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"B.u.d" - '74 M-950 Diesel Power Wagon

While it's been down I also re-did the exhaust, now sporting a 4" baffled and chambered muffler from Heartthrob exhaust - it's the only B&C muffler I could find in 4 inch - they call it the 'wife pleaser', so I'm looking forward to a quieter exhaust, especially on the road. Modified a 1st Gen downpipe I still in the rafters to fit my wastegated turbo (longer than a standard 1st Gen turbo, and rebuilt the rest to accommodate both the DP and muffler. Worked great -

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#7081Q -
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inlet -
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outlet -
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stack upright, now anchored to the cab -
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Cool - got all hatches battened and lug nuts back on, fired up and drove it around yesterday, and all systems seem to be good to go 👍. One girl in a JK hollered out the window "that's the sexiest truck I've ever seen!", which made my day :) . R-rear hub is dry, exhaust is maybe a bit less loud - not as quiet as I'd hoped for but any little bit helps. Steers and stops just as good as it ever has. So yayee 👍 .

One nagging issue I've been tracking (and resolved this morning) was a 'pulsing' voltage regulator/charging system. Since day 1 the truck charged its two big deep cycle batteries fine...but when it's running...every two seconds or so you can watch the voltmeter needle 'twitch' - meaning it'll be at ~14.2 volts and 'twitch' off/on every few seconds like clockwork - like the charging stops(?) for a very brief moment - not even a second's worth of time - it's like a blip in the charging system...and it has done this ever since day-1 nearly 9 years ago. It reads normally and charges the batts 'fine'...but every 2 seconds the needle will 'twitch' and simultaneously you can hear the engine rpms 'twitch' too - a very slight but noticeable rpm drop, kinda like the alternator is 'demanding' more for a very very brief moment, dropping the rpms...at least that was my theory.

If the rpm's were up the issue seemed to eliminate itself - just as a data point.

Whatever the problem was has never affected charging of the two big batteries nor has it affected engine performance...and it does not seem to be mission critical, but I know whatever is causing the 'twitch' is not normal and I wanted it to stop. It's one of those things you can't 'un-notice'.

I recently replaced the voltage regulator - no change. I checked all the connections, and added another ground, but again, no change.

What did make a change, albeit a small change, was separating the VR's green field wire from both the 12v wire and the big charge cable off the alternator and wrapped them in separate plastic conduit - just in case there was any minor voltage 'bleed-over' from one wire to the other(s); it was still pulsing...but much faster - like every half second. Don't know what the hell that means, but apparently having the field wire and 12v wire running 'alongside' each other from the regulator to the alternator...along with the big charge wire...for reasons unknown...seemed to make a difference, but the base issue still remained. Also, on a voltmeter it's pulsing up to 15.2 and down to 14.8 back and forth...so it was technically overcharging.

One interesting actual solution (on another guy's truck) I read about on the interwebs...and that I tried this morning...was using a relay to 'simplify' the 12v sense wire power to the VR/alternator 12v inputs, so I tried that this morning, and...so far...it seems to have resolved the issue. Source power is now coming from the alternator output charge terminal (with a 20a in-line fuse), 'signal-on' from the original 12v wire, output to the VR/sense terminal wires, and ground to the VR, and it now has no pulse and is charging at ~14.6 volts.


One note - on this truck, there are two big powerful batteries...but they are located 15 feet away from the VR, and the frame completes the overall circuitry as the ground for 'everything'. Lot of distance in the wiring, and I think that is what caused this particular issue to begin with. This isn't the first 1st-Gen-Cummins-powered-truck I've done this external VR 'upgrade' to, and I don't remember this issue occurring in any of the others, but again this truck has the batteries way far away, so maybe that is why this happened to begin with. Just a data point for anyone else considering wiring in an external VR.
I think the charge rate is a bit high because the batteries may be a bit low, and I'm going to drive it around a bunch over the next few days to ensure all is working properly. It may have simply been a crappy sense signal all along - not enough for it not to charge, but enough for it to...well to do all of the above shenanigans.

Diagram for easy reference -

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Booyah 👍

- Sam
 
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Not sure I follow correctly, but I don't see how a relay can filter anything. It's just a switch.

Keeping the sense wire 'clean' (free of induced noise from alt itself) can help. run separate wire all the way to battery, not close/parallel to high current wire. Maybe this is what you did by altering wiring.
 
well the relay isn't intended to 'filter' the power - it merely shifted the 12v sense wire to the actual battery charge wire...which it and of itself is 'a long wire to the battery', but with lots less 'interchanges' along the way. I'm not saying this is an ideal setup - not at all, merely showing the results of trying to trouble-shoot my charging issue.

All I really know is doing the relay thing did resolve the pulsing problem...but no I'm not certain yet if I've unintentionally induced another problem.

To get a warmer fuzzy that I didn't mess things up more I will be taking more voltage readings today to see what the batteries are 'getting'. If, however, the batts aren't getting great charge voltage I will run a separate 12v wire all the way back to the batts, which in my case is, I think, the ideal setup.
 
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just checked and the batts are getting 14.57 volts at the terminal - maybe a tad high but for now I'll take it as a 'win' 👍
 
...and in my continuing attempts to make the rig quieter, I installed a stock 1st Gen Cummins air filter assembly, only I bolted it to the fender and not to the inner fender which is not appearing in this film, yet. Haven't run it around yet but I know it'll make a nice difference because it will really tame down the turbine 'scream', which while fun now and then is not fun all the time, especially with no insulation anywhere...yet ;) . Plus it also makes the air intake significantly more 'water resistant' 👍. Eagle-eyed spotters will notice the air inlet is facing the back which was intentional as I am thinking of routing a snorkel down the road...not the big 'stack' type but just maybe to above the hood like I did on Nacho way back when...

before -

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after -

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So in the 'Things that Suck' category...,...on Day 1 of Chili Challenge the truck suffered another bent tie rod, and the starter began malfunctioning - both not good. The tie rod remained intact long enough to get off the trail without further carnage, and the starter managed to remain functional...albeit intermittently...long enough to get us off the trail. The starter I could have (probably) replaced that evening, but as it's still in the factory/OE location the tie rod simply hangs too low, and while I could have probably straightened/sleeved it...with the trails getting progressively worse and a near certainty of doing further and perhaps irreparable damage (and thereby becoming a very large and immobile pain in everyone's ass...and winch)...I opted to remove the truck from the remaining three days of fun...and while my wife would have been cool with me remaining and riding shotgun with someone for those three days...the wrangling of the kiddos was far more important, so I opted to cut bait and head home.

Reinforcing to the decision to head home was the feedback I got from other participants that the truck is both loud and...for anyone behind me smells like a diesel (duh), which I do not deny - yah it's a diesel but it isn't a big block with no pipes and it doesn't bellow black smoke everywhere. Anyway, the repairs took the truck out of the event, but hearing that some participants are annoyed by the truck...well it isn't hard to understand why folks used to wheeling in very quiet machines would be reticent to want to wheel near it. And yah it's really big, but I like how big it is, but I am aware that many don't, and that is something I'm aware of. In other words...many of the reasons we sold the truck before all came rushing back at once, which just sucked.

The Dakota will soon be ready for prime time and that's cool. But...what to do with the big beastie, and there are several options we're pondering, the leading ones being: 1) Sell it again, and put the $ someplace better. 2) Keep it, repair just what's broken and continue wheeling it as intended, perhaps with more of the full-size crowds. 3) All of #2 plus modify it for full-hydro, and do an engine swap to make it quieter, and continue wheeling it as-is. 4) "Buggy" - Do an engine swap, keep the driveline more or less as-is, and morph it into a lighter, quieter, and more capable 5-seater buggy; there's a lotlot of good hardware under the thing, and honestly transforming it into a buggy is very enticing - I'm fairly sure it would end up being something similar to Dibble's ASM buggy.

So...there it is. I've no idea what we'll do...but if we keep it I am 100% certain a few things will change, and as things progress with the Dakota I'm sure a solution will become clear. I have a new starter on the way and I'll have the tie rod repaired, and I'm planning to take Bud to our last trail run next weekend so things aren't over...just lots to ponder.

It isn't going anywhere anytime soon, and much more to follow...

- Sam
 
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Sounds like the people you wheel with are a bunch of sissies, lol. Personally I hate gas exhaust much more than diesel exhaust, especially if people aren't running cats.

Sucks about the tie rod though.
 
...while not really bad the noise is the biggest issue - I love the sound of a 1st Gen Cummins but even I would like a 'quieter' engine. All of my off-road rigs since '07 have been powered by a 6BT - ever since doing the first fateful conversion it's just been 'my thing', and wheeling a Cummins is fantastic, but I can get the same level of reliability and power with a lot lighter engine, and since it'd be a gasser it'd be tons quieter too...but man I will miss the Cummins resolute reliability and simplicity. So, assuming we keep it...an engine swap and full-hydro will probably happen regardless, and anything else is TBD...
 
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Sounds to me like you need some insulation.

Ive been wheeling and dailying my 4bt powered rig for 10 years and it's no where near loud enough to need ear plugs. Not even close, even with the windows open.
 
Sorry to hear been there.
Big block FORD would solve the noise issue. :smokin:

deep breath, don't spend any money until you know what you want.

6.7 Powerstroke is super quiet and smells like roses but really heavy...
 
Well dammit. Ok, due to circumstances beyond our control (above and beyond the last outing's shenanigans)...the big Power Wagon is again for sale, $25k. There's nothing we can do about it, and despite its fantastic capabilities and all the work I've put into it over the last several months, and so many other factors ...we simply find ourselves unable to keep them all, and the big truck is the one we need the least.

If things change and we keep it, great; I'll probably drop in a big block and full-hydro and keep wheeling it. Otherwise, if anyone happens to want a very capable and well built Cummins Power Wagon...lemme know. Lotta fresh hardware under it. $25k firm.
- Sam
 
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thanks. Yah we have the Dakota ready to be finished and as much silly fun as it is we just need to 'make some room'. Being what it is it might be a long while before it finds a proper buyer, and maybe things will change in that time, but inflation has really tore up our long-term plans so we're just wanting to free up some extra wiggle room.

In the meantime, here's a couple flex shots from our trail run last weekend - I've never had it on a RTI ramp but the thing can stretch its legs pretty good

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...I can't think of any reason why it wouldn't cruise from coast to coast - probably be good for it :dustin:
 
wait - yer in Ellicott? being about 10 miles away I'm certain it would make it :flipoff2: (I'm in Falcon)
 
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