| Author |
Message |
ktrout01 (12.243.136.90)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 27, 2002 - 12:57 pm: | |
OK, I'm looking for help on this one. My 4905 had been getting harder to start. It finally died when I was bringing it home for the first time. Mike McCarthy (another busnut here) brought over his batteries and jumping didn't work. Not the batteries. A wrecker got me started by pulling me. I thought it was the master switch and that would have been an easy fix. I jumped across that and proved that it wasn't the problem. Searching the archives here, I found several earlier posts and followed those suggestions. I took apart all the connections from the batteries to the starter and cleaned all the terminals and related hardware. I found the ground connection from the back of the starter to the bulkhead was frayed and I replaced that with a new piece of 2/0 welding cable (per da book)and shiny new copper lugs. The batteries are only a few months old and fully charged and the block is toasty warm from the block heater. On turning the key and pushing the start buttom I get a nice solid "click" of the solenoid pulling in and the starter doesn't do much of anything. The motor runs fine when the starter last worked. My next step would be to pull the starter if anyone doesn't have a better idea. Pulling the manifold above the starter wasn't too bad but I understand that bottom bolt on the starter isn't alot of fun to get at.
ktrout01
4905A-1539 |
Clarke Echols (207.92.201.104)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 27, 2002 - 5:19 pm: | |
Your approach is called "shotgunning", and it's a good way to waste time and money looking for a cause.
Get yourself a good voltmeter, and connect it across the +24-volt terminal on the starter solenoid that connects to the battery (+) side
on one lead with the negative lead to the engine frame and look for 24 volts. If you have that, hit the starter switch and see what it does. If it goes to zero, the starter isn't getting the current it needs. If you get a full 24 volts, the problem is in the starter or the solenoid. In normal operation, the voltage will likely drop to 18-21 volts or so, depending on battery condition.
Another measurement to make is from the engine frame to the battery (-) terminal while the starter is energized. Voltage should be minimal; certainly under a volt or so with engine cranking.
If the starter voltage is normal but it isn't turning when the starter switch is ON, check across the coil terminals on the starter solenoid to see if it is getting 24 volts. If not, there is a problem upstream in the circuit. Many times there is another solenoid that runs the solenoid on the starter because a starter solenoid can pull 20-40 amps, much too much for a starter switch.
Follow the voltages. Connect your voltmeter negative lead to a good frame ground, then measure voltage at the engine block ground -- should be zero. Then follow the +24 volt supply from battery to starter, including solenoids. That should quickly reveal the source of the problem. It's not rocket science, but don't go swapping parts until you find the culprit, keeping in mind there could be more than one.
Solenoid relays (including starter solenoids) do nothing until they have voltage across the coil. If the solenoid fires, the voltage on the input and output side of the solenoid should be the same. If the starter has voltage but isn't turning, it is likely the starter, but it's usually easier to troubleshoot voltages than to pull a starter and take it to the local starter shop to have it tested. |
Tom Caffrey (Pvcces) (12.146.33.83)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 27, 2002 - 7:54 pm: | |
You're right about the starter not being any fun. If you do get to the point of having to remove it, you may find that it has a 12 point 5/8 head on the lower bolt, without enough room to put a socket on it.
If you run into that situation, as we did, you may find the easiest fix is to get a manifold wrench. They are a U shaped double box end wrench, and when you have it on the bolt, you can turn the bolt far enough to reset it and do it again.
Straight wrenches are almost impossible to work with in that situation. If you need to make a wrench out of a straight one by bending it, you'll need to start with one at least ten inches long. 5/8 X 9/16 is the right size.
The good thing is that after a turn or so, you may be able to turn the bolt with your fingers. If it is tight, you may have trouble getting enough leverage on the wrench to get it to move.
We found our wrench at a Sears store after checking around quite a bit. We carry the wrench on the coach, just in case.
Even though DA BOOK says that the starter can be lifted up through your access hole, we found it much easier to slide it out over the top of the transmission (stick shift), partly because we had to unhook some of the shift linkage to get the room to work.
A mechanic warned me that if you remove the manifold, which is pretty easy, when you put it back on, it is easily broken as you tighten the bolts.
He recommended wiggling the manifold as the bolts were tightened a little at a time, so that I could be sure that it was seated properly. The manifold tries to hang up on the ledges that it sits on.
We had a bad rebuild in our coach, and got to take it out a couple of times before all the problems were solved. It was really messed up, but it wasn't obvious from the systoms.
I hope this helps.
Tom Caffrey PD4106-2576 |
Jayjay (207.30.115.92)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, January 28, 2002 - 12:51 am: | |
Drag your batteries to the engine bay, hook jumper cables directly to the starter,and ground, and then to the batteries. Makes a pretty big spark when you do it, so make sure there are no explosive fumes around. This will tell you if the starter is any good. If it won't spin this way, then go buy the u-shaped wrench. Keep us informed please? Cheers...JJ |
Oaepalmer (Oaepalmer) (208.164.96.34)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, January 28, 2002 - 1:33 am: | |
When I bought mt coach it had a very slow turning starter, the guy I bought it from said "I think that sounds like the starter is headed south, I'll toss in another one just in case."
2 weeks later the starter refused to turn the motor over.
No one told me about the access cover under the rear seat, but when I saw how they had the starter stuffed in there I KNEW from previous GM experience that the engr's would have made an access port somewhere.
I found the flange with a flashlight w/o going under the coach, and even tho I am small enought to fit into the space between the motor and the bulkhead, I decieded that the access port was there for a reason and to use it.
THEN I found out about "THE LOWER BOLT"..!!
I had been using my 3/8th's drive sockets, and quickly discovered that the socket wouldn't fit on the bolt head because of tight clearence, I started to think about a sacrifical socket, that I would grind down to fir the space, then it dawned on me that my 1/4 drive sockets were thinner.....GUESS WHAT...with an adaptor to a 3/8ths drive the lower bolt is a breeze with a 1/4 drive deep wall socket.
I pulled my exhaust manifold also.....and had it ceramic coated to keep the heat from escaping to the surrounding metal like the bottom of the seat which happens to be the TV support.
It is SOP whenever one removes a cast-iron manifold, it absolutly must be re-tightened in equal and sequenced ammounts to avoid cracking it....
I became a quick expert at changing out a starter motor because the "other one" I was given turned out to be just as bad as the one I pulled out in the 1st place.
While I was in tha area I replaced the battery cables that were starting to look worn and with brittle insulation, and found one that had worn thru due to contact with the clutch rod and I also replaced the original ground strap which was starting to look a little fuzzy.
Now that it has a new starter in it, the motor will turn over and fire with just momentary contact on the starter switch..!!
OAE Palmer 4106-2505 |
Frank Allen (205.188.197.51)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, January 28, 2002 - 4:49 am: | |
I pull mine out from the bottom working through the access hol;e in the bulkhead, i can get a socket on both of the nuts with an extension, dis conect the wires and it will come back through the hole , it is a dirty job but didnt have to have any special wrenches, i can sit up under there and work, i can change one in a hour. i have a 4106. there is some kind of breather on the side of the engine that has to be removed but is is easy to do.
Frank Allen |
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