Hey everyone, I'm pretty bummed that my first post is under these circumstances, but here I am and I need help ASAP. My bus is a 1969 GM model 4107 conversion with a strong 8v71t paired with a V730 automatic. It had been sitting for a couple years in covered storage when I bought it. I went through the basics and other than a typical slight oil leak,and airbag leak it fired right up and ran strong. I set out and made it about 300 miles before the temp started to rise. I pulled off before it had a chance to overheat (got up to 202) and waited an hour and when I went to restart nothing happened. It wouldn't turn over. I have power to the starter but when I looked at all the wiring in the engine bay I noticed that most of the wiring looks super old. there are 3 blocks that can be split and pulled away by hand and most if not all the wires going to those blocks and in very poor condition and the blocks themselves were full of dust and dirt. Does anyone have a repair manuals for a 1969 model 4107 and the 8v71t? Also if anyone has good wiring diagrams that would be awesome as well. Thank you all in advance!
A little help here. I am near two interstates but have no idea where you are. Your location would get you better responses I would think. With power to the starter is it possible for you to jump the solenoid?? Any additional information could be helpful. Yes most of the wiring is our older buses is old. Some of it keeps working and some needs to be updated as necessary. Keep us posted with any updates.
Melbo
Hey Melbo, so I was able to get the bus towed off the side of the freeway to a parking lot in Grandview, WA. I have only tried to jump a starter once in my life and it wasn't pretty so I figured since I'm in a better place to work on it that I would just take the time to fix it right. Do you have any manuals that include wiring by chance? Thanks for the reply!
First - don't panic and start tearing things apart. Now that you're in a safe place you can work through this methodically. Daylight will help a bunch.
Here are a couple of wiring diagrams from the 4108/4905 book - not exactly the same as your but hopefully you can get a general idea of how GM put things together. One is for the Engine Controls and includes the start circuit. The other is for the Alarm & Signal systems which include the shut down for things like over heat. Hopefully someone will post the 4107 diagrams later on when people wake up and see your posting. I do have the 4107 repair manual and will post the diagrams of the electrical panels in a few minutes.
As sketchy as that wiring looks, it's unlikely your problem. At least not the wires themselves. Likely the problem is confined to a loose connection, corroded terminal, bad ground, or other relatively minor thing.
In no particular order:
Switch out of place - In a panic shut down, it's easy to not go through the shut-down procedure correctly. Same for restarting in a breakdown. Make sure that all your switches are in the proper place for starting. Make sure that the controls in the engine bay have not been accidentally moved to the incorrect position. Can't tell you how many people suddenly discover their bus won't start, only to find the rear controls out of position. Happens to nearly all new bus owners, myself included.
Neutral safety switch - When you shut down during the over heat situation, did you put the bus in neutral? Won't restart if not. This may or may not be a problem, as some V730s are installed so that you can't shut down the engine unless you're in neutral. Also, check the neutral safety switch itself. If the switch fails, the start circuit won't complete and you won't start.
Overheat protection shut-down - If you actually over heated, your protection circuit may have kicked in. Should reset, unless a relay is stuck.
Stuck relay - the start circuit uses a number of relays, as does the safety shut down system. These are essentially the logic circuit/computer for the bus. Sometimes taping them gently helps if one is sticking.
Bad ground - these old buses are notorious for bad/loose ground connections. You might have been lucky when you initially started it, but those few hundred miles of travel were enough to loosen the connection enough that it's not working. Could be to the starter solenoid, could be the neutral safety ground, could be any number of places. I'd start in the battery bay and check the ground there, then work outwards.
Starter solenoid - they do fail sometimes. You can jump it to test, but I'll leave that to others to explain since I have never done it.
Start Circuit diagram from 4108 book.
Your safety shut down system may have kicked in when your temp rose. Should reset on its own, but perhaps a relay is stuck. Unlikely, but here's the diagram from the 4108. Not the same, but might be close enough to help.
Drivers control panel
Engine control panel.
I can take photos of other pages from the manual if you need. The manual covers 4107/4108 so it should be helpful. Just let me know what you need.
Good morning Dominick,
Any updates for us?
Also, when you say 'nothing happened', does that mean she tried to turn over but couldn't? Or complete silence; and maybe (as with MCI - automatic trans) if the gear shift is in drive vs neutral and she won't even attempt to turnover? Or ..?
Please let us know when you can! Best of success - Phil
You can jump the starter if it is not a battery problem,on a GM you need to go in from the rear floor for easy access ,only takes a wire from the solenoid (small terminal on the bottom of the solenoid) to the battery side of the solenoid
Yeah like plyonsMC9 said, I'd be interested to know if it's even clicking, does it try and stop? Obviously the worry here is Hydrolock. Try and bar it over , or hit the starter in the rear real quick. Don't want to lift the head with water in the cylinder.
If he has power it will click regardless and you can bypass the wiring,starter button or switch.safety shutdowns and relays to start the bus,I believe that is a 24 V system so check for power at the battery terminal on the starter
Since it is already converted, hopefully you have inside access to the starter. Some conversions covered over the access panel. If that is your case, you can easily get to it from underneath. First thing you MUST do though, is to place solid blocking under the body reinforcements where the torque rods attach, in case an air bag fails while you are under there. Now there is easy starter access through a hole in the bulkhead between engine and starter, unless you are...lets say overly thick. You sit up between differential and rear bulkhead, and there is the opening to access the starter and wiring. Btw, that is the best way if it is necessary to replace the starter. Lifting it up through the hole inside is pretty tough, as the starter is real heavy.
Has anyone made contact with the OP?
It would be really helpful for us offering advice if he could provide a bit more information. Otherwise, we're all guessing of course.
I'm still hoping for his sake that it's just a simple electrical gremlin - we've all experienced those and they're much easier to fix than having to pull the starter.
Hey guys, so far no change, I checked to make sure all my switches are in the proper spots, my batteries are brand new and fully charged. I'm not sure that my bus has a neutral safety switch as it does not have a neutral position on the shifter. The way it was converted, I can not access the rear of the engine from inside, I have to go in through the side above the transmission which is really making things difficult as I can't get as close to the starter and wiring as I would like. I was able to jump the solenoid a(by feel not sight) and my starter turned so I believe that tells me both my starter and solenoid are good correct? Does anyone know if those quick release blocks are in fact grounds? Cause I really believe that is my problem. I am going to run a new ground wire to the solenoid and see if it'll turn over. Any other ideas are welcome! Thanks again for all your help. I'll keep you posted.
There has to be a way to put your transmission into neutral. It may not be marked, but your transmission has a neutral. The neutral safety switch is on the transmission itself, not the shifter.
Not sure what you mean by quick release blocks??
Quote from: richard5933 on December 12, 2019, 12:21:23 PM
There has to be a way to put your transmission into neutral. It may not be marked, but your transmission has a neutral. The neutral safety switch is on the transmission itself, not the shifter.
Not sure what you mean by quick release blocks??
The neutral switch can be inside the shift tower there are lots of those around I keep the switch in stock for the shift towers
Quote from: luvrbus on December 12, 2019, 12:25:38 PM
The neutral switch can be inside the shift tower there are lots of those around I keep the switch in stock for the shift towers
Didn't know that. For the V730 or just the 4-speed?
Quote from: richard5933 on December 12, 2019, 12:26:55 PM
Didn't know that. For the V730 or just the 4-speed?
All old Allisons transmissions
Quote from: richard5933 on December 12, 2019, 12:21:23 PM
There has to be a way to put your transmission into neutral. It may not be marked, but your transmission has a neutral. The neutral safety switch is on the transmission itself, not the shifter.
Not sure what you mean by quick release blocks??
[/quote
If your looking at all the wiring on the back of the engine bay, there are 2 small blocks and 1 large block with wires attached. The blocks split in half with half the block staying attached to the firewall and the other half with the wires connected pulling free. I would post a picture if my camera wasn't broken.
PM sent with my phone number. I've got the manual in front of me - I'm happy to help you figure out the wiring if you want to call.
If he has a Stone/Bennet shifter he probably shut it down in gear, when that happens you get nothing till you manually put the transmission in neutral
Quote from: luvrbus on December 12, 2019, 01:46:14 PM
If he has a Stone/Bennet shifter he probably shut it down in gear, when that happens you get nothing till you manually put the transmission in neutral
That sounds familiar. Panic sure sets in fast the first time that happens.
Yep,been there, done that, saw the movie, twice.
Kind Regards, Phil
Quote from: 69M4107 on December 12, 2019, 12:49:04 PM
If your looking at all the wiring on the back of the engine bay, there are 2 small blocks and 1 large block with wires attached. The blocks split in half with half the block staying attached to the firewall and the other half with the wires connected pulling free. I would post a picture if my camera wasn't broken.
Sounds like you are looking at the "Regulator and Apparatus Panel". All those terminal blocks should be mounted to the firewall. I'll post a photo of this from the manual. I don't think this is where your problem is though. The controls for the starting circuit are in the "Engine Bay Apparatus Panel", which I posted a photo of earlier. It's likely got an aluminum cover on it and is located on the upper firewall above the engine.
At least on my V730, the neutral safety switch is inside the transmission. I know this since my cable shifter has some play in it and it can indicate neutral, but still in gear. Solution-always make sure it is in neutral before shutting down the engine. Good Luck, TomC
Try holding down crank switch while moving shift handle a touch back and forth.
I just got into this thread and realized your only about 40 miles from me. Let me know if you need a place to stay and if you were able to get the bus running. I'm not a mechanic, but I have had several buses and have gone through a myriad of similar issues. I would love to help in any way I can. Please don't hesitate to let me know. Glennman.
Thank you for the kind offer Glennman, at this time I'm not sure what I'm going to do. I am flying into Yakima this morning and am hoping to find a shuttle down to the bus in Grandview. I'm planning on staying there till its fixed. If you have or know anyone that has repair manuals for the 4107 and or 8v71T in digital format that would be an awesome start! If you feel like working on a really cool bus in sub freezing temps you're welcome to tag along! haha
What type of shifter do you have for your V730?
A toggle switch or a shift lever?
I have a shift lever.
Here's a photo of the top of the governor on my 4108. It's not exactly the same as yours, but the relevant bits are really close.
To shut down the engine, there is an air solenoid which sends air to the engine stop air cylinder. It will then extend and push the stop lever.
Got it. Mine is similar!
Dominic you can get about all the info you need if not here on Vintage Bus Repair or the 4106 group .I add a starter button to all GM because the rear start always seems to be a problem along with front :-X you can buy a remote starter switch from parts houses (2 wires clip on) ) that will help you a lot being able to bypass the OEM system those old engines are real simple to make run.
Bypass the starter buttons if it spins and no start that is a different game could be the safety shut down is not resetting and those are easy to bypass too let us know,if the engines spins over we can get you started and to a warmer place.The 4107 never came with a 8v71TA that was added and most likely the starter circuit has been modified to
So I have been all over that group and no one had the 4107 manual but I think I got everything I need for the time being from Ruchard. My flight just landed in Yakima, going to retrieve my tools and catch a ride down to the ole girl. She needs to come home to the heated shop that I just built just for her!
Your bus has been modified no telling what you find :-\ but if spins we can get it running
Please make sure you have good charged batteries. No need to burn up the starter in the process, due to weak batteries and cold temps. 22° doesn't help any.
So I finally got down to the bus, I have charcoal going under the oil pan to warm it up, the batteries are reading full and I'm about to rewire the solenoid. Can anyone tell me how many wires should be on each solenoid post?
You have the positive cable,a small hot wire at the bottom and a small ground on the solenoid at the bottom also grounded to the starter that is all, the start wire (button or key) will be marked "S" and the ground will be marked "G"
Before you rewire, have you confirmed that the ground is good?
I was just going to run a ground wire to the frame.
That will work - just make sure that the ground from battery to chassis is good, as well as the one from the engine to chassis. They can be rotted on the inside but look good on the outside, so give them a tug to be sure. Wouldn't hurt to check the connecting bolts on those cable for corrosion and such. I'm gonna guess that a huge percentage of all electrical problems on the older GM buses can be traced back to a ground problem.
Your starter has a ground lug for that wire with the ground for the starter keep it as close to OEM as you can is the way I would do it .On GM's I run the ground from the battery direct to the starter then to the frame,the connector at the bulk head always seems to be a problem on GM buses
Thanks, I'll do that. I'm praying that's it.
I'm about done guys. It's too cold and I'm getting nowhere. Is it possible to tow my bus with the rear wheels on the ground without doing damage to the transmission?
Rear axles should be pulled or the driveshaft or it will do damage the the tranny
What's easier to do? And do I need special tools to do either?
Wrenches for drive shaft ( don't know on a GM but on an MCI it hard to get under it unless it is jacked up and blocked first to get to it but once there pretty easy to get out)and add a double jack or 10 or 20 lb sledge for the axles. A good tow driver know how to pull the axles, not hard but have to hit it hard on the end after pulling the end plate and drain the oil into a short bucket under it. It will pop out just enough to get hold of it with a bar and out she will come then it just has to be covered so it doesn't eak all over the place. A bit messey.
If not far a wheel lift under the front wheels or landall and put the whole thing on it. Do not pull it from the front hooks or lift it by them.
Look in the book it will tell you how and where.
If it were you would you pull the drive shaft or the axles?
I call Coach net which I pay for every three years and let them know where I was and tell them I need a landall come pick me up. :) Then watch to driver to make sure he put it on the trailer correctly without bending it or scraping the bottom, etc.
If I didn't have them I would pull the rear axles unless I could get under it safely by blocking it up high enough to get to the drive shaft to pull it.
I had my old fishbowl (Allison Automatic) towed once. The driver disconnected the drive shaft with little effort, and it towed just fine. By the way, where are you towing it to? I have over an acre that you can park it on for as long as you need to. You can work on it at your pleasure, or have mechanics come by or whatever. I work full time, so I cannot make it down there right now, but plan to take a drive your way this weekend just for the challenge of finding you in Grandview. Hope to see you there. Glennman
Yea... 👍
I was going to mention that I am in Yakima Wash. Good luck.
Thanks Glen, that's very generous. I might just take you up on that. I'll shoot you a PM tomorrow when I figure out what my plan is.
Ok, I'll be looking for it.
We had our 4106 with a V730 towed after our wreck. It took the tow driver about 5 minutes to pull both axles. They are used to doing this, and if they don't you will potentially ruin the transmission. A guy on one of the boards ruined his rear axle towing without pulling the axles, and another had his transmission seriously damaged.
These tow guys know how to do it - insist that the axle gets pulled. Lots easier than pulling the driveshaft.
According to the manual your hubs have greased bearings, so pulling the axles should only result in a little oil coming out and not be a terrible mess.
Agree that the front tow hooks will NOT support the weight of the bus.
Sorry to hear that you couldn't get it running on the roadside.
Can you fill us in on what things you tried and what the results of the efforts were? Possibly we can help you continue troubleshooting once you get the bus somewhere you can work on it.
Were you able to get the engine to turn over with the starter? Did it try to fire at all? If it's turning over, was there any smoke in the exhaust at all or any indication that fuel was flowing?
Pull the axles and put plates over hub holes. If it has factory greased rear hub bearings, there will be plates behind axle shaft flanges to keep rear axle oil separate from hub grease. In that case, just securely stuff a rag in each axle tube. How far are you going to tow it? You could pull the driveshaft instead, but that would be a pita in your situation. The plates can be made out of cardboard or plywood.
It might be engine damage if the starter and batteries are good as he said 202 is hot for those cold temperatures,he needs to use a 1-1/2 socket on the cam pully and make sure the engine will rotate it is a bummer anyways
Maybe coolant in one of the cylinders from a cracked head? Good point Cliff. Although he should get it towed now to where it will be easier to diagnose the issue.
Quote from: 69M4107 on December 18, 2019, 09:46:49 PM
If it were you would you pull the drive shaft or the axles?
You had it towed on 11 Dec to the lot it is on now, what was done then, pulling the driveshaft or axles? I hope your problems were not added to by improper towing.
Why would anyone screw around pulling a driveshaft? Under there? And who is being PAID to do this...???
Just do the axleS, plural.
Beware the tow driver who takes shortcuts, both axles need to come out.
We can all list the reasons you CAN get away with one, but we know when and where. Most busnuts are towing and asking because they CAN't diagnose the problem in the moment.
The busnut that doesn't know, only needs to know, "Both axles out please."
Happy coaching!
Buswarrior
Ask for a flat bed and pull nothing
Flatbed is not much good in the east...
Someone put all those bridges in the way.
Even the tow has to be very careful not to hoist the nose into the air too far.
Broke down busnut is very much over a barrel...
Happy coaching!
Buswarrior
Quote from: buswarrior on December 19, 2019, 12:47:21 PM
Why would anyone screw around pulling a driveshaft? Under there?
My thoughts exactly. Whacking the end of the axle with the sledge can be a bear but crawling under there to disco the driveshaft? No thanks.
4107 along with the 49 series have about a 22 inch driveshaft. It is somewhat a pita to remove even with a pit. On the otherhand, a 4104 driveshaft is 4 feet. But some of the still original 04's still have the brake drum at the back. At least on the 04 you can unhook at the diff end and tie it out of the way. Not as easy on the newer models since they don't compress much at the slip joint.
Quote from: 69M4107 on December 18, 2019, 08:08:55 PM
I'm about done guys. It's too cold and I'm getting nowhere. Is it possible to tow my bus with the rear wheels on the ground without doing damage to the transmission?
His page three post was why He got the answer he did. It was an answer to his question and I agree with Clifford put it on a Landall or use a wheel lift but that was not his question.