MAYCO's 1982 310 TD

[mehes]

Check the feed to the regulator from your ignition switch. It turns the regulator/alternator on and off. A loose connection somewhere in this run might cause what you are seeing.

[mayco]

Lance, the ignition switch did come to mind but I didn't realize there is a wire that does that. Boy, that seems very plausible.

[mehes]

Mike on second thought with “0 volts” and loss of tach do you have a problem at your dash. Why wouldn’t the voltmeter show battery voltage without the alternator working? Just a thought. Sometimes we get tunnel vision.

[Smartstream]

Mike I unbolted the vacuum pump and removed the alternator without it. I took it out through the fender well and it is a pain in the a**. It's a long reach to some of the fasteners, a tight fit and the damn thing is heavy. People tell me it builds character.

[mayco]

I wasn't clear Lance, my volt meter IS showing battery voltage, also shows dips with blinkers and what not.

[bobmiller1]

Lance is on it.....check that the voltage regulator gets it’s hot feed when the ignition is turned on......Regards, Bob

[rmkrum]

Originally Posted by bobmiller1

Lance is on it.....check that the voltage regulator gets it’s hot feed when the ignition is turned on......Regards, Bob

Yup. Good idea. The voltage regulator uses a 12v feed from the ignition to energize the rotor windings when the ignition is turned on. It then controls the (average) current in the rotor windings to control the output voltage of the alternator.

It will also fail to work with a slip-ring and brush open circuit issue as I described earlier.

The alternator will sit there all stupid-like without power running through the rotor, no matter how fast you spin it, unlike the old self-excited generators.

[mayco]

We are rollin along just fine really. Just shortened our miles per day and putting a charger on the battery when we stop. Today our battery voltage started at 12.73 and only dropped to 12.4 or so. So no problems getting home to find the charging issue. Ill start with the voltage regulator connector, then replace the regulator if needed. (Since I have the extra one) From there I guess I'll move on the the altenator.

Actually I may start with a hammer on various parts

[mayco]

Made it home this morning after about a month on the road, the last 4-5 traveling days without an alternator charging my batts. Thank god for the diesel! Got things pretty well unpacked and started in on trying to diagnose the charge issue and it looks to me like my alternators bit the big one. Started in on it and this is going to be a pain in the rear to Rn R. There is just no room in there but it's doable, Dan did his on the road. Got most things out of the way and all but the bottom bolt out of the alt mounting. Tomorrow I'll go underneath to access that one. The new alt I had on the shelf has a new vacuum pump on it so I'm installing both. Looks like it's going to be some kinda challenge to physically get that thing out of there. Yeeeeehawwww, this is fun......right? We've had several thousand trouble free miles of adventures.......I was due!

[mayco]

Finished up installing the alternator this morning and everything is good. Charging back to normal and tach working as it should. I know Dan was able to replace his through the wheel well on his 280 but there was no way on my 310. It had to come out of the top or from the front which would mean pulling the grill, radiator, trans cooler etc etc etc. So that sucker was gonna come out the top one way or another. It was a bear of a job, tight as hell and all kinds of stuff in the way. But, got r done!

A couple of things for owners of the 310TD who need to replace the alternator in the future.
1. Disconnect the upper radiator hose so you can get it out of the
Way.

2. Completely remove the alternator tensioning bracket from the
Block.

3. Disconnect the voltage regulator and remove it for more room.

4. Be careful of the turbo sending tube, mine was brittle and
Snapped.

5. The oil lines look impossible to unbolt but if you swing the
alternator all the way to the drivers side you can get to the
bottom one. They take a 22mm socket, which I didn't have
But a 15/16" will work.
6. Move everything you can think of out of the way because
you'll need every square inch to pull that sucker up and out
Of there. It's heavy too.

Here are a few pictures of where she sits in all her glory.......

Attachment 1

Soooooooooo Ive got a new alternator, new vacuum pump, and new regulator. Ill take my old alternator in and have it rebuilt for a spare. Safe travels fellas

Mike

[mehes]

Hey Mike, I don’t know much about your engine. What’s the oil line to the alternator for? cooling?

[mayco]

It's for lubricating the vacuum pump that's attached to the back of the alternator. The main shaft of the alt extends out the back and drives the pump. The pump is bolted to the back of the alternator. I think they are most common on diesels. In our case, it only operates the step, in and out.

[Magnet18]

Odd that on a diesel, that doesn't generate vacuum, they found it easier to add a vacuum pump to the engine than just use an electric step...

[mayco]

I know Rob, but as you have and WILL find, Airstream did some pretty crazy stuff on our rigs. That's why no two are alike, it can be crazy making at times for sure. Thank god for this forum! We would all be lost with some things.

I think they did eventually switch to the electric powered step, maybe with the 345s. Is yours electric?

[Magnet18]

Mine is kwikee electric, as far as I can tell it always has been but I've never dug into it to check. If replaced it was a long time ago.

I'm guessing someone at airstream spec'd the engine with vacuum pump, then figured it was there so they'd better use it for something!

[Smartstream]

These coaches also used a vacuum cruise control and vacuum modulator on the transmission. The next year, 1983 used vacuum heat and A/C dash controls.

When I pulled my alternator the only thing I removed was the sheet metal inner fender panel. I think 2 bolts hold the vacuum pump so it and it's lines stayed connected. I was just to lazy too remove radiator hoses and all the other stuff. Also working in the fender well I was sitting on my butt most of the time. I will admit I might have pulled the front wheel but I really don't remember with my advanced age and feeble mind.

Anyway glad you got it done Mike and that all is well. It will be interesting what your rebuilder comes up with as the initial cause of failure.

[bkahler]

Originally Posted by mayco

It's for lubricating the vacuum pump that's attached to the back of the alternator. The main shaft of the alt extends out the back and drives the pump. The pump is bolted to the back of the alternator. I think they are most common on diesels. In our case, it only operates the step, in and out.

You should discard that alternator driven vacuum pump and switch to the Ford electric vacuum pump used in their Superduty diesel pickups.

Just a thought

Brad

[bkahler]

Originally Posted by Magnet18

Mine is kwikee electric, as far as I can tell it always has been but I've never dug into it to check. If replaced it was a long time ago.

I'm guessing someone at airstream spec'd the engine with vacuum pump, then figured it was there so they'd better use it for something!

The dash AC system uses vacuum actuators, hence the need for a vacuum pump. The steps were probably left vacuum for that reason.

Just a guess of course

Brad

[Smartstream]

The Isuzu vacuum pump is common and dependable on many of their small box trucks. The only reason to change would be to use a different alternator. The Isuzu is a big, heavy, well built and long lasting industrial unit.

[mayco]

We have a really good old school auto electric business in town here that's been around as long as I can remember, so that's where I'll be taking it for repair. Question: should I ask them to rebuild it or should I ask them to diagnose and repair it? For instance if it just needs new brushes or something. Please forgive my ignorance here.