"Banging" sound when starting?

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Twin Pinzies
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"Banging" sound when starting?

Post by Twin Pinzies » Fri Jul 29, 2016 9:30 am

So when I start one of my trucks, it now makes a loud "bang-bang-bang" sound as the starter is working. When it starts the banging stops.
I removed the starter and inspected everything and it looks fine. No worn teeth on the starter or flywheel, the starter shaft extends out like it should, tight mounting bolts,...
It's a new high torque version from Expedition Imports, not the stock starter.

Any clues to what this could be?

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Hotzenplotz
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Re: "Banging" sound when starting?

Post by Hotzenplotz » Fri Jul 29, 2016 2:09 pm

check your valve clearance and ignition timing.
sounds like you are backfiring through the carbs.

you can check it by opening the small lid in the "turtle" and placing a hand on top of the air intake there.
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Albert
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Re: "Banging" sound when starting?

Post by VinceAtReal4x4s » Fri Jul 29, 2016 2:45 pm

Could be a motor mount issue.
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rmel
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Re: "Banging" sound when starting?

Post by rmel » Fri Jul 29, 2016 3:42 pm

Do the bang bang bangs kinda go with the revolution
of the flywheel or the revolutions of the starter motor?
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

Twin Pinzies
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Re: "Banging" sound when starting?

Post by Twin Pinzies » Sun Jul 31, 2016 2:35 pm

rmel wrote:Do the bang bang bangs kinda go with the revolution
of the flywheel or the revolutions of the starter motor?
Seems to be in synch with the starter's revolutions, rather than the flywheel. Also, today the starter just "spun out" without engaging the flywheel. After moving the truck, it engaged and ended up starting.

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rmel
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Re: "Banging" sound when starting?

Post by rmel » Sun Jul 31, 2016 2:47 pm

Hmmm, starter is sounding a bit suspicious. How's the starter mount? Just thinking if
the rubber on it has deteriorated maybe the starter is not sitting in there square, although
I'd expect more of a binding than a banging and in sync with the flywheel than the starter
revolutions :?

Good luck!
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

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audiocontr
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Re: "Banging" sound when starting?

Post by audiocontr » Sun Jul 31, 2016 8:51 pm

^ what he said
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Twin Pinzies
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Re: "Banging" sound when starting?

Post by Twin Pinzies » Mon Aug 01, 2016 6:16 pm

So today the starter just spun and wouldn't engage the flywheel at all. I took it out again to make sure that didn't miss anything the first time.
This time, when I removed and inspected the starter, the shaft could no longer be easily pulled out by hand like before. So I tried extending it out with a pair of pliers. It extended with some force, snapped back in, then couldn't be pulled out again.
The teeth on the starter are perfect. The teeth on the flywheel are almost perfect.
I ordered ANOTHER one from Exp. Imports.
Now I'm kinda pissed that the high torque gear reduction "modern upgrade" starter only lasted about five years.
I hope to degotiate some kind of waranty replacement. Those things aren't cheap at over $525!!

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Re: "Banging" sound when starting?

Post by Texas710 » Mon Aug 01, 2016 8:41 pm

Curious how much usage that starter sees? Like daily driver or less regular?

No bueno either way...

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Re: "Banging" sound when starting?

Post by Twin Pinzies » Tue Aug 02, 2016 8:49 am

Texas710 wrote:Curious how much usage that starter sees? Like daily driver or less regular?

No bueno either way...
My Pinzgauers are used as commercial 4x4 tour vehicles. They get used daily but only from late May - mid October.
They are in storage half of the year.

Since the "outdated", "heavy", and "slow" factory-stock starters lasted over 30 years, I might go back to them!

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Re: "Banging" sound when starting?

Post by Jimm391730 » Tue Aug 02, 2016 11:57 am

First thing I'd check is to ensure that no teeth are missing from the flywheel and starter gears. But from your "spun out" comment, the Bendix one way clutch may be failing - slipping, then grabbing, etc. This happened to my starter but it was slipping only (no "grabbing") but would maybe finally catch and drive properly once out of 20 tries.
Jim M.
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Haf-e
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Re: "Banging" sound when starting?

Post by Haf-e » Tue Aug 02, 2016 1:25 pm

Hard to say how long the starter in your 30 pinz was there - the Swiss replaced let's of parts on trucks.

Would be good to know if the new gear reduction starters can be repaired/rebuilt? I'd give Scott a call to see. I'd probably even buy your dead starter and fix it...
Haf-e

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Twin Pinzies
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Re: "Banging" sound when starting?

Post by Twin Pinzies » Mon Aug 22, 2016 12:12 pm

UPDATE:

I replaced the flywheel ring gear, starter mount, and starter (and the clutch while I was at it)...
It still grinds, spins out, and only engages about 1 out of every 10 tries. It actually got WORSE with all of the new parts!

WTF am I missing here? It seems like such a simple working mechanism. How can it be F'ing up?

Any ideas???

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Re: "Banging" sound when starting?

Post by undysworld » Mon Aug 22, 2016 1:37 pm

With several parts having been replaced and something happening (it got worse), it's a bit hard to tell which one (or more) of them caused the change for the worse, and it still hasn't helped cure the original issue. I guess I'd start at the beginning.

I'd independently ground the starter with a jumper cable to the 24vnegative at the batteries. Then I'd verify 24v at the starter terminal (not the wire) and monitor it as you activate the starter motor. If you identify an electrical problem this way, fix it.

You mentioned ordering a new starter from EI, so I'll assume that's what is in there now (?). If it's a new starter, it has a warranty, USE IT. Have you called Scott to discuss your current situation? Scott has a good reputation and he got by taking care of his customers and a lot of that is just advice.

The problem began with a loud "bang bang bang", but you didn't mention this noise now. If it's no longer banging, perhaps the difference is the starters. You might bench-test this new starter against the old starter and see if you detect any difference in operations.

I like your idea of going back to the outdated", "heavy", and "slow" factory-stock starter, just as a test to see if it works okay. If it works fine, then I'd think the problem must still lie within your starter. If the stock starter does not work either, then you have to keep looking. It's possible that you have something wrong with this truck that has nothing to do with a defective starter. Perhaps whatever is wrong caused the failure of the first hi-torque starter.

You mentioned that you own multiple trucks. It might be helpful to swap parts, one at a time, between the trucks. If/when the problem stays with one part, you have identified the defective item. You could also measure clearances this way.

I know it's a bit of a hike, but you might also contact Linden Eng. in Littleton for help. http://www.lindenengineering.com/about.aspx I've always found Dennis to be knowledgeable and helpful.

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Re: "Banging" sound when starting?

Post by Jimm391730 » Mon Aug 22, 2016 3:35 pm

I've never had this type of issue with my truck, but if you have access to a video inspection scope (the camera on a flexible shaft) you might be able to remove the clutch linkage cover and physically "see" what it looks like when the starter tries to or does engage with the ring gear. As you said, it should be simple mechanism so the most likely issue is the gear alignment (or mis-alignment). I would think that with the replacement of the rubber starter mount that alignment should be a no-brainer, but...
Jim M.
712W and 710M

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