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Hi, I have a 1989 740 GLE, with the BF 234F 16valve engine.
A month or so ago I made a short trip to the store. Car started fine. When I came out less than 5 minutes later, the car wouldn't start. I checked the battery connections, and they were tight, and I use dielectric grease to prevent corrosion.
After 15 minutes of pondering solutions, I tried it again, and it started up weakly. I figured I hadn't driven the car enough the past couple of weeks and the battery was weak. I drove it around to charge for about 30 minutes. Seemed to solve the problem.
Has been starting fine in the mornings, but whenever I try to restart the car, less than 10-15 minutes after driving, it will not. Waiting seems to cure the problem. I checked the +/- connections with a multimeter, and I was only getting about 12V with the engine running. From what I've read, the alternator should be giving me about 13-14 at 2000rpm. I began to suspect a weak alternator.
Finally last week there didn't seem to be enough charge in the battery to start, so I jumped it with a portable jump starter, and it was fine. Later that day I replaced the battery. After installation, the car started weakly, and I had to wait 15 minutes after driving it half and hour to restart. Now I'm pretty sure of a weak alternator.
Has anyone had trouble like this? I believe the alternator is stock, or atleast a Volvo/Bosch branded alternator of indeterminate age. I've read about replacing the brushes and diode, but was wondering what type of shops rebuild alternators and if a rebuild is advisable over a total replacement (new or rebuilt). PS. I've recently moved to the coast, so I was wondering if the salt air could be corroding things like the grounding wires on the alternator or coming off the + terminal at the battery.
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I agree with the starter as the culprit, i had a similar issue just this past week. Warm car and it was hit or miss it would turn over fast enough to start the car, when cool the car would crank right over. New starter and problem solved.
Turned out in this case that the lever that throws the bindex forward to engace the flywheel was sticking when it was hot, but moved freely when it was cool. I assume this is due to heat expansion. Since the bindex never fully retracted and was drawing some current i wasnt seeing a full battery either and with a jump from a portable starter or another car it would turn better and often start. Plus the constant draw from the starter was creating a ton of heat in the starting system and like another poster mentioned heat increases resistance, making the problem worse.
Good luck,
Jesse
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A simple check with a meter will determine if the alternator is good. Simply check voltage at battery with car running. It should be around 14V, slightly lower with accessories turned on. Auto parts store such Advance or Auto Zone will do this free.
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David Hunter
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posted by
someone claiming to be Drew
on
Wed Apr 19 17:38 CST 2006 [ RELATED]
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Its not the alternator. You state after waiting ~15 minutes it will start. A battery will not charge on its own. If its dead, its dead. This issue is indicative of an electrical problem, probably the starting circuit. The problem being, as an electrical items warms, resistance to curreent increases. So, the problem is something electrical in the starter system is failing. The process being:
cold temp = normal resistance = car starts.
hot temp = increased resistance = car will not start
///10-15 minutes to return to cooler temp
cold temp = normal resistance = car starts.
I would check the starter. They are primary culprits for this problem. You may find some hits either here or on google searching for the term "heat soak."
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The only thing that indicates to me that this is a charging system issue, is that even with the new battery, I've had to jump it atleast once a day to get the car started. Also, when I run the car with minimal load on the electrical system (no lights, radio, AC), I can start it up again before leaving work, without using the jumpstarter.
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posted by
someone claiming to be Drew
on
Fri Apr 21 10:41 CST 2006 [ RELATED]
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That is still inidicative of a failing starter. The accessories turned off allowing the car to start situation is because you are removing just enough electrical load for the current to spin the starter. I will be very interested to hear the solution. It is possible your alternator is beginning to weaken and is exposing a failing starter sooner than it otherwise would.
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Well, I replaced the brushes and assembly. The old brushes were only about a quarter inch from the plastic, which I consider pretty worn. Installed the new unit, cleaned up the leads with solvent (old grease), scrubbed terminals and leads, and reapplied some corrosion protectant (red spray kind).
Car started find, drove for 10 minutes, turned off, started again fine 2x. The voltage coming from the alternator is about 13.87V with the AC on. Checked the battery voltage and it was about 12.8V. I'm waiting to see if the voltage on the battery drops off, since I'm afraid I fried it a bit after so many jump starts (5).
I'll keep watching for starter/heat issue. Thanks again everyone for your assistance.
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If the brushes were so worn that you had no charging then the first indication would be no BAT (and other warning lights) when the key is in II position before starting the engine. Those lights will flicker on while driving as the brushes become intermittant before complete loss of contact.
If you are certain that the warning light worked before the repair; I'd bet that you moved or removed the alternator to replace the brushes, as opposed to leaving it mounted, and then tightened the belt when you were done. In other words, your no-charge trouble (if the lights worked beforehand) was actually just a slipping belt.
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The regulator/brush assembly on your alternator is held in place by two phillips head screws. A new set of brushes is $3 or $4 and are quite easy to install (soldering involved). You don't mention how many miles are on the car or on the alternator currently in service.
I have never had to replace an alternator on any of our Volvos, but I have replaced a lot of brush sets. I always check the brushes out whenever I first purchase a car and everytime I replace a timing belt on one.
Electrical problems are not my strong suite and I am not sure a set of brushes will solve your problem. However, when comparing the cost of a new alternator versus checking on the condition (length) of the brushes the first option is a nobrainer for me.
Randy
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That's good to hear. The car has 177,000 miles on it, and the alternator like I said could be stock. I'll look into replacing the brushes, especially considering the costs of rebuild, let alone full replacement. Does anyone know how much a diode or voltage convertor run / if it's easy to replace them?
Thankyou!
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On a 700/900 it is totally straightforward to pull the brush/regulator assembly-- two phillips screws and you have it in your hand! No need to remove the alternator-- just pull the negative battery cable before you do it. If you have a pick-n-pull near you, you could simply pull out the assembly on a junker and put it in your alternator. I keep a few around as spares. If you want a new one, try online parts places like fcpgroton.com-- even at $35, it is way cheaper than a rebuilt alternator, and likely the only thing wrong with your current alternator-- these units are very robust.
Measure your alternator output at the battery with the car running-- if it is below about 13.7V, just replace the brush/regulator assembly.
Good luck!
--
Herb Goltz, Aurora, Ontario, Canada '92 245 w/130K mi, '92 945T w/200K mi
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Thank you so much for your imput. I'll look into grabbing an assembly from a parts dealer.
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