Cooling problems

[donald w. miller]

Increasing pressure increases boiling point of water but not sure what the
increase is from 9 to 16 psi.

I'm sticking with 9 psi as it should be plenty if all else is working
properly.

Robert Shaw thermostat #330-195 (available from Autozone or Murray Auto
Parts among others) is said to be the best.

This high performance thermostat supposedly flows much more water than the
original one.

I read the original thermostat is the weakest link in the cooling chain
because even when wide open, it limits the flow of water.

Cost was about 5 bucks at Autozone.

Don

>Advice please:
>Why 9 lb radiator cap per original vs 14 - 16 lb? Have installed 16 lb cap
but
>doesn't seem to draw water from reservoir when needed.
>What is best thermostat - just had one lock up yesterday in mountains -
only 6
>months old. Seems to run a little hotter than should - gauge reads 3/4 at
>normal driving speeds (when thermostat locks up, goes to past hot real
fast -
>good thing I was watching).
>Need to buy these items now and would like advise.
>Thanx
>Lanier
>

 

[samuel pickens]

I personally use an old approach: If you're still carburation and say
nearing 100Kmi or better; I like to drop down to 180 stat. more flow lower
temp more power from fuel and less expansion in engine which means more
power as well. Remember always keep clean air filters on. This avoids
tapering of cylinder walls. You don't want a cone effect and grossly alter
temps. Again older engines won't mind running cooler. Expect to lose 1/2 to
1 mi/gal. The power and peace of mind is worth it. Computers and sensors
demand a specific temp (197) usually on fuel injection systems. Regards, Sam
Pickens
- -----Original Message-----
From: HLBF
To: gmcmotorhome
Date: Monday, July 27, 1998 3:06 PM
Subject: Re: GMC: Cooling problems

>Advice please:
>Why 9 lb radiator cap per original vs 14 - 16 lb? Have installed 16 lb cap
but
>doesn't seem to draw water from reservoir when needed.
>What is best thermostat - just had one lock up yesterday in mountains -
only 6
>months old. Seems to run a little hotter than should - gauge reads 3/4 at
>normal driving speeds (when thermostat locks up, goes to past hot real
fast -
>good thing I was watching).
>Need to buy these items now and would like advise.
>Thanx
>Lanier

 

[samuel pickens]

One comment here; if you increase psi via cap, always replace old hoses.
Never put a new cap on old hoses; expect ruptures if you do.
- -----Original Message-----
From: Donald W. Miller
To: gmcmotorhome
Date: Monday, July 27, 1998 4:52 PM
Subject: Re: GMC: Cooling problems

>Increasing pressure increases boiling point of water but not sure what the
>increase is from 9 to 16 psi.
>
>I'm sticking with 9 psi as it should be plenty if all else is working
>properly.
>
>Robert Shaw thermostat #330-195 (available from Autozone or Murray Auto
>Parts among others) is said to be the best.
>
>This high performance thermostat supposedly flows much more water than the
>original one.
>
>I read the original thermostat is the weakest link in the cooling chain
>because even when wide open, it limits the flow of water.
>
>Cost was about 5 bucks at Autozone.
>
>Don
>
>
>>Advice please:
>>Why 9 lb radiator cap per original vs 14 - 16 lb? Have installed 16 lb cap
>but
>>doesn't seem to draw water from reservoir when needed.
>>What is best thermostat - just had one lock up yesterday in mountains -
>only 6
>>months old. Seems to run a little hotter than should - gauge reads 3/4 at
>>normal driving speeds (when thermostat locks up, goes to past hot real
>fast -
>>good thing I was watching).
>>Need to buy these items now and would like advise.
>>Thanx
>>Lanier
>>
>
>
>
>

 

[william d. minor]

I agree with the 180 Temp thermostat, as well as making it the
RobertShaw HP model. 180 is more than hot enough for the water heater
also. My dash guage reads just at 1/4 with the 180 (started to go to
1/2 when the fan clutch quit). As far as costing anything in mileage, I
don't think so. Mileage has been averaging over 10 since I got the
coach 3 years ago, including running the Onan and dash air together. I
went over Monteagle in Tennessee on Cruise Control without downshifting,
or even having to get in the 'truck' slow lane.

Bill Minor
'73 230 Sequoia