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THIS is why you should ALWAYS run a proper fan and shroud people!

Discussion in 'The Hokey Ass Message Board' started by decker, Mar 4, 2009.

  1. I have two late 80s cars, p/s, p/b, p/s, a/c, and the Rivi, loaded(four wheel drums on that one), all have mech fans, all weight over 3500#, all have closed engine compartments, none overheat. About the only thing worse on a period car is radials and disks. If you don't want to put in the effort, build a street rod.
  2. sergisbadass
    Joined: Jan 17, 2008
    Posts: 25

    from Dallas TX

  3. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,426

    Von Rigg Fink
    from Garage

    mechanical fans fail for only 2 reasons..the engine shuts down..or the belt breaks.
    water pumps another issue so dont mix that up in what im saying.

    electric? way too many to list..bad ground, bad sensor, bad connection..not big enough..shitty wireing,,the list goes on and on..

    one of the reasons why i will never run an electric fan

    i have 400 H.P. engine driving my fan..and when its running its cooling
    screw this electric crap

    if my belt breaks i can fix it or carry a spare..electric goes down..yer fucked out in the middle of no where

    its just my opinion..beat up on me if you must..but it will never change my mind, especially as i drive by you on the side of the road

    PS...if you wave your HAMB shirt ..I'll stop and help
    Last edited: Mar 4, 2009
  4. Weasel
    Joined: Dec 30, 2007
    Posts: 6,694


    Using electric pusher fans is a double edged sword. They may help cool at standstill or crawling speeds but at higher speeds they block airflow to the radiator core and so are, in a sense, self defeating.

    Never use mechanical Flex fans - they have a known tendency to crack at the hub and then will take your radiator out - ask me about my $700 flex fan experience!
  5. Johnny1290
    Joined: Apr 20, 2006
    Posts: 2,834


    As someone that's been stranded as a result of smoking an electric fan in an o/t new-ish car, I believe you!!!

    I *would* run a mechanical fan for just this reason, I like to KISS when I can, because there's enough stuff already for me to screw up!!!

    I have a dual electric out of a Contour right now, it kicks total ass, and I suppose when the low speed fan gets smoked I can at least get it home if I hotwire the high speed.

    I ran the electrics due to clearance, you gotta pick your battles and this was the compromise I decided to make. That electric moves a *shit ton* of air!!!

    Well, at least compared to the flex fan that was installed backwards that I previously had! (don't blame me!) :D:rolleyes::eek:
  6. I've been fighting overheating problems with my 40 Merc from the day I got it. It has a SBC .
    I replaced the original rad with a Aluminum one and the existing electric fan with a new one. More CFM. I thought "oh boy"! I'm all set. Typical scenerio, as long as I'm moving, it works great. I get in traffic or a slow crawl at a car show and SHIT!! I'm sittin' on nails. Had everykind of problem with overheating until I put a shroud on the car. I had to make one from aluminum. There's just no room for much of anything. It has the little flaps for road speeds.
    Also blocked the triangle shaped opening in the upper front of the rad to keep the air flow where it should be. Seems to be a common thing to do with the 40 Fords and Mercs.
    The shroud made all the difference. I might throw a few louvers in the hood just for insurance.
  7. Electric puller fans are better for performance, so I'll stick with them.

    Any puller fan reccomendations for the following dimensions?

    measurements are 21" wide/ 16 1/2 tall and a max of 2 3/8 deep with the motor.( space between the water pump and radiator)
  8. Johnny1290
    Joined: Apr 20, 2006
    Posts: 2,834


    I don't wanna derail the thread, but I'll send you a PM prostockjohn

  9. The upper triangle piece makes a lot of difference on the fat fender Fords.

    Have you read some of the threads pointing out that timing, vacuum advance etc. are a big reason as to whether your car overheats or not?
  10. That sucks that your radiator blew up, but I think you probably had a radiator cap with too high of a pressure rating or a faulty radiator cap, and the tank blew up before the radiator cap relieved the pressure. It may have overheated due to those dinky fans not cooling well, but the radiator cap should have released a gush of coolant all over the street BEFORE the tank blew up. You probably used a modern high pressure cap on your old radiator which wasn't meant to be pressurized that much.

    Electric fans look pretty tacky to me on a hot rod, so I go out of my way to do whatever it takes to make a mechanical fan work. A shroud sure makes a big difference when you have a mechanical fan.
  11. Retro Jim
    Joined: May 27, 2007
    Posts: 3,859

    Retro Jim

    I have to say I have only had the fan & shroud that came with the engine . I have had BB & SB and never had all these problem that people have with overheating . Maybe I am lucky but the good ol stock fan & shroud has always worked for me . I always used a 10-12 lb cap . If I didn't have room for a fan I guess I would go with a single big electric fan & shroud instead of little ones . I can't see how a bunch of little fans will do the job . They arn't getting air to the complete area of the radiator like on big fan with a shrould . You have to have fresh air moving across the entire radiator , not just some areas . Just my 2 cents and I am sticking with a fan & shroud .
  12. zzford
    Joined: May 5, 2005
    Posts: 1,823


    BULLSHIT !!! I have seen MANY cars that an electric fan is the ONLY solution.
  13. it's not mine dude... we just get to fix it!!!:D
  14. flynbrian48
    Joined: Mar 10, 2008
    Posts: 7,082


    I've got 2 1/2" between the water pump pulley bolts and the radiator core. From the center of the fan hub to the top of the radiator is 6", and 3 of that is the tank. The body of my car is channeled 5" at the cowl, and sectioned 6". The bottom of the pan is 6" from the floor, and the hood clears the top of the carb by 2". That doesn't leave room for a mechanical fan and shroud, and some wag suggested if there's no room, fix it so there is :rolleyes:. Great suggestion, but THERE IS NO ROOM FOR AYTHING TO GO ANYWHERE!

    I have a 14", 2000 CFM fan and temp controlled switch on the way for it, I'd have gone with a 16" but as thin as I could find in 16" was 3 1/2" thick. It's a Mustang V8 radiator, the core is 16x18, so the 14" is as much fan as I can get squeezed in, it's 2 1/4" thick. I planned on an electric fan from the get go, and that's what I'm using. It's not an engineering error.


    Attached Files:

    Joined: Jan 4, 2008
    Posts: 1,467


    i have used both mechanical and electric fans, i agree with some of ya that mech fans dont always work and you need to use elect...... the problem looking at this pic is that the fans are way to small for this aplication, those are ok for like a single core rad with a 4 banger but in a v8 you need more volume, this also could be the cause of a hot tstat also, dont know what he was runnin but the cap should have gone first, but the guage should have been a tell tale sign......

    split tanks are from pooor assembly or blown head gaskets

    just my 2 cents worth, also to many years as a lic mechanic as well and have seen alot of this
  16. B.A.KING
    Joined: Apr 6, 2005
    Posts: 3,717


    ok lots of good info here but explain sumthin to me. on a rad with a large tank you need a 6-8 # cap right.ok thats on a old rad original. but if its a new,say desert cooler replacement rad,same dementions/same size tank,BUT new,do you still need the 6-8 # cap.or can you step up on the pounds on the cap.??????
  17. I've been advised that way. I'll have to make sure everthing is up to snuff before the season starts up here(finally:rolleyes:) You certainly have to have all the bases covered on the FF Fords. I have heard the SBC generates more heat than some other engines. Don't know if that's a fact or not. I did put some Sanderson headers with the ceramic coating (I hope that's not too hitech for here:p) and that really helped lower the heat coming off the old headers. They cool down a lot faster too. :) thanks for the info
  18. Revhead
    Joined: Mar 19, 2001
    Posts: 3,027

    from Dallas, TX

    actually a the small block in my panel truck is so low the fan would hit the front crossmember, I had to use electric.
  19. Here's another one for the FF Fords.

    Got stock style inner fender panels?
    If so you can see that they have a bend/tunnel whatever you want to call it that lets hot air out.

    I've heard of guys replacing these with flat panels and going a bit crazy with trying to cure a hot running engine.

    Along these same lines I understand the aftermarket inner panels with louvers work fine.

    If I remember right, airflow through the engine compt removes 40% of the heat, radiator system, another 40% and engine oil is good for 20%.

    Some cars can get really hot under the hood - daily driver late models for the most part - and factory engineers will move components around to help underhood airflow.

    I believe underhood temps can exceed 300* F in many cases.
  20. Weasel, that reminds me of a blue and white '55 Ford that used to be around my home town that had this huge gash in the hood. The guy who owned it was revving up the stock 272 Y block sitting at a traffic light waiting for the light to change, fan blade on the stock fan came off and came right through the hood like a knife through hot butter. Drove it for years with the hood like that.
  21. although it's tough to see from here... i'd suggest that once you get your fan that you first take a few measurements and be certain to have a large enough blade size. the fan blade size should cover roughly 2/3rds of the core size. if it isn't send it back and find one that is. (there's a lot of "thinline" units one can purchase these days) next... once you have the proper size fan assembly make yourself a sheetmetal shroud that fits tightly and is the same dimension as the core. (enveloping the core to create the venturi is mucho-importante') make yourself a pattern of the fan assembly. cut out the hole for the fan... and if need be you can recess the assembly a little bit but ideally you want the blade as close to the outside edge of the shroud as possible... mount it and test it.

    a simple way to test air draw is to get some charcoal smoking on a pan or ??? and move it around in front of the radiator to make sure the fan is drawing air (or smoke in this case) through the core at a fairly good rate. this may sound pretty low-tech but if the fan isn't drawing air/smoke from 6" away no matter where you have it placed... you ain't drawing enough air bubba! ;)

    we can get into a deep "what size and thickness radiator do i need" thread another time if need be... but in this thread let's try to focus on drawing air through what we already have. (i've seen some two-row old school radiators easily cool up to 400hp... but if the air isn't being sucked through them you could have a ten row core and for the most part it wouldn't matter... air flow is our friend.
  22. kinda depends on your heat ranges and your overflow set-up... with more modern closed systems that utilize a recovery tank you can step up the pressure but for the most part... if you are already running in the proper operating range with a lower pressure cap... do the same with your newer radiator.

    mileage may vary... the views expressed in this program may or may not be ideal for you. :)

    just make sure your fan is suckin' enough air brah! ;)
  23. TurboHaddix
    Joined: Jan 10, 2009
    Posts: 184


    Most of the time I have to fix a friend's overheating car it's due to them running too lean.
  24. Parts48
    Joined: Mar 28, 2008
    Posts: 1,363

    from Tucson, Az
    1. Hot Rod Veterans

    On my very tight compartment..SBC in the narrow triangulated XK120..with very small grille..and a 17"X17.5" Aluminum radiator..I did both. 16lb cap..with recirc tube.
    I set the motor as far back as possible for handling..leaving a lot of space up front.
    The Griffin came as a unit with shroud and 1650cfm puller. The radiator is perhaps 14" or more from the water pump pulley.
    Because of the shape of the compartment a long pump would not allow placement of the alternator..and the slope of the hood would have interferred if placed high.
    My problem would and had been idle on a 110 degree day...if I kept just the mechanical fan.
    It cooled very well with just the electric..but underhood temps were such that I was percolating fuel..vapor locking.
    I added the flex in..mainly to get more air into the compartment and allow full ducting of the nose to the radiator. I left an area behind the radiator for air to come up..flex to throw more air..and it works great even in 110*+ heat here in Tucson.

    At idle..I can puff on my cigar 5 feet in front of the small grille..and watch it suck that smoke into the cowled nose.

    I guess some redundancy for a electric fan failure is a by product..but never have had an electric fan motor fail..

    Just got to be creative some times
    Last edited: Mar 4, 2009
  25. the obvious issue in this example is absolutely no shrouding/ducting and two extremely tiny draw area's on a large surface area... it doesn't matter if it's a 3-4-5-6-8-10-12 or 16 cyl engine really.

    tank blow off on the lower tank was the original solder from the factory... and it's fairly rare to actually see the bottom tank blow off. the poor undersized and utterly ridiculous fan layout plus a total lack of shrouding in this particular example made it worth showing an extreme example to folks here what not to do. we see this sort of stuff at the shop on a regular basis... this being an extreme example... point being... that a properly built cooling system doesn't just end with parts that hold coolant. it doesn't stop there. blown head gaskets will typically take out the weakest and highest point within the cooling system first.

    i see more of this sort of stuff on a fairly regular basis than i care to talk about... especially when people think they are smarter than the original folks that designed the entire "system" in the first place. :rolleyes: (i see ton's of late model stuff that you wouldn't even believe people attempt to change... also with failure.)
    Last edited: Mar 5, 2009
  26. hotrod-Linkin
    Joined: Feb 7, 2007
    Posts: 3,382


    i've got my engines hot enough to light cigarettes off the manifold and never exploded a radiator,i think there were many factors here. but we built cars for years before those chinese plastic thingies...
  27. The number one problem with this system is pressurising an origional radiator! If you run a shop that did the top tank you should have told him this was an issue and could possibly happen!
    Its not often we see this here in OZ, (Seems to be an issue with early Valiant and Falcon radiators, the ones where the header plate is the tanke with an almost flat top solderd on) I dont know anyone that uses original radiators, it seems a fir bit more work goes into the average car here (On account of our stiff rego laws).
    Guys have a cooling system built for your car, dont put one together from bits!
    As for the fan issue? It depends on what you are using the car for, performance, daily driving or just the odd week end.
    OK, dont run a fan on a car that is going to be run WOT, if it has a cooling system a puller electric fan wil be fine.
    Daily driver youneed air volume drawn through, a shrouded mechanical fan should be fine. If you go to an electric fan then the swept area come into play, the larger area of the core you can have swept by the fan the better it will cool. Sometimes two fans ARE better than one! (Ie, tall narrow radiators)
    If your just driving occasionaly, the mechanical fan with a small 'helper' pusher on the front can aid cooling in traffic.
    There is no one solution for ALL cars, these systems need to be built to work on the individual car.
    Fire away.
  28. AlbuqF-1
    Joined: Mar 2, 2006
    Posts: 909

    from NM

    Something I haven't seen discussed is that electric setups are constantly cycling up to their turn-on point, cooling off, then repeating the process over and over. You basically have no cooling, full cooling, no cooling... I had a couple of '90's Camaros with LT1's and stock electric fans, you could watch the gauge climb to 210, drop to 190, climb back up... That just isn't as good for an engine as a constant cooling from a mechanical fan.
  29. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    Member Emeritus

    Not knowing it's history, the first thing that I'd suspect is a frozen radiator. Ice will split a tank wide open like that and then of course the engine will over heat because the ice blocks any water that could flow. The first sign of a frozen radiator is steam from the over heat. Don't ask me how I know that. You won't see that too much in Arizona and California.:D

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