Buy

Radiator cooling fan quandary

Discussion in '308/328' started by bl10, Sep 7, 2021.

  1. bl10

    bl10 Karting

    Jun 8, 2011
    201
    Steve and Brian
    Yeah. It was probably a mistake to buy the generic fans. I had it out again yesterday and it definitely runs hotter than with the stock fans but not by much. It was about 102 degrees out yesterday and was running just a tick above 195. The odd thing about it is I drove it 20 or 30 minuets in traffic with the AC on and it got to about 190 and both fans were on. After sitting in the parking lot for about 1/2 hour the temp after starting was 195 and climbed to about 200 on the way home. That's the same thing that happened last time only worse (it was hotter out). Seems like heat soak which its unable to recover from.

    Brian did the 11 inch fans center on the round fan mount brackets? My 10" fans almost touch the bottom pan.

    Steve is pressure data available for most name brand fans?

    Turns out the AC was low on Freon. It has a slow leak probably due to using R135 in an R12 system without changing the hoses which I understand degrades the old style hoses. The Ac was at 40 degrees on way down and after the "Heat Soak" was at about 45 degrees which is fine. I hadn't checked the AC pressure levels in 4 or 5 months.

    I'm going to have to change the AC hoses soon which I'm not looking forward to. I'm considering one of the AC upgrade kits if I have to get that far into it.

    Barry
     
  2. To remove this ad click here.

  3. kcabpilot

    kcabpilot Formula 3

    Apr 17, 2014
    1,347
    California SF area
    Full Name:
    Paul
    Barry

    Based on my own experience with this I would say that the shrouds on the new fans are not a problem and that removing them is not going to improve or solve anything. In fact they should be mounted in contact with the condenser. Any gap just allows air to escape and lowers the pressure of the air being pushed through the radiators. Secondly, while the original fans are old and probably suffer from drag due to worn bearings, they are not as woefully inadequate as many people make them out to be. You can put new bearings in them and since you state that everything was hunky-dory before you replaced them, well...

    just my two cents
     
    thorn likes this.
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    22,162
    Texas
    Full Name:
    Steve Magnusson
    A quality fan manufacturer, like Spal, should have P-Q curves available on their website, but think you'd have a hard time finding anything for a Chinese/Amazon/eBay cheapy. Typically, fans capable of generating higher pressures have wider individual blades with more curvature and less open space between the blades.
     
  5. bl10

    bl10 Karting

    Jun 8, 2011
    201
    Kcabpilot
    My old fans work fine and don't feel like there is any unusual drag or roughness. I will probably clean them up and oil the bearings per a thread on this forum and try them again. One of the reasons I changed to "modern" fans was the current draw. When I started resurrecting the 308 I ran into fuse panel problems caused by poor contact between the blade connectors and the rivets that connect them to the strips on the back of fuse panel. At the time I opted not to change to Birdman's cool fuse panels but soldered all the connecting rivets instead which cured that problem. (besides I like the labeled fuse panel covers which don't fit Birdman's panels). At the same time I bought some new fuses off Ebay (original torpedo style) and changed all the fuses (for no reason other than I felt part of the contact problem may have been the old fuses). So after driving about an hour in traffic with both fans (stock) running the new fuses literally melted. Seems the original ones are ceramic (or some heat resistant material) while the new ones are plastic and couldn't handle the heat caused by the current draw. The fuses (both fans) didn't blow just melted and broke contact. So in went the old fuses and no more problems. As they say live and learn. It's a good thing I enjoy working on this as it has been an interesting journey to say the least. Don't get me wrong we have probably put 3 or 4 k miles on it the last couple of years and enjoyed every minute of it. In all the years I've driven it it's never let me down to the point I couldn't drive it home.

    Barry
     
  6. bl10

    bl10 Karting

    Jun 8, 2011
    201
    Steve
    Probably so. The fans I bought have straight blades rather than the scimitar type. In hind site (always 20 20) i should have gotten quality fans. I just looked at the CFM spec and figured they were so far above what other posters have said about the stock fans they should be fine. Not so much.

    Barry
     
  7. To remove this ad click here.

  8. kcabpilot

    kcabpilot Formula 3

    Apr 17, 2014
    1,347
    California SF area
    Full Name:
    Paul
    I don't know if you can still get them but member Sam Supranoff made some blocks that use modern ATO fuses and fit the original covers, I bought a set about 3 years ago.
     
    308 milano likes this.
  9. thorn

    thorn F1 Rookie
    Silver Subscribed

    Aug 7, 2012
    3,200
    Tallahassee, FL
    It's a great kit, but Sam doesn't make them any longer.

    Another alternative is this newer product/set from member TurtleFarmer.
     
  10. bl10

    bl10 Karting

    Jun 8, 2011
    201
    Thanks I'll look into it.

    Barry
     
  11. bl10

    bl10 Karting

    Jun 8, 2011
    201
    Thanks. I'll look into it.
     
  12. To remove this ad click here.

  13. afterburner

    afterburner F1 Rookie
    Silver Subscribed

    Jun 20, 2008
    2,855
    Hong Kong
    Barry, that in itself is reducing the efficiency of your setup - depressurising the back of the core is more effective than jamming more air in front of it and blocking it - higher pressure air is denser and flows less easily through the rad.
     
  14. bl10

    bl10 Karting

    Jun 8, 2011
    201
    Afterburner
    Your correct puller on back side of radiator is better than pusher on front side is better but there is very little room between the radiator and spare tire compartment for puller fans. The originals are, of course, pusher fans. I only changed from puller to pusher because the new fans come as puller and I needed pusher. The new fans are designed to run either way. It clearly would be better to build a complete shroud with two puller fans behind the radiator (like most if not all contemporary cars) but that's not really an option on a 78 308 without substantial modification.

    Barry
     
  15. afterburner

    afterburner F1 Rookie
    Silver Subscribed

    Jun 20, 2008
    2,855
    Hong Kong
    Barry thanks now I understand what you meant - I am surprised the fan blade's airfoil is reversible though. I guess it's symmetrical and so less efficient than a directional version. A standard airfoil would have considerably more drag and less lift when used backwards... so this must be some sort of a half-way solution of a foil that can run both ways.
    The air coming off the blades is very turbulent, so I wouldn't fit them right in front of the core. It also blocks some of the rad behind the motor from being blown at. Better get some distance between the blades and the core. The original setup was probably about right in that respect.
    Good luck!

    Urs (Mondial with 2 fans running cool in HK)
     
  16. bl10

    bl10 Karting

    Jun 8, 2011
    201
    Afterburner. The blades are curved, no real airfoil shape, much like the stock fans. Most, if not all, the "universal" fans are reversible by flipping the blade over. The fans are flush against the AC condenser which seems like it would, as you say, reduce the surface area the fan blows through. Due to the design of these fans they cannot be moved forward, without mounting structure modification, thus increasing the gap between the condenser and the fans. I'm toying with the removing the fan cage and shroud ring which would decrease fan efficiency but I believe permit air flow over a larger surface. There are, of course, varying opinions at to this option.

    Barry
     
  17. afterburner

    afterburner F1 Rookie
    Silver Subscribed

    Jun 20, 2008
    2,855
    Hong Kong
    Barry removing all the caging in front of the blades will help airflow for sure. But I'd leave the shroud in place, it should reduce tip losses. Urs
     
  18. bl10

    bl10 Karting

    Jun 8, 2011
    201
    I can't remove all the caging and leave the shroud in place as the caging holds the shroud in place. I'm going to leave it as is for a bit and decide what to do after I put some miles on it.

    Barry
     
    afterburner likes this.
  19. Brian Harper

    Brian Harper F1 Rookie
    Silver Subscribed Owner

    Feb 17, 2006
    4,008
    San Jose area
    Full Name:
    Brian Harper
    #41 Brian Harper, Sep 10, 2021
    Last edited: Sep 10, 2021
    Yes, perfectly. The Spal fans have a flat in the circular outside ring. They abut each other on those flats and are mounted with an adapter to the stock fan mounts.
    (Sorry, that picture is dark. This is from the top looking straight down.)
     

    Attached Files:

  20. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    76,094
    Houston, Texas
    Full Name:
    Bubba
    I want to toss in a modern 12V DC fan from the Grainger catalog fits the stock brackets with a longer bolt.
    The amp draw is less than the OEM Lucas for sure.

    Been using them for years.

    Are you guys SURE the OEM fans are "pushing" forward, against the natural flow of air with the car going forward???
    That seems intuitively wrong, to me.

    Reversing polarity on the Lucas (or Grainger ) fans would do that, but why would you want to??
     
  21. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    76,094
    Houston, Texas
    Full Name:
    Bubba
    No, it's just a round bare fan motor, no blades....12V DC I think the amp draw is about 3 amps.

    It's a round motor very close in appearance to the Lucas motor,
    Look at #3LCH7
     
  22. Brian Harper

    Brian Harper F1 Rookie
    Silver Subscribed Owner

    Feb 17, 2006
    4,008
    San Jose area
    Full Name:
    Brian Harper
    No, you missed the intent. Some of the aftermarket fans are designed to go behind the radiator and suck (pull) air through the radiator OR go in front of the radiator and blow (push) air at the radiator. When you fit these in front of the radiator they would blow the wrong direction. Some fans you just swap the polarity and they blow (push) instead of suck. Some you flip the blades around so they blow instead of suck. Other fans are only pushers or only pullers, probably because of blade design, maybe because of motor design.

    But your intuition is correct, you always move air from the front of the car towards the back of the car.

    (Also some fans suck no matter if they are pushing or pulling, but I digress....)
     
  23. mike996

    mike996 F1 Veteran

    Jun 14, 2008
    6,236
    TX//Mexico/UK
    Full Name:
    Mike 996
    "depressurising the back of the core is more effective than jamming more air in front of it and blocking it"

    Maybe so but the 328, with a pair of pusher fans, is well known for its engine-cooling capability. It can sit at idle/bumper-to-bumper traffic conditions in hot weather with no problem at all, the fans cycling on/off as necessary. Wish the AC worked that well! :)

    So clearly, pusher fans work fine if appropriately selected for the application. ;)
     
    afterburner likes this.
  24. BigTex

    BigTex Seven Time F1 World Champ
    Rossa Subscribed Owner

    Dec 6, 2002
    76,094
    Houston, Texas
    Full Name:
    Bubba
    Ah thanks so thy are mounted in front of the A/C condensor, and the radiator, in the "push mode"............hmm.

    I would say the without the two coils being sealed together somehow, (they are not, OEM) you are improving your A/C coil delta T, but on the radiator further away, maybe not so much????

    I think when they finally get "canted rearward" in later years perhaps they are better mated together, air flow wise???
     
  25. Lawrence Coppari

    Lawrence Coppari Formula 3

    Apr 29, 2002
    2,030
    Kingsport, TN
    Full Name:
    Lawrence A. Coppari
    I used to go to Road Atlanta about 6 times a year and run my 1986 water cooled 944 Porsche turbo (front engine) that had a number of engine modifications that gave it considerably more power. I would drive it there from NE Tennessee and would take a route that carried me over mountains. Once while driving to the track and climbing a mountain in 5th gear I noticed my water temperature was higher than normal and still climbing. I downshifted to 4th raising the rpm. That stopped the temperature from climbing. Turning on the heater brought the temperature back to the usual range. At the track there was no problem with coolant temperatures because rpms are high. The coolant level was where it should be. There was no slippage of the belt that drove the water pump because it happens to be the backside of the cam belt on this interference engine. Had the belt been slipping, it would have been disastrous. There was no evidence of slippage when I removed the belt cover at the track just to make sure.

    Upon returning home after the track event I ordered a new water pump. Water pump change on a 944 is a PITA. A month or so later I attended another track event at Road Atlanta. There was no problem with rising coolant temperatures as I crossed the mountains. A Ferrari water pump has to push the coolant from the rear of the vehicle to the front and back. If clearances of the water pump become too large, you will get less flow. I'm not saying this is your problem, but it was mine.
     
    waymar and Du_Man like this.
  26. waymar

    waymar Formula 3

    Sep 2, 2008
    1,211
    Northeast, PA - USA
    Full Name:
    Wayne
    You can check clearance with clay...... not sure what min or max should be.
     
  27. Brian Harper

    Brian Harper F1 Rookie
    Silver Subscribed Owner

    Feb 17, 2006
    4,008
    San Jose area
    Full Name:
    Brian Harper
    I don't have 328 experience, but from what I've seen here and in parts books they actually farther apart...way farther apart. The 328 condenser is off to the side of the radiator sort of under the head light, it has its own fan. So one of the 328's cooling improvements is that the radiator isn't impeded by the evaporator at all. From what I gather this was a cooling system improvement, but it was not an AC system improvement.
     
    BigTex likes this.

Share This Page