Would you do a 4104 today ?

[Dave Silva]

Finding service for any old two stroke engine is increasingly difficult and likely a DIY option. You might be lucky with a reputable 2 stroke mechanic in your area but this is a gift, not an expectation. I don't know the specifics but it is likely 20 years, a generation, of time since heavy duty diesel engine mechanics learned to work on these and far fewer with enough practical shop experience.

I'm here to have my ideas challenged, i have very thick skin.    But from my research, maintaining the engine is the easy part.   

The design was for them to be rebuilt by bus mechanics in the shop or on the side of the road. 

[luvrbus]

About all the parts you can buy for the 6L-71 are all aftermarket parts made off shore,BMW owns the rights to the  Detroit 2 stroke engines if you want sticker shock buy OEM parts. I have been pricing out parts for a rebuild on 6L-71T . James wants all OEM parts a set of liners and pistons @$1610.00 x 6= $9660.00 and a Re-con head is $3500.00, Detroit Diesel doesn't sell inflame kits you buy each friggin part. I am not happy with Detroit, I have been a battle for 2 years that is just now ending over a set of liners made offshore that pops the top off the liners, the box says made in USA and the liners say made in China. Dan is a lucky camper his 6-71 blew close to home, those engines will take the top of piston out or break a liner. Weigh your options you can spend more on a bus that you paid for it.@ 65 years old go for Monaco with the 8.3 Cummins it a durable engine and Cummin will work on it when needed and the chassis is off the shelf parts no chasing parts and the engine oil can be bought at Walmart no chasing the CD/ SD 2 -40w engine oil. I love old buses, but when I turned 65, I started going a different route because of the cost of owning a bus   

[dtcerrato]

With over 5000 4104s produced, it is the one antique bus running the roads where parts aren't as hard to find as other models. We have not ever not been able to find the parts we need. You asked what parts are mostly unobtainable - how about the engine rad fan hub or the rear window assembly. We're running a fan hub that is from a 92 series setup. Modification is fun. As far as the two stroke sound and smell - well that right there will never be able to be duplicated. Our favorite breakdown was an 11 day event in the Alaska Kenai. Just so happens it was among the best 11 days of our first 5 month AK journey.
Thanks for the kind words Walter.

[luvrbus]

With over 5000 4104s produced, it is the one antique bus running the roads where parts aren't as hard to find as other models. We have not ever not been able to find the parts we need. You asked what parts are mostly unobtainable - how about the engine rad fan hub or the rear window assembly. We're running a fan hub that is from a 92 series setup. Modification is fun. As far as the two stroke sound and smell - well that right there will never be able to be duplicated. Our favorite breakdown was an 11 day event in the Alaska Kenai. Just so happens it was among the best 11 days of our first 5 month AK journey.
Thanks for the kind words Walter.

[luvrbus]

I have 2 of the drives from the 8v92 military engines, I had 4 but used 2 on the 4104,you are just lucky Dan I have a crank from a 4104 6-71 the bad coupling snapped the end of the crankshaft off and took the radiator out too. Freightliner in Needles threw their hands up on the repair and had me do the repairs for them. It did tick me off how much the owner was charged by Freightliner and I did the all the work and bought the parts. I got paid but they added 60% to my bill and I thought that was wrong, I never did anymore for the dealer when they would call I would say I am too busy

[Dave Silva]

THis is turning into a pretty good discussion.

I would definitely want to avoid ever having to do a rebuild.    I think choosing the right bus with the right history, and regular oil analysis, that can be avoided.   But the risk is not a deal breaker.

The scarier thing is more about some tiny failure point that  has gone unnoticed for 70 years and fails at the worst possible time.   

In the 70,000 miles we put on the SPrinter in 3 years we've had two major breakdowns on vacation- of course vacation breakdown are a lot worse than cruising while retired break downs. 

I cannot afford a really new RV with dealer support so anything I do carries some risk.

I'm wondering if the risk with this coach can be mitigated to compare with the risk attached to a 97 Monaco?


But damn,  the more i learn about the 4104 the more i just want one because it's cool.   

[Boomer]

    Totally agree with Clifford.  There are a lot of quality Monaco or Country Coach units out there with low miles and modern engines that are still supported by Cat or Cummins, even going back into the late '90's vintage. What ever you paid for one would be cheaper than a breakdown in a vintage Detroit on the side of the road. Obsolete parts availability and no vintage 2 stroke mechanics anymore.  I asked a Freightliner dealership in a large central Washington city a while back if they knew of a 2 stroke mechanic anywhere and they didn't even know what I was talking about. I Love the old tin too and have owned quite a few of them and can fix most everything myself but being almost 80 yrs old the thought of pulling a trans or LH starter on the side of the road anymore just doesn't turn me on.  My 4106 is as nice as they get for early 60's vintage and I have a lot of spare parts but I plan my trips carefully "just in case".

[dtcerrato]

"The scarier thing is more about some tiny failure point that  has gone unnoticed for 70 years and fails at the worst possible time."

In the last 47 years of 4104-129 ownership lots of scary things have happened.
The more recent tiniest thing to grow into something much bigger again & again for the year that followed was when a four valve head bridge support stud popped out of the water jacket it was sealing to dump massive amounts of coolant into the crankcase - in less than 10 minutes there was ten gallons of 64% antifreeze on top of the five gallons of oil.
From the driver's seat we could feel the crankshaft counterweights and piston bottoms slamming the milkshake in the crankcase.
We speculate that's what caused the dampers hub to break in short order on the same trip right after the support stud was replaced. Then a year later with an AK round trip run under our belt on our return in middle Canada, we almost lost a flywheel to 5 of 6 broken crankshaft bolts. Again we suspect collateral damage from the earlier crankcase milkshake.
We always thought the worst thing that could happen would be loosing power or brakes on a steep bridge without shoulder lanes.
From past experiences the very worst breakdown is the one that you play over & over in your head before or if it ever happens. Just take it in stride and deal with it as it comes step by step.
The overruling thought is the long history of driving our bus and knowing it is as dependable as it's been thru all the great years of memories and experiences.
It has and continues to be the spice of our lives.

[Jim Blackwood]

I may not be a great person to respond to this for any number of reasons, but I do like to participate on the forum so here's my perspective. I'm 71 btw and going strong. A few years back I bought a bus, in 2019 I think it was and planned to be using it in 5 years. There has been a bit of slippage in the schedule, so it's looking more like a 7 year project but that's still acceptable. But here's the thing, you really need to honestly determine what your needs and wants are before picking a bus. I had wanted to do a conversion for maybe a couple of decades but was put off by the need to do a roof lift. I am 6'1" and like to wear a Stetson, sometimes inside. So this became a major consideration and it took a long time for buses with enough headroom to become available at a price I could justify and afford. It had to be a cash buy and I needed some way to finance the build. So I was looking for a bargain with headroom and it took me a couple years to find it. I went with a '96 MCI 102DL3 but the point here is that headroom was a defining requirement which meant that the earlier buses would not qualify. I also soon made a 4 stroke engine one of the requirements simply because I don't want to have to deal with the drivetrain any more than is absolutely necessary, but I am also very unwilling to part with money to pay anyone else to work on it. That meant it had to have a great reputation for reliability and the Series 60 looked like one of if not *the* best choice.

So my focus was minimal maintenance requirements, headroom, an extended service life and ease of conversion. True, I could probably have bought one that was already converted but we've been socking it away into retirement funds and I had no intention of inhibiting that program. We are now reaching the cusp where we tilt over into actual retirement and start making use of those funds. I intend to make this the last winter when we are not free to escape the cold. The plan is coming together.

This probably doesn't help you with your decision. FWIW unless I'd been a diesel mechanic working on those old engines I'd hesitate. It's not that they are complex, I'm reasonably familiar with how they are built and do not doubt my ability to rebuild one if I had to. It's more that I don't want to have to. So if I was considering one I'd want to run every test imaginable to get one in the best condition possible. Same for the entire bus for that matter. They are old and have seen a lot of miles. I'd also have to seriously think about something newer and or something with less miles on it. Sometimes you can find a deal.

Jim