Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 07, 2025 ...

1990 u300 6v92 engine fan

December 10, 2024, 08:07:05 pm

Engine fan turns with no air pressure
Well not work once air pressure has built up
Any help would be appreciated

Quote Selected

Re: 1990 u300 6v92 engine fan

Reply #1 – December 10, 2024, 09:37:48 pm

Running with no air pressure is normal, It takes air pressure to disengage the clutch. There is an air solenoid that should turn the fan on and off. Follow the air line from the fan to the solenoid and see if it's getting power to it. Could be that the valve is stuck.

Quote Selected

Re: 1990 u300 6v92 engine fan

Reply #2 – December 10, 2024, 11:41:19 pm

Like kgrover said that sounds normal. 
Except the air valve on mine is not electric but thermo-pneumatic.  It's screwed into the passenger side head (near the thermostat on that side) with two air lines attached; one going to the fan clutch. 
Fan should only engage if:
1. There is no air pressure in system (thus it fails in a "safe" mode of operation by keeping engine cool)
2. Coolant temperature reaches operating (180-190 F or thereabouts)

Quote Selected

Re: 1990 u300 6v92 engine fan

Reply #3 – December 11, 2024, 07:10:46 pm

This is called a "shutterstat". New-old-stock is still available. A search on eBay brings up several different temps available. Picture shows a 180 degree unit.

Quote Selected

Re: 1990 u300 6v92 engine fan

Reply #4 – December 11, 2024, 08:31:28 pm

I've never really looked to see how mine was set up. I just guessed that it was electric. now i need to go find the value

Quote Selected

Re: 1990 u300 6v92 engine fan

Reply #5 – December 12, 2024, 04:45:03 am

Quote from: kgrover – December 11, 2024, 08:31:28 pm

...now i need to go find the value

If you zoom in on my pic the temp rating is stamped on each part. You might be able to see it on engine or worst case pull the old part to read it - needs 7/8" wrench.

Quote Selected

Re: 1990 u300 6v92 engine fan

Reply #6 – December 12, 2024, 07:56:37 pm

Thanks for the help
I looked I believe it is on the passenger side rear
Am I correct

Quote Selected

Re: 1990 u300 6v92 engine fan

Reply #7 – December 13, 2024, 01:03:37 pm

Are you sure your engine is getting up to temp. The fan won't turn on until the shutterstat gets hot and turns the air pressure off. Maybe take an IR temp gun and check the engine temp near the shutterstat. If the engine gets to say 190 - 195 degrees and still no fan then the shutterstat is suspect. Have you noticed abnormally high engine temperature while driving?

Quote Selected