Coolant Pressure Control Cap

[Chuck Wheeler]

Leroy,



I am pulling at my memory on this one and have been thing about it since I
read your posts, but I spent one summer while in college working in a shop
that rebuilt DDs. I think some of the old timers got tired of all my
questions! At that time there were shutters in front of the radiator to
control the temperature. There were also thermostats in the engines. The
reason I was given was that the DDs were two cycle engines; I think they
were Xv71s, and the function of the thermostats was primarily to get the
engine up to temperature quickly to prevent fouling. The shutters
controlled the running temperatures. The shutters were set at a higher
temperature than the full open point of the thermostats so there would be
full coolant flow through the block to prevent hot spots that would occur if
the flow was restricted. These were trucks so the shutters controlled the
"ram" air, a bus is different, but cycling the fan has the same effect. The
other thing I remember was that the DDs being two cycle engines did not have
the intake stroke to cool the pistons. This is accomplished by the
scavenging and is why the condition of the charge air cooler is very
important. Your temperature gauge only shows the average temperature of the
engine coolant. I know there were some interesting discussions with DD
factory engineers when we were doing custom work on specialized construction
equipment. They wanted to keep the average temperatures up and the peak
temperatures down. I would expect that since BB was a builder and customer
of DD that there was consulting with the factory on the design of the
cooling. I do remember lunch time discussions about the condition of charge
air coolers that the customer would not repair, or someone who had blocked
the shutters open to make their truck run cooler, and how long it would be
until we had the equipment in for a rebuild.



If you have one of the 4 cycle DDs this probably does not apply.



- Chuck Wheeler -

82 FC 31 SB

Fort Worth, TX

_____

From: WanderlodgeForum@yahoogroups.com
[mailto:WanderlodgeForum@yahoogroups.com] On Behalf Of Leroy Eckert
Sent: Monday, March 05, 2007 6:13 PM
To: WanderlodgeForum@yahoogroups.com
Subject: Re: [WanderlodgeForum] Coolant Pressure Control Cap



Thanks: I have not experienced overheating problems, I am picking at it, and
I just do not yet understand why BB and their engineers specified an
Alarmstat fan controller which pushes the water temperature to the upper
limit. That is why I changed my Alarmstat to a lower temperature. I may yet
try a 185 degree just to see if it interferes with the engine thermostat
operation. I have a feeling that it will not. If I can get my coach to run
on the flat in the mid-range of DD specifications, an average of 185 degrees
I am going to do it. As always, thanks again for the input.

Again, I am posting what I am doing and do not suggest any one else try this
unless you understand how your particular system works. So far mine is doing
fine. If I blow my engine up that is my problem. If my theory works, I'm
happy and I will report.

For those who do not know, the Alarmstat, funny name for a part that
actually forces the water temperature up, is the part that cycles the
hydraulic fan on and off, assuming your chassis a/c is off and the fan
override is off. That is how mine works on the WB-40

I am going to install a supplemental water spray system, just in case I need
it.

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

----- Original Message -----
From: Pete Masterson
To: WanderlodgeForum@
yahoogroups.com
Sent: Monday, March 05, 2007 12:55 PM
Subject: Re: [WanderlodgeForum] Coolant Pressure Control Cap

I had some overheating problems with my Series 60 powered unit on my
homebound trip after taking delivery in Texas...

Upon opening up the radiator, it was found to be 2/3 filled with oily-
dirt pulled into the radiator. This could not be seen from the
outside due to the charge air radiator that's located in front of the
water radiator and it could not be seen from the inside due to the
metal shroud around the fan. The area under the fan was open and
clear -- it was everything else that was blocked up.

Although a simple cleaning of the radiator could have resolved the
problem -- I elected to replace the radiator core with a more
efficient design (since about 1/2 the cost was the labor to pull the
radiator).

My current temperature readings are quite similar to yours -- except
the water temperature has yet to go much above 180 -- and my retarder
is exhaust based, and doesn't have a temperature gauge.

When the radiator was replaced, the radiator service replaced the
cap ... it's rated at 15 lbs.

I do lose about 1 quart of radiator water each trip while using the
chassis heat. There's a minor leak somewhere, but I haven't found it
yet. When the chassis heat isn't used, then I don't seem to use any
radiator water. (I carry a couple of spare gallons of premixed
coolant along...)

Pete Masterson
aeonix1@mac. com
'95 Blue Bird Wanderlodge WBDA 42'
El Sobrante, CA

On Mar 4, 2007, at 6:09 PM, Leroy Eckert wrote:

> <Snip>
> 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

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