The Summer (Autumn, Winter, Whatever) of Ven: Fuel Return Line and Glow Plug Surgery on an IDI Turbo Diesel

This is the last of a three part series about retrofitting an electric fuel pump and frame-mounted fuel filter onto my 1985 6.9 liter IDI turbodiesel spool bus. Last post, I got everything wrapped up and operational from the fuel system end, but discovered that the steady 10PSI feed pressure was now causing a whole bunch of the injector return fittings to leak!

Go figure, as part of the problem is the o-rings that seal them become crispy. I actually drove for a while like this to make sure everything was operational when it came to the fuel system. However, by the late November into December timeframe, the leaking was getting steadily worse, and I really had to address it.

What it did show is that the electric fuel pump will help extend the time horizon of having to deal with all your fuel line fittings on one of these things. I could leave the key in the “on” position after it sits a few days and hear the bubbling and gurgling coming from the lines for the first few seconds. What the e-pump does is keep the inlet end of the injection pump primed, so it can at least light off quickly. Then you can usually inertia through any further problems.

But that’s no way to live, so before it got cold, I was out to correct the problems and also repair the glow plug circuit – up to this point, I was still monkey-starting it with a little shot of ether.

The downside to all this? I have to go back in there. UGH.

Off the cover comes! By now I’m well used to digging around under here, so the crankcase vent value, intake hose, and some other hoses actually went away quickly. I made sure to leave the hose clamp screws in accessible positions last time since I knew this would be inevitable.

A 5/8″ regular wrench (I guess you could use a 5/8 flare nut wrench if you wanted) releases the injector line fittings. They pull up slightly, and then the plastic return caps come off, leaving O-rings behind.

So here’s the story on these “return lines” and why they’re nightmares besides being hidden in a cave. The only thing sealing the fuel being returned to the tank are those O-rings. They’ll get old and crispy, and with the fuel system under vacuum due to the engine and filter being higher than the banks, they’ll start letting air in to drain out the fuel system slowly. Then you have a bad time.

Dunno why anyone thought a series of handmade rubber hoses with plastic caps was a good decision here (seriously, they definitely had to build each of these by hand on a stand). Maybe a single molded plastic or cast metal “rail” was considered but ended up being too costly. Maybe secondary compression/flare fittings were considered too underserviceable.

Whatever the case, just grab a return line kit from Accurate Diesel and use the existing line lengths as a guide. I’m being a little dishonest with these photos – I did the same operation for Murdervan a few months prior, but haven’t written anything else about it because it ended up being just quite functional and as you recall, I ended up selling it in early September.

I learned from that time to cut the hoses very slightly short, like 1/16″ short. It’s easy to pull them a little outwards from the fittings to get the line of them to sit straight. The spring clamps grab a fair bit of width, so I wasn’t concerned about having enough seated over the push fittings to seal.

Otherwise, if the hose is curved between them, looking like an S or snake shape installed, it’s exerting a pressure towards one side which could cause premature hardening/deformation of the O-ring over (let’s face it, a long) time.

Because Spool Bus has the aftermarket turbo system, the return lines are set up differently than OEM with the crossover line occurring at the front of the engine and the “master drain” at the very back of the driver’s side. I needed more of the 180 degree straight-through fittings than provided, so I ended up recycling in some of the old ones.

There’s nothing wrong with them, mind you. I cleaned them up and inspected them for cracks or chipping. The only thing that causes pressure sealing loss is the O-rings, which disintegrated as I was picking them off the injectors.

After crafting the two sides and the “reacharound hose” to connect the two, the installation involves lubing up the O-rings (I used some plain lithium grease; any petroleum grease will dissolve in the fuel bath to come), shoving them on, then seating the return line caps over them.

I used a remote hose clamp grabberator to maneuver the clamp into position on the Reacharound Hose, which is at the very front of this arrangement behind the A/C compressor – not super tight here, just awkward and out of sight. Remember what I’ve said about working on vans being Nightmare Mode Wrenching – you need to be comfortable with wrenching by feel and estimating positions.

I was expecting the turbo side to be impossible to access, but actually it wasn’t at all. I did undo the mounting bracket of the turbo itself to let it shift an inch or so to get better wrench clearance.

The injector train and Reacharound Hose connection on this side is actually easier reached from the front side behind the alternator, with an approach from the centerline (i.e. right in front of the grille). If the turbo wasn’t there, it would be an easy reach from the interior.

All return lines now installed and fully seated. I let the system fully prime and sit for a while with the fuel pump running to make sure nothing was coming out.

The next weekend, I was out to change the glow plugs, so I can continue building this thing up to turnkey operation (instead of, you know, Pop-the-hood-puff-the-ether-close-hood-open-door-get-in-then-turnkey operation). Another order from Accurate Diesel for their IDI 6.9 glow plug kit was on the way so that means….

Taking the fucking thing apart again.

I had ascertained from testing the circuit that at most one of these were still working. They’re positive temperature coefficient resistive heaters, so they start out drawing a burst of high current and very quickly settle down. I got the entire glow plug harness to draw only about 20 amps, when it should be 200 to 300 amps.

Before I started, I used alternating blasts of shop air and brake cleaner to really clean out the wells they sit in. Spool Bus had accumulated a lot of wildlife in its years of sitting wherever, and I did not want any grunge getting into the open glow plug holes once I removed them.

These dudes are one of the “middle difficulty setting” service items in an Econoline IDI engine setup. They stick out and can be grabbed with a 3/8″ deep-well socket on a swivel. But you do need to wiggle it through the injection lines and rely some on proprioception to land the socket. Loosening the clamps for the injection lines helps them be able to wiggle a bit to get you some more space. Notice in the photo I also swiveled the Diesel Delivery Dongle out of the way to get at the front two on the driver’s side.

For some reason, the passenger side is actually easier again, probably because they are displaced towards you instead of away. I used one longer extension to get around the turbo outlet pipe.

Now, installing them again is definitely a “By Feel” exercise. I started with putting some copper antiseize grease on the threads (In case I had to do this again…. or someone else) and started the thread manually. If everything’s clean, you can thread all the way up to when it stops by hand, then tighten with the socket handle.

I decided to connect them up one at a time and measure the increase in current draw. Each plug will add about 20 to 30 amps at the start and taper down to ~7-9 amps each, after which they should be cut off from power to prevent damage. I suspect a failed glow plug controller, apparently a known defect in this generation of the engine, caused them to burn out.

A shot after all 8 were hooked up. The current momentarily bursts up to 280A and falls rapidly to about 100 over the course of 10 or so seconds. Obviously, taking a picture of this was hard.

With this complete, I know that the glow plug contactor was working fine – since I’ve been throwing it with an alligator clip touched to the battery – and all the heavy wiring leading to it. What was not working was the glow plug controller. I obviously couldn’t tell exactly why not, because….

Yeah, uh, this is going to be a problem for another day. My upcoming mission was to tear out this Wiring Teratoma as I called it and just start from scratch after reaching the OEM layer.

For now, I just rigged up a switch as usual so I could activate the glow plug contactor by hand, count to 10, and let go. Spool Bus then starts with a single key bump, so all is good up to whatever has happened to the control wiring for the OEM glow plug control module!

Norwalk Havoc May 2021: Scale Model Testing Your BattleBots in Nightmare Mode

It’s time for robots once again! I think what I’m planning on doing from here is, barring one or two more Summer of Ven posts (which is now well into the Fall and Winter of Ven anyhow) I’m going to begin transitioning towards Overhaul, finally.

You see, a major over-winter project of mine was trying to get Overhaul 1 up and running again, at least walking. There was a good bit of fabrication and “What in the everloving fuck did we do here…” reverse engineering your own work from 6-odd years ago. While it’s cool enough in its own right, I’m planning on using that to move towards the long-overdue Overhaul 3 design and build series. I mean, y’all already know what the bot looks like since it’s appeared on here by now, but there was a lot of translation from 30haul’s geometry to the full size bot.

But in the mean time, let’s talk 30haul. Recall the “lessons learned” of the previous March Norwalk post

I’m revising the Snout design to be stiffer on the corners, trading the internal webs for a U-shaped bottom truss shape. The metal is rigid enough on this scale that I don’t think the center webs contributed much.

Next up, after watching enough Battlebots and seeing enough matches at this point, I’m going to make 30Haul an entry in the “fork wars” currently ravaging the combat robot landscape. The joke is that ground-scraping forks grew a foot over the course of the 2020 season, as one of the only ways to ensure a vertical spinner doesn’t get under you, is to get under it first. Keeping the opponent away and under control is just as essential as being able to take (or deliver) the hit…

I’m also beginning to like the Vex wheels less and less, because while they initially offered the bouncy compliance I was looking for, once they start disintegrating, they become more liabilities. The spokes will tear through, leaving the big gaps in the perimeter that then flap in the wind. I decided to try and find some thick foam rubber I can use to make at-scale foamy wheels, not dissimilar to Overhaul’s.

Before any of that can happen, though, I had to have a 30haul that was functional. The damage from March wasn’t that bad in the grand scheme of things, but in the name of thoroughness I decided to completely take the bot apart and remanufacture it to address some of the frame damage and retighten the motor screws, among other tasks.

So here’s 30haul in a pile of itself! I planned to repair the frame as much as I could and keep it around as a backup, because…

Prior to March, I commissioned an entire new chassis to be machined by Wedge Industries. I figured as long as I actually had new 30haul parts, why not just move the bot to the new chassis and keep the old one as the “Just in case…”

To save some expense, I had Alex pound out only the net shape geometry. Since I have my own capabilities, I save some on the machine time and setup when it comes to tapping and countersinking, among other operations. So the first order of business with this new chassis was just chucking the ol’ spiral-flute 1/4-20 into my drill and having a pleasant time.

To the old frame, I repaired the damaged threads in multiple frame rails with threadlocked Helicoil inserts. The rear bulkhead shown here was actually quite bent up from the Ripto match. I used my arbor press to straighten it using some cleverly placed spacers.

Original chassis coming back together with an added weight-shaving pocket that I designed into the one that was sent out for manufacturing. There’s nothing over this area worth hitting really, so no reason to have the weight.

And the original chassis fully repaired and assembled!

The new chassis needed the end-tap holes put in. The way to do this would be to set them up at an angle on the drill press, but I was confident enough in my drill bit rodeo skills such that I just clamped everything together on the bench and hit the front (angled irritatingly – that got designed out of Overhaul 3) bulkhead holes. The rear set I piloted and threaded in one screw before finishing the rest on the drill press.

New chassis fully assembled and ready for population.

Next item on the agenda was to make some wheels. I said earlier that I wanted actual foam rubber wheels for 30haul now to get away from the Vex wheels, as while they did offer the compliance I was looking for, their failure mode was becoming big rubber flaps.

I looked into a few difference sources of “rigid” foam rubber, such as anti-fatigue floor mats and similar. Ultimately McMaster-Carr came to the rescue with a sheet of natural rubber foam – the nice thing was, in the time I had, it just offered a compression/deflection rating in PSI so it was easier to visualize how much give it would have.

To manufacture the wheels, I initially tried to find a hole saw set where I could get a 4 inch and a 1 inch saw on the same arbor. Maybe this was possible in the ol’ glory days of Comedy Central Sports Presents BattleBots™ as I recall a few builders’ reports saying they mounted two hole saws on one arbor to cut washers (e.g. for clutches, spacers, and wheels as well). But these days the consumer systems seem to have evolved and specialized, so the smaller sizes of hole saw usually have direct screw-on mandrels and larger ones have the pin locking ones.

I ended up picking up probably the most horrible Chinesium hole saw set Amazon had to offer in the hopes that it had generic mandrels, but alas, I found that the D-bore of the saws were different sizes as well. Either way, I found out that just hole sawing into the rubber wasn’t bad for alignment anyway. It’ll become round once I do enough burnouts!

I drilled these wheels using the Vex hubs as a template and put the same hole pattern into them.

For now, I made only the two (well, four…) front wheel assemblies to alleviate the worst of the wheel compression issues. What would happen is the Vex wheels would flatten between spokes and then bounce up once it reaches a spoke, and it actually made the bot drive a little bouncy as a result. These are a good deal lighter than the Vex wheels as well.

Hey, no use in spending too much time making wheels if I don’t have the rest of the bot yet. So off we go with populating the new chassis!

While doing so, I re-discovered a problem that might have prevented 30haul from being able to lift much. Recall that I had to step down from a 3-stage P60 gearbox to a 2-stage because the torque of the 3-stage type was rounding off its own output spline. This design stands in contrast with Overhaul 2 (and 3) because 30haul doesn’t have an intermediate gear stage, the lift motor directly fiddles the Big Gear.

I noticed the motor would bind up whenever I spun the gearbox one way. It turns out the output spline on this gearbox was deformed helically in a fashion that positive torque (lift) tended to shove the carrier off the spline, causing it to bind up like a clutch plate against the first stage.

Well, to repair this, I’d just have to replace the output shaft. Trouble with that? To clear the Big Gear and lifter forks, I had to position the motor farther away from the sidewall with the support bearing. Namely, about 2 inches. The stock Banebots P61 gearbox has a 1.5″ shaft.

I was at a juncture where waiting for Banebots shafts to be ordered would mean delaying the bot’s assembly into the week of the event, which I really didn’t feel like doing. So I decided to make a shaft extender, just a turned piece of 7075 rod with a 1/2″ socket on one side and 1/2″ stub on the other, long enough to bridge the gap. A 10-32 screw goes through the middle into the end-tapped P61 shaft.

Here’s what it looks like installed, along with the rest of the motors. Again, the motivating factor here was just to be able to reach that outer support bearing with a stock-length P61 shaft, of which I have plenty of spares.

Wheels loaded on and chassis off the ground now. I like these front wheels already – they don’t cause the front of the bot to sag at all, but are still very bouncy. Boy I wish someone made 3-4″ thick chunks of this stuff!

I finished assembling the bot and put it in “Sportsman Mode” since I didn’t yet know who I was fighting at the time – I’ll change things once I get there. In the time between this and leaving for the event, I put together what I think are the last two 6-fet Brushless Rages left and readied some other spare parts.

You see, by checking out the registration roster, I found out that every other 30lber was a vertical spinner of some sort. Whether disc or drum, this tournament was going to be absolutely fucking brutal. Hence why the title is….

Scale Model Testing Your BattleBots in NIGHTMARE MODE

I teleported up to Norwalk over the course of the day on Friday, May 14th, and got to my (now usual…) Norwalk generic business hotel around 10pm. The event started at 9 the next morning, and it was a full house.

I started 30Haul out in the “sportsman mode” configuration anticipating needing to change out to anti-vert forks. I got “Hyperbite XL” as a first draw. It’s an homage to Deathroll from BattleBots, and luckily was very high off the ground, so I actually decided to roll with these. I was out to test a “Just reach out and grab it” strategy.

Hear me out here – pretty much every vertical weapon worth its mettle takes a few seconds to get up to dangerous speed. I’m content with declaring the clamp disposable and just going up to it and grabbing it. If they try to turn away to prevent this, so much the better.

Well I mean it kinda worked. The only downside of declaring the clamp arm disposable, is you better have a whole lot of them, which I… didn’t. So this was the outcome of “Just grab Hyperbite XL as it’s trying to spin up” – while I was able to keep it at bay, the buckling actually jammed the clamp motor so I couldn’t grab and lift so much as just toss around.

There’s no “stream clip” like some of the other matches, but the match is at 3:12:36 in the main stream recording.

Hyperbite XL managed to machine some of the tips off the forks and snap some of the threaded rods, all from the small amount of contact we made in the match. That’s the downside of fighting a modern vertical spinner – there’s so much power density that the damage slope is very steep. You can really just mess up once.

Nonetheless we were both thrilled enough with the outcome that we decided to call it “Overhaul vs. Death Roll”. See? Battlebots should just be 30lbers.

Great, one match in and I’m already on my spare clamp. I managed to hammer the other side of the first clamp (the half that didn’t become wall art) straight, just in case I had to use it again.

Of course, the next match was against Other Disko, which is a more traditional 4WD vert architecture and multiple-time champion of northeastern events. Great. Luckily, this meant i got to bust out some experimental “Vert Blockers”, extended forks that act as a ground-level push-me stick. There was a lot of fork and counter-fork action at BattleBots this past year, so I decided why not give it a try as well.

This one was fairly brutal and took a long time to recover from. The key takeaway is that Vert-away forks work until they don’t. I mean, the opening gambit was about the best I could hope for, and then it just became pear-shaped.

I think that’s my main beef against the KE meta, really. That because of brushless and lithium batteries, there’s no more compromises that need to be really made on that front. You can have a fast and maneuverable drive, a solid chassis, and an extremely effective weapon, so there’s little point in having anything else.

At one point 30haul must have gotten booped hard enough on the snoot to buckle the leadscrew that drives the clamp. Luckily I decided to actually cut one of these as a spare, or else I might have had to resort to being a lifter only!


(Maybe that would have been better….)

I next faced Marathon, which was an “Overhaul vs. Minotaur” moment, and I was rather pleased by the outcome except that Marathon was counted out under what we think were incorrect conditions. I was still manipulating it when they pulled up the countdown. I was extremely peeved to find that for some reason, perhaps due to accumulated damage and misalignment, that I couldn’t manage a lift after the grab – something was stalling out the lift motor.

(I would find out after the event when I tore the bot down that one of the matches before, likely Other Disko, had bent the lift shaft into a shallow U shape that was binding up if it had much load on it)

By this point, I’d basically run out of fork parts and standoffs, so I was just going into the last match against Stop Hitting Yourself in “With your shield, or upon it” mode. I think it was a little more “upon it” as the dual vertical disks slowly plucked the remaining wheels I had cobbled and assembled out of whatever still was kind of whole.

I mean, in the grand scheme of things, the extremely prototype-y nature of 30haul has been its downfall all along. I was more out to get the shape correct and get a feel for how it’ll drive instead of focusing on functionality, and it still ended up using a few legacy parts from 30hauls and Uberclockers past.

The most important thing was I got a lot (a whole lot, let me emphasize) of recon on how to handle the vertical spinner EDM party that is BattleBots. A lot of the design issues I didn’t like about this 30haul had already been changed on Overhaul well before now, so I got to leave Norwalk this time with some “hmm” lessons for Overhaul, such as….

  • Just grabbing the vert is a valid approach, as long as I can line it up or force them to turn away.
  • The clamp head and forks are considered disposable and will be both treated and duplicated as such.
  • Vert-away sticks work until they don’t, and I’m not sure I’m a judicious enough driver to use them effectively.

I never actually got to test the new “snout” spinner wedge, first because there weren’t any horiontal bar or shell weapons, and second because I just never finished welding it after seeing there weren’t any! To be fair, Stop Hitting Yourself had a horizontal component, which would have been trouble if they decided to use it against me.

Hey, at least a clean picture of 30Haul is on the NHRL hall of fame wall! I think this photo was actually taken during the February one I went to.

With this NHRL, this 30haul’s story comes to a close. Like I said, it well outlived its original purpose and I was just running against opponents with a whole slew of design handicaps. There will be another one in the future, probably not this year, as Overhaul itself is now my focus of attention. And of course the new one will have conversely back-propagated design elements from Overhaul 3!