Starter help

[Cary and Don]

Hi,

We have been checking our previous, now continous, starter problem.  It appears to be the starter solinoid.  With the batteries off, all four posts on the solinoid check ground.  With the batteries on, the magnectic switch clicks when you hit the start button,  but nothing else.  The batteries and cables all checked out. So the thought is the solinoid is frozen inside.

So now the big question. How much of a pain is this going to be to get out?  I can barely reach the wires through the access hole over the engine.  It is really tight under the starter and there is a wall between the starter and the only place I can sit under the bus.  And it looks really heavy.

Is there a magical trick, short of hiring somebody, young, dumb, and strong?

Cary
GMC4107

[Ncbob]

Sure, the secret is to give it a substantial rap with a good sized (not tremendous) hammer.  If that doesn't work try to rap it while someone is pushing the starter button.

Most of these MT-40 and MT-50 starters can experience either a bad solenoid or a brush hang up.  You certainly won't hurt anything by doing the above.  If you have a good Volt/Ohm meter read the battery voltage at the solenoid while cranking...if it drops below about 15 volts...you might have some bad battery connections or perhaps a bad battery bank.

Just went through all this on my MCI...found that my 24V alternator wasn't charging my batteries....and the fun started.

Wish you well......

Bob

[Jerry Liebler]

Bob,
    Cary's voltage at the starter will be waaay below 15 volts.  He has a 12 volt bus!  So cary divide Bob's 15 by 2.
Regards
HJerry 4107 1120

[Dallas]

Cary,

Before you go to a big hassle getting the starter or solenoid out, replace the ground from the engine to the body. Also try running a booster cable from the batteies to the ground lug on the starter.

Many of the starter problems on these old aluminum dinosaurs stem from the fact that when you put dissimilar metals together you get eventual corrosion, screwing up the circuits royally.

And to everyone else....... If you are having electrical problems like fluctuating gauge readings, poor starting, solenoids that don't engage fully.... check the grounds, ALL of them, especially the ones that go fromthe engine to the body and the ones that go from the batteries to the engine.

Dallas

[jjrbus]

My bus has always started, but sometimes when I push the start button it will just click. the second time I push the button it starts. I mentioned this to someone. They asked me if it was after the bus had sat for a long time. Long time is a relevant term so we will say 1 month. Jack said that if it was only after sitting that surface rust could be building up in the selonoid and hanging it up.
I began to pay attention and it only happened after the bus sits for a "long time".  I have also noticed it is worse in FL, higher humidity!!  So if your bus has sat for a "long time" that could be your problem, a few light hits with a hammer may free it.
                     HTH Jim

[Barn Owl]

Here is my starter swap post:

http://www.busconversions.com/bbs/index.php?topic=4610.0

Cary, I had a solenoid freeze up on me and I am going to post the conclusion as to why in the future, but I don't have time at this moment. If you send me a message from the MAK board with your phone # I will call you and help you with it.

Jim, my bus also had that symptom. I can call you also if you would like.


Laryn

[JohnEd]

Guys,

Measuring from the terminal lug(or battery) and touching the frame "can" be misleading.  If you want to know how much battery voltage the solenoid is seeing you need to get on the solenoid "post" and measure to the starter "frame".  The actual voltage drop "across the winding" is the only thing that matters.  A bad terminal lug will show full voltage at the lug but the coil will be seeing the bat voltage minus the loss in the lug.  It is hard for non-electric oriented people to appreciate that what is a mechanical unit may not be an electrically complete circuit.  I had a neighbor that worked on his LARGE Suziki MC for days trying to find out why he had voltage everywhere he was supposed to but when he hit the starter everything went dead....I found LOCKTITE between the frame ground cable lug and the frame that was making a poor connection but it would open up when strong current was called for.  Drove him nuts!

Place a meter on the battery terminal and measure between the terminal and the clamp when you run your started.  If you see more than a half a volt on the meter, you have work to do.  That goes for both the pos and neg terminlas.  You can walk through the system and continue to check each connecting point.....connector to ground, input to fuse block (when there is a current draw through the fuse block.  Low voltage is so very very strange and the grounding circuits are where most of the failures are found....as has been said.

And the only battery voltage that matters when evaluating a bat is measured at the lead terminal and not at the frame or anywhere else. 

Good hunting,

John

[Cary and Don]

Update,

Well, it looks like we are back to possible intermittant starter problems.  While I had been checking wires, and cleaning up the spagetti that the previous owner called a wiring job, a connection gave way.  This wire went into the old engine harness and back over the transmission to who knows where.  When the starter button was pushed, the end going over the transmission became hot.  The other end showed ground.  We have no idea as to where either end went.  When connected, the engine turned right over.  There was another wire with this mystery wire that goes from the magnetic start switch, ground side,  to somewhere out over the transmission. Since the fuel pressure switch isn't hooked up, we have no idea as to what these two wires do.  We do know it will not start if the tranny isn't in neutral.

So, the old girl is starting.  We will do all the suggested checks and additions to the grounding.  Our volt meter on the dash seems to have a little bounce from time to time.  Maybe, it's related. I guess we will find out how our multipule fixes work the next time we run long enough for everything to get good and warm.

We have learned why all the knowledgable busnuts rip every little last bit of wiring out and start over.  If we had only been smarter in the beginning.

Don and Cary
GMC4107

[jjrbus]

Thanks Laryn, but it is a non problem.

[Stan]

Once again, I will point out that the frame of a DD starter is not in the electrical circuit. The positive connection is an insulated bolt on the top of the starter and the negative connection is an insulated bolt on the end of the starter. No current should be flowing through the starter case. If you use any part of the engine or engine cradle as a ground reference, the accuracy of your voltage readings are dependent on the quality of the electrical connections between the engine and cradle, cradle and bus chassis to battery negative.

This is the reason I recommend going directly to the starter negative bolt from the battery.