BJ73 from Holland 24v Alternator & Oil Pump?!

[Gyrkin]

Hello, folks. Elsie the Beast has done it again... not starting with two new maint. free batteries about dead. The belt was squeeling, but I didn't think that would be enough, in and of itself, for the battery to be flat out dead. As I inspect the alternator, I see that it has an oil pump attached to its back end? And I am only assuming that this is all 24 volts because the headlights are. The preheater module says 12 volts, so I dunno what to make of THAT...

Any advice, or experience with that odd alternator? I am guessing a rebuild is the only real choice? Thoughts? THANKS!

 

[_Walker_]

That pump on the back of the Alternator is actually a vacuum pump, for running the brake system, not an oil pump (although it is lubricated with system engine oil if I am not mistaken...)

You will want to make sure that the problem is actually the alternator first, so recharge the bateries, clean all the contacts, attach a digital volt meter to the bateires and then start the truck, what you are looking for is the change in voltage, once charged before the engine is running you should see something like ~26 volts. After the engine is running I would expect to see things jump up to 28-30v. If you do get this jump in output try turning on the lights and fan with the engine running, how much does the voltage fall? if you start getting a major drop IE below what your original readings were BEFORE starting the engine then it is a likely bet that the alternator is not charging and a rebuild/replacement will be necessary.
IF you do not get a major drop then the alternator is probably fine and you have a phantom load somewhere draining power when the engine is off.


The other thing to ask is are the batteries matched? are you running a 12V stereo/accessories off of one of them, and if you are do you have a load balancer in line? measure the voltage on both the batteries individually they SHOULD be almost identical within 0.1 volt or so.... If they arn't youv been bitten by unbalanced batteries and a shoddy stereo install,

let us know what happens!

 

[Gyrkin]

Well, here is the follow-up: After changing the offending battery, it seemed to work fine. Then I took it to a car-wash and paid an obscene price to have it detailed, as I want to sell the beast before I fly out on the evening of May 8th. Since, it will NOT start without a jump. (Before, it was only not starting if left overnight.) I dunno what they could do by washing it but this is the current condition.

I do not understand how it can be the Alternator, when the one on the right side (the 24v end) is fully charged, and the one on the left near the firewall, the 12 volt part, is not getting the charge. It bothers me a lot, makes no sense to me. Since there is that oil thing on the back, I am less than thrilled to have them taking it off and such, but I now have people wanting to see and buy it, so I need a real-world fix FAST.

Direct email is to gyrkin at gmail dot com, and I hope one of you guys comprehends this, because I am at a loss, and the guys calling themselves electricians around here don't even own a voltmeter. They go by how brightly a bulb shines. (Yes, I am serious.) Your help would be GREATLY appreciated!

PS the majority last time was the loose alternator/fan belt. Tightening it seemed to fix the biggest of the problems, but it is not loose now.

 

[Gyrkin]

And the Preheater?

While we're at it, the Prechauder starts up when I hit a bump. Seems that unit may have a bad relay in in, needing replacement... but that small detail was happening before, too. Any experience on that little 12-volt box in my 24 volt system?

I love the truck, but the way it's electronics function is maddening!

 

[Gyrkin]

Amazing duh!

Unbelievable though it may seem, it SEEMS the lump sum of the problem was bad contacts between the cables and the terminals. To make it worse, there was some wire that some so-called Electrician put on there, and since I couldn't find a use for it, I disconnected it. Now it all works fine, including the preheat. Go figure...

Thanks for the help!

Now let us hope it STAYS working til I get it sold!

That pump on the back of the Alternator is actually a vacuum pump, for running the brake system, not an oil pump (although it is lubricated with system engine oil if I am not mistaken...)

You will want to make sure that the problem is actually the alternator first, so recharge the bateries, clean all the contacts, attach a digital volt meter to the bateires and then start the truck, what you are looking for is the change in voltage, once charged before the engine is running you should see something like ~26 volts. After the engine is running I would expect to see things jump up to 28-30v. If you do get this jump in output try turning on the lights and fan with the engine running, how much does the voltage fall? if you start getting a major drop IE below what your original readings were BEFORE starting the engine then it is a likely bet that the alternator is not charging and a rebuild/replacement will be necessary.
IF you do not get a major drop then the alternator is probably fine and you have a phantom load somewhere draining power when the engine is off.


The other thing to ask is are the batteries matched? are you running a 12V stereo/accessories off of one of them, and if you are do you have a load balancer in line? measure the voltage on both the batteries individually they SHOULD be almost identical within 0.1 volt or so.... If they arn't youv been bitten by unbalanced batteries and a shoddy stereo install,

let us know what happens!

 

[roscoFJ73]

Unbelievable though it may seem, it SEEMS the lump sum of the problem was bad contacts between the cables and the terminals.

Unbelievable! Not really ,probably the cause of 90% of the electrical problems around here.
If the current cant flow through the body and electrical system without resistance ,then everything dies slowly.