Benny's Move

[Leroy Eckert]

Curt:
Just off the Thanksgiving trip 10 pounds heavier. I did some road testing on my
hydraulic fan system. This is what I found. Haven't replaced the fan sensor
yet because the plug is different. I have not traced the plumbing either.

1990 WB-40 8v92 475hp
Fan Sensor Ops
Outside air temp 65 degrees, pulling a trailer, 70-75mph
1. Fan override switch on. Fan runs at high RPM and holds thermostat
temp.(about 180)
2. Fan override switch off. My system fan is designed to run at approx 500-600
RPM until engine water reaches 195 degrees. At 195 degrees the fan sensor
sends the fan to high RPM( about 1800) until water temp is decreased( happens
quickly) and then back to idle RPM. Hence, the guage cycling. My coach has done
this but not now, the sensor is bad. Temps are creeping above 210 and I didn't
want to see how high it would go. I am told that the sensor is designed to
default to the high fan mode if sensor failure occurs. Apparantly, my sensor
has not completely failed yet, just is not cycling.
3. Fan override switch off. If chassis air conditioning is turned on, either
pilot, copilot or both, the fan runs at continuous high RPM and holds engine
water temp at thermostat value. Same affect as having the fan override switch
on. As long as the a/c is on the fan runs at high speed. In this configuration,
the fan override switch has no affect as the fan is already in high mode.
This explains something I have been trying to figure out for two years.
Intermittant water guage cycling. In summer I use the genset and the roof air
to keep the family cool on the road. Generally, I do not use the chassis air
while the genset is running. In this configuration, the guage cycles although
not as pronunced as in winter. If I turn the chassis air on guage cycling
stops. In summer my water temp runs about 190 in fan override, or chassis a/c
on.
4. The fan RPM is not progressive, it is either idle RPM or high RPM
On this trip I ran in fan override. I saw an overall decrease in engine oil,
tranny and retarder temps.
Engine water--180
Engine oil--215
Tranny oil--170
Retarder---230
Based on the foregoing, apparently the basic function of the sensor is to tell
the fan to run high RPM when 195 is reached and go to idle RPM when you get off
the road and cool down. I'm trying to determine why it's in the system. Why not
run the fan 1800 all the time? It has no role if the chassis air is on anyway.
Wish I could hear that fan cycle but cannot get back there while driving.
That's it for now. After I install the new sensor I'll check what happens on
the trip to Texas in Dec. If it starts to cycle, I'll leave it alone. Wish I
had a drawing of the total system. BB does not have one.

Leroy Eckert
1990 WB-40 "Smoke N Mirrors"
Niceville, FL







.

----- Original Message -----
From: Curt Sprenger
To: WanderlodgeForum@yahoogroups.com
Sent: Wednesday, November 22, 2006 8:41 PM
Subject: Re: [WanderlodgeForum] Benny's Move


Leroy,

Please keep us posted. Much appreciated. Anyone know if the '87 PT38
8V92 has the same system?

I'll second Leroy...HAPPY THANKSGIVING TO ALL OF THE FORUM MEMBERS! I'm
looking forward to deep fried turkey and all the goodies...and left over
turkey for sandwiches.

Curt Sprenger
1987 PT38 8V92 "MacAttack Racing"
Anaheim Hills, Calif.

Leroy Eckert wrote:

>Since we are leaving tomorrow I elected to have the fan sensor air expressed
to me. I will take it on the trip as a precaution.
>I certainly cannot fault a person trying to better himself and his family.
Good for him. I just hope his successor can fill his shoes. I will continue to
support BB.
>In my case, I found the answer elsewhere. I will know for certain after I
return, install the new sensor and test the system. Then I will know how it
operates.
>Just the facts in my case.
>Still looking for a wiring and plumbing schematic of the system. It would be
very helpful when testing.
>
>Happy Thanksgiving to all.
>
>Leroy Eckert
>1990 WB-40 "Smoke N Mirrors"
>Niceville, FL
>
>
>
>




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