Starter question and a story

[SUX2BU99]

Simple question first: I think my starter has gone south. I have no idea how many teeth my flexplate has but my 350 is I believe an early 70’s model and it seems that 168 tooth is the most popular so should I just look for a starter for say a 75 GM pick-up with 350? I have seen on here too that staggered bolt holes on the starter usually means 168 tooth flexplate and that the 153 tooth are usually installed on 305 motors.

Longer story is that my truck has been starting slowly the past week or so. My wife and I recently bought a 26-foot travel trailer and my truck has been doing pulling duty to some local campgrounds. Truck has been running and pulling like a champ after putting in a 4-core rad from a 454 truck. I had to get the trailer brakes and controller wired up from scratch. Monday I noticed the truck started kinda slowly. I figured my 3-4 year old Optima yellow top was having old-age issues as it has done before a few times and I believe they are sensitive to being drained entirely dead and it had been drained dead as a doornail a few times over the years from my truck sitting for a long time. Anyway, I hadn’t had a need to jump it or anything except yesterday morning when we went to leave the campground the truck turned over slowly, fired up, stalled (as it usually does once when it’s cold), and then didn’t want to turn over again. I plugged in the trailer brakes, which then connects the trailer battery to the truck, and it fired up good. Okay, so my battery is getting weak I thought. Ran the truck for a little over an hour and got home buuuuut I left my park lights on for a couple of hours. Came out to start it, and it turned over slowly, fired but didn’t want to run or rev up which I figured was from a lack of voltage. It just couldn’t really get over 1000 rpm. It sputtered out and died. Then it turned over really slow and finally just would click. Tried jumping it and nothing but a click. I would hear this high pitched whine like when an electric motor is trying to turn but can’t. Trailer was plugged in as well and it didn’t help. Unplugged the trailer and no change. Left it on the charger for about 8 hours. Tried it again and nothing but a click. Everything else electrical worked fine and lights were bright. Swapped out battery for trailer battery (brand new Interstate). Exact same result: just clicks and this high-pitched whine like the starter motor is trying to turn but can’t. Tapped the starter with a hammer, no change. Felt the B+ wire on the starter and it was warm.

So does it sound like my starter is dead? It has had heat soak issues before when I’m at the gas station or something and it hasn’t had time to cool down. It would turn over slowly but would start. I have headers and I’m sure that pulling a trailer now has caused more heat down there. I live on a hill and pulled it up a long grade for the first time right before having these troubles so I’m not surprised if this was a severe heat soak that finally did the starter in, which is about 10 years old now.

I wouldn’t doubt I may have a secondary issue of my battery getting weak but I also have 4 ga. Wire running from my battery to starter, alternator to battery, and battery negative to frame. Engine to frame ground strap is a heavy braided wire.

I suppose it’s possible too that the B+ at my starter may be loose or worn or somehow not getting a good connection for a high current draw when starting the motor so I’ll check that out when I’m under there before yanking the starter.

Thanks for reading my mini-novel and appreciate any insight and help!

[bake74]

    Well I will try not to miss anything I wanted to say.  LOL  From what you described, I see 3 different possible problems.  #1. If your alternator is not working properly, you would drain your battery ( you are right Optima batteries do not like to drain completely, ran for years in jeeps, been there, done that ).  #2. If you are not getting the right voltage or low voltage to starter, over time the winding in starter will wear out causing it to turn over slower and slower. ( deal with that at work on a daily basis ).  #3. You said you started your truck and it would not rev over 1000 rpm.  Once started, your alternator should take over and give full charge to starter. ( that is why I question your alternator)  The whining you described could be your starter trying to engage the flywheel, but not getting enough voltage would only part way spin out on the shaft and not connect, and just spin at full speed or slower if starter is going out.  So If it was me, if I had a spare starter, I would put it in and get the truck started and do a voltage check at alternator, and like you said, check all grounds and wires for good connections and no burnt wires. Hope this helps, keep us updated on what you find.....tom

[Grim 82]

I would go with a new starter, fully charge the battery, and give that a shot. I have heard that (even though it works and I've done it many times) GM alternators are not designed to and should not be used to recharge a drained battery, like after a jump start. I don't remember where I heard it or know if it's true, but maybe you have that 1 out of how many thousand alternators out there that can't keep it running when the battery is dead.

[Lt.Del]

i'd go with the 168 tooth, staffered bolt pattern.  Each time I go to the salvage yard I look for the off-set staggered bolt starters on chevys.  Never had a problem w/ one not matching my 79 350/383.  My experience is that the starters w/ holes in line are for a smaller application (ie: 305?). 
When pulling my 30' camper, the first thing I do is disconnect the wiring harness on the trailer.  Trailer batteries (marine batteries) are designed to go dead, then recharge several hundreds of times (deep cell), however, a car battery is not designed---a few drains and that's all she wrote.   So, I unplug the trailer as soon as I park for fear of the car battery draining into the trailer when the engine is off.

Put a voltmeter to your starter red wire and ground and see if you are getting around 15 volts when engine is idling.   

[fitz]

I'm not sure that I would want to jump start the truck with the trailer batteries basically using the trailer brake wiring as a pair of jumper cables.
I know sometimes you have to do whatever is necessary to get the truck started, but I don't think those wires are designed to carry that much current.
As far as I know they stopped using the 153 tooth flex plate somewhere around 1968. 

[SUX2BU99]

Thanks guys. I went out and bought a new Bosch starter for a 75 GMC 1/2 ton, 350 V8, 2wd today. $139.  They didn't ask me anything about flexplate teeth or anything like that and it has the staggered bolt pattern.

About it not wanting to rev past 1000 rpm, my alternator doesn't seem to 'trigger' until about 1500 RPM upon initial start-up. That seems to be when the voltage regulator kicks in and my voltage goes up from 12v on battery to 13.8v or so on the alternator. After it triggers, it will then put out 13.8v at all RPMs including idle but seems to need that initial rev to get it operating.

[Lt.Del]

i wonder if your coil may be going bad---got an extra laying around?

[bake74]

     I'm with sgtdel, that doesn't sound right about your alt.  I would get that checked.

[SUX2BU99]

I do have a spare HEI with an MSD coil and rotor that I replaced before I put in my new Mallory HEI.

Can someone tell me what size of socket fits on the SMALL wire terminal? I'm having a heck of a time accessing it to see what fits on it. It doesn't help that the ring terminals might be getting in my way but if I knew what size fits it, that would alleviate a bunch of aggravation. It's a stock, full size starter. The Bosch replacement I have bought is smaller and has different size nuts on the terminals it seems.

[SUX2BU99]

Eventually got it figured out: 11/32 1/4" drive socket. That and I had to drill out the terminal a little to fit the new, slightly larger, post. So starter is in and works like a champ. Truck runs great too. Starter sounds a little gnashy but I'm not entirely sure if it SHOULD sound like that, since it's a 'mini' starter or if I should be concerned.