A nICE Bus - Blue Bird CS RE 3904 - Full-Time Home

Busjamin

Senior Member
Joined
Feb 28, 2025
Posts
173
Location
Maryland, USA
- Welcome Thread - < Reached four pages and covered some of the research & shopping process I may not include here. If you want to watch my sanity slowly unravel over the course of two months, check it out.
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60 Days.

60 days spending practically all of my time thinking about this project. I noticed many on the forum had taken 2-3 years to find the perfect bus, but we weren't working with that kind of time. 60 days pouring over auction sites, facebook, craigslist, ebay, purplewave, iron planet (etc etc etc), forum posts, youtube tutorials, bus driver training manuals, CDL coursework, you name it. 60 days learning new skills like welding so that I can apply them to the project myself. I was absolutely stuffing information into my brain and burning up 12-18 hour days most days. I ended up *working* way more than before I was unemployed...but I was doing something I 100% wanted to do.

60 days to lose track of why I'm here, and succumb to the pressure of life queuing up, waiting for me to make my move. 60 days to wonder if I did the right thing by leaving my job to build a bus house. 60 days to budget and re-budget and try not to panic. But, with a solid partner and a bit of a tailwind, I managed to keep my head on my shoulders. I feel like I am where I am supposed to be, doing what I am supposed to be doing. I think that makes for a solid launchpad into the build.

After the first 30 days I felt like I knew enough to rule out practically every bus in the country for one reason or another, so I started to get my priorities straight. I had made serious offers on three other buses before we successfully purchased our Blue Bird. The first was a built-out camper in an 80s GMC gasser that was cool and very close-by, but probably would have been disappointing in the end. The second was a 35' Thomas MVP, but it didn't have quite enough going for it... for the price. Then we pursued a bus that was for sale on the forum, but it ended up being just a bit too complicated and risky for our taste. 60 days was starting to feel like 600 days.

But, then, there it was. And that's how I knew it would work, because that's how it has worked for every other vehicle I have purchased and I have been fortunate to love all 13 of them dearly. It was suddenly there on eBay of all places...a source I was barely checking compared to the auctions. I looked for the deal-breakers but they never surfaced so we paid the man.

What we ended up buying checked nearly every box, and it feels right. Sorta a skoolie, sorta something different. It's an ICE bus. A nICE bus, if you will.
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The Bus

2004 Blue Bird CS RE 3904
~200k miles
Cummins 8.3L ISC-300
Allison R400 Transmission
17 Different keys
Allison Engine Retarder (w/ 7 stages and a cool joystick)
12R22.5 Tires
Air Suspension front & rear
Quick-Release Shotgun Mount
Air Brakes front & rear
BIG HORN (Foot button) & little horn (Steering wheel button)
Aux. Engine-driven Air Compressor & 3x Carrier Roof-mounted aux. AC Units
Custom locking steel AC shrouds to keep your SO from ****ing with the thermostat
Spare handcuffs with no spare handcuff key
10kw Onan Diesel GenSet w/ 2x 1300W DuraComm Inverters
50A Shore connector w/ IOTA Auto Transfer Switch
Opaque window film to shut the world out. Cozy.
33 Roadside Flares
143 copies of the Spanish Language Version of the Immigration and Customs Enforcement Detainee Handbook
The most degrading shitting experience of your life
Emergency Door Handle Delete 🔥
Full axle-to-axle storage bays
Reinforced rail-mounted moveable steel partition with bomb-proof door
25gal Fresh Water holding tank w/inline pump
Anti-zombie window bars
Air ride driver's & 2x air ride passenger's seats
Stainless-steel passenger's seats
Did I mention there is a quick-release shotgun mount?

- PICTURES- < 70 images from yesterday and today.


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The Buy

We purchased this bus from a small dealer in Missouri. Jason at I-70 Motors was a pleasure to deal with and everything was pretty lowkey. They operate out of a lot right off the highway and bring buses from out west back to clean up and resell. They had several there at the time, and another customer drove off in one while we were waiting.

This one came from Sacramento, CA and we purchased it for $10k. We put our deposit down and headed east on Thursday, overnighted at a family house in Kentucky, then made the rest of the trip west through St. Louis on Friday. Friday was an 18-hour day but we got the bus back to Kentucky, where I'm now typing this up. The only minor hiccup was my ****ing COOLANT TEMP GAUGE PINNING ITSELF TO MAX SUDDENLY.

It was just a silly little gauge joke. I guess Blue Birds have a sense of humor. :HaHaHa: 😐

There is some other tech stuff I'll get into later, but she runs pretty OK for a 20-year old BIG girl.

Was $10k a good deal? I suppose time will tell, but if it doesn't cartoonishly disassemble itself before we get back to Maryland, I will consider it a very good deal. Frankly it's insane that you can buy this kind of vehicle for $10k in the first place.

The Plan

Ugh...actually you know what, my eyes are starting to cross and I'm exhausted. I'll tell y'all the plan another day, but it hasn't changed much from what I described in the welcome thread. Next time you hear from me, I will either be stranded on the side of a mountain troubleshooting, or parked comfortably at home enjoying one of the more well-earned beers of my life.
 
I paid 3.5k for mine, put another 5k into the mechanicals to get everything buttoned up and fixed. And I agree, it's a lot of metal for a functioning bus at such a price, but the country is saturated with buses, they aren't rare, hard to store for people who don't love or drive them, so they gotta go quick, and that drops the prices down.
 
We made it.

Day of rest tomorrow.

Then, I'll be focusing on the powertrain until I've either cleaned up the top end power or accepted my place in the slow-lane convoy.

The only running issue I observed was poor performance on really any kind of grade. I could hold 70mph at around 1900rpm easily on flat ground, but even a 2-3% grade was pulling me down to 65. Steeper climbs were done as low as 40. Don't ask me how I know this, but she will do 90 given enough flat runway, so it's a high-load issue. Right?

While we were in Kentucky I took the opportunity to do a lot of performance looking and staring. Crawled all around underneath the bus seeing how much I could identify and inspecting for anything obviously out of place. Despite a healthy coat of road grime, the chassis is in amazing condition. I have yet to find any significant spot of rust, frankly I'm having a hard time finding insignificant rust spots...I will eat these words when I tear out the flooring, because there is a floor drain drilled in a few places between the seats inside... presumably to facilitate power-washing the interior. At least it should be easy to snap the bolts holding the seats in.

I got tunnel vision on fueling as the cause for my power loss. Perhaps motivated by the eye-watering cost of replacing the CAPS unit. I changed out the fuel filter as well as the water separator I found while spelunking the undercarriage. Pretty easy tasks although I did emerge looking like a coal miner. Managed to lose minimal diesel when I realized the water drain on the bottom of the fuel filter was counter-intuitive and needed to be fully UNscrewed...

I should just read the damn directions, man. They even put it in pictograms for idiots like me. But sometimes it's so easy to just send it and see what happens...

I also gave the three screws holding the transfer pump down a few turns given reports of ISC lift pump gasket failures. 2004 should be updated for ULSD but better safe than sorry. A new CAPS pump could be $10k as a good deal these days. We're going to check boxes.

I'll come right back to the fuel system if the air cleaner doesn't help. Mine has a date from 2016 written on it in sharpie 😬.

Couldn't find one locally in KY. I did pull the unit to inspect and while dirty, it's not obviously dusting. I reinstalled it and planned on letting the motor set the pace for our last leg home. My knuckle is a little sore from tapping that ****ing troll of a temp gauge every 30 seconds for 7 hours. Replacement will be a snap, even though it's one of the disposable canister type that's the size of like, at least six breadbaskets.

I feel like a saturation diver in the sea of skoolies. I will be taking the next day or two to decompress from being at depth for two months.

Cheers to everyone on here who provided input and feedback. I'll do my best to make my future postings more concise. As it stands, the human experience of diving into this ocean is all I have to report.

🚌
 
I haven't heard of an R400 Transmission, so I don't know the specs. What is your Rear Diff ratio? If it's too tall or too short, it can affect performance up hills. If you can hit 70 at 1900 it's not likely a transmission limitation likely. Find out what your gear ratio is on the rear.
 
I haven't heard of an R400 Transmission, so I don't know the specs.

Apparently, neither had the dealer as he was listing the bus as having a 3060 😅

To oversimplify my already basic understanding, it's a step above the 3060. As such, regardless of rear end ratio I would expect better, or at least more consistent performance out of the bus up any grade.

But you're right though, I don't know the rear end ratio and I suspected someone might bring it up before I had a chance to figure it out lol
 
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I'm sitting on the bus now. Silly to think exhaustion would let me rest.

This is the view from 10D.

I want to take a moment to acknowledge the sheer amount of anxiety that this bus must have harbored. It doesn't take much to imagine what it must have been like to ride on this bus during it's hayday. The seats aren't nearly a comfortable as they look. The combination of engine noise, road noise, and the incessant clanging of all this godforsaken steel caging would be less than cushy. Even less so if seated near the latrine, which as far as I can tell is a sort of direct-feed black tank made out of stainless steel.

Over the course of 20 years, the passengers on this bus kept it in great shape. There is no evidence of vandalism or tampering anywhere that I have been able to find. I can only hope most of them are living well these days...but that is a contrived sentiment in it's best form coming from a white dude in rural USA with no real fear of gov't retribution (yet).
 
I imagine prisoners being transferred, with hands cuffed to those top rails on the seats. If they weren't cuffed to it, I'd imagine carnage of prisoners banging someones head against the seats since they are all hard metal if they weren't cuffed, so likely that's their purpose.

The pic looks like something out of a movie. You could film some fun scenes in that before you demo.
 
I imagine prisoners being transferred, with hands cuffed to those top rails on the seats. If they weren't cuffed to it, I'd imagine carnage of prisoners banging someones head against the seats since they are all hard metal if they weren't cuffed, so likely that's their purpose.

The pic looks like something out of a movie. You could film some fun scenes in that before you demo.

I was definitely struck by how easily I could imagine any number of nighttime scenes with detainees packed into the seats, each quietly pondering their fate. This bus wasn't used to transport violent criminals, at least not that we can really know. It was used to transport people caught up in the immigration system, many of whom are just good people trying to provide for their families. Some of whom likely haven't seen their families since that long ride from Sacramento to the border on this bus. I won't get into the political nature of the issue in this thread, but I also won't ignore the origin of this bus as a rather tragic piece of human history.
 
CAPS & Fueling

OK, let's talk about the ISC fuel system. Given my issues with sustaining speed up hills, I figure this should be the highest priority. There are components that may be taking a beating from any lack of fueling.

2004 was the last year of the CAP (Cummins Accumulator Pump) system before Cummins went to a common rail system. This unit pressurizes the fuel in a reservoir, which is then distributed to the injectors.

These CAPS units are susceptible to failure due to overheating when starved for fuel. It lubricates and cools itself with the fuel, so when it's sucking air it can lead to failure and a $10k replacement bill. This problem is exacerbated by a couple factors:
  1. The transfer pump (also referred to as a lift pump) that primes the fuel system only runs for 30 seconds when you turn the key to "On", then once the engine has been started, the CAPS has to do all the work pumping fuel from...
  2. ...the fuel tank, which is mounted up near the front axle. There might be 30'+ of fuel line to suck through...imagine drinking out of a 30' long straw.

Fuel filters. Cheap, easy; check the box. Remove obstructions and free up fuel flow.

The primary fuel filter is simple. In the RE bay, I was able to climb inside and sit down on the body to work on this. The instructions are in pictograms right on the side of the filter housing.

I still ****ed up, lol. The drain on the filter I bought needed to be fully un-screwed to close (all the way down toward the ground when mounted). I had simply tightened it down like anything else and when I ran the transfer pump, soon diesel was absolutely blasting out of the bottom of the filter. Thankfully I just reached over and cut the battery switch off before causing an ecological disaster. I caught it in my drain pan but it was a close call. At least we know it's working... Lesson learned...maybe.

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Next up was the water separator, which I had happened upon while exploring the undercarriage and is mounted to the underside of the floor just behind the rear axle. I need to get back under there and figure out what that disconnected switch goes to...

I probably drained a cup of water or more before it started running straight diesel. I let it drain until it slowed to a drip and then the filter housing unscrewed very easily. Borderline loose...but not evidently leaking. Screwed the new one on per the cave drawings on the side, made sure the drain was shut and it was time to prime the system and try to start her up.

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She wouldn't start. 🫀

It would crank once then do this horrible clacking/clicking noise. Turns out that's just the big-diesel-engine version of insufficient starting current. Batteries were at <11V.

I had drained the batteries by forgetting to disconnect them at the cutoff switch for the night. I knew I was going to do this right away. I was relieved when I got the batteries recharged in about 20 minutes and she started right up.

Still getting intermittent loss of power...


Something I plan to do sooner than later is install a FASS lift pump, which supplies constant positive fuel pressure and helps protect the CAPS from the overheating issues mentioned above. They have a few different configurations but I'm going to look into the kind that replaces the primary fuel filter first. Seems like a convenient package, albeit an expensive insurance policy.
 
Air Cleaner

Given fresh fuel filters didn't clear things up, the air cleaner aka engine air filter is the next obvious step. I couldn't source one locally in Kentucky, so with new fuel filters installed, I watched my coolant temp closely as we made the last leg home over the mountains. If it's gasping for air, I think theoretically it should be running hotter. I don't fully grasp that concept yet but I guess it makes sense. My knuckle is a bit sore from tapping that damn trolly Blue Bird gauge every 30 seconds, each time getting it to reveal it's secrets.

Most of the drive was bang on 198-202*F range. There were times during intense climbs that it rose to around 207-208, although the hashmark intervals on this gauge are not consistent. Never got up above 208ish at most, but still I'd say that's running hot. It did well to cool itself down as the load tapered off, so I never felt the need to stop and let it cool down.


My ISC has a disposable canister type with a bonded filter element which is 11"x24". Little bigger than the one in my Miata.

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She's definitely got many years of dirt in there, but the filter element is not evidently dusting. Reinstalled and hit the road from KY to MD.

I am not convinced this is the true source of my power issues, even though the canister has 2016 written on the side. I would expect a consistent loss of power across the RPM range, like you would get with an intentional restrictor plate. There are moments when I can put the pedal to the floor and the bus just stops trying to apply power entirely. Feedback in this chassis is relatively numb, but here are my observations:
  • Almost every hill coming home would reduce our speed proportional to the grade. I've read reports of most 250hp buses climbing very well, so with 300 I should be doing better than this.
  • There were moments when it would suddenly be fine with cruising right up a slight grade at 70mph. Most of the time it would slow to 65-60 on the tiniest upslope. Steeper climbs got dragged down to as low as 40mph.
  • At WOT (Cruise Control off), power will often cut out entirely until I ease up on the pedal.
  • With Cruise Control on, the bus would just naturally fall back to whatever speed it could maintain. I didn't notice any total power cut with CC active.
I'm looking around locally to see if I can find a solid parts supplier near me. This kind of air cleaner should be on someone's shelf somewhere. I'd like to establish a relationship in the area and spend my money there when I can, rather than order online.
 
Regarding that mystery connector near the fuel/water separator, could possibly be a connector for a fuel heating element that was part of a reusable bowl for the filter element.

Attached are pics of my filter - the plastic bowl contains a heating element and a water sensor…the old filter had an open bottom (I guess to help with preheating the fuel??) …. Could not find a similar replacement, but new one seems to work fine.IMG_4552.jpeg
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Regarding that mystery connector near the fuel/water separator, could possibly be a connector for a fuel heating element that was part of a reusable bowl for the filter element.

Attached are pics of my filter - the plastic bowl contains a heating element and a water sensor…the old filter had an open bottom (I guess to help with preheating the fuel??) …. Could not find a similar replacement, but new one seems to work fine.

Well, cheers man. Thank you. Occam's Razor would conclude this is definitely it.

Makes sense; someone probably just couldn't get that kind of filter or didn't care bc the bus was never in cold climates. Once it was swapped for this style without the bowl, it's easy to imagine every filter change after that following suit.

I'm not going to worry about it. I'll clean up the connector and get it stowed away, then eventually when I'm looking into winterization I can look into going back to the style with the preheater.
 
Took some seats out. Pretty simple stuff. Brain off, let breaker bar take the wheel. 10D is no more.
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The bolts are stiff, but not seized. Drilled out the riveted covers. Feeling grateful. Praise the impact driver. Also hoping I didn't just contract tetanus.

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The Rivet Corpse Piler:

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I haven't heard of an R400 Transmission

Oh yeah and to correct the initial post, the transmission is an Allison B400. Buh-buh BEE as in Bravo 400. And, to the dealer's credit, it is at least still part of Allison's "3000 series".

I haven't read up enough on it yet to really say, but I believe it comes with more beef. Maybe that's what the B is for.

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All passenger seats removed (except the two mounted to the rear bulkhead. For lols with friends until we fully gut it). Also took down the steel partitions. Tomorrow I'll suit up and tackle the toilet enclosure and associated plumbing, plus the window bars to be rid of pretty much all the "prison" parts of the bus.

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