| Author | Message | ||
| John_Miles (John_miles)
New member Username: John_miles Post Number: 23 Registered: 7-2001 |
Actually it's easy enough to diagnose a failed voltage regulator without the use of a voltmeter, once you know what to look for. When stopped at a light at night, rev your engine from 1000-2500 or so. Your headlight brightness should not change significantly. If your lights get more than just a tiny bit brighter, you've got regulation problems. Also pay attention to how quickly your turn signal flashes. An unexplained increase in flashing frequency means your flasher is seeing more voltage than usual. (This is a very sensitive test if you have any sense of rhythm at all, because the resistive heating that triggers the flashing mechanism is proportional to the square of the applied voltage.) 17V is about what you would normally see at cruising speed with a bad voltage regulator. It's an open-and-shut case. | ||
| Mike Procopio (Pupz308)
New member Username: Pupz308 Post Number: 36 Registered: 10-2002 |
Thanks again for all your help guys. I'm headed for a 1.5hrs labor alternator remove, rebuild (new VR as well) and replace. Not a terribly expensive repair, and a healthy one at that for upgrading to 85A output. Regarding the 17 volts, I too, could absolutely not believe it. This was with a new digital voltmeter, though. I checked it twice, and left the leads on for 30 seconds. Constant 17V at constant 1500 RPM. Backed down the RPM, fell to 13V or so. It's clear, as some have pointed out, that 17V charge to the battery is consistent with my water caps blown off on the battery, as well as a dry (no water) condition inside the battery. This rebuild should be done and replaced within a week. I will follow up then on this thread to post the results. Appreciate all of the great advice! P.S. Just purchased a VDO Vision lighted voltmeter for the car. I just have to know now ;). --Mike | ||
| Odhran McConnell (Kryzian)
New member Username: Kryzian Post Number: 9 Registered: 11-2002 |
Guys, A quick tip if you're interested. In order to save yourselves jump starting constantly, there is a battery disconnect plug on the left hand side of the car in front of the spare wheel down by the radiator pipe. Simply disconnect this while your 308 sleeps for the week (if you're a weekend driver). This will conserve the battery and make sure you don't have to jump start the car constantly. The only drawback is that you have to reset the clock, and if you have a modern radio you'll have to reset all the stations you've programmed into it. For me, it's no big deal. | ||
| James Selevan (Jselevan)
Member Username: Jselevan Post Number: 299 Registered: 6-2002 |
Verell - well, so much for my dissertation. Without the long field voltage lead, my discussion is not applicable. Sounds like a regulator problem. I would first recheck the battery terminal voltage, however. Seventeen volts sounds like a lot, even for a bad alternator. Thanks for the information. Jim S. | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 483 Registered: 5-2001 |
James, I concur with your analysis except for one detail: VOLTAGE REGULATOR IS MOUNTED ON THE ALTERNATOR The regulator that was installed when my alternator was rebuilt looks like:  The regulator that was on my alternator when it failed looked like this:  (This view is rotated relative to the other view) I believe this was a 3rd party regulator as it didn't have the BOSCH logo/part#s on it. The brushes contact the rotor slip rings, so the regulator directly supplies the alternator field current with no intervening wiring to cause problems. Down side is that when a brush or brush mounting fails, the entire regulator has to be replaced. There are 2 (?possibly 3?) additional spring wiper contacts between the alternator & the voltage regulator module. | ||
| Mark (Markg)
Member Username: Markg Post Number: 358 Registered: 2-2001 |
Mike - we have identical problems (82 GTSi) - voltage regulator was bad. Over-charging and boiling the electrolite - mine also blew off the caps and was dry. Common on Bosch Alternators. Double check fuse boxes, thay may have been damaged as well - mine were. I spend a lot of time in Albuquerque, grew up in New Mexico; I'm actually looking at possible move to Los Lunas area! Good luck | ||
| James Selevan (Jselevan)
Member Username: Jselevan Post Number: 298 Registered: 6-2002 |
Mike - I have been following this thread and believe you have gotten good advice. Verell's observation concerning the sensing lead is worthy of emphasis. I preface my comments with my lack of knowledge concerning 308s, but will make some gross assumptions, one of which is that the battery is in front. Also, I assume that the regulator is a separate unit under the dash, and not built in to the alternator. That said, a review of how the regulator and alternator interact might shed a bit of light (no pun intended) on the subject. The regulator senses system voltage. When main electrical bus voltage drops below a preset value (12.5 volts, for example), the regulator increases the alternator field current (electromagnet), which increases the magnetic field in the alternator with subsequent increase in alternator voltage generation. (The alternator is really a current generator, but not germane for the moment). The alternator generates voltage/current by moving a coil of wire through a magnetic field. The faster the coil moves, or the stronger the magnetic field, the more current/voltage generated by the alternator. Thus, when the field current increases, the electromagnet is stronger, and the alternator generates more voltage/current. Clear as mud. The regulator is not a current generator (we are getting a little technical here - bare with me), so in order to increase field current, the regulator increases field voltage, which drives more current to the electromagnetic field, which leads to increase in alternator voltage/current output. Why the dissertation? To circle around back to Verell's comment. The field lead from the alternator must run the length of the car, from the regulator under the dash, back to the alternator field lead. This often passes through a dedicated fuse box located on the firewall (at least it does in my Dino - may be different in the 308). If there is significant contact resistance at the regulator, the fuse box, or at the alternator, then there will be a voltage drop along the field lead, and the alternator will not see the increase in field current. The regulator will continue to raise the field lead voltage, but the alternator will not see all of it (because of the contact resistance). Now, if you are really seeing 17 volts at the battery terminals, then 1) your alternator is working fine, 2) your regulator senses a low bus voltage, and is beating the alternator with higher field voltage/current. This (#2) suggests that your field lead from the regulator to the alternator is fine, and not experiencing high contact resistance. It is possible that everything is working fine. Your concern over 17 volts at the battery is well founded. One would expect 13.8 volts when charging. However, if your battery is in need of a charge, the regulator will raise the voltage to charge it. May I suggest that you disconnect your battery, and give a trickle charge overnight. Trying to diagnose this without knowing the state of charge of the battery imprudent. Second, re-measure the voltage at the battery terminal at 3,000 RPM. If around 13.5-14.0 volts, everything is Jake. If 17 volts, then your problem is the regulator. Third, identify the field lead at the regulator. There are only three leads on the regulator. A ground, a positive, and the field. Measure the voltage at the field. As the engine RPM rises and the alternator generates higher voltage, the field voltage should go down. (If I recall, it should drop to below 10 volts. I will double check this later.) If the field voltage does not fluctuate inversely with battery terminal voltage, then the regulator is south of the border. (As the battery terminal voltage rises, the field lead voltage should go down). Long winded, but I hope this helps. The last thing I would do is remove the alternator. It seems to be doing everything it is being asked to do. Finally, don't ask me what time it is - I will tell you how to build a watch. (A common trait of engineers.) Jim S. | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 482 Registered: 5-2001 |
A blown diode reduces the total available output current, hence reduces output voltage. A voltage regulator is a complex circuit that can fail/miss-behave in several different ways including: - No output - Low output resulting in an under-charged battery - Excessive output resulting in an over-charged battery. MIKE COULD JUST HAVE A WRONG VR FOR THIS CAR BOSCH makes several VRs that are identical except for the voltage they regulate the alternator's output to. They even make an adjustable VR! It's possible that someone installed too high a voltage VR in Mike's alternator. (Unlikely though with the output voltage at 17 volts & climbing with engine rpm.) Mike, rebuilding generally consists of replacing any failed components, and the alternator bearings. The rotor slip rings are generally turned or at least burnished depending on their condition. The brushes are replaced. In these alternators, the brushes are built into the VR, so it usually gets replaced. It's important that the VR that's installed has the correct voltage for your car. Also, replaced are any components (diodes, rotor...) that appear degraded & likely to fail to the rebuilder(your mileage & price may vary). Before rebuilding, the whole alternator is disassembled & the parts are soaked in a cleaning solution that's usually mineral spirits based as it doesn't attack the varnish that insulates the windings. WATCH OUT FOR: The case is generally tumbled in a barrel with the cleaning solution & a bunch of metal 'rocks' (or assorted large nuts & bolts) that clean & abrade the case giving it the somewhat sand blasted appearance you see on rebuilt alternators & starters. (I stopped my rebuilder just in time as I wanted to keep the smooth polished aluminum finish on my alternator.) When my alternator was rebuilt, the standard rebuild fee was ~$125: $40 for the VR, + $85 for new bearings, disassembly, cleaning, reassembly & testing. However, my rotor's slip rings were excessively worn & so the rotor had to be replaced (another $200 & 5 weeks as BOSCH USA was out & it had to be special ordered from Germany). Apparently you can get replacement slip rings, someone posted a web site that sold them in one of the alternator threads. Wish I'd known that. By all means take it to a store that'll test alternators. I'm so used to doing the testing myself that I forget that this option is available & generally free. | ||
| Steve (Steve)
Member Username: Steve Post Number: 267 Registered: 2-2001 |
Mike wait for others to give their opinions but if you take it out and get it tested you will know for sure what your next move is. Also check around because anyone that rebuilds Bosch stuff can do it and at a reasonable price. Bosch alts are used in a whole bunch of cars. The only concern that you should have is to make sure that you get it back with YOUR pulley.Also when the do the rebuild they replace the VR but you need to tell them to rebuild it with the largest AMP output they can put in that alt. frame.They'll tell you how much they can do.If you want you can tell them its for a Fiat just so they don't pull the "oh its for a Ferrari" price list out. I got mine done at a Big A parts place.Good luck | ||
| Mike Procopio (Pupz308)
New member Username: Pupz308 Post Number: 34 Registered: 10-2002 |
Steve, Interesting point... At this point, it sounds like the best thing is to do as you suggest and remove the alternator. Does rebuilding the alternator imply replacement of the voltage regulator? I might replace the VR as well, just so I don't have to fuss with this again. What sort of shop would rebuild the alternator and do the 85 AMP upgrade? | ||
| Steve (Steve)
Member Username: Steve Post Number: 264 Registered: 2-2001 |
I seem to recall that when you have an OVER voltage condition it comes from a blown diode in the alternator and not a voltage regulator. The sign of a bad VR is NOT charging which would give you a 12V or less reading. I would take the alt. out and take it to a local autozone type parts store and let them test it. Its easy and even the joe blow counter berson can tell you it either good or bad.If bad just get it rebuilt.I had my 77 redone right after I got the car because it was filled with oil from a leaking rear cam cover.Had it bumped up to 85Amps and cost $100. | ||
| Mike Procopio (Pupz308)
New member Username: Pupz308 Post Number: 32 Registered: 10-2002 |
Verell, Thanks very much for your help! Does NOT sound like the most fun way to spend a Saturday, but it does sound doable. Before I get into the voltage regulator replacement, I wanted to investigate the voltage sense lead more--where is this wire? Where does it connect? There was a wire connected to the positive battery terminal (near a custom electrical-taped 5A fuse), but I *thought* I had traced that back to an aftermarket AC-plug-in battery charger... How can I test this lead? | ||
| Verell Boaen (Verell)
Member Username: Verell Post Number: 479 Registered: 5-2001 |
Mike, Sounds like either a bad voltage regulator, or the voltage sense line from the battery back to the alternator is open so the regulator isn't getting feedback. Since you're charging the battery (even tho it's over-charging), the basic alternator is functioning. It's just not cutting back on the current to keep from over-charging the battery. This is consistent with your original dry battery. A modern battery should never need to have fluid added. When a battery's low on electrolyte, it's a sure sign of over-charging. 1) Make sure the voltage sense lead between the battery & the alternator has continuity. (Because of the very long battery cables, the alternator has a separate lead to permit it to accurately measure the battery terminal voltage. 2)Check to see if you've got the correct voltage regulator. BOSCH makes several voltage varients of the basic regulator, including one that's adjustable. This web site lists a lot of them, you should be able to match your alternator # (stamped on the side of the alternator) with one of them. http://www.usi.com.tw/capabilites_products/usi_b1_3a_4.htm If you've got the right regulator, but the wrong voltage, then the regulator's failing & needs replacing. It's about a $45-$55 unit. You can access it to check the numbers or change it w/o totally removing the alternator, but it's still a PITA. Tips: 1)Unbolt the alternator mounting bracket instead of fighting with the pivot bolt that's got a lock nut nut you can't quite reach. 2) You can reach up between the exhaust manifold & horizontal heat shields to hang a 17mm box end wrench on the nut for the alternator tension adjustment. (You'll probably loose a bit of hide from the back of your hand if you're not careful.) Once there's pressure on the wrench it'll usually jam itself in place & you can just work on the bolt's head with a long extension, a flex & socket. 3) On re-assembly, you'll need to use a pry bar on top of the alternator to get the leverage to re-tension the belt. I forget what you're prying against, maybe it's a part of the cam cover, or something to do with the A/C. It's a dance w/your left hand on the pry bar & the right hand tightening the bolt that locks the alternator in place. If you're used to working on conventional cars with classic v-belt driven alternators, you'll be surprised when you tension the alternator belt. That thin Gates polyflex belt requires a surprising amount of tension to keep it from slipping. BTW, Don't start this job unless you're in a pretty good mood, otherwise you'll find yourself flinging a wrench or something across the garage. Also, make sure there are no children or easily offended members of the opposite sex around as there's a chance their vocabulary will acquire a couple of new 4-letter words. It's actually pretty easy once you figure out how everything goes together, & the tricks for getting at all the obscured nuts 'n bolts. The last time i had my car apart, I welded a short pieces of ~6mm dia (Ok, really 1/4" dia.) steel rod to the tensioner bolt head, and also a piece to the pivot bolt head. No more contortions & blood sacrifices. For photos, search the archives. | ||
| Mike Procopio (Pupz308)
New member Username: Pupz308 Post Number: 31 Registered: 10-2002 |
See, it's always a tough call. If there's a problem with the charging system (alternator), a failure here could ruin a good battery (overcharging it, running off of the battery only). If there's an underlying problem with the charging system, you'll ruin, in time, your new battery. A starting point is to get a voltmeter and masure voltage across the battery when the engine is off, and then when the engine is on at various RPMs. Search the archives here for "alternator" and "voltage regulator" and you'll come up with some good info. --Mike | ||
| Andr� Ferreira da Costa (Oporto328)
New member Username: Oporto328 Post Number: 22 Registered: 9-2002 |
Just another thing. This problem happens to me since I picked up my car from a car showroom. I was trying to sell my car but didn't find a buyer. The car was there for about 5 months. Always stopped. So when I went to pick it up again there was no battery power. Using cables with another car at the showroom (2001 Boxter) I made the mistake of mounting the cables thw wrong way. The positive side of the boxter with negative side of my car, and negative side of boxter with positive of my car. I tried to start the car severall times with no luck till I figured the problem. Almost burned the cables. Then I tried the correct way and it started. But since then I have the problem described before. I wonder if I ruined the battery with this mistake? Since then i didn't speak with the showroom owner. Hope didn't damaged the boxter! | ||
| Andr� Ferreira da Costa (Oporto328)
New member Username: Oporto328 Post Number: 21 Registered: 9-2002 |
Today that happened to me in my 328. For about two months i always have to use cables to start the car. I drive it only at saturdays or sundays so I've been living with it. But till today if I started the car with cables, that same day or the following day the car would start with no problem. Today I started the car with cables of course, and went for a ride. I shut down the car for about half an hour. When I was going to start it again no battery power. The battery has one year so it must be the alternator. I wonder if that's too expensive to fix? Anyway, I was told today that some batteries don't even last a year. Maybe i'll buy a new battery first and see what happens. | ||
| Mike Procopio (Pupz308)
New member Username: Pupz308 Post Number: 29 Registered: 10-2002 |
Hi guys, Thanks for your responses--I'm starting to feel a bit better at least understanding what's going on. I had mentioned before that the alternator light wasn't working. It now works, and the alternator light behaves normally. The problem wasn't the bulb--it checked out OK. I seemed to be with the assembly unit that houses the bulb. I swapped out both the bulb and the bulb housing with the hazard light unit, and now the both work. Strange! I've missed not having the alternator light! Now, the behavior is what I expect--it's on when I turn the key to the Accessory position, is on right when I start the car, and goes off with a little bit of an engine rev. Perfect. Now, what's VERY strange are the new voltmeter readings. At 800 RPM indicated (car idles cold), I was getting 12.4V. Maintaining revs at 1500RPM gave 16.8, then 17.0V across the terminals. WOW! That's way too much, right? Bringing the idle back down with the engine a bit warmer (1000 RPM indicated) yielded 13.1V. The Optima battery clearly states that it doesn't like to be charged with 17V--I think the spec was 13-15V if I recall correctly. Clearly, this is something that left untreated will kill the battery. Questions-- What precisely does the alternator light indicate by being off? That the alternator itself spinning? That the battery is receiving some minimum charge (13.5V, say)? What about by it being on? Why would I be getting 17.0V at 1500RPM? Bad voltage regulator? Is that what "cooked" my old battery? Recall my old battery was both dry and once of the caps was off. Could the cap have been blown off from gas expansion? Jay, these voltage readings are all I have right now--don't have a helper to take a reading for me. The lights definitely get brighter as I rev the engine, this I believe is normal. Accessories seem to run OK--no dimming of the lights. If the voltage regulator is flaky, this could intermittently affect the operation of current-drawing accessories... Magoo, must I rebuild the alternator? The archives seem to suggest going after the regulator first (not too expensive, apparently) before removing/rebuilding the alternator... Thanks again for all your help... --Mike | ||
| magoo (Magoo)
Advanced Member Username: Magoo Post Number: 3944 Registered: 2-2001 |
Mike at one time the reg. was more than likely not working properly and it ruined the old battery. Evidence by the batt. being dry and no caps. Like Mark says replace the alternator or have it rebuilt and repair the Gen. light on the dash. It just pulls straight out to replace the bulb. | ||
| Jay S. Morris (J_saber)
New member Username: J_saber Post Number: 21 Registered: 12-2002 |
I may be having the same problem in my Mondial. What does the voltage read at 2000 and 3000 rpm? What happens when all of the access. are on, i.e. radio, interior and exterior lighting, ect.? Let me know, I am very intrested. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 302 Registered: 5-2002 |
You are running off the battery. No doubt. You might want to start by checking the wires, but most likely you need to repair or replace the alternator. You should check that dash like too. | ||
| Mike Procopio (Pupz308)
New member Username: Pupz308 Post Number: 28 Registered: 10-2002 |
Hi guys, Was wondering if anybody could help out here. I've got a sick 308. (I've posted this as well on the FerrariList.) Well, back on Nov 2 of last year, my 78 308 GTS (Albuquerque, NM) broke down on I-25. I had a catalytic converter meltdown due to an ignition failure, and subsequently blew a header. 2 months and $2500 later (I did some carb tuning in there as well), the car came back to me and seemed to be running well. Yesterday, after shopping, the car wouldn't start. Had to get a jump. With the jumper cables, it started right up. Every time I turned it off thereafter, the car still refused to start--more jumpstarting and I eventually got home fine. Clearly, I had a dead battery--I noticed that the water level cap was missing on the battery, and saw that it was completely dry. (sigh). My fault; regardless, it was time to get a new battery (approx 3 years). The voltage on the "dead" battery (I say "dead" because it wouldn't start the car) was 12.5V, but I suppose I just wasn't getting enough current (amps) to start the car. Fast forward to today. I put in a new Optima Red Top battery. New, it measured 12.5V across the terminals (engine not running). It started the car right up. However, I've spent a day reading the archives, and I'm not sure it's just a problem battery. Here are some things I've observed. 1. My generator light NEVER comes on, and never has. (Red light labeled "G" on console in lower right corner.) I've never seen it light up. (Blown bulb?) Which is frustrating, since this is an important piece of information. 2. The Optima battery starts the car right up, measures 12.5V across the terminals when the engine is not running. 3. WITH THE CAR RUNNING after start (and with some revving), the Optima battery reads 12.1V or 12.2V across the terminals. Uh oh--it doesn't look like I'm charging here. (I should expect to see 13.5V or so...) I'm beginning to suspect that I'm running off of the battery? 4. I read this tip off of FerrariChat. With the car running, I disconnected the negative terminal. The car died immediately. Apparently, if the alternator was working correctly, the car should have kept going--but I'm not sure--wouldn't I still need a connection at the battery? 5. I've had the symptom of headlights getting brighter/dimmer randomly while driving (constant 3.5k RPM). This seems to be linked in the archives to a bad voltage regulator, or an alternator in need of a rebuild. 6. The day the car wouldn't start (during an 80mi drive in the mountains), I had a radar detector (V1) plugged in through the trouble light socket under the dash. Several times, I noticed, it reset all by itself--indicative of a current or voltage drop. So what to do? Am I running off of the battery? Wouldn't, then, the car have eventually died while driving (the car never died while driving)? Or was I getting enough current to drive (ignition system) but not start the car (turn the starter motor)? I'm trying to give this car a good home--I really am--but I'm growing increasingly frustrated and sad. It'll sort out soon enough I suppose. I'm not sure what's killing me more--the $6k I've put into it since June (budgeted for it over the first year), or the constant ridicule at work about my "reliable" car ;). Any help you could provide would be appreciated. Best, --Mike Albuquerque, NM 1978 308 GTS US Spec, Carbed |