Temp gauge

Whether coolant or oil temp, if the temp goes down when you drive but rises when you idle, the problem is typically a cooling fan that isn't coming on (so check your fuses in your passenger footwell first).

High coolant temps will warp your aluminim heads, which will then blow your head gasket...an expensive fix.

So you want to fix your fans and you want to be careful to not let the gage go too high until then.

 

Yup...sounds like cooling fans.

 

Could be the relays. Could be the fan motors. Could be the thermo-switch that turns each fan on.

But it usually wouldn't be two fan relays going bad at once, so a reasonable first test is to swap the right fan relay with the left fan relay.

I've got some other easy tests if that doesn't work for you (so just holler, Alabama football doesn't start quite yet today, so you've got some time).

 

Are the fans coming on when the temp gauge gets to just over halfway? You should be able to hear them easily.

I would recommend that you replace those 40amp fuses with correct ones ASAP. Which would you rather have, a blown fuse or a burned out fan motor? Or a melted wiring harness? Or a burned fuse panel? NEVER put in a fuse of higher amperage than the rated size. If the proper fuse blows out, then something needs attention.

 

Good man!


Nice work. Life is good.

 

Top of the heap IMO !!!! It even sounds way better than a capristo equiped 360.... !!!

 

Where did you see that the fans should have 30amp fuses? According to the Owners Manual, the left fan(#13) should have a 25amp fuse, and the right fan (#17) should have a 20amp fuse. I have no idea why they would be different. But don't use 30amp fuses, and certainly don't use 40amp fuses.

Edit: Looking in the Parts Book, I see that both radiators use the same fan motor, but the left radiator uses a larger fan than the right radiator, since the left radiator is bigger than the right radiator. If the fan is bigger, perhaps there is a little more electrical draw to that motor, hence the bigger fuse???

 

Interesting! The label on my fuse box cover says that both fan fuses should be 25amps. The Workshop Manual says the same thing as the Owners Handbook, that the left fan fuse is a 25amp and the right fan fuse is a 20amp. I don't see anything that says to use a 30amp fuse. If the fans work OK on 30amps, and that's what your cover says is correct, then I can't argue with that.

But if someone put 40amp fuses in those slots, there must have been a reason for it. If you feel like doing some investigating, you could pull out the rear wheel inner fender liners and take a good look at the fans. It's possible that the connections are bad, or that there are mouse nests in the shrouds, holding the fans from turning freely.

Hope you enjoyed the car show. We have one coming up tomorrow.

 

355's require/specify a 30 amp fast blow fuse for the radiator fans. It is not uncommon for them to blow; and it is surmised they fail during start, due to a voltage surge. I have seen another 355 with 40 amp fast blow fuses, so I suspect this may be a uncommon dealer fix for cars that frequently blow the stock 30 amp fuses. In the almost 3 years of ownership, I have blown only one left hand side fuse, and have not had a recurrance. A friend blows them every few months. His fix was to install 30 amp circuit breakers. This way, if they trip, they will automatically reset, so there is nothing for him to do. I have not spoken to him recently about it, but I would assume that would solve the issue. 30 amp circuit breakers that fit in the normal fuse location are available at some autoparts stores, but may require some searching. Otherwise you can find them on the internet. I would recommend buying the "auto reset" ones which are most common, but check to be sure what you are buying. http://www.delcity.net/delcity/servlet/catalog?parentid=151&childid=46529&page=1&pageitem=2&tabset=1

I really doubt the radiator fans draw anything near 30 amps during operation, and the only reason they are rated so high is to overcome the initial voltage surge during start up.

 

I thought the car in question was a 348 - sorry!!!!

 

I think you meant to say "current surge" not "voltage surge." There is a current surge when electric motors are energized (and often a voltage drop).

 

What would happen to the current surge if a capacitor was installed in-line with the fan motor?

 

The motor would not run if the capacitor were in-line (in series). I think electric motor current draw can be as high as two or three times normal run current but it's usually for a really short time and is not an issue. Sometimes you just need to install a slow blow fuse or slow trip breaker. If there is abnormally high mechanical resistance in a motor (bad bearings or other cause of high drag) that can create fuse blowing situations. Best thing to do is measure the run current of a known good motor (same exact motor) and compare it to the one that may be suspect. If the current measurements are very close the motor is most likely fine.

 

Incidentally, if the car is already moving the fan will probably be spinning somewhat from ram effect. This will reduce the start-up current requirement as you don't have to bring the motor up to speed from a dead stop. So highest current draw would be start-up when the car is stationary. Of course the fans probably never come on when you're travelling at high speeds. If they do there could be cooling system issues.

 

What would happen to the current surge if an inductor was installed in-line with the fan motor?

 

It wouldn't have any real effect on a DC circuit (other than adding some more resistance).

If these cars have a history of blowing fan fuses then there must be some fundamental design flaw. Something is not rated correctly, a certain electrical contact(s) develops high resistance etc. Cooling fan circuitry is pretty basic and similar in all cars. If there are thousands of models of cars that have no problem with electric radiator fan fusing then something is not right with this model. Of course I don't know how widespread the problem is. Was it a certain year, just a few cars, after a new fan part number was used.... just the fact that there seems to be some discrepancy between what the owner's manual calls for fuse-wise and what is printed on the fuse box cover tells me there was some lack of attention to detail by Ferrari.

Things with high power electric motors or compressors often specify a slow-blow fuse (or breaker) so I'm surprised to see someone mention that a fast-blow fuse is specified. Having said that I don't really consider a radiator fan motor to be high power especially since it's not "fighting" against solid mechanical resistance (such as an elevator motor does).

 

What would happen if one connected an inrush current limiter (NTC thermistor) in-line with the fan?




http://en.wikipedia.org/wiki/Inrush_current_limiter

 

That might do the trick but it still seems like there is a design flaw that should be addressed instead. Why should one model of car need this and not any others?