly, I finally gave up on messing with him as I got the idea he didnt have a clue anymore and was done trying. Was also scared that he would screw it up even more. Funny thing is he was highly recommended on this site. Guess it goes to show that anyone can have an off day. lol

 

Brando (or anyone else who may have experienced the same issue), was the situation ever fixed? What was the problem?

I too am having the same issue where after only 15 minutes of driving with A/C, my fan revs ridiculously loud along with pressing on the acceleration. Getting those weird looks in the parking lot...

NM... took some extensive searching through the forums but I diagnosed it as the Fan Clutch. Spins like a top when the engines off. Getting it replaced.

If I haven't said it yet...I love the search feature here.