Coolant Pressure Control Cap

[Bob & Carol Howald`]

Leroy: If you want to increase the cooling of your 8V-92 you
could install a 4" air scoup behind the radiator opening to help
catch the air and redirect it into the radiator. I did this on a 6V-
92. I had it made out of stainless steel it had nice curve to it to
help capture the air. It worked well. Bob
93pt40--Bunker Hill, Illinois....Soon to be back in Jackson,Wy.



wrote:
>
> Your theory may be totally correct.
>
> My understand of cap pressure values, the higher the pressure, the
higher the boiling point. Assuming BB used top quality hoses and I
believe they did I have some trouble differentiating between the bus
and my Cummins SLT 3/4 ton PU, when it comes to cap pressure. My
diesel truck heating system is tied to the cooling system and it has
a factory 15psi cap. My bus has a 13psi cap that I did not install
and over the past 3 years all has been good. The DD service manual
says 7-9 psi. I give up, maybe.
>
> Over the past few months I have been making small changes to the
cooling system in my bus. I am taking chances, testing them on my
bus, in an effort to reduce overall temperatures in the engine,
transmission, retarder and engine oil. I have changed the Alarmstat,
which operates the hydraulic fan to 190 degrees from 195 degrees.
> I will not know the full extent this change until summer, but so
far it is working.
>
> Before I decided to make the change I consulted with DD approved
shops and BB. I was not satisfied with the answers sooooo, I pressed
on.
>
> The DD manual says to be careful not to have cooling system
components operate out of sequence because the result will be
overheating. At this point in my testing I have concluded the
foregoing to mean, the cooling fan, the engine thermostats, and the
alarmstat, primarily because I do not know of any other cooling
affected components other than the cap.
>
> Before I embarked upon my mission, I was told that temperature
cycling was the result of the engine thermostats cycling.
Unfortunately, I cannot force that to happen and I have tried. I
have driven the coach in temperatures of below 32 degrees with the
fan override on and my water temperature gauge stabilizes at about
170 degrees, the engine thermostat value. In other words, it doesn't
move once stabilized, so the engine thermostats are not cycling
(possibly). If they are it is happening so quickly that it does not
register on the temp guage or they partially close and shut down the
water flow to hold the constant temperature. I cannot see them
work. When I turn the fan override off the temperature begins to
cycle off the Alarmstat between 180-190 degrees.
>
> All of this fits the DD published coolant Series 92 publication in
my possession. Why BB dedided on a 195 degree Alarmstat, only BB
knows and they aren't talking, because I have asked. I simply does
not make sense to force the temperatures to the outer limit of DD
specifications, ;and that is what happens in summer. Heat is our
enemy and I have been able to reduce the heat.
>
> Most likely, I will change my cap to 9psi sometime in the summer
and see if that makes any difference. My guess is it will not simply
because keeping the engine cooling system within temperature
specifications precludes any real need for the cap to blow off.
>
> I like my drive train component temps now.
>
> Engine Oil-215
> Water Temp-Cycles between 180-190
> Transmission Temp- 170
> Retarder Temp- 220
> All recorded in flat conditions at cruise speed of 68 mph, pulling
a 20ft trailer w/car.
>
> I do not suggest you try anything unless you fully understand your
system, I'm simply reporting what I did.
> The foregoing presumes that all system components are in proper
working order.
>
> My next project is to install MH's water injection system so when I
climb the mountains next summer I'll have a water flood just in case.
>
> Alright, fire away, I have Redneck engineering paperwork on this
one. LOL lol, lol
>
> Leroy Eckert
> 1990 WB-40"Smoke N Mirrors"
> Niceville, FL
>
>
>
> ----- Original Message -----
> From: Fred Hulse
> To: WanderlodgeForum@yahoogroups.com
> Sent: Sunday, March 04, 2007 11:44 AM
> Subject: Re: [WanderlodgeForum] Coolant Pressure Control Cap
>
>
> My theory about the 7 lb. cap is the coach heating system is tied
into the cooling system and Blue Bird has used that pressure to
protect the other systems in the coach,let alone miles of heater hose!
> Fred & Jeanne Hulse
> Morristown Arizona
> 1997 Wanderlodge WLWB41
>
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