8v92 Fan Thermostat

[Leroy Eckert]

Just in case ya'll don't know what the thing does, it cycles the fan with the fan override switch off and the chassis a/c off in earlier birds. With either the fan override on or the chassis a/c on the fan runs full blast. In all other cases the fan cycles(you can see it on the water temp gauge). The Alarmstat in the early coaches have a range of 7-8 degrees on/off. I have jacked with mine for two years, spoken with Southern Power and BB about this instrument or sensor and was told by BB via email that BB engineers in cahoots with Detroit determined that 195 degrees was appropriate. In later years it is called something different but still has a 195 degree rating. I have not been able to prove that 195 degrees is required under any circumstances. The theory is if you cool the engine to much this instrument will fight with the engine thermostats causing hot spots in the cooling system. I have tested my coach using VMSpc real time data, charting temperatures in OAT's from 15
degrees F to 100 degrees F and cannot make the engine thermostats cycle once initial activation takes place. Accordingly, I cannot see how hot spots could occur. If it ain't happen'n at 15 degrees OAT it aint't gonna happen. I am running a 190 degree unit. I know a couple of other folks that are doing the same but do not know the results.

Think about it this way. The radiator cools the water that cools the tranny, retarder, engine oil and the engine not necessarily in that sequence. There is probably 100 feet of coolant hose in the compartment. If the Alarmstat fires the fan right at 195 degrees the water outside of the radiator is hotter than hell and by the time it cools and recycles temps really do not drop significantly on the accessory components,ie, trans, retarder etc. Lower the temp that the fan comes on and you lower the temps of the accessory components. I have proven this in my tests. The back side is the HP loss argument and I have not been able to
prove that either using VMSpc, either max HP or max torque. In my opinion the HP loss argument is a mute point anyway because when you have the HP available you do not use it(ie. on the flat) and when you need the HP(climbing the mountain) it is not available because the fan is running full blast for max cooling. Pick your poison, cool the engine or blow it up. It is said that running the fan full blast robs 40 HP. Who cares.
I really think I could run a 185 degree unit and all would be well. I will try that when I get around to it.

Leroy Eckert
1990 WB-40 Smoke N Mirrors
Dahlonega, GA

Richard Hayden wrote:

How much Mike? I could use the 190 deg. I haven't had a bad heating problem but Leroy has sold me on the modification. (He doesn't know he did and I'm probably not the only one).

Dick Hayden - '87 PT 38 - Lake Stevens, WA

----- Original Message -----

From: "mmcmahan@hot.rr.com"

To: "WanderlodgeForum@yahoogroups.com"

Sent: Monday, May 19, 2008 6:10 PM

Subject: [WanderlodgeForum] Re: 8v92 Fan Thermostat

I have a brand new
one, a 190 I believe that I bought for my 89 PT 40
8V92 and never used. I'd sell it if anyone needs it. Mike Mcmahan
1996 42" Wanderlodge

--- In "WanderlodgeForum@yahoogroups.com", Leroy Eckert
...> wrote:
>
> Here is the company that manufactures it.
> They would not sell one to me(about 2 years ago) so I special
ordered from BB. http://www.medallionis.com. You may find that yours has
screws attaching the wires. The new units are slip on connectors. I
changed the connectors and filled the cavity with epoxy. No problems.
> The part number I show for 190 degree is (my hen scratching isn't
the greatest so double check)-
> PN-1002-07478-30
> BB# 1594951
>
> Leroy Eckert ...> wrote:
Sorry, I had brain
fade. Curt is correct. My alarmstat is just to the
left of drivers side of the water pump. It is a bulb looking device
with two wires. Typically, on later model coaches it is next to the
water temp sender. I also have a drawing for my coach. I would not
know if it is the same for earlier years.
> Do you have a fan override? This device is also controlled buy the
chassis air conditions on switch in my coach.
>
> Curt Sprenger ...> wrote:
> I believe they are located on the drivers
side, lower portion of the thermostat housing. There are to senders,
two wires each. I don't recall if the 2 or just 1 work with radiator
fan.
>
>
> On Mon, May 19, 2008 at 2:49 PM, Scott Forman <sforman@...<wbr>> wrote:
> Where is the thermostat for the
radiator fan (I think some call it
> the "alarmastat") on my 8v92? At the
advice of my mechanic, I am
> considering switching out to a lower temp.
>
> Scott Forman
> 86 PT38
> Memphis
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> --
> Curt Sprenger
> 1987 PT38 8V92 "MacAttack Racing"
> Anaheim Hills, CA
>
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> Leroy Eckert
> 1990 WB-40 "Smoke N Mirrors"
> Dahlonega, GA
> Royale Conversion
>