Humvee Water Temp ( was RE: New main bearing caps!)

From: G Shaw (milspectruck@verizon.net)
Date: Mon Nov 21 2005 - 06:29:03 PST


>From what I read from AMG you are correct. They pushed it towards the high
end for those reasons. The other problem with the humvee is the rube
goldberg system of using the hydraulic off-on fan clutch controlled by an
electric/hydraulic valve in turn controlled by a water temp sensor. We all
understand it is part of two systems, one is to allow the fan to be
completely declutched during fording ops which was a USMC requirement due to
their water landing mission, and the second is to allow the fan to be
dropped from engine load for short term burst of high power when the pedal
is floored completely (I know I know everyone is smiling). The typical
Humvee is much happier and runs 190-200 degrees all day long if the mil
hydraulic fan is replaced by the thermo-viscous clutch system used on the
civ version along with the proper thermostat and assuming all cooling system
components are in good condition. Another fix is simply to set the fan
clutch to remain engaged all the time. If this is done and you are using
the standard thermostat the truck runs cool. All the National Guard shops
FMS shops have a bulletin to do this, for the same reasons they have another
that instructs them to disable the CTIS except on the wreckers. KISS.
Having said all that, the humvee and the civ H1 for that matter run the way
they do because the manufacturer intended them to do so and engine life was
not the over riding concern to them. Mission functionality was.

Regards
Glenn

-----Original Message-----
From: MV [mailto:MV@dc9.tzo.com]
Sent: Sunday, November 20, 2005 10:32 PM
To: G Shaw
Cc: Military Vehicles Mailing List
Subject: Re: [MV] New main bearing caps!

I would bet that AM General does that to minimize pollution or maximize
mpg. A hotter running engine tends to be more fuel efficient at the
cost of engine life (sometimes).

Dave

G Shaw wrote:
> They run too hot a thermostat among other things.
>
> -----Original Message-----
> From: Sonny Heath [mailto:sonny@defuniak.com]
> Sent: Saturday, November 19, 2005 2:31 PM
> To: Military Vehicles Mailing List; G Shaw
> Subject: Re: [MV] New main bearing caps!
>
>
> How do you set an engine to run hot other than by way of a different
> thermostat?
>
> Sonny
>



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