And still another starter issue.

[Fred Mc]

4 or 5 years ago I re-located my batteries from the normal battery compartment on a GMPD4106(just in front of the rear wheel drivers side) to the compartment vacated by the otr air conditioner compressor which is just behind the rear wheel drivers side. I also replaced ALL the battery cables to go directly to the starter  At this time I also replace the 2 8D's with 3 group 31's. However, in testing I had a brain fart which resulted in frying the starter. After replacing the starter  I found that it will start very well EXCEPT when the engine is hot. It takes a couple of hours of cooling before it will start again. Even starting down to low temps (35 deg) it will start with a little patience. This problem creates dicey situations when refueling (some places want you to shut the engine down) and gets really interesting when trying to get the propane tank filled. I don't even want to consider what would happen if the engine stalled in rush hour traffic.
Anyway, any and all suggestions are welcome. Although I HATE the thought of having to remove and replace the starter again I hate the other alternatives even more.

Thanks

Fred

[desi arnaz]

Remove and replace.....".

[zimtok]

It may not only be your starter.

I know from being an old Pontiac owner that that one of the main problems they had was trying to start while the engine was still hot.
Hot electric motors are less efficient and require more amperage to run.
The farther the batteries are away from the motor the more voltage drop there will be.

Because you moved the batteries farther away you need to have larger cable to carry the current/voltage. Every place there is a connection could be a point of power loss. And if your connecting to the chassis near the batteries for your ground it now has to go through more chassis connections to get to the starter.

First thing I'd do is clean all of your connections including the ground cables from the chassis to the engine/starter motor.
Add a ground cable directly from the battery to the starter.
Make sure your battery cables are large enough to carry the amperage the added distance.

.

[bobofthenorth]

I don't know what engine we're dealing with but for our 8-92 it took a double run of heavy battery cable (2 runs of 2/0 cable), double ground cable and finally a switch to an MT39 starter to solve the same problem.

[Fred Mc]

Actually Zimtok, I moved the batteries closer to the starter. And when I did the change I put in all new cables, connection etc. The cables now run Directly from batteries to the starter rather than through connection on the original setup.

The motor is an 8-71 left hand turning so I can't use an MT39 starter Bob, Too bad. But I might just try the double cable thing. Probably the easiest to do at this point.

Thanks

Fred

[Lin]

Have you used an IR gun to see how hot the starter is when you shut it the engine down?  Does bypassing the solenoid or relay make it spin?

[bobofthenorth]

Before you start spending a bunch of money it might be a good idea to figure out what you're actually drawing on those hot starts.  Copper's expensive now.  Prevost Mira Loma told me I was drawing over 1000 amps when they advised putting on the 2nd cables.  I'd have a real good look for a high resistance connection before I coughed up for the 2nd set of cables. 

[Red Rider]

I experienced the exact same situation with my 4106 8v71 spicer. I bought it from the  PO in Quartzsite several years ago. I drove it to my home town and dropped it off at a shop to have it serviced. Keep in mind we are in snow country so COLD starts are the norm. The next day I went to the shop to move to the service bay. Right there and then the starter died. Of all places for a starter to go out-- in a repair shop. The took the old starter out and sent it to a rebuild shop and put it all back together. I didn't travel again until the following May. I drove to Las Vegas (250 miles) and fueled up. I shut down to fuel and guess what? No start, not even a click. I was at Love's plugging up the fuel dock and the manager vary politely said move it or get it moved. I had to call Coach-net and have it towed 100ft to a parking place. It was a cold day with big winds so crawling under the rig was out for the time being. Anyway one hour later I tried it and it started right up. I went on with the trip and had the same problem outside Tucson.

The bottom line is-- when they installed the starter they connected the jumper that is supposed to go to the ground lug-- to the hot side of the solenoid.When I was driving, the Alt. was heating up the solenoid. Once it got hot it wouldn't "pull in". I put the wire where it belonged and have since found another repair shop.

Hope this helps.

[luvrbus]

How many amps are your G-31 batteries you may not have enough battery you get the same amp with one as three on a 12 volt system the Mt 42 is a high amp starter if you installed 925 amp G-31 batteries you will always have starter problems.

A Mt42 Delco starter will draw 1650 amps on a 12 volt system 800 on a 24 volt systems that is a 10.4 hp starter fwiw,a 1750 amp 8D is the battery is what you need.

The Mt 42 is a good starter and will last for a long time but they will not tolerate low voltage and amps for very long


good luck

[Fred Mc]

I'm not sure of the amps on a group 31 but if it is 925 am I wrong in assuming that 4 would give you 4X925=3700 which is a little more than 2x8D's at 3500 amps?
I went with 3 smaller batteries as I read many posts on here where people got rid of their 8 D's and went with 2 smaller batteries with seemingly no ill effects.

[akroyaleagle]

I relented last year after all these years of 8Ds and decided to replace my two with three group 31S.

Bad mistake! I too had to replace my starter and the coach sometimes wouldn't start.

I would rethink the connection from the batteries direct to the starter. I run two 8ds and each one goes through a master shutoff. That gives me two sets of cables also. I believe the batteries should be shut off any time they are not needed. I can see problems in not having a battery disconnect.

[JohnEd]

Fred,

Listen to BON.  Work smart!  Just the facts, Ma'am, just the facts said Friday.

Call you repaid shop for electrics and find out what the minumum voltage spec is.  That is your critical number and if you grind away at a voltage lower than that you can expect to overheat the starter and burn it out.  That's a fact!  Facts are stranger than fiction and wouldn't you think that more current would be worse than less, as far as heat is concerned?  You would and you would be right...its complicated.  Your bats may be under sized but adsequate.....I don't know....but you can easily tell if the bats are the problem.

Attach a volt meter to the plus and minus terminals of the starter.  The terminals, now, mind you...not the nuts that attach or the cable fitting....use the actual stud that runs into the starter and if there is no ground stud then get a really good contact on the starter frame.  Disable fuel so it won't start and crank the engine.  Remember that minimum voltage that the manufacturer specifies?  Do you have that or greater?  If so the starter is bad.  If not, find the poor connection with a IR heat gun.  Connect a volt meter "across" the connections or the wire runs to learn what their resistance is dropping.  If you have low voltage at the starter then the seconfd thing to verify is the battery(s).  To do that connect the voltmeter to the battery posts, not lugs or cables... posts.  Crank and you should see no more drop than a couple volts.  Remember that min voltage?  Can't get there if the bat actually drops below that value.

Batteries actually perform better when warm, most knew that.  The resistance of metal goes up when it gets hot so when hot the starter should work with less efficiency while the opposite is true for the battery.  The loss in the starter is a really minor value while getting the bats to 32 degrees cuts the power a lot.  You knew that, also.

Measure the bat term voltage while cranking and also the volts at the starter posts and post that info...please.

Thanks,


John

[Fred Mc]

"Measure the bat term voltage while cranking and also the volts at the starter posts and post that info...please."
John, should I do this when engine is cold(no problem starting then) or when it is hot (problem time) or both.

Thanks

Fred.

[JohnEd]

It would seem to be so much fun i would do it twice.   All the data helps to figure the problem.

What temp does it have to be before it won't start?  180 for 5 minutes?  heat soak after climbing a hill?  Start it after measuring the voltage at the starter and at the bat.  Enable the fuel, start it and drive it warm and home the stop the engine and try a restart.

Use thin wires from the terminals to the digital volt meter.  it draws so very little amps that the wires can be no thicker that a hair.  Use good clips to attach the voltmeter extension wires and leave them in place after making the first measurements of the starter and bat.  You should only have to crawl around in there once to hook up.

I forgot to mention that you should measure the bat voltage before starting the measurements.

When you say "won't start" do you mean that the engine turns over as it should but the thing just won't start or do you mean that it won't turn over?

Good luck,

John

[luvrbus]

When you wire batteries in parallel on a 12 volt system you get more capacity not cranking amps if you going to use that system use at least 2 cables you can start a 8v71 on a single g-31 when cold but not hot and other things can cause the problem besides the electrical  but that is another story.
Eagle has used 3 group 31 (1050 amps each) for years without problems but it is not a single cable system

good luck