47-55.1 Radiator question

[TX3100Guy]

I'm chasing an over heating issue with my 53 pickup. I thought I knew the answer to this question before a friend asked me if I was sure......all of a sudden I wasn't.

What is the normal flow route of hot water. I thought it was hot water into the radiator from the top when the thermostat opens and cooled water out from the bottom of the radiator sucked up by the water pump to the block.

For some reason, when he asked if I was sure, I blanked out.

[nvrdone]

What engine do you have? If it's a sbc, that is the correct flow. Remember, heat rises

[TX3100Guy]

Originally Posted by nvrdone

What engine do you have? If it's a sbc, that is the correct flow. Remember, heat rises

I have a 261 straight six

[geezer#99]

When is it overheating?
At around town drive or on the highway?

[geezer#99]

And what temp does it get to?
And do you have a closed or open cooling system?

[TX3100Guy]

Originally Posted by geezer#99

And what temp does it get to?
And do you have a closed or open cooling system?

I have had it out two times for drives of modest distance. The first was about 20 miles of city driving, with some stop and go at traffic lights. It heated up to 180 after five or six miles, then to 200 about five miles after that. When it hit 210, I pulled over and let it cool down for 15-20 minutes. When I got to my destination, it was back up to 210 +/-

The second drive was about 10 miles, with only one or two traffic lights. The truck ran in the 160 to 180 +/- range for almost 8 miles, then up to 200 for the final few miles. Unfortunately, I was then in stop and go traffic getting to my spot at the car show, and it went to about 210 before I could shut it down.

At this point, I have done the following things:
- adjusted the carb mixture to be richer
- check my timing to ensure it hasn't been overly retarded
- adjusted my electric fan to come on at 160 instead of 180
- changed the thermostat from a 180 degree to a 160 degree
- removed the AC condenser from in front of the radiator
- moved the pusher fan (3,000 CFM) to directly in front of the radiator

There is no room for a puller fan behind the radiator given the clearance between the rad and the supercharger, alternator, compressor, and harmonic balancer.

I am in the process of fabricating a shroud to fit on the front of the radiator to hold three 11" pusher fans for a total of 6,000 +/- CFM. Theoretically, I could fit another 11" fan on the back side of the radiator off to one side, but I'm going to hold on that pending the results of the 3 - 11" fans.

Here is a photo of my mock-up shroud.



The current electric fan is a

[geezer#99]

You might be blocking more air with that shroud.
When the hood is closed do you have a tight seal between it and the rad?
Sometimes electric pusher fans will tend to circulate hot air back to its inlet from over the top of the rad.

[mr48chev]

I'm a big NO on that thing. I have never seen anything like that used with a pusher fan on any rig. That will make it overheat at road speed let alone at and idle or low speed.

[TX3100Guy]

The hood has louvers cut in on both sides in terms of airflow


Should I just use the zip tie things that came with the fans to mount them directly to the rad?

[TX3100Guy]

Originally Posted by mr48chev

I'm a big NO on that thing. I have never seen anything like that used with a pusher fan on any rig. That will make it overheat at road speed let alone at and idle or low speed.

The fans cover 80% of the shroud. I could cut openings in the remaining areas to allow air to flow, but even if I use fans alone, they will cover 75-80% of the surface area of the radiator.

[geezer#99]

Something I’ve had success with is an air dam mounted directly below the rad. About 4-5 inches in height.
Creates a low pressure area behind the dam allowing a place for the hot air to flow to.

[mr48chev]

Well All I can say is do what you are planning and let it be a learning experience.

On the zip tie thing I AM NOT A FAN IN THE LEAST BIT I've replaced a couple of radiators on people's cars that had things tied to them with those plastic pegs. One was a big honking transmission cooler that a guy put on his truck and the ties wore through the tube on the radiator. He just had me repair the radiator because the radiator shop was so far behind that his truck would be down a lot lot longer than he could do without it during harvest.

After I had that piece of aluminum with a ton of holes cut with a hole saw that still blocked way too much air I put two pieces of 1 inch flat bar across from side to side and fastened the fan to them.

The thing is that fans of any kind usually go out of play when you hit 40 or so or are cruising down the highway at 70 or so unless you are pulling a grade or pulling a load. I lived in McGregor for the first 8 years my wife and I were married (still are #56coming in August) and know Texas heat and you flat need air flow at road speed. You may pull more air at a crawl with that setup but at 70+ it will block a lot of air.

[leegreen]

261s seem to build heat fast, we were testing my son's PS setup at idle without a rad fan and it boiled within a minute.
You are running the full hood latch panel and lower grill support panel, so the air isn't just by passing rad?
Waterpump pulley and crank pulley are stock sizes?
Does it cool down quickly if you pick up speed and stay cool at speed?

You could try your three fans with just the zip ties as a proof of concept before adding the shroud. If you do the shroud, you could add rubber flaps in the blank areas....SPAL 30130012 or similar.
I would not run the zip ties as more than a test, in my experience they do not hold. I replaced zip ties with 3mm SS threaded rod and nylocks on a off topic swap. Keep the rubber gaskets under nuts/fans so nothing vibrates around....cutting into the core is a fear. I like the idea of a shroud less mount that hold fans close to rad.

I like geezer#99's air dam idea, worth a test. I might try that later this summer. Maybe a drive with the hood off would confirm if the problem is fixed with better air exit.

I have 2 * 12" puller fans cooling the 250 in my 52 with a shroud something like yours. stop and go traffic gets hot. I added slots in shroud to improve low speed cooling. It helped. I also have a switch on dash that turns the fans on regardless of thermal switch - I just leave them on in stop and go so it does not cycle up and down.

[TX3100Guy]

I'm going to experiment with flat bar to see if I can arrnge the three fans using that method.

Alternatively, I have found 16 guage aluminum that is perforated with 1/8 holes over its entire surface.

[mr48chev]

on my 48 I have been thinking about running a larger electric fan as a pusher on the top half of the radiator and running as large of a one as I can put in there probably off a Dodge mini van to supplement the too small fan that you can fit on a later six in the AD trucks. The GMC radiator just gives me more space between the radiator and the fan but doesn't allow for a larger fan.

Still I believe that what you are planning will cause more issues than it fixes. You have to have that free unblocked air flow over 35/40 mph.

[TX3100Guy]

Originally Posted by mr48chev

Still I believe that what you are planning will cause more issues than it fixes. You have to have that free unblocked air flow over 35/40 mph.

So far with a 16 in pusher and loads of open radiator space, the truck still over heats both at a standstill and moving. Admittedly, the high temps are worse at a standstill than moving. But I have got to do something to get more cooling capacity to the radiator.

Theoretically, I can fit one additional 11" electric puller fan on the top (drivers side) of the radiator. I'm just not sure that a pusher and puller on each side of the radiator will make that big of a difference. I guess I could wire the puller to a switch in the cab and let the three pushers up front continue to be thermostatically controlled......

[leegreen]

Is the radiator large enough; does it cool at speed under load?

With the supercharger, power steering? and AC you have, plus the flat plate mounting bracket, is there enough airflow past the motor? geezer#99s suggestion of a dam under rad again.

[TX3100Guy]

Originally Posted by leegreen

Is the radiator large enough; does it cool at speed under load?

With the supercharger, power steering? and AC you have, plus the flat plate mounting bracket, is there enough airflow past the motor? geezer#99s suggestion of a dam under rad again.

While it is a stock size radiator, it is all aluminum. I had to have it custom made due to the traditional lower return pipe being in the way of the supercharger belt and idler pully. Ron Francis Racing had the dimensions for the traditional radiator and moved the return port over to the driver side.

Power steering is an electric unit, much like a Prius or Telsa, so it has no effect on the engine. At this point the AC compressor is just free spinning since, I removed the condenser, so the crank spins the supercharger belt and the water pump and compressor belt. The compressor has double V grooves and there is a separate belt to drive the alternator.

As far as a dam is concerned, I know what they are, but I'm not sure I understand where its being suggested that I mount it.

[geezer#99]

Mount the dam directly under the rad.

[TX3100Guy]

Originally Posted by geezer#99

Mount the dam directly under the rad.

What material have you used to fabricate the air dam?

[mr48chev]

Originally Posted by geezer#99

Mount the dam directly under the rad.

He still has the original frame and original apron in front of the radiator and not a cobbled up S-10 swap with a butchered apron.

He is just trying to do something that I firmly believe will hurt more than help but he will figure that out with one drive down the highway and if the engine didn't overheat too bad will go back to square one and call it a learning experience.

This is the pusher fan that fits a 91 Dodge Grand Caravan with a 3.3 V6 like the all wheel drive one that I would probably still have if my wife hadn't wrecked it as it was the best all around vehicle I ever owned in all my years of owning cars and trucks. That fan will move air and doesn't block air flow. Plus they aren't expensive and it will cover the top part of my radiator from the front side while my fan on the water pump will cover the lower part.

[geezer#99]

Originally Posted by TX3100Guy

What material have you used to fabricate the air dam?

The first one I did was on a 70 chevelle. Adapted a dam from a 76 nova.
Later ones I used plexiglass mounted with strap iron.
FWIW the dam was suggested by a retired nascar guy. He used one to help cooling his Boss 429 he squeezed into his 68 short box merc.

[TX3100Guy]

Originally Posted by geezer#99

The first one I did was on a 70 chevelle. Adapted a dam from a 76 nova.
Later ones I used plexiglass mounted with strap iron.
FWIW the dam was suggested by a retired nascar guy. He used one to help cooling his Boss 429 he squeezed into his 68 short box merc.

If I can find a piece of plexiglass I will do that, otherwise I've found a cheap air dam for a Camaro online that I can cut and fashion to work.

[dsraven]

try asking the plastic supplier before you use plexiglass. it is relatively brittle so if it takes a rock it may shatter. maybe something more durable could be used, from the plastic store. UHMW (ultra high molecular weight) maybe? puck board is usually cheap (the stuff they use around hockey rinks) if you want something just to see if it works.

[TX3100Guy]

Originally Posted by dsraven

try asking the plastic supplier before you use plexiglass. it is relatively brittle so if it takes a rock it may shatter. maybe something more durable could be used, from the plastic store. UHMW (ultra high molecular weight) maybe? puck board is usually cheap (the stuff they use around hockey rinks) if you want something just to see if it works.

I found an inexpensive air dam from a Camaro that I'm going to shorten to fit my needs.