dino charging problem

I have been reading various threads regarding Dino charging problems. My Dino 246GTS is not charging and any help would be appreciated. The following is the history:

The alternator was rebuilt probably five years ago and a solid state regulator installed. Some time in the last 2-3 years the ammeter would not show a charge until driven for 5-20 minutes. I learned to live with this as it always seemed to eventually start charging after being driven for some time. My mechanic said that he thought that oil was dripping on the brushes (I did't really buy that). My ammeter always shows a discharge when the lights, blinker, brakes, front fans etc are on. I have been able to drive it (during the day) after the battery has been charged up.

In any event, in the last week or so, no amount of driving (even more than 1 hr) caused the ammeter to charge. Therefore I started reading the Ferrari Chat on this topic and performed the following tests:

After charging with a battery charger, the voltage prior to my testing was about 12.3 vdc. When a multimeter is placed across the battery terminals, the battery voltage did not change with engine rpm. The solid state regulator has two terminals in addition to a ground terminal (which is the metal case). There is a green input wire to one of the two regulator inputs. This measures the same as the battery voltage (12.3 vdc) when tested with a multimeter and ground. The other terminal has a white wire input which I assume is connected to the alternator field (F) terminal.

The alternator field wire on the regulator (white wire) does not increase with engine rpm. On the contrary, with the engine running, and the headlights turned on, the field
voltage dropped to about 11 vdc and continued to drop in voltage slowly for the next 10 to 20 sec with the lights on.


I tried to reach down on top of the alternator and it seemed that both the red wire and white wire were connected. However, I cannot verify this for sure.


My next step is to bite the bullet and either take it to a Ferrari mechanic and pay $1,000+ to have the alternator looked at or try and do it myself. After jacking the car up, removing the right rear wheel and stone guard, I gave up after lookup up at the exhaust system and other(?) things in the way of the alternator.

Help!

Thanking you in advance.

 

One quick thought - your battery could be completely shot and therefore will no longer charge. It's a cheap thing to check even without tools. Just buy a new Optima red top and drop it in.

...Keith

 

Fan belt is loose. Don't know why Ferrari didn't use a standard V-Belt on the water pump and alternator but there must have been a reason. When cold,belt slips easily. Once warm, doesn't slip easily. First sign is no charge at start-up. Also slips if weather is wet. Easy to fix. On mine, two 13mm wrenches and a pry bar. Have to jack car up, remove right rear wheel, loosen bolt/nut on belt tensin arm, pry alternator away until belt tight, tighten, put wheel back, done.
John

 

I could not go to sleep without responding to this. I have spent the last 4+months fooling around with my alternator& voltage regulator...God bless Jim S. & Bob Z. and many others as they have helped me...hugely! I hope to help you and save you a ton of time by avoiding the many stupid mistakes that I have made! Firstly...what year is your 246 gts..is it a US spec or a euro spec? do you have AC? More to come...

 

Thanks for your interest.

My Dino is a 1972 (s/n 03762) USA spec with A/C. According to the Dino Register it is the first 246GTS imported into the States.

 

ok...well for starters you can absolutely do this yourself. However, before you take it out check that the alternator is in fact the problem. I would first check the voltage (current) at the bottom of the large fuse holder on the rear firewall. The fuse for the alternator and field wire is behind the plastic square cover. I would then check the current on the top of the fuse holder and then I would check the fuse. Obviously if the fuse is bad you will get different readings at either end of the fuse. The problem is sometimes you cant see if the fuse is blown so by checking either end of the fuse holder you can see if you get the same readings. I would check the voltage(current) at the white field wire as well. I would then check the voltage at the battery. As previously explained put a new battery in and see if that is the problem. Jim Selevan wrote a marvelous piece on the alchemy of alternators and voltage regulators in an earlier thread. He explains it perfectly and after several readings even I got it (I think). In short..check, recheck & triple check EVERYTHING before you pull the alternator. If in fact the alternator IS bad then you have to do the following.
1) you said that your alternator was replaced with one with an internal voltage regulator...does your alternator still utilize the Gates polyflex belt? It is about 1/4" wide and comes to a triangular point. Alternatively you may have the euro style belt and pulley's which utilize a 3/8" sort of triangle with the top cut off. It is important because all of your pulleys will have the same groove into them. I suspect that since you have a US AC version that you have the Gates Polyflex belt which is the same one that I have. In fact if you have AC I am fairly certain that this is what you have. If you rebuild the unit that is now on the car you dont have to deal with pulley sizes etc ( I have spent alot of time on that and will save you the details). I will not get into the voltage regulator itself as you said that your unit is an internally regulated one.

2)so lets assume that you have a replacement alternator with the polyflex belt. The question is do you still have it mounted to the waffle cannister housing which also had the original smog pump (most have been removed). In order to take these alternators off (whether or not they are mounted to the original mount)you must-
(*** I had my AC removed when I rebuilt my dino and so it was not an obstacle ... I am pretty sure that you need to remove your compressor unit in order to take the alternator out. There are other guys here that can opine on this. Again, it is not impossible to do and you will get a better idea of how things work if you do take it out.)
a)disconnect battery (you have live current going to the alt terminal), remove the top adjustment arm bolt (which adjusts the tension of the belt)on the top of the alternator. Remove the alternator belt.
b)take the mounting strap on the right gas tank and loosen it alot or completely undo the nut and push the tank to the right. If you can get even an extra 1/4" room by pushing the tank over to the outside of the car (away from the engine) even this small amount of additional room will give you enough to get the alternator through and out. This may not be an issue for you if the replacement alternator was a smaller diameter unit than the original Magnetti Marelli unit. The original (magnetti) unit was a large diameter deal and tough to slide out (but it was do-able).
c) you will have to undo the cooling hose from the metal pipe to the oil/water exchange unit in order to be able to slide the unit out of there. (It will be necessary to have a car lift when doing all of this and a good portable light of course. You will have a crink in your neck as it is a weird position to be in!). Make sure you have a bucket to catch the coolant. When you put everything back to gether & fill the radiator you have to elevate the rear end of the car and open the bleed screw on the top right of the radiator to get the air out. I did not remove the right rear wheel but maybe it would be helpful to do so.
d) I have found that lowering the alternator with the pulley side pointing skyward and (this is important) have the mounts on the alternator 180" from how it is mounted when you pull the unit down. In other words rotate the alternator so that the mounts are facing skyward when you undo the long bolt which attaches to the alternator mount . So you will undo the long bolt, rotate alternator 180" lift the pulley end up (pointing skyward) and lower the rear end (where the electrical cables were attached) and slide the unit down along the gas tank (and you have removed the cooling hose that was attached on the exchanger) and take it down & out of bottom of the car. If you do it this way you will avoid getting hung up on various obstacles on the way out.
e) once it is out you can have it checked and rebuilt. I was mad that my unit which was rebuilt when I took my engine out so I could avoid this whole mess was not working after 350 miles! The rebuilder said that the brushes were coated in oil and thats why it was not working. I was getting readings just like yours which unfortunately merely reflects the battery voltage. I was doubtful that any oil got on the unit and assumed that the guy never rebuilt it. However, he sent the brushes back which were oil covered. I was still suspicious but then I noticed oil (my engine was pretty immaculate) had dripped onto my newly installed alternator & I looked and saw a small amount had dripped from the chain tensioner housing (which I tightened up a little)onto the alternator. It dripped right onto a spot that could have gone into the unit and on the brushes. So, I was mad at the wrong guy! So please check that area. I dont know that if by tighteneing down the chain tensioner adjuster housing it will affect the actual chain tensioning itself ( I may put a new gasket on & see if it stops the leak).
*****It is not an impossible task by any means and like anything else once you have done it it is not so hard. You can find a way to spend a thousand bucks some other place I am sure!! If you have any questions please PM me and I will give you my tel #. I have spent a lot of time on this (I put a replacement GM alternator in) and had a lot of help in doing so. The guys on this Fchat have been absolutely invaluable to me in working on my car and I would like to reciprocate if possible. Good luck!

 

Thanks again for your detailed reply. A lot of information to digest so I will print it out and study it carefully before I start. By the way, since the external battery charger seems to charge the battery, do you still think I need to try a new battery? Also, the fuse holder on the engine firewall does not have a main fuse, only the 8amp fuse (the small fuse on the right side). I think that during the rebuild of my alternator and installation of a solid state regulator under the dash, my mechanic said I didn't need the big fuse on the left--anyway it hasn't been there for a long while.

After I carefully read your comments and check some things I will get back to you.


Thanks again,

Dennis

 

Dennis - Tom Champion, unfortunately, has become the world's expert on dealing with Dino alternators. His write-up is worth printing and studying.

Here are a few more thoughts.

As Tom suggested, the LAST thing you want to do is to take out the alternator. It is a royal pain.

As far as slipping belt, yes, this can happen. However, if the belt is tight (proper tension), then with no electrical load, there is little (mechanical) resistance to spinning the alternator. The belt should not slip (with no electrical load). However, if there is heavy load (lights, fans, etc.), then a compromised belt might slip. I would not (yet) attribute your issue to a slipping belt.

Your experience of no charging in the first few minutes mimics my situation for the past several years. I have totally restored my car, and I am an electrical engineer (by training), and I have not found the issue. Nor do I care. It works after a few minutes, so be it.

I am curious about the absence of the large 60 amp fuse on the firewall. This is the main current conduit to the car's system bus. All current comes from Rome (the alternator), and gets to the amp meter via the 60 amp fuse. Where is your alternator plugged into?

The 8-amp fuse on the fire wall is used to protect the field current circuit. Current from the regulator (originally in the red box under the dash) goes through this 8-amp fuse to the field windings of the alternator. I assume that your solid state regulator sits under the dash where the old one sat, and uses the same connectors. Hence, the 8-amp fuse on the firewall should read the same voltage as at the regulator box. One of the issues with the Dino is the long run from the regulator to the alternator. If you have significant voltage drop from the regulator under the dash to the alternator, the alternator will overcharge and cook the battery. I would check all of the contacts in this circuit, clean them with sandpaper, and re-measure the voltages. Yes, your battery is not charging, but as mentioned in a previous post, the battery may be bad at this point.

As the engine RPMs rise, and more current is produced by the alternator, the system voltage will rise (if working correctly). The regulator senses the rising system voltage, and reduces the field current. This lowers the system voltage. The battery (and all of your electrical equipment) does not want to see more than 14 volts, hence there must be a feed-back control system to prevent rising alternator RPM from generating too much current (which leads to rising voltage). This feedback system is the regulator. Summarizing, rising system (battery) voltage leads to falling regulator field voltage. Your comment that the field wire voltage does not increase with engine RPM is as it should be. In fact, the field voltage should fall with rising RPM. If you turn on a load (fans or lights or both), then the falling system voltage will trigger a rise in field voltage.

Just to be sure, and I hope that this makes it more clear, the alternator is an current generator. Remember from high school science that if you pass a wire through a magnetic field, a current is produced. This is what is happening in your alternator. The armature is nothing but wound wire passing through a magnet. Here is the fun. Instead of a permanent magnet, the alternator has an electromagnet. The magnetic field is produced by the field current flowing through surrounding wires. Hence, the more field current, the more magnetic flux, and the greater output of the alternator. Also, the more lines of magnet flux passed through in a unit of time, the more current generated by the alternator (RPM up). Hence, the regulator "regulates" the magnetic field. As the system voltage rises, the regulator decreases the field current and hence the strength of the electromagnet.

Hope this helps.

Jim S.

 

Really only 3 things happen to the alternator: slipping belt, bad (oily) brushes, something really bad like bad diode, burned winding. Since alternator works sometimes, big pieces are probably OK. Belt or brushes have the same symptoms. Won't charge until warm. If belt tension is OK, you won't be able to rotate water pump or alternator by hand with engine cold. Easy check. If belt is OK and you have more than 10 volts on the field and no charge, pull field fuse and check resistance from field to ground. Should be virtually 0 Ohms. If high, brushes are bad. You will have to pull alternator. Take alternator wires off of fuse panel. Take right rear wheel and stone shield off. Tall jack stands or center lift are necessary. If you get to the point of getting the alternator loose and rotatable you might be able to get brush holder out without taking alternator out. Only held with one small screw. Better yet, just bite the bullet and pull the whole thing. Oil from the tensioner is the culprit 9 times out of 10. Tighten things there as long as you are under the car. Remember to put both wires on alternator before putting it back in. Good luck.
John

 

Jim, Sorry to butt in over the post but i get the opposite problem.

My ammeter tends to flicker a lot, measuring the voltage at the battery at 2500 rpm i get 14.58V, this sometimes peaks to 16v when fully charging, then you can notice the VR cut in and it drops to 14.58v and so on.

The ammeter is always showing a full charge rate (not at idle though) and then for some reason tends to flicker back and forwards, but never to a discharge state. ie It tends to be all or nothing.

Any ideas?

 

Tony - your symptoms suggest that the regulator is not sensing the system voltage correctly, and believes that the system voltage is too low. Hence, the regulator raises the field voltage, resulting in high current output of the alternator. This leads to high battery voltage readings.

The big picture, in your case, is that the alternator is working fine. In fact, it seems to be working overtime. Thus, it appears that your field wire, from the regulator, through the 8-amp fuse on the firewall, is doing what it is asked to...creating more magnetic field in the alternator. I would, nonetheless, clean all field connections, including the 8-amp fuse and clamps that hold it to the firewall. Also, tighten and/or clean the spade connector of the field wire where it attaches to the alternator (if possible as this is difficult to access).

Consequently, I would carefully check the voltage that the regulator is seeing. That is, carefully clean the ground and plus + connections on the regulator itself. I might even add another ground wire for testing. The symptom suggests that the regulator THINKS that the system voltage is low.

Jim S.

 

Tony,
Regulator gets regulator output at it's + terminal. If bad connection, no output to alternator, no charge. Pull 8 amp fuse. Charge should stop and it's a reglator problem. Sounds like bad regulator or bad regulator ground. If ground is OK with Ohm Meter from terminal to car chassis, get new regulator. Any solid state 3 Terminal regulator will work. Ferrari is not required. Don't replace old mechanical regulators under any circumstances. Go solid state.
John

 

After reading all of the suggestions for in-car checks, I also checked my mechanic's invoices for work performed. My battery was replaced in July 2006 (Sears Diehard gold). It seems to take a charge when I plug my battery tender into it. My alternator brushes were replaced in April 2003 (I vaguely remember that the entire alternator was checked at that time). An interesting note on that April 03 invoice was a "repair oil leak chain tensioner".

I checked the fuse box on the firewall and found that nothing has been connected to either the 8 amp fuse or the 60 amp fuse side. I guess the mechanic bypassed the fuse box altogether (see attached photo). By the way, there is a black wire connecting to what looks like a capacitor Also, my belt to the alternator/water pump is tight and and it is the smaller (gates?) type.
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John C. and Tony L. - if there is high contact resistance either at the + terminal or ground of the regulator, it will sense something less than true system voltage. (Technically, the voltage that the regulator sees will be influenced by the effective voltage divider created). As a result, it will increase field current, and the battery will over charge and result in the 14+ volts that Tony reports.

Dennis - Yes, I see that the fuse block has been bypassed. Perhaps the mechanic was experiencing similar problems and chose to eliminate from the circuit. As John C. suggested, oil soaked or failing brushes will result in failure of the alternator.

One other thing to consider. The capacitor that you mention is a noise suppression device (Electromagnetic noise). If the capacitor has failed, it could appear as short circuit. If it acts as an open circuit, no big deal. BUT, if it has failed with low resistance to ground, it could be bleeding current to ground, and either reducing the charging current, or more likely has resulted in high current density to the brushes, effectively frying them (that's a technical term).

You can unplug the capacitor as a test to see if anything changes.

Jim S.

 

I hate to admit my ignorance here, but I thought alternators didn't have brushes. Generators do. Alternators generate AC and it is converted to DC via a diode. Or is my memory from my 30yrs ago college physics class failing me?

Jim O

 

Jim O.
Physics class only told you half of the story. Auto alternators do have brushes. They do not work nearly as hard as those DC generators and motors though.
The brushes in a DC generator handle the full output current as they run against a commutator. Typically 50 amps or more through a million small pieces of copper. Output comes from the coils on the rotating armature. Outside this armature are field coils that provide a magnetic field. The voltage regulator varies the voltage going to the field to control charging.
Alternators turn things inside out. Fixed coils outside the armature provide the output and the armature coil is fed a small current to control that output. The outside coils generate AC voltage that is converted to DC by a string of Silicon diodes. The armature coil gets its current from the voltage regulator through two brushes rubbing against 2 smooth slip rings. These brushes typically carry less than 2 amps so should last almost forever. Unless they get oil on themselves. Then the brushes turn to mush and you have to replace them.
It all makes sense. Alternators were not practical DC sources until solid state diodes were invented. Now they are universal.
John

 

Tom, John, Jim and others:

Thank you for all of your comments. At this point everything is pointing to bad brushes due to oil dripping from a leaky chain tensioner housing. In addition, if I understood the "short course" given by all of you on the Dino's charging system, the fact that the falling system voltage did not increase the field voltage also suggests no output from the alternator.

In any event, I will now follow Tom's step by step alternator removal process and keep you posted.

Thanks again.

Dennis

 

Just a quick follow up here - my alternator packed it up TWICE from oil collecting inside it. Over time the oil reached a grease like consistency, and the alternator simply stopped working. I was finally able to address the problem during my engine rebuild.

Mark

 

dwilliams,
Since you've been the rebuild route already, you may wish to consider mothballing your factory alternator & following champtc's lead: Update to a modern, more powerful, more compact, readily available, reasonably priced US (or Japanese) alternator. You've already stepped up to the solid state regulation that Corbani alluded to. Your search should have revealed the pros and cons, as well as different applications, discussed in several threads.
Also, make sure your heat shield is in place to ward off the principal threat to your dynamo.
Good luck...& do keep us posted.
Coop

 

Thanks Coop -- good suggestion.

Tom:

Could you please tell me model no. and specifications of the GM alternator that you installed and if it bolted right up or had to be modified?

Thanks,

Dennis

 

Is there a small red light on the ammeter that indicates a not charging situation when glowing? I can't remember from when I had mine. If so does it light in the garage position? This light has to be working (not burnt out bulb) inorder for the excitation circuit on the regulator/alternator to charge the battery; screwy design.

If no light disreguard post.

 

well...it gets interesting here. I bought a 60 (maybe 63 )amp from Jegs. It is an external GM regulator type, I think it cost about $100 bucks. However, the pulley that comes with it is designed for the wider belt that is used on normal GM applications and not our little unique Gates polyflex. I looked all over to get a pulley that would fit the Gates belt. No Luck. So I used the original pulley from the Mangennti Marelli alternator and had the diameter of the hole where the nut goes slightly enlarged to accomodate the slightly larger nut which goes on the GM alternator. A VERY helpful Bob Zambelli machined this for me. I have tested the alternators in various configurations. I found that The GM alternator worked best when I had the GM pulley on it (which is smaller diameter than the Magnetti). The problem was that the belt slipped as the pulley was desingned for the wider GM type belt. So I modified the alternator housing to push the alternator back further in its mount-since the Magnetti pulley sticks out further than the GM pulley. I did this by shaving off 1/2 of the mount on the alternator. I then used the pulley form the Magnetti alternator and was expecting great things. However, since the pulley from the Magnetti alternator is a larger diameter than the stock GM pulley (remember I have a GM alternator & Magnetti pulley on the car at this point)the alternator spins more slowly than it did with the stock GM pulley. I checked the voltage and I was getting merely 12+ volts at the battery. However, when I had the GM alternator even with the slipping GM pulley I was getting 14+ at the battery. Now you might wonder why I did not just have the GM pulley machined to fit the Gates polyflex belt in the first place? Well I was told that pulley could not be cut down to accomodate the Gates belt. I have since gotten two new pulleys and had them cut down to hopefully accomodate the Gates belt. Now why did I get two pulleys cut? because I thought that someone might need one if they ran into the same problem that I did!! So I am to pick up these pulleys up on Saturday and I will gladly send you one (for free!!) I have tested and done every variation of this alternator deal that you can do (no kidding). However, I have changed from the waffle cannister type that was originally on the car to a euro bracket but it shouldnt make too much of a difference. My goal is to see if I can help you do this in about 2 hours versus the crazy amount of time that I have spent on this. It can work, it will work & I can help!!

 

Alternator removal update.

Following champtc's suggestions, I removed the right rear wheel, stone guard, drained the water/oil heat exchanger, removed the small hose, removed the heat shield on top of the exhaust system and the strap holding the fuel tank.

I ground to a halt after removing the upper bolt (the adjusting bolt) on the alternator. I also managed to remove the nut on the lower alternator bolt but I could not get the bolt itself out and the alternator would not move. Is there some trick I need to employ to pry free the alternator and remove the lower bolt? I assume that these are the only two bolts holding the alternator onto the housing. Also, am I going to have any problems getting the alternator past the exhaust system?

Dennis
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There are three bolts holding the alternator, remove the heat shield and you will see it.

I always take of the alternator bracket as well. Easy to remove but watch out for the small spacer that fits between the bracket and the timing casing.

You will need to remove the heatshield from the exhaust and remove the manifold above. The alternator normally comes out through the other side of the car (clutch end)

Hope this helps

 

Tony- send me your tel # , my email is [email protected]