So I have been working on a 1980 240 B21 and the alternator and bushings have gone. The original alternator has the ground and Battery connections on the back, and then the battery dash light wire is spade connected onto a spade connector coming from the back of the alternator. NEXT, I pulled an alternator from a 92 240 with a slightly different set up on the back, with same connections. Alternator fit right in and got everything put together. The dash light wire I left unconnected because there was not a spade connector coming from the back of the newer alternator to plug it into. I did notice a small rectangular box on the newer alternator that has a short wire coming from it which connects to a possible spade looking part. Could I possibly connect the dash wire there? The guy at the shop said its just a different alternator altogether and isn't going to work. I feel like I could rig it to work somehow. Thanks!

 

the alternator should have *something* labeled D+, thats where the wire from the dash light goes (the big red wire from the battery via the starter goes to B+).

on many of them, D+ is a small bolt+nut, rather than a spade lug, so you'd need to replace the spade on your wire with an appropriately sized ring terminal or find a ring terminal to spade adapter.

some alternators have a little black box on the back thats a noise suppression capacitor, not to be confused with the voltage regulator. this noise thing has a little wire that goes onto a "W" terminal on the regulator, leave that alone.

typically newer style alternator...


B+ (main power wire) is at 3:30 on the clock, D+ (exciter wire from dashboard) is at 2:30. black box noise suppressor is at 10-11 oclock, and is plugged into W at 12:30. regulator is at 6 o'clock. grown wire connection is at 7:30...

 

Thanks pierce, so I did exactly what you said and added the ring terminal on the newer alternator with everything hooked up properly but voltage still drops and the car dies obviously. Is it ok if the little ground is tightened right on the Alternator or should it be on a wAsher or something? Also I took the old alternator to get checked and it was cranking out strong at 80 amps. So I put the old one back in with the new bushings and car still dies. The alternator shop thinks something is goin on with the exciter wire not getting power to charge the system. They said I should jump a wire from the large battery connection to the small on on the alt and it should charge the system. So does that mean taking a ring connector from the large battery bolt to the spade connection on the old alt or ring to ring connection on the newer? Thanks

 

when you turn the key on, does the alternator light on the dashboard? and when you crank the car, does it go out? if yes and yes, then it SHOULD be working. if it doesn't light with the key on but no engine, then either the bulb is bad or the wire is not connected properly. the bulb must be working for the alternator to get excited.

also, engine off, ignition switched on, check the voltage on the D+ terminal at the back of the alternator (with the D+ exciter wire connected), it should be something midrange, like 7 or 9V, maybe even 12V. Key off, and it should be 0v.

 

Ok so its pouring outside so I was unable to check voltage of the exciter wire. Voltage in the car is very low so it will not crank fully and start but it will crank a few times. This is a 1980 so the battery light is next to the oil light and says AMP on it, so I am assuming this is the battery light. When key is in on position the AMP light is on. When I crank it and it cranks a few times the light does go off. But I should probably jump it and get a full test crank and start to see if the light goes off, but we haven't seen it staying on at all. ALSO, heres this, I added a new belt to the alternator and its running much better. Instead of dying completely the voltage is staying low for a long period of time. Where before its just dying out after taking it off the jump and then it won't restart. After adding the new belt yesterday we were able to crank it after shutting it off about 6 times and it drove around. So the alternator is charging the system, but not at full capacity.

 

if the battery has run down, I would put it on a proper battery charger overnight before doing more cranking or before jumping, its much better on the battery. if you jump a car with a dead battery, the alternator will try to dump like 100 amps into the battery to fast charge it, this greatly shortens the battery life.

 

Thoughts about my answered alternator questions? Were you able to come up with any speculation from my given details. I have not been able to check voltage at the exciter wire yet. Thanks.

 

without the voltage tests I asked for earlier, I hesitate to guess what could be wrong.

 

Just a quick review before I check voltage. I put the car in the ON position. I then put the positive test lead on the D+ terminal. Where can I place the negative? Anywhere against the car to ground? I should then get a voltage of 12V or so if its "excited" correct? Thanks.

 

negative to any good ground (the fuel rail, the alternator body, the battery - terminal), and yeah, plus lead to the alternator D+... you should see a voltage somewhere around 7-10 volts probably because there's a resistor in series (the dashboard ALT light), so it won't be the full 12.6V or whatever battery voltage.

 

Ok Pierce sorry for the late reply, will have voltage of exciter soon. But interesting dilemma. I found a guy who had the same issue as I and said that after dealing with alternator and all he discovered that the crankshaft pulley had actually went. Causing speed of belts to lessen, etc. So speaking of voltage issues, you know the rest. The harmonic balancer on this 240 is very rusted and I do suspect the bushing in the middle has went. I had a similar issue on my 92 240 and when I replaced the pulley it was like a whole nother car. Anyway, thoughts?

 

yeah, if the harmonic damper/pulley has crapped out, you need to replace it.

 

Quick question. I know the pulley on this 1980 B21 looks similar to the B230F pulley, 3 slot, etc. Are they compatible? I'm not finding a "B21" crankshaft pulley. Thanks.

 

hmmm, drawing for a 1980 B21F shows two different 'stacks' on the crankshaft, designated ALTER 1, and ALTER 2.

alter 1 uses a woodruff key in the slot on the crank, has timing pulley consisting of a sandwich of parts 2 each 'locating plate' 463576, and timing belt cog 463575, then uses alternator pulley hub 1219368

alter2 uses no seperate woodruff key, instead the timing pulley bits have the key machined into them, 2 each plates 1276141 and timing cog 1266920, to which is attached alternator pulley hub 1276151.

the main alternator belt pulley is 1219148 for both alternates, and if you have PS with no AC, you also have pulley 1336647 sandwiched on top of this, if you have AC, its (PN not given)

the pulleys are held to the pulley hub with 6 M6x16mm bolts 946544, and the pulley hub is held onto the crank with 970933 M14x90mm

confusing. anyways this doesn't look anything like the harmonic damper used on later motors.

 

Well like I said his crankshaft pulley looks like the similar 3 slot B230F. Not the old school skinny one with the multiple bolts. I am going to take a look at it today. I will let you know.

 

Ok Pierce I know this getting onto a whole nother topic but this is my first experience with a B21, so I am trying to understand. The crank pulley is actually two separate "hubs" attached to each other. The pulley on this B21 was 3 slots with the 6 bolts. But is there an oscillation dampener in it that goes bad or does this pulley system itself go bad? I can tell by the wearing of the belts unevenly that this crank pulley has gone off "center" or something similar. ALSO, I am not able to find the crank tool for this engine online. I have the B230F tool but its not compatible. I'm a little nervous to try the Rope Trick.

 

I've never had a b21, so I got no ideas.

here's the drawing for the 1980 B21 family



'alter 1' is the 18-19-18 stack, while 'alter 2' is the 20-21-20 stack. the 'hub' for the alternator pulleys is part 22, and the pulleys are 24 and optionally 25 for A/C. the woodruff key used with alter-1 is 17 shown above on the crank itself.

thats literally all I know about it.

 

Ok really appreciate it. This will be my final post before I start a new thread on this topic. Last question, these B21 crank pulleys seem like all solid metal, not like the B230 ones with the oscillation dampener in the middle. I could be wrong, but do these older ones actually ever "go" or have issues that would cause the belts and entire system to turn slower causing voltage issues, etc? I know its common on the B230. Which has been my final concern with this 240 because like I said alternator is good and battery is new. And exciter wire is the final piece but this crank pulley is very old and rusted. Also, any info on the B21 crank tool, thanks.