Hydraulic fluid heat exchanger fans - Printable Version
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+--- Thread: Hydraulic fluid heat exchanger fans (/showthread.php?tid=5067)
RE: Hydraulic fluid heat exchanger fans - RegaNewell - 01-19-2022
Richard,
The Relay does not cause the fan to run on low when the engine is running.
I removed the wire connector from the DDEC. I cleaned the connector and DDEC pins with electrical contact cleaner. I checked the end of the yellow wire from inside the wire connector to the end of the yellow wire going to the relay and I am reading 0.04ohms, so I believe I am on both ends of the same wire. Checked both ends to ground, one at a time and read open. In the past post, I stated I had 48,000ohms to ground on the yellow wire, now I am showing open. I also back probed the yellow wire after connecting the connector back to the DDEC and read zero ohms to the other end and open to ground. I started the engine and checked the yellow wire by back probing and checking the end of the yellow wire going to the relay (disconnected from relay), both showed open to ground. I believe now that the wiring from the DDEC to the relay are good and the relay functions like it should. Looks like the issue is with the signal coming from DDEC.
Jeff
RE: Hydraulic fluid heat exchanger fans - Richard - 01-19-2022
Yep. Thorough job of isolating the issue.
RE: Hydraulic fluid heat exchanger fans - Georgeb - 03-09-2022
I now have a issue, while in heavy Houston my trans
Temps level gauge jump to the 250 range. The warning light
Did NOT come on
385 has the trans cooler under coach in front of drive axle
Now I’m faced with understanding on to proceed with diagnosing
My problem
Is there a sending unit on trans that powers fans? Does the warning
Failing to come on mean I should think gauge??? Should I think
Jumper wire to fans
I need input before sliding under Coach
Maybe a work around to get home
RE: Hydraulic fluid heat exchanger fans - Richard - 03-09-2022
First, according to Allison, that temp is not a problem.
Second, is this the VDO gauge on the dash, or are you getting this number from a VMSPc.
Third, when you cleared the traffic, did the temp come back down? What does it normally run?
And the big one, the fan under the coach cools the HYDRAULIC temp, not the transmission. The transmission is cooled via a cooler on the aft side of the radiator. Look at the rear bottom of the radiator and you can trace two large hoses in and out of the cooler to the Allison.
RE: Hydraulic fluid heat exchanger fans - Fulltiming - 03-09-2022
You did not exceed the max temperature of your transmission.
Per the Allison Transmission Operators Manual https://www.wanderlodgeownersgroup.com/downloads/Allison%20Transmission%20Operators%20Manual.pdf
Temperatures:
"Normal transmission operating temperature is 160-200 degrees F. Maximum transmission to cooler oil temperature for the AT, MT and HT (non-retarder models) is 300 degrees F. If excessive temperature is indicated by the transmission oil temperature gage, stop the vehicle and shift to neutral. Accelerate the engine to 1200-1500 rpm and allow the temperature to return to normal (two or three minutes) before resuming operation."
You might want to check your transmission fluid level and make sure the fluid doesn't smell like it is burned. If you haven't changed the transmission fluid or filter in a long time, you might want to do that. Generally, driving in stop and go traffic will result in higher transmission temperatures than any other condition since the torque converter is never locking up.
RE: Hydraulic fluid heat exchanger fans - johnkosir - 03-09-2022
The torque produces heat when slipping, I tow a 30' stacker loaded when in stop and go traffic on a hot day and trans temp starts to rise above 230 I shift to neutral when stopped and increase idle speed. My transmission normally runs 5 degrees warmer than my motor, my high fan turns on often.
RE: Hydraulic fluid heat exchanger fans - Georgeb - 03-09-2022
Trans fluid and filter change last year. Normal trans temp per dash gauge around 200.
The temp did not return to a normal reading, but did lower a small amount when returning
To Hiway speed. Engine temp remained normal 190/200 .
Today I found the fuse for hydraulic fan cooler defective. I replaced it and fans run when
You turn on key
Could hydraulic fluid be over heating and causing fan to slow??
RE: Hydraulic fluid heat exchanger fans - Georgeb - 03-09-2022
Trans fluid and filter change last year. Normal trans temp per dash gauge around 200.
The temp did not return to a normal reading, but did lower a small amount when returning
To Hiway speed. Engine temp remained normal 190/200 .
Today I found the fuse for hydraulic fan cooler defective. I replaced it and fans run when
You turn on key
Could hydraulic fluid be over heating and causing fan to slow??
RE: Hydraulic fluid heat exchanger fans - bestgenman - 03-09-2022
George, the transmission is cooled through a heat exchanger imbedded in the engine radiator, as @richard stated earlier. The hydraulic system has its own tubed - fan cooled heat exchanger and is not tied to the engine radiator. Mine is mounted ahead of the drive axle.
Your question is about fan speed of the hydraulic system, I believe. They are electric driven, usually a pair of them. Not a part of the engine fan..
I hope I understand your question !!
RE: Hydraulic fluid heat exchanger fans - Richard - 03-09-2022
That is a possibility. Did you notice any difference in your steering?