Help needed badly

[Essexeddie]

I have a problem with my starter motor on my 54 3100. Its slipping on certain sections of the ring gear. We have had the ring gear off and moved it round twice but still slips at TDC on certain cylinders (obviously the highest compression).
Should the starter motor be adjustable as mine isn't, it looks newish and 12v. Have I got the wrong starter motor which I believe is not running close enough to the ring gear causing it to slip?
It's bugging me. Any info would be great thanks.

[dsraven]

is your truck 12volt? is the solenoid/bendix 12 volt? is the end of the starter gear ground up? possibly the starter gear is slipping or the solenoid isn't strong enough to "pull it in" all the way. yu could try bench testing to see if the drive engages all the way.
check all the connections from the battery to the starter, I mean like take them off, clean then and re-attach. ensure there is a good ground strap from the battery to the engine and frame. a lot of starter issues are a simple poor connection or a battery post terminal that "looks good" but when taken off it is black with corrosion so there is a lot of resistance. also. a lot of guys will overlook the ground cabling because they feel it is the positive terminals that do all the work because usually they are the corroded parts. in reality the negative cables do just as much work so everything needs to be bright and shiny. a star washer under the frameand engine ground cables is a great idea as well. it helps keep the connection tight and making good connections. lots of guys will forget to install a good ground cable to the frame and the engine as well.
just some thoughts

[Essexeddie]

Originally Posted by dsraven

is your truck 12volt? is the solenoid/bendix 12 volt? is the end of the starter gear ground up? possibly the starter gear is slipping or the solenoid isn't strong enough to "pull it in" all the way. yu could try bench testing to see if the drive engages all the way.
check all the connections from the battery to the starter, I mean like take them off, clean then and re-attach. ensure there is a good ground strap from the battery to the engine and frame. a lot of starter issues are a simple poor connection or a battery post terminal that "looks good" but when taken off it is black with corrosion so there is a lot of resistance. also. a lot of guys will overlook the ground cabling because they feel it is the positive terminals that do all the work because usually they are the corroded parts. in reality the negative cables do just as much work so everything needs to be bright and shiny. a star washer under the frameand engine ground cables is a great idea as well. it helps keep the connection tight and making good connections. lots of guys will forget to install a good ground cable to the frame and the engine as well.
just some thoughts

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[Essexeddie]

Originally Posted by Essexeddie

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Thanks for reply. Yes it's 12v and always understood that the truck was originally 6v which makes me think it's the wrong starter motor. It does start after I move the engine over slightly using the fan. Once it's turned it carries on.
I've always understood that the starters are adjustable with shims but this one doesn't. I'm stumped?
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[dsraven]

when it cranks over does it sound like it is turning as fast as it should be? check all the cables full length for bulges etc that would indicate corrosion inside the cable sheath. they may not be as bendy in some spots either which can indicate corrosion under the sheathing and poor conductivity. you could also do a voltage drop test to see if the cables are conducting as they should be with no resistance from corrosion or poor connections. if all connections, cables etc are good and it still cranks slow then I would remove it and have it checked out for rotational speed free running etc. a starter rebuild shop will know the specs and be able to test it.
if it is a key start, not a pedal on the floor, then it could be a bad solenoid, inside the solenoid is an electromagnet that is energized by the key and pulls in a plunger that contacts 2 points together. sort of like a big washer on the end of a plunger that is drawn back against two contact lugs. one lug is battery power and the other lug goes to the motor. that is how the starter gets power to the motor. anyway, over time or non-use the contacts can get corroded or worn so there is not a good contact anymore. the result is a starter with less power to turn because it is not seeing full voltage due to the resistance of the connection in the solenoid. the solenoid also pushes the starter gear out into the flywheel teeth, if it is a key style starter system, so if it isn't getting full power it may not contact all the way into the gear on the flywheel.
a pedal on the floor style starter has a mechanism that pushes the gear into the flywheel ring gear as it also pushes a switch, mechanically, to energize the starter motor. the contacts can get dirty or corroded as well as the linkage can also be out of adjustment so the gear is not fully engaging the flywheel ring gear. one issue could be a bad engine mount allowing the engine to move around which can affect the linkage. check it all out then get back to us. some pics would help.

[dsraven]

does your starter look like one of these? one is electrically operated solenoid switch and the other is the pedal on the floor mechanically operated switch.


http://pic20.picturetrail.com/VOL131.../214808855.jpg

http://jimcartertruckparts.com/image...arters%202.jpg

[Essexeddie]

Hi thanks again. It's a floor pedal operated. I really don't think it's an electrical problem as when it does engage it spins it over easily. It just doesn't engage all the time. I have chalk marked the flywheel where it doesn't engage. I feel it's just not engaging deep enough and it can't be adjusted. The existing starter looked new when I bought the truck a couple of years ago. Which was imported from California. Which makes me wonder if it was a short quick fix to an existing problem. The problem is getting worse.
Btw it's the second picture (floor operated) looks identical.
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[dsraven]

I would say pull the starter and check the depth of the starter gear from the mounting flange, then compare that depth with the depth of the ring gear from the starter mounting flange. I also think there is a different ring gear for a 12 volt starter compared with a 6 volt starter. maybe the teeth are not matched up so they don't match. number of teeth on the flywheel maybe not right for the starter, or vice versa.

[Essexeddie]

Originally Posted by dsraven

I would say pull the starter and check the depth of the starter gear from the mounting flange, then compare that depth with the depth of the ring gear from the starter mounting flange. I also think there is a different ring gear for a 12 volt starter compared with a 6 volt starter. maybe the teeth are not matched up so they don't match. number of teeth on the flywheel maybe not right for the starter, or vice versa.

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[Essexeddie]

Sorry for the delay. Time scale. Your comments are my sentiments. I think it's not quite engaging and only just on good teeth but it soon wrecks them. My ring gear has 139 teeth which I would presume was for a 6v starter. How can I get over using a 12v starter? I will as you suggested measure the distance of the throw and compare with the flywheel. As I sure this is the problem. If it is I'm not sure how I can get over it? May not have time for a week as I'm off to Prague for a week. Thanks for your input.
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[dsraven]

you know, the 6v starters will handle the intermittent load of being used with 12v quite well.as long as the engine tune is good so they don't crank the starter for extended periods, like more that 10-15 seconds. longer will start to melt the solder in the commutator. is there a 6v starter available that you could borrow or get for a decent price so you could try it? otherwise, my suggestion is to check the web for specs on the diff between the 6 and 12v ring geras and starter drives.

maybe someone else has the answer about the different ring gears? I think it has to do with the number of teeth on the 6v compared to the 12v flywheel. if I remember correctly, and it has been awhile, the 6v ring gear has 139 teeth and the 12v ring gear has 168 teeth? there are different style starter drive gears as well, some with more or less teeth and they don't swap because of different shaft sizes, i think, and also they are a different diameter. this may explain why the starter doesn't seem to work properly.

possibly start a thread with that title? there are some really smart guys on here and someone has probably had the same issue if the thread is titled correctly and they actually look at it.

cruise the net for a thread about ring gear differnces on the chevy 235?

I found this that may be helpful. the second link has a good explanation that may be pertinent to your truck. it may be hard to figure out though because you don't know the complete history on the unit, just know what you have now. anyway, maybe worth checking out.

http://www.stovebolt.com/ubbthreads/...t&Number=11056

http://www.devestechnet.com/Home/Flywheel

[Essexeddie]

Thanks for your interesting comments. You have just endorsed what I have been thinking for some time. I will first measure the distances as mentioned before and try to locate a 6v starter. A lot of guys here rip the old six pot engine out and fit in a V8 so hopefully I will get hold of a starter. Great posting thanks. Gives me some hope at last.
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