Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (
-   Troubleshooting/Problems (
-   -   2004 hydraulic fan noise (

Planenut 12-11-2010 07:06 PM

2004 hydraulic fan noise

I know I should do a post in the new guy forum but I am on the road with a little problem.

I have a 2004 grand Cherokee Laredo 4wd with the 4.7 and auto transmission.

After running 65 - 75 on the interstate and then slowing down on an exit ramp, the fan is making a lot of noise. I can shut off the engine and restart approximately 5 seconds later (waiting on fan to wind down) and the noise is gone.

I can drive around town for 45 minutes or more with no problems!

What can try to further troubleshoot this problem and what is your best guess as to what I am going to have to fix?

Thanks so much for your help!

FYI: I replaced the water pump and thermostat and belt about 6 weeks ago? Possibly the fan/shroud is loose or moving from wind load at high speed?

Frango100 12-11-2010 08:27 PM

Re: 2004 hydraulic fan noise
What was the reason that you had replaced the waterpump and thermostat? Did you check the coolant temperature when exiting the highway?

Planenut 12-11-2010 09:07 PM

Re: 2004 hydraulic fan noise
It developed a small leak. I replaced the thermostat because I thought most people did it at the same time. The old one looked perfect though. At the time temperature was a non issue.

Currently on the interstate, the temp is a little over the 210 mark. Maybe a little higher than I consider normal. Outside temp was in the 45 f range so with interstate airflow and outside temperature, overheating should not be possible as long as water is flowing.

Frango100 12-11-2010 09:34 PM

Re: 2004 hydraulic fan noise
After filling the coolant system, did you bleed all air out of it?
Will the fan slow down by itself after leaving the highway, or do you have to switch off the engine? I have never heard my hydraulic cooling fan in high speed mode after leaving the highway, also with 35 C outside and airco in full.
My Jeep runs a little below 100 C normally, not sure how much that is in degrees F. Are you sure they sold you the right thermostat?

Planenut 12-11-2010 09:51 PM

Re: 2004 hydraulic fan noise
I did bleed it at the time. I will check it again tomorrow. I'm not sure that will still explain it not happening when city driving?

Ps: just turned 60'000 miles

Planenut 01-04-2011 10:58 AM

Re: 2004 hydraulic fan noise
I meant to get back on the forum sooner but...Hopefully this will help some others...

Anyway, before leaving Ky to head back home to SC, I bought a gallon of Dexcool and topped off the overflow tank. I didn't even bleed it again. It took almost a half gallon in the tank but I did not have a "coolant low light" illuminated.

Anyway, the problem has gone away and not returned. It was due an oil change when I got home so I did an oil change and checked all the fluids. It did not use any more coolant on the way home.

All I can think is that it had an air bubble near the temperature sensor and it was making it the fan go into high speed mode. When I installed the water pump, I did bleed the system and operated the heater as well. It just seems funny that it only happened on the interstate.? I could drive around town for an hour at temperature and it never spooled up into high speed mode.

Now at 70,000 miles, I think I should be replacing some other fluids... Differentials, Transmission and transfer case so I'll be reading up on that.

Thanks for all the suggestions.

Frango100 01-04-2011 03:04 PM

Re: 2004 hydraulic fan noise
I'm not sure about your jeep, but on mine there is no sensor anymore on the cooling expansion reservoir to show low level.
But half a gallon low is quite some. Is the temperature now back to normal level as well? Glad that your problem is solved.

Planenut 01-04-2011 10:29 PM

Re: 2004 hydraulic fan noise
Yes temp stays below the 210 mark (guess about 200). 500 miles home plus another week or so around town. Love my jeep again and my duramax too!

The forum is great!

Planenut 02-05-2011 09:25 PM

Re: 2004 hydraulic fan noise
Well, It has been almost 2 months since this original post and problem. The jeep worked great on the way home from KY and has since driving around town in SC. I've done some more Preventative maintenance changing some fluids. Full transmission flush with filters and front differential fluid change and new front brake pads with rotors turned and new air filter.

Well my wife drove to KY again yesterday and the problem came back exactly like last time. Driving much over 60 on the interstate with the outside temperature just above freezing, the coolant temperature would get above the 210F mark (boiling) and the fan would cycle on. It was pretty hard to drive that slow on the interstate with the speed limit at 70 and cars zoomimg past but she did make it to KY.

Left it at the Jeep dealership in KY and hope to know more on Monday. Initial observation at jeep showed it hard to repeat w/out driving above 70 and all they have done so far is to rebleed the cooling system to see if that helps. They are going to check more on Monday.

I would really like to find out what is going on!

It never did this until after I changed the water pump, thermostat and belt. Water pump was changed due to small coolant leak from pump shaft. Thermostat and belt were changed because I thought I should do them while I had it apart.

I don't understand how it would run hotter on the interstate with near freezing temperatures when it doesn't run hot around town with temperature in the 70's...

Maybe it is a faulty temperature sensor or an air bubble in the system near the temperature sensor? The only other things I can think of are:
Transmission temp causing coolant temp to rise?
higher RPM's on interstate at 75mph?

Any ideas or suggestions?

Planenut 02-05-2011 10:23 PM

Re: 2004 hydraulic fan noise
test of signiature with my data

Frango100 02-05-2011 10:57 PM

Re: 2004 hydraulic fan noise
Hi Planenut, im having some problems with a little higher coolant temperature at highway speeds around 120 Km/h ( approx 4 C) and coolant coming out via the expansion reservoir. My biggest bet at the moment is the radiator cap. The cap has 3 functions: 1 - to seal off the cooling system from the outside, 2- to pressurize the cooling system (and by doing this, to increase the boiling point of the cooling liquid) and 3- to let the cooling liquid flow back from the expansion reservoir to the radiator when cooling down.
If the radiator cap will not let the system pressurize (enough), the boiling of the cooling liquid can start as low as 100C, very close to the normal operating temperature of the engine (mine normally runs around 98/99C). So when driving on highways, the produced heat by the engine can let the liquid start boiling, resulting in higher cooling liquid temperatures. Will not say this is your problem, but could be a cheap fix. Surfing around on the web, i found out that the radiator cap should be changed every year, because of the important function it has and the relatively low price.
Also you did mention your cooling fan never behaved like this before you changed pump, thermostat etc. When you did this change, you removed the radiator cap.............
One thing to look at the cap is for indents in the rubber seals. As soon as you see that, its a good time to change the cap. Never knew this before and i never changed any cap on my cars before.

Planenut 02-06-2011 05:32 PM

Re: 2004 hydraulic fan noise
That is a great point and a cheap thing to try. I'll be calling the shop in KY tomorrow and make the suggestion to them and make sure they at least consider it..


All times are GMT -5. The time now is 10:19 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community