1975 MCI MC5B Questions

steve.barnett71 · May 10, 2016, 05:37:02 PM

I am considering the purchase of a 1975 MCI MC5B conversion. It is a beautiful bus and the conversion looks well done. I have some concerns about the 8V71 2 stoke diesel engine. I hear they are noisy, leak oil and may not have the power needed for a bus this size. We are wanting a bus conversion or RV that we can comfortably take anywhere in the country.

I look forward to your thoughts

lvmci · May 10, 2016, 06:29:55 PM

Hi steve, the 5 series mci buses are all 35', most parks allow 35', limited 40' and hardly any 45'. It's the most usable motorhome size if you want to go to federal and state parks, good luck, lvmci...

RJ · May 10, 2016, 09:53:04 PM

Quote from: steve.barnett71 on May 10, 2016, 05:37:02 PM
I hear they are noisy, leak oil and may not have the power needed for a bus this size.

Steve -

The simple answer to the above quote is: yes, yes and sometimes.

They are noisy because the cylinders fire every stroke of the engine, not like every other stroke on a 4-cycle. The rootes-style blower, needed to provide enough air for combustion, also contributes to the noise, especially that distinct Detroit "whine" when revved up.

They often leak oil because of the engine's design. Because it's a two-stroke, the block is pressurized by the blower. This internal pressure can cause weaker areas of gaskets and seals to start leaking - but not always. If the engine has been rebuilt (and most have been at this point) and the technician knew what he was doing, often they can go many thousands of miles before they start weeping. OTOH, if you see a big puddle under the coach, look and see if it's been dripping from the air box drain tubes. Big puddles under them mean that the oil control rings on the pistons are getting tired.

As for your third concern, buses are not BMWs. If you want an RV that will climb 6% grades at 65-70 mph, then buy a two-axle stick-n-staple with the 500+ hp Cummins in it. That coach will weigh somewhere in the neighborhood of 20 - 25,000 lbs. My MC-5C weighs in, with full fuel and water, at a little over 27,000 lbs, and is pushed along by an anemic 6V71 putting out 235 hp. Translation: 25 mph up 6% grades - even most of the truckers are faster nowadays. An MC-5B with the 8V71, which, in normal bus configuration puts out 275 hp, weighing roughly the same as my coach since they're both so similar, will end up dropping to about 30-35 mph on that 6% grade, and yes, the newer trucks will be going around it, too.

But you know what, Tortoise gets me there! Over 18,000 miles since I bought it 18 months ago, from New Hampshire to CA, from CA to British Columbia, from CA to CO, and to some local CA/AZ events. I just putter along at 60-62 mph in the RH lane and flat don't care if others want to go faster (it's also a more relaxing drive!) Being only 35' long, it's like piloting a giant minivan on steroids, and, like Tom said, is easier to get into a lot of campgrounds the bigger boys can't. Do I wish it had more power? Of course, we all have our "Tim Allen Syndrome," but I'm not going to let it's lack of power take away from the enjoyment of using it! That's what I bought it for, after all.

FWIW & HTH. . .

TomC · May 10, 2016, 10:20:43 PM

The best part of the 8V-71, is in original tune and just a 4spd manual, they were just about impossible to hurt. With the engine in the back, driver's couldn't hear too much so when something went wrong, usually took out the engine. With a slide in cradle, they are relatively easy to R&R the engine/transmission. Pulling my car puts me at 35,750lbs. And with my 8V-71 turbo'ed and air to air intercooled, it is just about as fast as a 5B with stock engine. Have run with one and neither of us could out pull each other. 30-35mph isn't that bad going up a hill. Good Luck, TomC

steve.barnett71 · May 11, 2016, 05:00:01 AM

This bus has an Allison 4 speed automatic. Any concerns that the automatic will hurt the performance?

Here is a link to the ad on RV trader.

http://www.rvtrader.com/listing/1975-MCI-Bus-Conversion-115146731

Oonrahnjay · May 11, 2016, 05:44:19 AM

Quote from: steve.barnett71 on May 11, 2016, 05:00:01 AM
This bus has an Allison 4 speed automatic. Any concerns that the automatic will hurt the performance?

Here is a link to the ad on RV trader.

http://www.rvtrader.com/listing/1975-MCI-Bus-Conversion-115146731

IMO, unless you have 100,000 miles driving a bus or tractor-trailer with a manual transmission, you should ONLY buy an automatic. And, no, an auto won't hurt performance (in fact, where a manual can do better than an auto, the driver has to be skilled to "get that performance" out of it -- see my first sentence above). An auto often gets slightly lower fuel economy but it's about the cheapest money you'll ever spend owning a bus conversion.
The driver who has the skills and experience to handle a manual/clutch/crashbox transmission has a useful and valuable blessing -- the rest of us had better be very careful.

lvmci · May 11, 2016, 07:07:23 AM

nice bus Steve, take a look at air box above engine, look on top of the radiators for rust, take a long screw driver, if it just a scratches, it's probably just surface rust, if it flakes off or you can push it thru thru the metal support beam, walk away, lvmci...

TomC · May 11, 2016, 10:40:36 AM

I drove truck for 21 years a 1.3 million miles with exclusively a 13spd transmission. When I started converting the truck for a motorhome, the first thing I did was remove the 13spd Roadranger and replaced with an Allison HT740. Granted, no more overdrive, but with 3.55 rears, will cruise easily at 65 turning 1880, or slow down to 1600 at 57mph. The main reason for changing was so my wife could also drive the truck. Personally-I have nothing to prove with shifting. There is nothing like both the performance and ease of driving with an Allison automatic-even with the fuel mileage hit. Good Luck, TomC

Tom Y · May 11, 2016, 06:56:07 PM

I was in Yellowstone this past winter. Saw 4-5 MCI 5s up in the north end. They where sitting out all winter but no salt I would guess. They may have been 5Cs I do not remember. Good luck with your shopping.

steve.barnett71 · May 12, 2016, 05:08:33 AM

Anybody near Seattle that would be willing to check this bus out and give an opinion? It is a very long way for me to travel just to look it over.

jav9956 · May 12, 2016, 08:19:59 AM

You may want to check out this bus (It is a 5C):

http://orangecounty.craigslist.org/rvs/5544459079.html

Looks good and for the price you can drive it anywhere and still pay less. I don't know if it has all the amenities you are looking for... check out craigslist. Seems like a lot of conversions get posted in the summer months.

lostagain · May 12, 2016, 09:33:56 AM

I am an MC5 fan. About the one near Seattle, the 8V71 will get you around quite well, as long as you don't expect sports car performance. 50 gals of water is not very much. Most conversions have 100 to 125 gals fresh water and the same of combined black and grey. That lasts the two of us 4-5 days to a week. That is important if you are travelling long distance and dry camping in Walmarts and truck stops, or anywhere with no water hook ups. Oh and I don't like those square head lights on top of each other... They should be beside each other. But that is just personal preference.

JC

RJ · May 12, 2016, 09:00:50 PM

Quote from: jav9956 on May 12, 2016, 08:19:59 AM
You may want to check out this bus (It is a 5C)

No, it's not a 5C, it's a 5A. 5Cs weren't built until 1977.

But it's definitely worth looking at, and there are several busnuts in the SOCA area.

FWIW & HTH. . .

DoubleEagle · May 13, 2016, 07:00:56 AM

I prefer Eagles, but that MCI is an attractive good looking bus that will be worth checking out. The 8V71 is a good dependable engine, and the Allison is bullet-proof. Being a 35 footer, it will get you into places others can't go. The Allison will get you up steep campground roads that the four speed manual would ruin a clutch on. If you take off what looks like a pair of loudspeakers on the top front, your fuel mileage will go up.