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Author Topic: Fan shroud on my old pickup  (Read 1422 times)

patkelly4370

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Fan shroud on my old pickup
« on: March 24, 2019, 06:54:54 pm »
Daily driver is a 1968 F100 with the 240 "six-banger".
My Grandfather bought it new in 1969. It was given to me in 1986.
Over the years the cooling system has been upgraded. First, a 30% larger radiator. Then the solid-mounted fan was replaced with a thermostaticly controlled electric fan (mounted directly to the radiator).
Decades went by and the radiator was re-cored from 2 row to 3 row. Good thing because we now live in the hottest part of Arizona.
Today I made a fan shroud out of some sheet steel we have laying around.
Initial drive seems encouraging. I'll find out this summer when it's over 120° and I'm climbing 3,000 feet in 12 miles to get home. Last summer the engine ran hot, but didn't overheat (came dang close a few times).
If there's no issues I'll take it back out in a few weeks, weld the corners for strength & paint it.

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    coelacanth

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    Re: Fan shroud on my old pickup
    « Reply #1 on: March 24, 2019, 09:16:40 pm »
    Looks good to me.  That hill is a real killer - especially in the heat of the day in the middle of summer.  Hope the new mod works out well for you.    :thumbup
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    Pwc

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    Re: Fan shroud on my old pickup
    « Reply #2 on: March 24, 2019, 10:56:33 pm »
    Wow, you can actually see the ground.  Last time fpr me was  1975 Dodge van.  Actually removed the cover and sat on the floor straddling the engine to work on it.  My hand me down 1953 Ford Fairlane was my first car in 1963.  All the others were so crowded under hood, couldn't see the ground.

    anm2_man

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    Re: Fan shroud on my old pickup
    « Reply #3 on: March 25, 2019, 05:54:18 am »
    Hmm @patkelly4370, I have to question your shroud.   Dealing with a similar overheating issues of an older (1966 Chevy Impala 396) after moving here in the early 70's, most automotive fan shrouds are used to increase the amount of volume moved thru the radiator of engine mounted fans at lower RPM's.    They do little to help improve the flow of air thru the radiator via electric fans since most are single speed or maybe multiple speed but not variable speed units. 

    The design of your unit is flat and looks like it will impede the flow of the air thru the fan ?   The shroud should be like a funnel where the air is forced towards the fan from across the entire radiator.   

    But good luck, you  need to report back  on how well it works in the June/July time period.   I've also run up  that hill you climb to get out of Bullhead City (Its long and steep).  OUCH
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    Funflyer

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    Re: Fan shroud on my old pickup
    « Reply #4 on: April 07, 2019, 01:15:18 pm »
    Hmm @patkelly4370, I have to question your shroud.   Dealing with a similar overheating issues of an older (1966 Chevy Impala 396) after moving here in the early 70's, most automotive fan shrouds are used to increase the amount of volume moved thru the radiator of engine mounted fans at lower RPM's.    They do little to help improve the flow of air thru the radiator via electric fans since most are single speed or maybe multiple speed but not variable speed units. 

    The design of your unit is flat and looks like it will impede the flow of the air thru the fan ?   The shroud should be like a funnel where the air is forced towards the fan from across the entire radiator.   

    But good luck, you  need to report back  on how well it works in the June/July time period.   I've also run up  that hill you climb to get out of Bullhead City (Its long and steep).  OUCH

    I have to agree. I battled an overheating issue with my 66 Pontiac for years and learned about everything there is to know about cooling systems. The OP's electric fan (16" it appears to be) has to be used without a shroud because it will not pull the CFM needed at speeds above 50 or so MPH. That fan will actually restrict air flow at speed and increase engine temps. What is needed is the mother of all electric fans. The Lincoln MKVIII fan from the mid 90s is the best available, or it was at one time, and what keeps my Pontiac happy during the hottest part of the summer. I believe the Merc Cougar and a few other Fords use the same also. The only problem is that fan pulls 5000CFM and needs some serious amperage to get it turning. I had to add a 120A alternator.

    Here's a good article on the fan. https://www.hotrod.com/articles/ccrp-1111-electric-radiator-fans/
    « Last Edit: April 07, 2019, 01:17:54 pm by Funflyer »

    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #5 on: April 07, 2019, 02:42:20 pm »
    Not close to hot yet, only 90° today.
    Overall the temp gauge has read the cooling system running cooler and more consistent. Climbing the hill yesterday afternoon, the gauge read probably a little cooler than before the shroud. It still gets up there, but hasn't overheated. At it's hottest last summer the needle went past, but still touching, the high end of acceptable on the gauge.
    One good thing is that I can remove the shroud and have everything back the way it was in about 10 minutes if need be.
    Also, I'm 'that guy' in the older truck with historical plates that does 60mph tops climbing the hill. Some sections or can only manage 50 mph.
    Around town the shroud seems to be an improvement.

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    coelacanth

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    Re: Fan shroud on my old pickup
    « Reply #6 on: April 07, 2019, 03:58:00 pm »
    Hey, anything that keeps you driving instead of stopped on the side of the road is good - right?   :yes
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    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #7 on: April 29, 2019, 01:10:17 pm »
    Well the shroud works very well, and also doesn't work very well.
    Around town, stop and go, idling at red lights it works great.
    Climbing that 12 mile 6% grade at 50 mph tops, not so much.
    But it still hasn't overheated.
    Options are:
    Dual fans either with or without a shroud. This involves spending more money.
    Or going back to the previous setup with less restrictive supports. The first version had the fan mounted to the core, the core supported all the weight of the fan. Eventually caused core leaks. Second version (shortly after moving here) was plate brackets the supported the fan to the radiator frame with the plastic bolts holding the fan against the core. Better support, but blocked a bit of airflow.
    Maybe a mounting strap to each corner from fan to frame and the plastic bolts holding against the core.
    Ironically, space is an issue. Mounted in the center of the radiator, to the core, there is 1/4" clearance to the water pump pulley bolts. The shroud was to offset the fan for more clearance.
    Nothing ventured, nothing gained.
    Thanks for the feedback. Creative suggestions considered.

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    « Last Edit: April 29, 2019, 01:17:29 pm by patkelly4370 »

    coelacanth

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    Re: Fan shroud on my old pickup
    « Reply #8 on: April 29, 2019, 02:26:04 pm »
    I'd say dual fans if your space is sufficient and the alternator can support it.  Shrouded works better than un-shrouded but that gets into the space calculation as well.  Are you using straight water and anti-freeze?   Maybe a coolant additive could get your efficiency where it needs to be without additional modifications.   :hmm
    " A republic, if you can keep it. "
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    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #9 on: May 08, 2019, 04:07:37 pm »
    Practicing my budding welding "skills".
    So, first I had just the fan. It was "secured" with 4 plastic bolts to the radiator through the core.
    This destroys the core on our Golden Valley dirt roads. It cooled the truck adequately.
    Next I made some brackets that supported the fan to the radiator frame. It does impede some air flow, but it didn't overheat last summer (very close though)


    Next, we've all seen the full shroud I made. It works great around town, but climbing the grade out of Bullhead it got hot at only 90° outside.
    So this time I made a framework that the fan is attached to, and attaches to the radiator frame. Not attached to the core at all.
    Just warmed the truck up and it draws at the fan like before. Big test is "the hill"
    « Last Edit: May 08, 2019, 04:57:08 pm by patkelly4370 »

    coelacanth

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    Re: Fan shroud on my old pickup
    « Reply #10 on: May 08, 2019, 04:40:46 pm »
     :thumbup  Just keep working until you get it figured out.   ;-)
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    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #11 on: May 15, 2019, 03:28:39 pm »
    Nearly 100° this afternoon as I climbed "the hill" (unnecessarily).
    Ran cooler than with the shroud when the ambient temperature was lower, so things are looking better.
    Now I may bump up the temperature of the thermostat, currently a 165° unit. When the outside temps are low it runs too cool, barely into the acceptable range.
    Of course everything can't be rosy. Now the fan connection has issues at the fuse (block). Fan occasionally doesn't come on until I tap it. Time to clean some connections.

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    coelacanth

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    Re: Fan shroud on my old pickup
    « Reply #12 on: May 19, 2019, 12:16:11 am »
    Always something with the old iron.   :facepalm   Don't forget to check that radiator cap when you switch out the thermostat. 
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    GTGallop

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    Re: Fan shroud on my old pickup
    « Reply #13 on: May 19, 2019, 07:21:47 pm »
    Dumb question - Did you replace the Thermostat and Radiator Cap yet?
    That's $50 of the easiest things to do that fix 90% of all cooling issues.
    The only thing that separates man from animal is our affinity for toilet paper.
    Once we, as a society, lose that affinity, we begin to descend back into the animal kingdom, and after three or more days you will find the food chain beginning to invert on itself.

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    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #14 on: May 19, 2019, 07:34:54 pm »
    The engine was rebuilt exactly one year ago, so both are new. Well, a year old.
    The thermostat is newer as I replaced the 195° with a 165° mid summer.
    When not under load (the hill) when it's hot out, it's now running too cool, barely in range.
    I'll see how it goes as it gets hotter outside. I may bump the thermostat to 175° or 185°.
    Power source to the fan decided it wanted attention too. So I bypassed a fuse bank that the relay was connected to. Unfortunately, it was cool enough today that the fan didn't come on.
    A little background, I'm an ex auto mechanic and parts dept manager. Service writer too. Plus working on race cars and bikes. Now a truck driver.

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    Ballistic Therapy

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    Re: Fan shroud on my old pickup
    « Reply #15 on: May 19, 2019, 07:50:50 pm »
    What was wrong with the original fan and shroud ?

    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #16 on: May 19, 2019, 08:23:27 pm »
    What was wrong with the original fan and shroud ?
    The truck didn't come with one.
    1968 F100. Straight six cylinder 240cu/in. Granny-low 4 speed. No power anything.
    Original fan was a solid fan bolted solid to the water pump pulley. Four inches from the 2 row radiator that was 6" narrower than the grill opening. There was no shroud. Just spinning blades.
    At the time I worked in an auto parts wholesale warehouse. I got a radiator the was the same with as the opening along with an electric fan/shroud. Removed the original fan. This was in 1987.
    Jump to 1998 and the fan/shroud hanging from the radiator core eventually trashed the core. Radiator rebuilt.
    Jump to 2018. Engine rebuild just before moving to AZ. Rebuild radiator again with 3 row core. New 16" fan (lighter, no shroud) on new (rebuilt) engine.
    Last summer climbing "the hill" from Bullhead to Golden Valley had it running HOT, but never overheated. Dirt roads in Golden Valley were going to quickly cause the fan to destroy the new radiator core. So I made some brackets. They somewhat blocked airflow, but not bad. But the fan was now supported by the radiator frame, not the core.
    Then I thought I'd make my own shroud  moving the fan to the left a bit for clearance. This was the start of this thread. I had sheet metal sitting there so it only cost me a little time. It didn't work on "the hill", but everywhere else it was great. Nothing ventured, nothing gained.
    So now I've made a framework that supports the fan by the radiator support, not the core. It let's air flow through the entire radiator at speed. So it's now cooling the best it can.
    So now I swap thermostats to get it more stable.
    Now, climbing "the hill" it runs cooler than before. Going down "the hill" it's running too cold.
    Good part, the truck is 51 years old so it's not as delicate or finicky as a new truck.
    Another thing cooling it s bit. Went from a full camper to a shell.

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    coelacanth

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    Re: Fan shroud on my old pickup
    « Reply #17 on: May 19, 2019, 09:09:42 pm »
    Good lookin' old beast.   :thumbup
    " A republic, if you can keep it. "
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    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #18 on: July 10, 2019, 04:38:26 pm »
    112° today and it ran hot up the hill, but didn't overheat.

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    coelacanth

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    Re: Fan shroud on my old pickup
    « Reply #19 on: July 10, 2019, 05:50:50 pm »
     :thumbup
    " A republic, if you can keep it. "
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    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #20 on: February 15, 2021, 11:03:58 pm »
    My old universal plastic coolant recovery tank lost its cap looonnng ago. Finally replaced it.
    I was surprised to see how much sludge was in the bottom of it. Not good as coolant (and the sludge) gets sucked back into the radiator when the engine cools back down.
    Have a new universal aluminum tank with a cap. I'll flush the cooling system and hopefully get any sludge out.
    A good time to paint my fan bracket, which is holding up quite well.

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    Pwc

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    Re: Fan shroud on my old pickup
    « Reply #21 on: February 16, 2021, 07:40:17 pm »
    Wow!  Doesn't seem like a year and a half since following the old truck's cooling problems.  Good post.

    patkelly4370

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    Re: Fan shroud on my old pickup
    « Reply #22 on: February 16, 2021, 07:47:16 pm »
    I bought a 4runner to give the pickup a break. It still gets the attention it deserves and is driven regularly. Just not as much in summer.

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    coelacanth

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    Re: Fan shroud on my old pickup
    « Reply #23 on: February 16, 2021, 10:34:59 pm »
     :thumbup  Thanks for the update.
    " A republic, if you can keep it. "
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