HELP!!!Starter Woes

[Fred Mc]

A couple of years ago I moved my batteries to the old air conditioner compartment(GM PD4106). At that time I also replaced the cables. Unfortunately one of the cables was a little to short and subsequently shorted out the starter so I had to get a new starter(rebuilt unit).I also put in a longer cable. The ground cable goes directly from the battery to the starter and the positive cable goes through a marine cutoff switch to the old terminal mounted on the firewall. A cable then goes from that terminal to the positive side of the starter.The 2 cables are sandwiched together on this terminal. All terminals are clean. The batteries are older but I had the battery shop test them and they are fine.I also had the starter shop test the starter and it is fine.

What happens is this. With cold starting the bus starts fine. It cranks fast and starts almost immediately. But, once the engine is warmed up it won't start. The solenoid clicks in and the starter TRIES to turn the engine. To me it sounds like dead batteries.

Last week I called a tow truck to boost me.I had already waited a couple of hours to let the bus cool down. When he hooked up his booster batteries and  we tried to start it gave the same results-no start. HOWEVER, once he let his truck charge MY batteries for a few minutes(about 5 minutes) the bus started right up.

When I got the bus home I shut it off and tried to start it-same result,no start. I then duplicated what the tow truck did.I boosted the bus with my work truck (a diesel with dual 12 volt batteries). Same result, it wouldn't start. But when I let the truck charge the batteries for a few minutes it started right up.

So off I went to the battery shop with one of the batteries which they said was good.(I didn't take both batteries)

I'm not 100% comfortable with the battery guy(young kid) or the starter guy but I presume they know more than I do.

Any ideas??
THanks

Fred Mc.

[Dreamscape]

There have been numerous posts regarding the same problem lately, here and on the BNO Board. Seems to be more prevelant during the hot summer months. Most of the replies suggest a poor ground somewhere on the frame.

HTH

Paul

[niles500]

Fred - did he specifically "load test" them?

[Stan]

I agree with your assessment that it sounds like bad batteries. Can you try another set of batteries (out of your truck, car or lawnmower)? A battery shop should be able to do a proper load test on batteries used for starting a diesel engine but if you were not watching the test done you really can't be sure. Auto parts places usually don't have the equipment to do a high current load test.

You don't say where the tow truck connected his jumper cables so if you have a high resistance somewhere he may have been going through it. If he connected his ground to your bus frame or engine cradle, you might have a bad connection between the starter ground and the engine cradle or the engine cradle to frame.

It is quite simple to trouble shoot the system with a volt meter. Using the starter ground bolt as your negative reference (connect the meter negative lead there) take the meter with you and take voltage measurements at the following points while someone else pushes the starter button:
1. Battery post
2. Battery cable terminal on battery
3. Battery cable terminals at junction point
4. Battery cable connection on solenoid
5. Solenoid bolt that is jumpered to starter
6. Starter bolt

When you see the big voltage drop when the starter button is pushed, you have isolated the problem to whatever is between the two test points. Unfortunately, if it occurs at the starter bolt, that is a bad starter. If it is between the solenoid bolts, it is a bad solenoid. If it is right on the battery post, it is a bad battery. If you have two batteries, you have to do check #1 and #2 at each battery. If it is between those points, it is bad cable or connection (or your disconnect switch).HTH.

[luvrbus]

I had this problem when i changed out my 2 8Ds to group 31s i tried to use just 2  group 31 batteries and it would not start when hot i installed 4 and have not any problem since i have a 8v92

[Don4107]

Fred,

Sounds like you may have a problem with the charging system in the bus too.  Your batteries should be full charged when you turn the bus off after a trip.  Hooking up another rig to them to charge them sounds like a problem with the bus system.   If you are plugging it in when home the batteries may be charging from a built in AC charger or inverter. Hence the cold start. 

Another possibility is that something in the bus is draining the batteries when you turn if off.  Again this might be masked by plugging in the bus when parked.

If you note the battery voltage with the run switch in the run position but without the engine running, then note the voltage with the engine running, it should increase when running.  If not the charging system is not working.

You can do your own load test of the batteries.  You did not say what batteries you have or how old they are so it is hard to estimate the time they should last.  Start by charging each battery separately.  Check the voltage with nothing connected to the batteries.  Should be something more than 13 volts.  Then with only one battery hooked up at a time turn on the headlights and see how long it takes for the battery to get down to 11.5 volts.  Then do the same other one.  Report back how long it takes.

Sorry if this is over simplistic but it is a place to start.

Don 4107

[jjrbus]

I hate to replace something that does not need replacing! I'm cheap. I will not just throw money at a problem. But when it comes to starting batteries, at the first sign of trouble, out they go!!!  I've had bad battery's test good, next time you go to use them there no good. A battery is a very simple but extremely complicated item.
I would follow all the suggestions here to eliminate any trouble spots or potential trouble spots and then just buy new batteries.  Questionable battery's will not give out in your driveway on a nice day when you have nothing to do!!
Just my way, your milage may vary. Jim

[DrivingMissLazy]

So off I went to the battery shop with one of the batteries which they said was good. (I didn't take both batteries)

What makes you think the battery you did not take to be tested is good?
Richard

[Fred Mc]

"What makes you think the battery you did not take to be tested is good?"

Good question. I will be taking it tommorrow to get tested.

Thanks

Fred

[Cary and Don]

We had the exact same thing happen to us a couple times.  It starts right up when cold.  We stopped at a rest stop and it wouldn't even goan.  The batteries were charging off the regulator when we stopped.  We put a charger on it for about a half hour and it started.  We thought there might be a wire getting hot or the starter was hot or something.  It always starts right up cold.  Guess we'll check or batteries too since they are about 4 years old now.

Don and Cary
GMC4107

[roadrunnertex]

Starter problems?
I had at one time many years ago a 1960 PD4104 that was doing the same thing it would start fine when the engine was cold and would not turn over when the engine was hot.
The problem was one of the field windings in the starter was bad.
I had the old starter rebuilt by Kirks Automotive and never had a problem after this.
I talked to a old bus driver who had driven PD4104's in revenue service for many years and he said that he use to cool have to the starter down on some of the old 4104's with ice water at a rest stop so he could finish the trip.
jlv

[JimC]

I have the same problem with my 4106 once in a while, mostly when trying to start after a long run. I replaced the starter and it was fine for a year or so, then it started acting up again.

I have determined that the starter is getting hot, now when it won't start, I buy a bag of ice, set it on the starter, and 10-15 minutes later it starts right up.

On my TO DO list is to fabricate some type of heat shield, right now I have the exhaust manifold above the starter, and the exhaust pipe and muffler running under the starter and out to the passenger side. 

Next time it acts up try the ice it may just work for you also.

Jim

[Fred Mc]

Here is an update.

I took both batteries this time for testing. The one that tested good last time did not test at all this time. Guy said probably an internal short. And the one I didn't have tested was also no good.

So, I replaced my 2 8d's with 3 900 cca 12 volt batteries. Two wouldn't cut it but 3 seems to work just fine.

Now, Another question.

I have the 3 starting batteries in a new compartment closer to the engine. They have their own cutt off switch. I want to put a deep cycle battery in the old compartment. My coach is mostly 12 volt and I don't have an inverter. This deep cycle battery would be in parrallel with the 3 starting batteries, however, when I disconnect the starting batteries the coach would continue to draw off the deep cycle.Of course when I went to start the deep cycle would work along with the starting batteries.

Is there a drawback to this setup.

Thanks

Fred Mc.

[Don4107]

Fred,

If you are saying that your bus would not start with 2 group 31 batteries but did with 3, I think you still have other problems unless the group 31s were not at full charge.  This time of year 1 group 31 should do the job unless you live somewhere that is a lot cooler that I.

My 4107 8V71 will start on one old group 8D or one Optima.  Works when the block is a ambient temp as long as it is not cold out and when the engine is at operating temp.  I have a Cummings 350BC that had 4 group 31s.  Will start just fine with 1 when warm out or the block has been heated.

As to putting a deep cycle battery directly in parallel with another type, that is not a good idea.  They will have different charge/discharge characteristics and voltages. An isolator would be one way to go.

Good luck

Don 4107

[pvcces]

There is another thing about starters that I did not see mentioned in this thread. That is, if the bushings are worn, temperature may affect how close the armature gets to the field pieces. If it gets too close, or if there is contact, you will lose a lot of starter torque, but the current consumption will climb.

Another thing that can cause hard starting hot, but not cold, is if injected fuel ignites before the piston gets close enough to top center. If that happens, the kickback will stall the starter. When the engine is cold, ignition is delayed a bit, which is enough to let the piston reach top center before building a lot of pressure.

If the starter stalls, and you let up immediately on the button, then press it again quickly, there is a good chance that the engine will kick right over and start. You should not hold down on the button for even a second if the starter stalls because you can damage the starter, and possibly weld the contacts in the solenoid.

For what it's worth.

Tom Caffrey