Coolant temperatures while towing

[Schurkey]

Coolant flow is restricted through the heater core(s) on purpose.

Reduces noise from turbulence, and reduces the peak pressure the heater core is exposed to. Lower pressure = reduced risk of leaks from over-pressurization.

 

[L31MaxExpress]

Yea Id definitely prefer not to risk my head gaskets in exchange for a few extra hp which I probably won't even notice cause I dont have a lead foot on the pedal nor plan on drag racing with it. They say in reality you can't feel less than a 10% increase in hp. So if the engine has 200hp you wont feel a differece unless its 20 or more hp

I can feel 5-10 hp. At the track I could always feel a 0.05s change in the run and know it was going to breakout. If you know the vehicle well you will know the difference.

 

[whataTRUUUCK]

You know, a lot of vehicle owners out there have been sold on the concept of electric fans
by countless magazine articles.

One possible solution to your situation is to use the best bits of factory cooling available
sourced out of the local Treasure Yard, and then help offset the cost of doing so by selling
your used twin fan setup online once removed from service?

I know this seems like a lot of time & effort to properly sort out your cooling system,
but subjecting your engine oil, piston rings, valves, and transmission fluid to the higher
end of the 210-260 range you quoted from the owner's manual is not a good long term
plan. (I seem to remember reading that at a certain point, for every 10°F rise in ATF temps
the useful life of that same fluid was cut in half?)

Not to mention that the higher the cylinder head temps, the sooner the engine will start to
ping & knock, which in turn causes the computer to pull timing out, both lowering power
output & worsening your MPG.

I just looked at the photo of your fan setup, and those 2 fans mounted on a flat surface
that close to the radiator causes sub-optimal air flow through the radiator down the highway.

Those fans are being forced to work uphill at all times. Contrary to all the ink that's been
spilled in the mags over the years, for best results with those aftermarket electric fans it's
sell sell sell! :0)



Yes it is -- that's expected behavior. Using rough numbers, the small block tips the scale
in the neighborhood of 500 lbs all dressed, and the 454 is on the far side of 600 lbs.

When all is well, between the radiator, exhaust, and airflow past the engine, this mass
of metal will be on average in the neighborhood of 195°. However, once the engine is
shut off and the air stagnates under the hood, thanks to all the stored heat in the engine,
exhaust manifolds, etc., will move into the coolant, with reported temps immediately start
to climb, for all that heat that's banked in that large metal mass is no longer being
constantly removed by the cooling system.

If you happen to run a mechanical water temp gauge you will see this temp rise every
time you shut down. This is only one of the many reasons why it's a poor idea to run pure
water as a coolant. (50/50 water/antifreeze mix is good to 223° unpressurized, but up to
268°F with a 15psi cap?) Even so, lubricants have been proven to work best/last longest
when we get them just over 212°F. (So that moisture will boil off.)

The bottom line is that we can get our fluids too hot, too cold, and just right. Goldilocks
would approve. :0)

Hope this sheds a little more light on the GMT400 cooling subject.

Phewwww thats a relief! You brother just saved me the hassle of unnecessarily changing the coolant temperature switch on the drivers head (for the gauge) cause I was really starting to think that it may be inaccurate even tho I compared readings with an infrared thermometer pointing to the thermostat housing. Thanks again!

 

[whataTRUUUCK]

I can feel 5-10 hp. At the track I could always feel a 0.05s change in the run and know it was going to breakout. If you know the vehicle well you will know the difference.

Thats believable....im just saying that 10% figure goes for the average person who isnt very in tuned with their car and has little to no automotive knowledge. But then there's also the placebo effect to consider where someone changes any little thing on their car and then feels like they got a noticeable increase in hp....like changijng their engine oil....or even a light bulb

 

[whataTRUUUCK]

Listen to L31! It takes horse power to move air, and some engine powered fans can take up to 9hp (maybe more?), which is good. Forget CFM and look at the size of the electric motor on your fan. As an electrician I have dealt with a lot of fans, up to 30 footers to cool refinery operations. You do not move air without HP!

The dual fans on mine are 80W each. Is that too small for an electric fan?

 

[Cadillacmak]

The dual fans on mine are 80W each. Is that too small for an electric fan?

I don't want to say what is right or what is wrong for your application, but that is only .1hp each if they are 100% efficient. Watts x efficiency / 746 or 80w x 100% /746 = .107 or 80 x 1 / 746 = .107. If your having trouble cooling, you might want to go for more hp. The thing to remember is the you have .2hp of fan all the time and the engine powered fan might take 5hp at 6500 rpm and we don't know what that is at 2000 rpm or at idle. I went with electric fans on my F250 because I needed the cooling when crawling through the woods in 4 low at 800 rpm.

 

[whataTRUUUCK]

I don't want to say what is right or what is wrong for your application, but that is only .1hp each if they are 100% efficient. Watts x efficiency / 746 or 80w x 100% /746 = .107 or 80 x 1 / 746 = .107. If your having trouble cooling, you might want to go for more hp. The thing to remember is the you have .2hp of fan all the time and the engine powered fan might take 5hp at 6500 rpm and we don't know what that is at 2000 rpm or at idle. I went with electric fans on my F250 because I needed the cooling when crawling through the woods in 4 low at 800 rpm.

Smart man! Thanks for the calculation to hp....yea 2hp is NOTHING to cool a big block especially while towing. Someone on here mentioned that those clutch fans can even output up to 9hp. So looks like im sold on the idea of goin back to the old school clutch fan

 

[Cadillacmak]

Smart man! Thanks for the calculation to hp....yea 2hp is NOTHING to cool a big block especially while towing. Someone on here mentioned that those clutch fans can even output up to 9hp. So looks like im sold on the idea of goin back to the old school clutch fan

Now we need a tin-knocker to explain to us how to properly move that air with the fan and we can all fine tune our cooling.

 

[whataTRUUUCK]

Now we need a tin-knocker to explain to us how to properly move that air with the fan and we can all fine tune our cooling.

Hahaha

 

[Oakr11]

I recently bought this 95 suburban 2500 7.4L and Ive done everything possible to try and get it running cooler such as flushing and backflushing all the cooling system inlet/outlet tubes, installing a lower temp 180 degree thermostat (and testing it before installation), making sure none of the coolant hoses are kinked, properly bleeding air out of the system, testing the temp sending sensor for accuracy.....but still on a hot day driving uphill just for 2 miles the temp will reach 230ish even while blasting the heater. The only thing left I can think of is a bad coolant temperature sensor or remove the dual electric fan conversion installed by the previous owner and get a heavy duty clutch fan. What do you guys think?

I had the same problem and had to retrofit 95 watt fans in mine. I even put a four core radiator in mine.