355 fan fuse blowing | FerrariChat

355 fan fuse blowing

Discussion in '348/355' started by eric355, Jul 4, 2008.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. eric355

    eric355 Formula 3
    Silver Subscribed

    Nov 30, 2005
    1,235
    Toulouse (France)
    Full Name:
    Eric DECOUX
    #1 eric355, Jul 4, 2008
    Last edited by a moderator: Sep 7, 2017
    Last Sunday was a warm day in France. Had a good time with the F355 but I noticed that the coolant temperature was not as stable as usual. Not a big issue because I was driving on no-traffic roads and the temperature didn’t increase so much, except when I reached home where it peaks at 100°C. I knew something was wrong and that I had experienced my first LH fan fuse blowing. I take care to check the fans operation at the end of each run so I know it is a recent blowing. I don’t know if it was fuse time or if the fan is starting to go but I don’t feel comfortable with that in mind : not knowing exactly when this fuse blown and when will be the next time, if any.

    I decided to implement an “alarm” on these 2 crucial fuses. Not a very clever mod, very simple, but I thought it could hep someone else. Here it is : 2 very cheap buzzers soldered in parallel with the fuses and double-side taped on the relevant relays. The result, no alarm if all is OK, but a continuous bip when the fan is supposed to run with a blown fuse.
    Nota: the buzzer being polarized, the fuse is now also polarized and must be installed with the negative side upward (connected to the fan).

    Hope I will never hear the bip :)
    Image Unavailable, Please Login
    Image Unavailable, Please Login
     
  2. FandLcars

    FandLcars F1 Rookie

    Aug 6, 2006
    3,057
    Tempe, Az
    Full Name:
    Rick Schumm
    Sounds like a great idea Eric. I think you'd want to make sure the buzzers are high enough in impedance so they wouldn't normally work while the fuse is good. If your setup works, can you provide a little more info about impedance or specs on our buzzers?
     
  3. eyboro

    eyboro Formula Junior
    Silver Subscribed

    May 30, 2004
    989
    Chicago
    Full Name:
    Eitan
    I was driving my car 2 weeks ago when the weather was very hot in Chicago. All the major highways are under construction here. My F355 was over heating over stop and go traffic. As soon as I got home I checked the fuse and sure enough it was blown.

    I'm going to Radio Shack right now with a picture of your setup to see if I can do the same thing.

    A very clever idea thank you.
     
  4. eric355

    eric355 Formula 3
    Silver Subscribed

    Nov 30, 2005
    1,235
    Toulouse (France)
    Full Name:
    Eric DECOUX
    You don't have to worry about the impedance of the buzzer. When the fuse is OK, the buzzer is very well short-circuited by the fuse and it sees only a very low voltage even at maximum current during fan start-up. Choose any 12V buzzer and it will be OK. Mine are working between 3V and 15V and they did not bip when I by-passed the relay for testing.
     
  5. greyboxer

    greyboxer F1 World Champ

    Dec 8, 2004
    12,709
    South East
    Full Name:
    Jimmie
    #5 greyboxer, Jul 5, 2008
    Last edited: Jul 5, 2008
    Eric - I'm pretty sure this must have been covered but I was told the left hand fan takes at least 28 amps to start and the fuse is usually only 30 amp - so it blows - as a result most independents recommend fitting a 40 amp fuse

    The other thing is that if the water level is slightly low the temperature seems not to cause the fans to actuate
     
  6. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    18,055
    USA
    Eric, the fuse blowing is a common problem. In all likelihood, it will get worse. The fans seem to progressively draw more and more current upon starting as they age and wear. A friend of mine even went so far as to replace the fuses with self-resetting 30 amp circuit breakers. He also noticed that as his fans turned on, that is idle speed would drop a couple hundred rpm, as the engine struggled to maintain idle...but would stabilize after several seconds.

    He replaced both his fan motors, and now he has a perfect idle, and and no more fuses blowing.
    I had my left hand fan motor fuse blow once about 2 years ago, but has not recurred. I have no idle issues either. But if I ever blow a fuse again, I will replace both motors.

    See this thread for more info on a less expensive source for the Spal fan motor assemblies and how to install them:

    http://www.ferrarichat.com/forum/showthread.php?t=194555&highlight=355+fans
     
  7. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    18,055
    USA
    All true, but as the fan motors age, they draw much more that 30amps, causing the frequent fuse replacements. I have another friend with a 355 with the 40 amp fuses. Appears they have been there for years (he bought the car with them already installed). No worse for wear, but I have noticed that 40amp ATO/ATC fuses are not easily found, except online.

    Again, with a 10+ year old car, probably best to simply replace the fans, expecially now that we have a relatively inexpensive source for them, other than going to Ferrari. ;)
     
  8. mwhitesell

    mwhitesell Formula 3

    Sep 17, 2006
    1,083
    Atlanta
    Full Name:
    Mark

    Somewhere there is a thread about the actual cause of the engine stumbles when the fans come on. Some people have made plasic bits to go around the fan since the problem was caused by the air temperature difference from warm air going around the fan and into the intake in the first few seconds of the fan running.
    Sorry to hijack the thread. I too have had the fuse blow. Although mine came back from an engine out service blown. I fixed it and it's been perfect since. I like the buzzer idea. Somebody make a bunch and sell them to everyone.
     
  9. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    18,055
    USA
    #9 f355spider, Jul 6, 2008
    Last edited: Jul 6, 2008

    Mark, if you read the thread I posted, one of the folks who was involved in the fan shroud thing (aeroengineman) tried the shrouds, but did not seem to have much luck. In the thread I posted, he replaced his fans and that solved the idle drop from the fans coming on. The excessive current draw causes a lot of parasitic drag on the engine by the alternator working so hard. This seems to be the cause of the idle drop when the fans come on.

    Here is his quote:
    http://www.ferrarichat.com/forum/showpost.php?p=137693408&postcount=48

    The problem is the fans start drawing more and more current upon start up as they get old. I agree the alarm idea is neat, but really unnecessary. I think we should all consider the fans a "consumable" item, that should be replaced after 8 to 10 years. The link in the thread shows a source for new fans for only $125 each, a literal bargain. And these are oem type Spal fans with the exact same specs. The only difference is they have a different electrical plug, so you will need to splice your original one onto the new fan.
     
  10. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    I thought aeroengineman said he did see an idle improvement with the shroud but saw further improvement after replacing the fan assemblies. I absolutely saw an idle improvement with the shrouds and am only changing the fan assemblies to reduce the load on the charging/electrical system.
     
  11. eric355

    eric355 Formula 3
    Silver Subscribed

    Nov 30, 2005
    1,235
    Toulouse (France)
    Full Name:
    Eric DECOUX
    Yes I agree that fuse blowing is not nominal and may be the sign of fan degradation. But I suspect that the fuse was the original one (11 years) and may have been stressed by the numerous start-up of the fan. I will stay for the moment with 30A fuses with the alarm system. If it blows again I will have a closer look to the fan itself.
     
  12. conscom

    conscom Formula Junior

    Jan 6, 2008
    467
    Vancouver BC Canada
    Full Name:
    Gary
    I thank all of you for this thread. I'm just nearing completion of my major engine out service. When the mechanic got the engine running today, the LH fan quit - fuse blown. This seems to be an omen for me to replace the fan (the RH fan was replaced 5 years ago by previous owner). So now I'll be ordering my fan from Street Rods by Michael and replace by myself with all your valuable advice. Thx again! This is really a Ferrari brotherhood that warms my heart!
     

Share This Page