F40 Alternator light on at high RPM

My F40 alternator lamp illuminates over 3,000 RPM and stays on pretty solid at 7,000 RPM. What causes that?

Also, how do you check the alternator belt tension?

 

Bill:

Hard to say what is causing this, remotely. Alternator itself, or belt tension.

However, I know that to check the alternator belt tension it needs to be done with the engine stone cold. Ive had this done but Ferrari did it for me using their own tensiometer. Also, due to the location of the alternator, driver's seat and firewall have to come out, so assuming you have the right tools, there is quite a bit of effort. The tension load is in the owner's manual (I forget but its 30-something kg I think).

 

Thanks Joe, I'm ready! I guess I need to buy a new tool.
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OK perfect, see that nut on the curved adjustment bracket? You will have to loosen that, then the one directly beneath the spool, then move the alternator unit outwards to increase the belt tension.

Thing is, I don't have the tool to measure belt tension!!! Maybe Paul can overnight you his unit if you tell him he forgot to tighten it ;-). That said the book says 33 - 37kg is the magic range. I bet if you re-set it the light will go out!

 

Use a lever to tension alt. Tighten. Hit bracket with a hammer. Put F over high C tuning fork on it. Adjust until it vibrates. (I think it's F over high C but check to make sure either with spring scale or by comparing it to second soprano solo in Aida third note from opening)

(Sal sets tension by ear) or; convert KG to lbs. Buy a spring scale form Edmond Scientific. (Cheaper than from Ferrari).

Loosen bolt. Use a lever to tension alt until scale reads proper tension when attached to alt.

Cut end off that tie tie so car weighs less. If that doesn't work put that alternator in museum.

Repalce it with this one:

http://shop.ebay.com/i.html?_nkw=Ferrari+F40+alternator&_armrs=1&_from=&_ipg=

Once again much cheaper than from Ferrari.

Or if you never want to have an alternator problem replace it with a Lexus alternator which is what we do.

 

Its probabley the alternator. Whatever you do dont let the rebuild shop throw away the parts they remove and make sure that they reuse the same case. A Ferrari alternator has part numbers stenciled onto the case. A standard rebuild will cause the engine not to start when reinstalled if they give you a standard delco rebuild kit. The Ferrari ECM looks for a signal from the alternator to disable the starter circuit when the engine is runnning. The weatherpack connector is wired differently although it looks the same. Have them replace only the defective parts . Check your lower alternator bracket for cracks by removing it completely. They break often.

 

Jim, there was a refit kit offered about 10 years ago that uses the ND alternator. The kit was 3K at the time. Haven't seen one it years. Unfortunately, Ferrari does not sell the bracket by itself so I had to make a new one. I run a TAG alternator which is just an upgraded ND unit from a toyota. That alternator on ebay is for a very early F40 and it wont last long. It's easier and cheaper to get the alternator rebuilt as long as the factory specific Ferrari parts are OK. Anyone that had a local alternator shop do it and have it work didnt get a complete rebuild which was probably a good thing.

 

I had the same problem. Eventually the alternator failed after a few days. I kinda ignored it only to get stuck with no battery. Check it out soon.

 

Thanks guys. The belt does feel tight, so I suspect it's the alternator. I'll run it to see if it looks like it's slipping.

Does any one know where to get the re-build parts? It seems wasteful to buy a new alternator when it's probably just a worn internal brush.

 

Sounds like the way to go. Personally we've gone to ND on everything and have had great results.

Best.

 

Excellent info here.

 

Did you ever get the issue resolved? It turns out that the correct rebuild parts are available through the factory.

 

Yes, I have a local guy rebuilding it for $500 including parts and labor.

 

The F40 valve covers tend to leak and drip oil right into the alternator. When they take it apart check if yours has any oil in it, and if so fix the oil leak too.

 

Thanks. We fixed all the oil leaks. The car is bone dry, at least for now.

 

Hi Jim,

which Lexus alternator you use?? Our alternator is just gone.


Thanks for you help.