Edgar lets look at it from a different angle. The GMC was designed with
excellent cooling with an oversized radiator. If you are not doing a lot of
heavy towing it should run fine no matter where you drive if everything is
up to snuff. from what you have noted I would like to make some comments;
1."have considered headers" I chose them and it is one more way to sink the
heat FROM the engine. Unless you coat them with a ceramic coating, you are
going to dump that heat from the engine right into the engine compartment.
we would like it to go out the tail pipe.
2. "More air flow", might work if it is ducted into the right place and
that is from the front of the radiator through the cooling tubes and out of
the engine compartment, and not over the engine. I see a lot of engines that
have the fan shroud removed because the owner thinks it is more important to
be able to work on the front of the engine easier. not good!
3. " I challenge any of you to find how much air the stock fan uses when
engaged" To many are worried about the correct design parameters of the
original coach and not enough with properly diagnosing the problems. The
point of the fan has been lost in your comment. If the fan is working as
designed, and it comes on at compartment temperatures of 150-190 degrees F,
and off at a lower temp, than it is working as designed. Remember it is not
designed to engage at high engine RPMs. That is all it is supposed to do
and the volume of air it provides is of no consequence to us. If the fan
works as stated and you still have a cooling problem, than the problem is
somewhere else. In addition if you desire to remove the fan and substitute
electric fans, install them, drive under the most severe conditions that you
are liable to contend with and see if the setup can maintain the correct
temp without overheating.
4. " I remove the oil cooler from the main rad and the tranny cooler also"
it is what I am going to do but only for an extra measure of reliability.
If you don't tow under severe conditions it is not necessary. Remember the
GMC was never designed to tow a vehicle, only a 1000
5. "In second gear up a good hill I may maintain 1800-2000 >rpm if I'm
lucky. How much air am I moving with OEM now? Not much." I don't believe
that is true. Remember the fan is only designed to flow air at low engine
speeds and not when we are cruising. If the fan is roaring you are moving
air, if not it is not working right.
6. "My goal is to run this thing at the 180 to 185 degree mark" I agree
with you and that temp is the desireable range to be in. Recommended my Joe
Mondello by the way. I have 185 degree thermostat in mine. By the way not
all thermostats will work satisfactorly.
7. "No thermostat, only a flow restrictor" In my opinion that is the worse
thing you can do is run a restrictor since you defeat the
intent of the radiator. It increases wear on your engine, and almost ensures
that you will over heat on hard pulls. The block needs to run at a constant
temperature (185 degrees F), ,and the radiator needs to be able to cool the
water down if possible without the water running constantly through it.
>I have spent the last three years trying to solve an overheating problem on my
>sob. I have cleaned, replaced, renewed, added, subtracted and worried about
what
>is going to be next. I have come to the realization that OEM is not always
best.
>We all, at one time or another, have considered headers, bigger rads, more air
>flow and so on and so on. This is what took me to this point. I challenge
any of
>you to find how much air the stock fan uses when engaged. One problem with this
>is that the low rpm at which these things run is not helping any. If the fan
>runs at 2500 rpm, which is about what the coach is cruising at, give or take a
>little, then how much air does it move. I approached this from one angle.
Reduce
>the temperature.
> I remove the oil cooler from the main rad and the tranny cooler also. Give
>each of them their own rad and leave the big one for the engine. I know that
>the two double fans will move 4000 cfm and I have the control. I live in the
>foothills of Alberta and flat driving is not in the cards. Holidays are in the
>Rocky mountains and this is not flat either. Altitude is 3600 ft. in
Calgary and
>it is uphill to the west. In second gear up a good hill I may maintain
1800-2000
>rpm if I'm lucky. How much air am I moving with OEM now? Not much. As a "been
>there done that" scenario I am going to solve this problem before it starts.
>Last year I was changing power steering belts in 95 degree heat in the
middle of
>the parts store parking lot, after going over two monster hills. I couldn't
even
>get close to the engine for an hour. My goal is to run this thing at the 180 to
>185 degree mark. Some of you will say, "not warm enough" but it is warm enough
>for me. No thermostat, only a flow restrictor and my electric fans. Being
>parked, halfway up a hill while it cools down is not going to be in my
future, I
>hope. Got Jimmies side vents and the "hum" of the electricity to make me happy.
>My thoughts not yours. Darren
>
>
>> Darren, I have known others who have tried replacing the engine driven fan
>> w/electric fans. ALL have removed the electric fans & restored the engine
>> driven fan. A second & possibly minor point: if you rebuild your alternator
>> for 120 amps, there's a slight possibility the original belt will not be
>> able to handle the extra "drag". Obviously that's why some alternators use
>> larger &/or multiple belts.
>>
>>
>> >
>> > What this means is that I can get rid of the oem cowling and belt
>> > driven fan. ( these units come with their own cowling ) This makes the
>> > life of the water pump easier and gives me that previously lost
>> > horsepower from the belt driven fan. Add all of this to a rebuilt rad
>> > with the engine and trans oil cooled remotely, without going through the
>> > radiator. Well, I'll let you know how it all works out. All of my
>> > research says, "this is a good thing you are doing." I will find out if
>> > that is true. Darren
>> >
>> > Most of Flex-a-lites info is on their web site at
>> >
www.flex-a-lite.com
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
wner-gmcmotorhome]On Behalf Of Darren Paget
