1980 Steel Nose E6901 Mack Starter Removal Help

[Wirlybird]

Need to get the starter (40MT starter) out on this Mack and my friend says that last time is was a major undertaking.  Said the bold on the engine side was extremely hard to get on.

Reason to take it out is I think we have a bad solenoid.  We get an arc at the back of the solenoid when turning the key.  The arcing is in the area of the red arrow.
I tested for continuity to ground at the terminal by the red arrow that goes into the starter and got it, and also tested at the yellow arrow and the same which I expected since they are connected.

I will remove the strap between those two terminals tomorrow to see if continuity is at the terminal on the start or on the solenoid.
It seems I need to remove the starter to remove the whole solenoid.  I am wondering if the plate on the rear of the solenoid that has the terminals can be removed without part flying everywhere!

Thanks for any suggestion, tips or advice.

Edited January 12 by Wirlybird

[Freightrain]

The red is the hot from the battery which connects to one side of the contacts inside.  The yellow is the lead into the windings of the motor.  The small wire is the coil to the solenoid which when powered pulls the contacts closed and connects the main power to the windings.

 

Sounds like the contacts are burnt in the solenoid, which would make the starter not run.  That is the flash you are seeing.  Or, the motor is bad(shorted) and the flash is the high current when applying power to the bad motor.

Removing the screws, there is a spring loaded plunger inside, so be careful that it doesn't pop apart and things fall out.

Yes the block side bolt is a PITA to get out.  Either a box wrench and just 1/16 turn at a time or swivel socket and get out enough to use a rachet.

 

Besides it weighs a ton to hold onto.  My B is a real bitch because it is a lower right side starter and it falls in your face if you don't get a hold of it.  Reinstalling is another WTF moment.

[Wirlybird]

1 hour ago, Freightrain said:

The red is the hot from the battery which connects to one side of the contacts inside.  The yellow is the lead into the windings of the motor.  The small wire is the coil to the solenoid which when powered pulls the contacts closed and connects the main power to the windings.

 

Sounds like the contacts are burnt in the solenoid, which would make the starter not run.  That is the flash you are seeing.  Or, the motor is bad(shorted) and the flash is the high current when applying power to the bad motor.

Removing the screws, there is a spring loaded plunger inside, so be careful that it doesn't pop apart and things fall out.

Yes the block side bolt is a PITA to get out.  Either a box wrench and just 1/16 turn at a time or swivel socket and get out enough to use a rachet.

 

Besides it weighs a ton to hold onto.  My B is a real bitch because it is a lower right side starter and it falls in your face if you don't get a hold of it.  Reinstalling is another WTF moment.

Thanks, I am hoping that the solenoid shows as grounding from the post with he yellow and I can take the rear plate off.
My friend said he uses a swivel on the engine side and it is turn a tiny bit, remove and reset and do it again.  He's had it out a few times.

At firs we would get  a "click" when trying to start, like the solenoid engaging but not turning the starter.  A little rapping on the start and it would go.  the last few times though we got that arcing and I didn't see anything obvious on the outside so we gave up for the day.  Going to be a cold on today so don't know how much we'll get done.

[Brocky]

Before you dig deeper, take all the wires off (including the 90* brass strap to the starter housing) and CLEAN all the surfaces with a file or emery cloth to make sure you are getting good contacts.. I have seen many times where  1/16th turn on a nut cures the no start problem..

[terry]

That real hard bolt to reach, replace it with a 12 point head bolt, makes it easier.   Terry

[Wirlybird]

1 hour ago, Brocky said:

Before you dig deeper, take all the wires off (including the 90* brass strap to the starter housing) and CLEAN all the surfaces with a file or emery cloth to make sure you are getting good contacts.. I have seen many times where  1/16th turn on a nut cures the no start problem..

Yes, going to finish removing the strap and small wires to test and see if I can determine why I get continuity from the left post to ground with batteries unhooked.

[Wirlybird]

3 hours ago, Freightrain said:

The red is the hot from the battery which connects to one side of the contacts inside.  The yellow is the lead into the windings of the motor.  The small wire is the coil to the solenoid which when powered pulls the contacts closed and connects the main power to the windings.

 

Sounds like the contacts are burnt in the solenoid, which would make the starter not run.  That is the flash you are seeing.  Or, the motor is bad(shorted) and the flash is the high current when applying power to the bad motor.

Removing the screws, there is a spring loaded plunger inside, so be careful that it doesn't pop apart and things fall out.

Yes the block side bolt is a PITA to get out.  Either a box wrench and just 1/16 turn at a time or swivel socket and get out enough to use a rachet.

 

Besides it weighs a ton to hold onto.  My B is a real bitch because it is a lower right side starter and it falls in your face if you don't get a hold of it.  Reinstalling is another WTF moment.

Ok, to clarify, I can take the plate with the terminals on it off the back of the solenoid ok?  Just concerned it will come apart and have to pull the starter.

Hoping that it is bad contacts and I can replace without pulling the starter.

[Freightrain]

4 minutes ago, Wirlybird said:

Yes, going to finish removing the strap and small wires to test and see if I can determine why I get continuity from the left post to ground with batteries unhooked.

You are getting continuity from the left post to ground because that is the power lead to the windings and they go to ground.  If you had the proper meter it would give a specific resistance reading for the windings.

 

I've never personally had that solenoid apart so I can't confirm or deny what you will get once you pop it apart.  I know the basics of what it should have to function.

[mowerman]

Good luck if it’s anything like my DM, I can’t get to the starter from the floorboard or the firewall. It’s a real bear. Bob

[Wirlybird]

1 hour ago, Freightrain said:

You are getting continuity from the left post to ground because that is the power lead to the windings and they go to ground.  If you had the proper meter it would give a specific resistance reading for the windings.

 

I've never personally had that solenoid apart so I can't confirm or deny what you will get once you pop it apart.  I know the basics of what it should have to function.

I had my meter on 2k setting which gives a tone as I couldn't see the meter while hanging over the fender to get to the terminals!
Also I was first trying to see if I had a dead short in the starter motor.

[terry]

1 hour ago, mowerman said:

Good luck if it’s anything like my DM, I can’t get to the starter from the floorboard or the firewall. It’s a real bear. Bob

Two people, one with a rope around starter from the top, and one leaning over left steer tire to guide in,   Terry

[mowerman]

Haha everything seems to be a little easier if you have help last time, I changed it. I put a brand new one in. I was only 38. It was a little bit easier then but I still struggled with it by myself.

[terry]

2 hours ago, mowerman said:

Haha everything seems to be a little easier if you have help last time, I changed it. I put a brand new one in. I was only 38. It was a little bit easier then but I still struggled with it by myself.

Yeah I have done it by myself too. Not no more, my skin has gotten so thin just a nick and I bleed all over, I sold my truck, but the last starter I put in I had blood dripping everywhere!  Terry

[mowerman]

Oh man that’s messed up. I know my wife gets big brown spots, but just barely hitting her hands or arms on anything and getting back to the starter. I put an air starter in mine. I am thinking about electric job is probably even heavier I don’t know for sure. 

[mowerman]

I just got an engine crane for Christmas. That ought to save a lot of BS for one thing I have to take the steering box out and rebuilt it. And it weighs 100 pounds there’s no way I could get it out of there without this new Christmas gift.

[Freightrain]

3 hours ago, Wirlybird said:

I had my meter on 2k setting which gives a tone as I couldn't see the meter while hanging over the fender to get to the terminals!
Also I was first trying to see if I had a dead short in the starter motor.

Ya, it will just show continuity with that meter.  If the big wires aren't smoking, then likely not dead shorted.  Either bad brushes, commutator or bad solenoid.  Start with the easy stuff first.

 

If daring enough, use a big fat insulated screwdriver and jump the two big terminals.  If the starter spins, then you know it's the solenoid.  If it just arcs, then bad motor.   Do at your own risk!  Just saying.  Doing this on a car starter is not a big deal, but a truck starter is a bit more juice.

[Vladislav]

3 hours ago, Wirlybird said:

I had my meter on 2k setting which gives a tone as I couldn't see the meter while hanging over the fender to get to the terminals!
Also I was first trying to see if I had a dead short in the starter motor.

Starter windings have so small resistance in relation to common electrical pieces so testing by multimeter in a "normal" way looks like short circuit. Starter motor operates on very high amps so winding wire is reall thick.

[mowerman]

He did say it spins when he bangs on it … I’m hoping he can get away with brushes 

[mrsmackpaul]

Sounds to me like the shaft on the starter needs some lube for the solenoid be able to slide the bendix and close the contact

Brushes could also be a issue

If it winds over sometimes after tapping with a hammer then the windings are fine

I would pull it out and fully apart

Clean it, remove any rust or corrosion  lube the shaft and the plunger, test the windings, file or sand the contact disc amd reassemble, test and put back together

Nothing worse than been broken down on the side of the road because of a dud starter

 

Paul 

[Wirlybird]

Ok Guy's, thank you for all the ideas and info.  Problem solved, at least for now.

This AM, 17 degrees out, I removed the strap between the left solenoid post and the starter post.
Found the nut on the starter post to be a bit loose as in not tight enough.  that was a good sign!

Once I had the strap off I found the arcing/pitting on the underside of the strap where it goes onto the starter body post.  Another good sign.
Tested the solenoid and constantly got power to the left post when turning the key.  Good sign.

Jumped the starter between right post and start post.  Starter spun good.

Cleaned everything up and after several trips inside to thaw out I got it all back together.  Cranks right up and engaged and cranked strong.
NOW, I have to replace two little plastic pieces and springs in the fuel supply pump and we'll see if it will start.

[mrsmackpaul]

A good result then

Hopefully the good results keep on coming for you

 

Paul 

[Vladislav]

11 hours ago, Wirlybird said:

Ok Guy's, thank you for all the ideas and info.  Problem solved, at least for now.

This AM, 17 degrees out, I removed the strap between the left solenoid post and the starter post.
Found the nut on the starter post to be a bit loose as in not tight enough.  that was a good sign!

Once I had the strap off I found the arcing/pitting on the underside of the strap where it goes onto the starter body post.  Another good sign.
Tested the solenoid and constantly got power to the left post when turning the key.  Good sign.

Jumped the starter between right post and start post.  Starter spun good.

Cleaned everything up and after several trips inside to thaw out I got it all back together.  Cranks right up and engaged and cranked strong.
NOW, I have to replace two little plastic pieces and springs in the fuel supply pump and we'll see if it will start.

All is done the right way! Great to learn the problem is solved.

If you're going to use the truck in the future and taking to account that machine isn't new it worth to remove the starter and go through it completely. Mostly for cheking contition of the brushes and shaft bushings and also for cleaning and grease. These starters seem able to work for really long time. But preventive service would minimize chances of unexpected failure.

[Wirlybird]

3 hours ago, Vladislav said:

All is done the right way! Great to learn the problem is solved.

If you're going to use the truck in the future and taking to account that machine isn't new it worth to remove the starter and go through it completely. Mostly for cheking contition of the brushes and shaft bushings and also for cleaning and grease. These starters seem able to work for really long time. But preventive service would minimize chances of unexpected failure.

Actually the starter was redone about a year ago.  that's why it was a little disappointing to find the loose connection.  This truck is an old oil field winch truck so it sees pretty harsh conditions!  I am sure it shakes everything loose.

Parts are ordered for the fuel supply pump and then we can get it started again.  She always drains off the fuel when sitting for periods.

 

[mowerman]

Mines the same way. Glad you got it figured out. I wouldn’t be surprised if some of the lines on my  truck were original… bob

[JoeH]

Not sure what the E6901 is. Is this an E6 engine? Or an endt675/6 engine?

The ENDT engines use  plastic fuel return leak off lines that jump from injector to injector and then run back down to the injection pump/fuel return I believe.  These lines get brittle and crack eventually, and 99 times out of 100 I'd bet this is the cause for draining off fuel when sitting. Easy enough to buy a coil of this stuff from your Mack dealer and replace any that are damp.