> i think im reading genes site wrong, if i change my sending unit ill get a
>lower water temp. mine runs at the 1/4 mark and rises a little when i go up
>hills then returns to 1/4 on the downswing. what can i do to cool things down
>some more.
>thanx christopher 75gb
>
>p.s i would hit a hill at 70 mph and bog down to 50 at the top is thi normal
>for these coaches?
Chris - the sending unit will not give you any lower water
temperature. It'll just change the scale on your dash temperature
gauge. Right now, normal is about 1/4 on your gauge. If your gauge
gets up to 1/2 its probably too hot and is ready to boil over. The
NAPA sender just changes the sensitivity of the gauge and normal will
be just a shade below 1/2 on the gauge and when you are ready to
overheat or boil over it'll be more like 3/4. The existing sender
just didn't give much of a gauge range and it was difficult to really
tell from the dash gauge when you were in danger of overheating.
It doesn't seem that you really have to cool things down any. Your
description sounds normal. The thermostat controls the normal
running temperature of the engine. GM put in a 195 degree
thermostat. This will open when the engine reaches 195 degrees.
Some have put in a 180 degree and occasionally a 160 deg. I run with
the RobertShaw 330-195. The Robert Shaw has a bit better flow
through it than some. AutoZone carries them (but there are no
AutoZone in California - I just mailed a RobertShaw to California to
a fellow GMCnetter.)
It is not so much keeping your engine cooler as it is keeping the
coolant from boiling out. The radiator pressure cap will allow the
coolant to get hotter without boiling. Also the use of a 50/50%
antifreeze/water mix will also raise the boiling point. The
antifreeze/coolant should be changed every two years. The radiator
pressure cap usually goes bad within a year or two. Replace it with
an A/C Delco one that is a 9 pound cap. You can find Stant 7 pound
or 10 pound in most auto parts stores. Don't use over a 10 pound cap
because your radiator is not designed to take higher pressures and
will develop cracks and leak if you use too much pressure.
Among other things that help your GMC keep its cool are good
condition fan belts, propelyr working fan clutch, proper water pump,
clean radiator (inside the tubes), aux. transmission cooler, the
proper weight motor oil, properly set timing (retarded timing will
cause overheating), and watching your loaded weight. The more load
you put on your engine, the more heat you have to remove from your
cooling system. This includes fast driving and the use of the dash
air conditioner.
Bogging down going uphill is normal. Remember that you'll trying to
climb that hill with 6 tons or more weight. It's going to be a bit
different than driving a car. It also depends on the steepness of
the hill. Out here in the Rockies you might bog down to 20 or 25 on
some grades. As your engine RPM goes down from its peak point, your
power and torque available from the engine go down. You help this by
keeping your speed up before you hit the start of the climb but you
can't prevent it totally.
Some of us have put in lower gear ratio final drives to bring up our
RPM to give more power on grades and when pulling vehicles. Again
there is a lot of information posted on sites such as Gene Fisher's
that you referenced.
Emery Stora
77 Kingsley
Santa Fe, NM
>lower water temp. mine runs at the 1/4 mark and rises a little when i go up
>hills then returns to 1/4 on the downswing. what can i do to cool things down
>some more.
>thanx christopher 75gb
>
>p.s i would hit a hill at 70 mph and bog down to 50 at the top is thi normal
>for these coaches?
Chris - the sending unit will not give you any lower water
temperature. It'll just change the scale on your dash temperature
gauge. Right now, normal is about 1/4 on your gauge. If your gauge
gets up to 1/2 its probably too hot and is ready to boil over. The
NAPA sender just changes the sensitivity of the gauge and normal will
be just a shade below 1/2 on the gauge and when you are ready to
overheat or boil over it'll be more like 3/4. The existing sender
just didn't give much of a gauge range and it was difficult to really
tell from the dash gauge when you were in danger of overheating.
It doesn't seem that you really have to cool things down any. Your
description sounds normal. The thermostat controls the normal
running temperature of the engine. GM put in a 195 degree
thermostat. This will open when the engine reaches 195 degrees.
Some have put in a 180 degree and occasionally a 160 deg. I run with
the RobertShaw 330-195. The Robert Shaw has a bit better flow
through it than some. AutoZone carries them (but there are no
AutoZone in California - I just mailed a RobertShaw to California to
a fellow GMCnetter.)
It is not so much keeping your engine cooler as it is keeping the
coolant from boiling out. The radiator pressure cap will allow the
coolant to get hotter without boiling. Also the use of a 50/50%
antifreeze/water mix will also raise the boiling point. The
antifreeze/coolant should be changed every two years. The radiator
pressure cap usually goes bad within a year or two. Replace it with
an A/C Delco one that is a 9 pound cap. You can find Stant 7 pound
or 10 pound in most auto parts stores. Don't use over a 10 pound cap
because your radiator is not designed to take higher pressures and
will develop cracks and leak if you use too much pressure.
Among other things that help your GMC keep its cool are good
condition fan belts, propelyr working fan clutch, proper water pump,
clean radiator (inside the tubes), aux. transmission cooler, the
proper weight motor oil, properly set timing (retarded timing will
cause overheating), and watching your loaded weight. The more load
you put on your engine, the more heat you have to remove from your
cooling system. This includes fast driving and the use of the dash
air conditioner.
Bogging down going uphill is normal. Remember that you'll trying to
climb that hill with 6 tons or more weight. It's going to be a bit
different than driving a car. It also depends on the steepness of
the hill. Out here in the Rockies you might bog down to 20 or 25 on
some grades. As your engine RPM goes down from its peak point, your
power and torque available from the engine go down. You help this by
keeping your speed up before you hit the start of the climb but you
can't prevent it totally.
Some of us have put in lower gear ratio final drives to bring up our
RPM to give more power on grades and when pulling vehicles. Again
there is a lot of information posted on sites such as Gene Fisher's
that you referenced.
Emery Stora
77 Kingsley
Santa Fe, NM
