Troubleshooting start problem

[jjrbus]

 Checked batterys I have 25.6 volts on start batteries.   I used driver start button, starter clunked?? but did not turn, no noises, no spinning sounds. released button and tried again instant start. i checked voltage of start batteries befor alternator engaged. They showed 24.7 volts,  Would a .9 volt drop be acceptable? Can not seem to locate this info on the internet. Jim

[JohnEd]

Jim,

I would say you have weak bats and a defective starter solenoid/armature.  Time for the ole hydrometer.  How old are each of those components?  This is one of those rare cases where "size doesn't matter"...really!  They are all basically the same and it in your technique of rebuilding and practice, practice, practice makes purrfecto.   Take you armature into a shop and ask them to put it on a Growler for you....you can clean the thing yourself with sand paper(not emery).

That and : Col. Mustard in the den with the knife

John

[Busted Knuckle]

I'd also suspect a corroded connection somewhere! The coach we just bought does the same thing! I've been so busy fix'n more important stuff and making trips all over the country buying other stuff, haven't had time to fix it yet! Besides until it leaves a driver stranded somewhere with a load on it's no big deal right  (just kid'n it really is on the TO DO LIST, just gotta find someone to do it! LOL!)    BK 

[jjrbus]

Thanks,, as usual the bus Gods are smileing on me> I am sitting in a Executive Class A Motorhome Resort and Spa  and not on the side of the road somewhere, the rent is paid for a month. So I have plenty of time to muddle through this.
The starter/selonoid was rebuilt 60K miles and 10 years ago, so are suspect. The start batteries are a few months old, I  dont trust these batteries, I have taken them back twice since new and they pass a load test but they do not hold a charge like the old ones did. These are 2 group 31 like the old ones, but seem weak. I  will pull them one more time and have them tested. Also it seems after this much time it would pay to have the starter PM'd
I finnaly thought to check the house batteries, Voltage was low, I added water and am chargeing now. I am not sure on the sequence I will follow but hope to do one thing at a time to isolate problem.
Maybe Chaz and I could have a two for one sale??



                                          Thanks again Jim

[Barn Owl]

Time for the ole hydrometer.

If you don't have one of these you need one ASAP. They are not all that expensive. It will tell you more about your batteries than anything. If you can, get a refractometer, it is the ultimate cool tool for testing batteries and antifreeze.

Discussed here one time:

http://www.busconversions.com/bbs/index.php?topic=6895.0

I think your batteries are fine. You need to clean every connection you have from the batteries to the starter, then locate every ground you have and clean them all (Not just tighten but take them apart and clean to bare metal). This needs to be done no matter what component you have that might be bad. That will eliminate the possibility of a very common gremlin if you do. Not to mention that it is also part of a good preventive maintenance plan.

[jjrbus]

I have a hydrometer. But the start batteries are maintanence free sealed type!!!!

[Sojourner]

Checked batterys I have 25.6 volts on start batteries.   I used driver start button, starter clunked?? but did not turn, no noises, no spinning sounds. released button and tried again instant start. i checked voltage of start batteries befor alternator engaged. They showed 24.7 volts,  Would a .9 volt drop be acceptable? Can not seem to locate this info on the internet. Jim

Jim....Yes, it always drop about 1 volt once after been charge with a charger, to remove "float" voltage via load (on & off) and then read lower then first read....the voltage report is normal and very good.

Now here the important part:
1) What was the voltage while it went "clunk" at the starter + post? _______ If it near battery voltage....brushes hanging up or worn. If none....solenoid contact is worn.

2) What was the voltage while it cranking with no fuel at the starter + post? _______ Should be at least 18 volts

3) After done both above test, recheck battery + voltage_______ It should be at least 24 voltage if the battery was fully charge before the test.

Post the resuilts if you will...Thank you.

I wish I was there to help.

Sojourn for Christ, Jerry

PS...we will talk about why your battery is weaker than other Gr31 after this reports.

[NJT5047]

Jim, still sounds like you have a starter issue, but maintenance free batteries can be a huge headache.  Your voltage readings are WNL.   
FWIW, if using maintenance free batteries in place of 'real' batteries, problems with charge profile can cause problems for the maintenance free batteries. 
If you're charging maintenance-free batteries and lead acid batteries  from the same alternator/regulator, the maintenance free batteries may be overcharged and possibly damaged.
Others may disagree.  No problem.  Not really.   
My experience with batteries is that I've had to replace about 2 to 1 maintenance free to lead acid for failures.   Most failures are related to either the higher self-discharge rate of maintenance free when not used, or improper servicing when initially serviced new.
High quality AGM batteries are good items, but they have an approved charging profile, that if violated, will screw up the batteries pronto. 
Maintenance free batteries soak up the electrolyte and the battery will look dry...if one gets the caps off.  These batteries should never have water added to them. 
JR

[JackConrad]

Jim,
   I would first check clean all connections, sitting in all this Florida humidity can easily cause corrosion on a conection(s). Besides,this is the cheapest repair LOL. The first attempt to start causes enough heat in the poor connection(s) to improve the connection(s), the second attempt gets enough power through the poor connection(s) to operate the starter.
   Another component I just thought of is the pressure switch on the secondary fuel filter. This switch completes the ground from the starter relay or solenoid (I don't remember which). Anyway, when this switch failed on our bus we had similar symptoms. To rule out this switch as the problem, simply put a jumper between the 2 terminals on the switch.  Jack

[chazwood]

I had something similar happen...... it turned out to be a loose battery cable. I called myself cinching those puppies down real tight the first time, but somehow one came loose.

Tightened it back up and problem vanished.

[Len Silva]

All are good trouble shooting and repair suggestions.  One point I'd like to make is that I would not be without my heavy duty 300 amp commercial charger/booster.  Hook it directly to the starter if you have, it get you back on the road (assuming you have ac power available).

[kingfa39]

What i do is a once a yr go over , beginning at the batteries i clean every conection shiney from the batt to the termination, i learnes this early on, the ground conection on the rear bulkhead was just a little dirty and all i got was a click, after the cleaning she took right off. Thats always my first thing to do. i also do a hydrameter check and a load check. these pretty much tell the story. Takes a long time to fully charge these batteries as they are so big.
Frank Allen

[pvcces]

And one other thng that I don't see mentioned is that some coaches will do this, even if the whole starter system is in good shape. There is a sentence in our 4106 operator's manual that describes this. I did not find it in the service manual.

It says something like "If you press the starter button and the engine does not crank, simply release the button and press it again". I was very puzzled by this, and after we had some starter problems, I learned that the starter drive will occaisionally butt up against a flywheel tooth without engaging it.

If the starter has been assembled and adjusted correctly, the failure to engage will also prevent the main power contacts in the solenoid from powering up the starter motor. This prevents the destruction of the starter drive gear and the flywheel ring gear. The key adjustment is the starter drive gear to end bell clearance, around 1/8", if IIRC.

Since the solenoid pull-in current is passed though the starter motor, the motor turns a bit with each attempt to pull the drive into engagement. So, releasing the button and pressing it again causes the drive to line up the teeth. When the drive engages, the main contacts make, and the motor turns over.

While this setup may apply to our 12 volt coach, I don't really know if it applies to yours, but i can't think of a good reason it shouldn't. And I'm not trying to discourage you from maintaining your coach. But, I think that you could spend quite a bit of time chasing a non-problem, if you didn't really have anything wrong.

I hope you find this useful.

Tom Caffrey

[jjrbus]

I have been puttering with this and found a corroded terminal on the fule pressure swith. I managed to destroy it while trying to fix it. So am now sidelined waiting for a new switch.
In the meantime as I pulled terminals to clean, i figured as long as I have it apart I might as well take the batteries back to be load tested for the third time. Of course one battery showed recharge and retest. I refused the recharge as this battery showed full voltage this morning. I'm not 100% sure I did the right thing, but I have been unhappy with these batteries since new.
Will putter with it again soon, I may jury rig the switch and see if I still have a starting problem.

Thanks for all the help   Jim

[Len Silva]

I have been puttering with this and found a corroded terminal on the fule pressure swith. I managed to destroy it while trying to fix it. So am now sidelined waiting for a new switch.
In the meantime as I pulled terminals to clean, i figured as long as I have it apart I might as well take the batteries back to be load tested for the third time. Of course one battery showed recharge and retest. I refused the recharge as this battery showed full voltage this morning. I'm not 100% sure I did the right thing, but I have been unhappy with these batteries since new.
Will putter with it again soon, I may jury rig the switch and see if I still have a starting problem.

Thanks for all the help   Jim

The fuel pressure switch shouldn't sideline you at all.  Just connect the two leads together.  It's function AFAIK is only to prevent the starter from engaging when the engine is running.  Just be careful until you can get it replaced.