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Need New alternator or Voltage Regulator? 1985 300td wagon
1985 300td wagon,
Something is wrong with my charging system. It seemed to have occurred after I had to crank the starter for a really long time and multiple glow cycles (10 degree morning), which I think really drained the battery, and seemed to really put a heavy load on the alternator for a few minutes (difficult to maintain an idle). Ever since the battery light has been on and the battery has gone dead. Autozone tested the alternator and I only have 9V across the battery terminals at idle (I know I should have reved the engine). Is is likely that I just need to replace the voltage regulator? I don't really want to throw a bunch of parts at the car, but if I don't need to remove and repaace the alternator that would be great. Any suggestions for troubleshooting. Thanks
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'85 300td Frybrid WVO Kit |
#2
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I would try a search for how to replace the diodes in your alternator...if you have that type.... some are on the back of the alternator and pretty easy to check and replace..old fashioned soldering a component...as compared to circuit board stuff...
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
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are these diodes and voltage regulators available at most parts stores or will I need to go to the dealership or online?
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'85 300td Frybrid WVO Kit |
#4
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Have you pulled the voltage regulator out to see if you have any brushes left? Could be an easy fix.
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1985 Euro 240D 5 spd 140K 1979 240D 5 spd, 40K on engine rebuild 1994 Dodge/Cummins, 5 spd, 121K 1964 Allice Chalmers D15 tractor 2014 Kubota L3800 tractor 1964 VW bug "Lifes too short to drive a boring car" |
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Have Autozone charge and load test your Battery. Not enough origional Voltage from the Battery will also cause low charging.
On day I drove to a Realitives house; let there and stopped to buy something to eat. When I got into my Car and turned the key nothing happend at all. To shorten the story my Battery died; most likely due to some internal problems with the plates. It showed 12 Volts with a meter but when you put a wire between the Battery Terminals there was very little spark. So sometimes the Battery itself can cause issues. Having the Battery load tested is free; but they cannot load test a Dead Battery. You might consider the other things that would cause your hard starting. You need to take apart your Alternator to get at the Diodes. One of the members had an extenal test with your Meter to determine if it is a Diode or not. I did not entirely understand it so I cannot repeat it. I believe it used the A/C section of the Meter on one of the milivolt settings. However, I did find this: AC voltage across battery VAC across battery should be under 100 mV; excess AC voltage on the DC line means one or more of the rectifier diodes in the bridge are leaking or shorted. Such a problem is relatively rare but unfortunately means replacing the entire alternator. Another: ALTERNATOR DIODE check with volt meter With your meter across the battery, on Volts DC, you should read 12.5 - 14VDC If not, set your meter to Volts AC and you should have a reading of ~100mVAC. If the VAC is too high, then look for a rectifying diode failure. If VAC is OK but the VDC is not correct, then the problem is with the voltage regulator. ALTERNATOR REGULATOR charging rate chart
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84 300D, 82 Volvo 244Gl Diesel Last edited by Diesel911; 02-25-2010 at 12:39 PM. |
#6
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Quote:
You might try swapping a know good Battery and see if this brings the Voltage up. If not it could be that the Battery and Chassie Ground Strap/Cable contact areas need cleaning.
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84 300D, 82 Volvo 244Gl Diesel |
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For a no charge situation you are pretty much limited to the following 3 things causing it-
1-Alternator 2-Battery 3-Wiring Eliminate as many possiblities. Easiest starting point is the battery. Take it out and fully charge it, then have an autozoo employee test it. But don't always trust their tests. They have told me a bad battery was good. You can also fully charge it yourself, then let it sit out side of the car for a few days and check the voltage. If it checks good put it in the car and try and start it. This will tell you if your battery is good. Once you have verified it is not the battery and have it fully charged move on to the alternator testing.
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2009 ML320 Bluetec 1985 300CD 1981 300TD Past Mercedes 1979 300TD 1982 300TD 2000 E320 4Matic Wagon 1998 E430 1984 300SD 1980 300SD |
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Quote:
I learned this week that when the regulator goes... It can go bad and you wind up with a "no battery light" situation. In my case, one of the brushes was not contacting one of the slip rings inside the alternator. This caused a "no battery light" condition. One of the brushes was stuck in the bore of the regulator. The light would NOT come on when the key was set to glow and the light would NOT come on while the car was running. I'm not sure and I am by no means an expert... But, since you have the battery light working... This would tell me that the regulator brushes are in contact with the slip rings. Unless the regulator can fail in a different way? Just one of my observations this week.
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AJ 1985 300D (SOLD) |
#9
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If the battery is brought up to snuff..
the next thing to deal with is the wiring... particularly the ground to frame and body.. as the alternator and regulator will be depending on the battery power GETTING to it to work correctly...
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
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Thanks for all the input. I troubleshooted a little more, I charged the battery to the point where I could start it..and then took a VAC reading across the battery with engine reving (charger unhooked). I had 25V of alternating current across the battery!! I interpreted this as bad diodes in the alternator so I decided to replace the whole thing. Not a fun job especially in 25 degree weather in the street (I really need a garage) !!...the top bolt on the inboard side is ridiculously hard to access. Now I'm having a heck of a time removing the pulley which is severely corroded on (already got 22mm nut off). I've soaked it with penetrating and tried heating the pulley with a torch but it isn't budging. I got a rental 3 prong puller from AZ but it bent the pulley (hopefully I can bend it back) Any advice about how to get the pulley off..I'll do some searching on the forum too. Anyone have a replacement pulley, fan etc.? (sorry I didn't take everyone's advice about other possible problems, but I just read those because I've been working on the car all afternoon and this is my first time back to the computer.
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'85 300td Frybrid WVO Kit |
#11
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An impact wrench gets those pulleys off for me.
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1985 Euro 240D 5 spd 140K 1979 240D 5 spd, 40K on engine rebuild 1994 Dodge/Cummins, 5 spd, 121K 1964 Allice Chalmers D15 tractor 2014 Kubota L3800 tractor 1964 VW bug "Lifes too short to drive a boring car" |
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I've already got the nut off with an electric impact wrench. Is there a way to get the pulley itself off the shaft using an impact wrench?
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'85 300td Frybrid WVO Kit |
#13
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Even if you get the Pulley off ; if the Pulley is bent inwards towards the Belt your Belt will not last long.
You might start sourcing another Pulley.
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84 300D, 82 Volvo 244Gl Diesel |
#14
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Congrats on the diagnosis. After that pully's been bent, I think you're better off getting a replacement. Pick and pull.
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Codifex 1981 240D ChinaBlue (Got her running with a donor engine.) 1983 300DTurbo w/sunroof. 1984 300TD manual sunroof. (Electrical Gremlins) |
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Thanks for all the help. If figured I might be hunting for a new pulley...so if anyone has one i'm interested.(I also just put a WTB post on the parts board). Does anyone know of a a source of alternators that come WITH the pulley attached. I'd really prefer to not have to go to the junk yard...pulling the alternator was really not a experience I'd like to repeat, and I fear I'll have the same issue removing the alternator. thanks again for the help.
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'85 300td Frybrid WVO Kit |
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