THoughts on salvaging a 6-71 from non-bus places

[Dave Silva]

My obsession with owning a 4104 has led me to all sorts of questions about long term care of the engine and recovery from a catastrophic failure.

Apparently, a simple in-frame rebuild has become more expensive and less reliable that it was 20 years ago.

In the T1N SPrinter world,  bottom end failures are rare  so a used engine with fresh peripherals is a pretty good strategy over a $9000 rebuild.

I'm wondering if the same is true for the  6-71?   These engines were still in new boats, generators, fire trucks  heavy equipment up to the late 90s.   

Some of those places have good records and maintenance (boats) and some have low miles  (fire departments)

Of course there are trade offs,  high idle hours, sulphur in old oil, wrong rotation etc. 

Curious if anyone has gone this route to re-engine an old bus?

[luvrbus]

The 6l-71 are out there but there are so many variations of it one needs to be sure it is the right model number or you have a boat anchor unless you spend big bucks to change one to your model number ,the 6L-71 is unique both ends are the same and you flip ends to get the blower on the side needed. Back in my younger days rebuilding a quad (4) I made the mistake and got the blower on the wrong side on 1 never forgot that again . FWIW now a good Re-Con 6L-71 not the so called rebuilt or in frame kit engines are in the $20,000 + range in cost if you have a good core engine. Those engines will just take so many pistons and liners kits then they need to be a complete re-con back to OEM specs big dollars with just the machine worked involved, in frame kits were never design for the long haul they were made to squeeze a few more miles from a engine till you did a complete Re.con .  I just bought a aluminum block 6L-71 in Texas I going to pick and tinker with if times allows   

[Dave Silva]

The 6l-71 are out there but there are so many variations of it one needs to be sure it is the right model number or you have a boat anchor

Yeah, it would take some research. But these are not auction sales.  Within 400 miles of me there are a bunch of 6-71s under $2000 and they are not selling. 

One from a generator, a couple from boats, one from a fire truck

Further south there is a very nice pair from a boat that had been re-engined by a new owners shortly after the 6-71s  were rebuilt.

I doubt the sellers would object to me doing a thorough  inspection.   The biggest risk is how it was stored.  A sump full of old oil can cause real problems.   

[dtcerrato]

Yeah, it would take some research. But these are not auction sales.  Within 400 miles of me there are a bunch of 6-71s under $2000 and they are not selling. 

One from a generator, a couple from boats, one from a fire truck

Further south there is a very nice pair from a boat that had been re-engined by a new owners shortly after the 6-71s  were rebuilt.

I doubt the sellers would object to me doing a thorough  inspection.   The biggest risk is how it was stored.  A sump full of old oil can cause real problems.

Of coarse thanks to Luvrbus's wisdom & knowledge we learned that the engine in our 1953 4104 was a rebuilt 1969 oem Gray Marine block. Didn't even have any Detroit Diesel serial numbers for ordering parts. Cliff also said it was a port side boat engine (I think I got that right?) because it was a left handed reverse rotation as in the Vee drive buses.
I wasn't aware the DD made an aluminum IL671 block! But there's a whole lot I don't know. And want to say it's really cool to have worked on a quad setup!

[luvrbus]

Yeah, it would take some research. But these are not auction sales.  Within 400 miles of me there are a bunch of 6-71s under $2000 and they are not selling. 

One from a generator, a couple from boats, one from a fire truck

Further south there is a very nice pair from a boat that had been re-engined by a new owners shortly after the 6-71s  were rebuilt.

I doubt the sellers would object to me doing a thorough  inspection.   The biggest risk is how it was stored.  A sump full of old oil can cause real problems.

There is process to follow when storing a 2 cycle engine if not followed they are pretty much just a core engine after 2 or 3 years. I started one on generator from the 40's that had been in storage a low block with eternal fuel lines on the 2 valve head with the antique starter the old H injectors were not even stuck, prime it filled, with oil and water and it fired up with a little smoke that cleared in minute of running ,the mine still uses it for backup     

[windtrader]

Scott Crosby is purported to be a knowledgeable steward of these old beasts. Go check out how he got a big one right up the backside on purchasing a used engine that was supposed to be well stored. It's a crap shoot even for professionals. I dont want to sound like I'm pissing someone's dream but just make sure to keep a reality frame around what your real intent and goals are. These old buses are fine as antiques to drive in a parade or a short trip but if you have any distant goal of putting anywhere the use you did on the sprinter, you really need to get something more serviceable.


Dan is a unicorn, I'd say one of literally a handful that drives their vintage bus this much and has many decades of experience working on his bus. BGM is all about getting his bus in shape to go to Florida? You mean after all this time even his bus needs lots of work. Check out the trill of busting off hub bolts.


Get one if you love to wrench.

[Utahclaimjumper]

I could invision one with the 5.9 Cummins,, it would last a long time with reliability and good power  Put a 3060 Allison behind it for ease of driving, >>>Dan

[dtcerrato]

"These old buses are fine as antiques to drive in a parade or a short trip but if you have any distant goal of putting anywhere the use you did on the sprinter, you really need to get something more serviceable."
LOL.
We've been to 5 parades in Tok AK with the bus at 10K miles per trip. As far as our vintage & antique buses are concerned that's all they are - is serviceable! Unit repairs on them on anything yields components like stainless steel, copper, brass, etc. that can be rebuilt over & over. Not like the throw away crappola of today.
Pre trip inspections are smart - being proactive not reactive.
There are many dozens of Utube videos showing old vintage & antique abandoned buses sinking into their unintended graves for many decades being rescued on scene and driven away on their own power. The best videos are the ones with full grown trees having to be cut down just to get the bus separated from nature it's been there so long.
Try that kind a voodo on a Monaco or Sprinter! I gotta quit, I'm bias. Rant over, carry on.

[luvrbus]

It is a love -hate relation with an old bus, the owners that depend on a shop for the up keep on 1 pay a steep price and most walk away ,buying a DYI conversion can be a challenge. I have a lot of friends that own the GM some have the funds to keep on going some just park one a sell the parts. There is no hiding the cost of keeping a 50+year old bus going, operators like Greyhound and Trailways sold off the buses with millions of miles on it because the operating cost outweighed the revenue. Now you can buy factory conversions Prevost from the 90's with the 8v92 engines from 40k up with less than 200k miles, lol they always say health problems forces the sell and it does they are sick of paying for repairs. If the poster wants a 4104 let him go for it, he is the one that makes the call.I was happy with driving my Country Coach Magna with the Cummins ISX 15- 650 hp 50,000 GVW and would cruise all day @ 70 mph up hill or down hill and average 7.7 mpg. The higher end class A motor homes are not bad for safety either with a double frame from front to rear. In the end it depends on what a buyer wants ,but they do need to know the pit falls and $$$$ of keeping it on the road. Driving from Az to Texas last year I counted 14 buses at shops of different brands, I stopped and looked at one for sale the shop was selling for the repair bill, the shop had a 10k bus for sale with a 22 k repair bill he was trying to recoup, I wished him luck.FWIW Luke does a fairly good job at sourcing parts for the older buses but they come at a price