Community Forums

GlennLever · 09-09-2015, 09:33 PM

My radiator fan has started to run all the time.

It is not supposed to.

I think I have figured it out.

I believe the Air Inlet Fan Temp sensor is no longer working.

I believe this symbol is for a diode, but have forgotten how to read it, I believe the current flows in the direction of the arrow inside the symbol??? Help??? That does not make sense as as there are arrows pointing in both directions.

Gary RVRoamer · 09-10-2015, 09:44 AM

I had to replace the variable hydraulic control on mine this spring. It had failed and ran 100% fulltime. However, that's an ISL with side radiator and a purely hydraulic fan. I think you have a mechanical "C" engine (8.3L) with a direct drive fan and a clutch for fan speed control? That's what a friend's 2000 Dream has anyway.

GlennLever · 09-10-2015, 09:58 AM

Quote:

Originally Posted by Gary RVRoamer

I had to replace the variable hydraulic control on mine this spring. It had failed and ran 100% fulltime. However, that's an ISL with side radiator and a purely hydraulic fan. I think you have a mechanical "C" engine (8.3L) with a direct drive fan and a clutch for fan speed control? That's what a friend's 2000 Dream has anyway.

My fan is also hydraulic, with no direct link to the engine other than hoses.

When power is supplied to the fan solenoid it slows down as it should.

I believe the air inlet temperature sensor has been locate, I need to go look in the engine compartment and see if there are red, green and yellow wires foming from it.

See below, note in the upper left corner a sensor screwed into the air inlet. The name had me fooled was looking for a sensor around the fan.

koda59 · 09-10-2015, 01:38 PM

I have the isl 8.9 engine with the side radiator. When my fan started to run all the time, they found the Direct fan controller had gone bad. It is a 3x3 box that sits on the back side of the radiator. My temps ran 175 to 179. Now my temps run 195 to 199.

GlennLever · 09-10-2015, 02:02 PM

Quote:

Originally Posted by koda59

I have the isl 8.9 engine with the side radiator. When my fan started to run all the time, they found the Direct fan controller had gone bad. It is a 3x3 box that sits on the back side of the radiator. My temps ran 175 to 179. Now my temps run 195 to 199.

I do not believe I have that controller♠.

GlennLever · 09-11-2015, 04:28 PM

Ok...I'm sure everyone is waiting with batted breath.

I did find the Air Inlet Temperature Sensor

and it did have the correct color coded wires.

I have said this before, I love weather pack connectors, you can make up what ever you need, they can be taken apart and rebuild another way. In this case I needed to connect the red and yellow wires to test if the Air Inlet Temperature Sensor was the problem.

This is the shut plug I made up.

And now for the test, I fired up the engine with the sensor unplugged, the fan ran full speed, I plugged in my shut plug and the fan slowed right down.

Success.

So now is the question will the fan run up to speed when the coolant reaches 195?

Strangely enough I cannot answer that.

I ran the engine at 1,500 RPM for 30 minutes and the temperature gauge never went above 170. I let it run while I greased every grease fitting under the Motor Home, still never went above 170. I loaded the Motor Home with stuff for our trip to Bowling Green, still did not go above 170.

I took the Motor Home for a drive all the way around the outer loop of Rochester (30 miles) still did not go above 170.

I started to suspect the gauge was bad, drove to my home and got an infrared heat gun, and went all over the engine. The highest temperature I got was 175.

I have said in the past this radiator and fan are huge. Apparently on a 75 degree day the fan running at slow speed moves enough air to keep the engine cool.

The real test will come when we drive to Bowling Green pulling the trailer.

It is a simple fix to get the fan to come back on if it does over heat, just remove the shut plug.

Gary RVRoamer · 09-11-2015, 06:42 PM

Good diagnostic work! And thanks for the feedback on the problem.

Is that a side radiator configuration I see in the coach picture in your signature? Have not seen a older Dream with a side rad.

GlennLever · 09-11-2015, 07:33 PM

Quote:

Originally Posted by Gary RVRoamer

Good diagnostic work! And thanks for the feedback on the problem.

Is that a side radiator configuration I see in the coach picture in your signature? Have not seen a older Dream with a side rad.

Yes I have a side radiator.

And the radiator behind the grill is huge (there is the A/C condenser, A transmission cooler, An inter cooler for the air, and in back of all that running the full length and height of the compartment is the radiator).

FORTRIDER · 09-11-2015, 09:11 PM

I have a similar configuration, 1998 American Eagle, Cummins, side radiator. You mentioned the air temp sensor, did you raise the bed to get to it or is it accessable from the rear?
I changed the thermostats, cleaned the radiator fins and doing a fresh flush and fill, have not had a chance to test but I do not think I have solved the overheating issue.
Thanks

GlennLever · 09-11-2015, 10:17 PM

Quote:

Originally Posted by FORTRIDER

I have a similar configuration, 1998 American Eagle, Cummins, side radiator. You mentioned the air temp sensor, did you raise the bed to get to it or is it accessable from the rear?
I changed the thermostats, cleaned the radiator fins and doing a fresh flush and fill, have not had a chance to test but I do not think I have solved the overheating issue.
Thanks

The air temperature sensor is the easiest component of the whole system to get to. I am sure glad that it turned out to be the problem.

Yes, raise the bed, lift the engine compartment lid, it is in the 90 degree elbow that feeds the intake.

If you kneel between the bed and passenger side wall and look at the top of the engine you will be looking right at it.

The fan defaults to run full bore, you have to supply 12 volts to the fan solenoid in order to slow the fan down. If the fan is running full bore with the engine at 1,000 RPM it should suck a piece of cardboard to the side grill of the radiator and hold it there and resist being removed. It also makes a lot of noise. If the engine compartment lid is up you will be blowing air all around the bedroom.

If you are having an overheating problem it should not be the sensors (if they have failed the fan runs full out).

For overheat, I would look at a air lock in the engine (there are a three bleeder hoses to remove air bubbles in my engine, remove one at a time from the expansion tank and make sure there is water coming out of them and not clogged).

Make sure the water pump is pumping (I have no idea how you would do that (remove the inlet hose to the radiator and see if water is gushing out)).

Make sure the radiator is not clogged, remove the outlet hose and water should gush out.

To do those check you might have to remove the thermostat.

I am talking off the cuff here, I have done no investigation on how do do these tests.

Gary RVRoamer · 09-12-2015, 12:15 PM

My '04 Tradition has a similar side rad. I knew the Eagle had a side rad in those years, but thought the Dreams were all rear radiator. I have a pal with a 2000 Dream and he has an 8.3L Cummins ISC engine and rear rad. Ditto for a guy I know with a 99. Wonder if there was an engine or chassis upgrade option, with the "L" engine and side radiator available as part of the upgrade? Do you have a Gillig chassis, or maybe a Spartan Mountain Master?

Thanks for all the detailed info. I've learned something new today!

GlennLever · 09-12-2015, 02:07 PM

Quote:

Originally Posted by Gary RVRoamer

My '04 Tradition has a similar side rad. I knew the Eagle had a side rad in those years, but thought the Dreams were all rear radiator. I have a pal with a 2000 Dream and he has an 8.3L Cummins ISC engine and rear rad. Ditto for a guy I know with a 99. Wonder if there was an engine or chassis upgrade option, with the "L" engine and side radiator available as part of the upgrade? Do you have a Gillig chassis, or maybe a Spartan Mountain Master?

Thanks for all the detailed info. I've learned something new today!

The original purchaser of this Motor Home paid for the Gillig Chassis upgrade and for the upgrade from 300 HP to 325HP

Smitty77 · 09-13-2015, 07:19 AM

Nice detective work, and I also thank you of sharing the approach and the results... These are the kinds of posts that can really help people in the future, as they are in 'What the heck is going on?' mode problem solving!

Best, and travel safe and cool,
Smitty

GlennLever · 09-13-2015, 07:31 AM

Quote:

Originally Posted by Smitty77

Nice detective work, and I also thank you of sharing the approach and the results... These are the kinds of posts that can really help people in the future, as they are in 'What the heck is going on?' mode problem solving!

Best, and travel safe and cool,
Smitty

Thank You, I'm learning a lot about RVs, if you like problem solving take a look at my projects thread.

http://www.irv2.com/forums/f107/proj...am-174380.html