Greyhound - The MCI Years - Part 3 of 5

[Gary Hatt - Publisher BCM]

The MC-7 took a beating but kept on ticking.  This model never had great Rub Rails so they got pretty beat up by rolling baggage carts.

The main service garage in NYC stayed very busy.

All buses had in-station heating and air conditioning connections so they could shut the buses down while loading and unloading passengers.  Does anyone still use this when parked at your home?

MC-8 buses became very popular by now.

Fairs were $75 to anywhere.  Fuel prices were lower then.

Some MC-7 buses had 4-digit numbers that started with "0".  What did that mean?  These were special buses.

Do you know why some MC-5C buses had a Heat Plate on the roof?

In 1926 in Portsmouth, NH, the first Greyhound Commission Agent in a small restaurant.

Greyhound had a great Freight Business at one time that generated a lot of revenue for the company.

Learn what the "MCI Lean" is all about.

This is a video by Robert Redden. Subscribe to our Channel to be the first ones notified as we upload more bus videos.

https://youtu.be/g7eSi8u7f8Y?si=eFt5C2CKp3LWHD8A

[Coach_and_Crown_Guy]

Some,(most?) MC5C's were built for a contract with Saudi Arabia for oil bidness purposes and the workers. Aramco?

They were the first and only ones I'd ever seen with the added sun roof/heat shield above the bus body roof.
It was ventilated with air ducts running the length of the sun roof, actually the whole shield was supported a couple inches above the roof creating the flow through channels from front to back, and apparently was required due to the insane temperatures in Saudi Arabia (120+), boy I guess.

Another consideration was the MC5C's only had a naturally aspirated 6V-71 engine and therefore not a lot, (actually almost none) leftover HP to drive any sizeable A/C compressor. Also at the time they were built there wasn't that many options for really high capacity A/C systems in any coach. Most coaches of the day only had 3-4 ton capacity and either an engine driven (8V-71) or auxiliary engine like in the 4104's which again wasn't much more than 3-4 tons. So the sun shield was a pretty good solution to the overall massive heat load gain from the direct sun on the roof and a lack of a very large A/C system to cope with it.

I guess MCI kept the tooling for them because I've noticed them on lots of the recent MC12 variants being auctioned off by the Gov't recently. They also have the exact same sun/heat shield installed, most likely for the intended South Western desert regions of operations.

[dtcerrato]

At purchase our 53 4104 had an 84K btu Trane A/C compressor ran by a four cylinder pony motor on a dedicated gas tank that kept EVERYTHING up and running with main engine shut down.

[Coach_and_Crown_Guy]

Everything??? My experience driving them in service with a company that had about 15 superbly maintained 4104's, all with the Continental gas engines, and none of the ex-Greyhounds with their diesel conversions, was that we were required to keep the main engine 6-71 running at a fast idle to maintain the generator speed to keep the batteries up or the main cabin blowers would kill them in very short order. I'm pretty sure the auxiliary pony engine didn't have a large enough generator, which I don't think they even had, or the left over power after running the A/C compressor and the belt driven condenser fan it also had in there.

84k makes it 7-tons and more than I figured 4104's were. I always thought about 4 tons was the norm. 12k per ton as I recall. So maybe the A/C system was modified by a previous owner. I just checked my handy dandy original GMC 4104 Maintenance Manual and nowhere could I find an overall specification for the A/C ton/btu rating. It might be there somewhere as an overall description but my cursory scan didn't see it. It did call out the Trane Model C-563 running at 250psi max high side pressure and all the other mechanical components of the A/C system, which doesn't include any electrical generator at all by the way.

As originally envisioned and designed the whole package was meant to operate with the main engine running on down the highway. Where the two engines contributed their part of the overall A/C system operation. The whole body ventilation heating and A/C blowers (they are the same of course, A/C merely ran faster) were hardwired into the vehicle charging and battery circuitry with all the voltage regulation etc. dedicated to vehicle electrical integrity. Those 12V DC blower motors drew an astounding amount of current and would kill the batteries in no time at all unless the large main engine generator (not alternator by the way) was running at a speed faster than the normal 500rpm idle. So we had to attempt to raise the idle speed manually when stopped for any length of time while loading or waiting with the  A/C running.

There was a "T" pull handle just to the right and above the drivers right leg mounted under the dash above the throttle pedal. It was a crudely simple cable that connected to the throttle bell-crank under the floor and simply pulled the throttle like the treadle pedal did. If you've ever tried to make a 6-71 or any DD 2-stroke hold a speed above the low idle buffer setting then you know it's very temperamental and will not stay at whatever speed you want it to hold. This was always a challenge to get the 6-71's to find and settle in at about 800-1000 rpm and stay there. No built in air actuated fast idle cylinder or fast idle ability built into these early governors, nope, it was all done by hand with the cooperation (or not) of the engine in question.

If your particular 4104 was able to run the A/C and keep the batteries up without the main engine running it would be the first I've ever heard of and may have been modified to do that by some previous owner/operator. It might do it for an hour or so but the batteries would be severely drained because they aren't being charged. It would have been an engineering challenge because it requires a 250+ amp generator and the switching circuits to remove the main engine generator and isolate it and the regulator that controlled it.

Lots of things to modify and even then I'm not sure the gas engine would have enough power to handle all that load. If there was even space to mount such a large generator in the A/C compartment. Lots to consider to make the system run in a stand-alone mode with the main engine off. Everything is possible if you throw enough money at it but I doubt it was any as-built factory standard 4104 if it could really run stand alone.

I'd be interested in hearing more about it if it really could do that and broaden my knowledge base. Feel free to email me direct rather than tying up this site on frivolous stuff. mikemcc2k@yahoo.com

[CrabbyMilton]

That's interesting about the auxiliary gasoline engine just for the AC system. I always thought those were small diesels which would have made sense to avoid 2 fuel tanks.
Were some of those ever converted to alternators since it was long proven that dynamo's were inferior at low rpms and shorter life than alternators? Bah, who says things were always better in the old days?

[dtcerrato]

When we purchased our 4104-129 from a Southern California charter company in 1979 the bus was 26 years old. Pacific Greyhound ran 129 for 20 years of it's initial commercial  service life. The charter company we bought it from was 2nd owner and 129 was the 1st of a 17 mixed bus fleet there. Three of the fleet were 4104s. So we purchased it in it's 6th year of 2nd party commercial service. I was told that 129 was dedicated to the route between Los Angeles and San Francisco for Pacific Greyhound. Our bus purchase ommitted the seats, overhead storage shelf, & the A/C only portion of the HVAC system. I personally read the Trane compressor lable as 84K btu. The pony engine had a sizable generator and huge regulator. There were more maintenence records for the A/C system then for the entire bus so we wanted nothing of the otr A/C. We love the T handle and refer to it as our cruise control. My mention of it running everything may be misleading in the fact that it would maintain the running A/C w/o the main engine running but only for a spell, not indefinitely which may have been the reason for all the A/C system issue evident on the maintenence records that scared us away from the unit.
We lived on the charter lot in the bus shell for 3 months, bartering time and parts back & forth. Made good fiends with the owner and would work for free in the pits with the mechanics that talked highly of 129 always returning on it's own power. As far as tying up this site on frivolous stuff! What? This is what the bus world is all about, right? And yes I would like to chat more of of what these buses are made of...
One more unique note about 4104-129 that some forum members are aware of is it had been repowerd by the charter company with a 1969 Gray Marine port side two stroke. When we did a recent in-frame there was no Detroit engine numbers to give to the parts house. Just another learned thing after running 129 since 1979 and still going strong.

[Coach_and_Crown_Guy]

ALL 4104's were built with two fuel tanks. The main diesel tank was 140 gallons and the second one for the gas engine driving the A/C compressor held 24.5 gals. The two fueling doors are both on the right side immediately behind the right front wheel well. The smaller one furthest to the front and slightly triangular in shape following the curve of the wheel well was for the 24 gallon gas tank. The main engine fuel door was just slightly behind it and shaped as a proper square lift up door common in all buses. It was for the 140 gallon main engine fuel tank and equipped with a whistle that stopped a few gallons before the tank was all the way to the top.

GMC built all the 4104's with a 4-cylinder Continental Y91 L-head gasoline engine running at 2000rpm as the standard sold to all customers. Greyhound was interested in having the A/C engine be diesel for the obvious benefits of not having to handle two fuels in the terminals and simplifying the supply chain for their fleet. Even though they still had gas engines in older buses like Brills and whatever else was still hanging around, they saw the diesel as the future and was willing to embrace it and retire the dual fueling headaches.

I don't know if Greyhound did the initial A//C diesel conversions in-house (probably for sure as an experiment), or if they did them in volume on their existing fleet. I suspect they may have done some of that and then approached GMC to custom order for their use only specially ordered 4104's with the modifications they wanted. You can still to this day spot an original Greyhound ordered 4104 by the configuration of the condenser grill work on the left side.

The GMC standard model was a single large condenser grill while the Greyhound models all had a split grill arrangement with a solid panel between them, where one of the grills was slightly larger than the other grill on either side of the vertical separating side panel, I can't remember which was which but it's real obvious.

Another fun fact regarding Greyhound spec'd coaches was that Greyhound had both of the exterior rear view mirrors mounted low with the mirror frame ABOVE the mounting arm. The GMC standard was to mount the right mirror low while the left mirror was mounted high at the top of the driver side window and the mirror frame hung down from the mounting arm. Check it out and you'll see what I mean. This is how I can spot GMC's that were originally ordered and used by Greyhound before being sold into the secondary market to other charter and line operators after Greyhound put a million or more miles on the units and got all they could get out of them before they were mostly all used up. The GMC standard model was sold to all the other customers with the GMC regular features and not the Greyhound mods.

All Scenicruisers that ever left Greyhound service had multiple millions of miles on them and even then they were successful in the after markets and did great for their new owners, and I was one of those. I had two Scenicruisers that I ran the hell out of and they were the best buses, except for the Crowns, that I ever ran.

Very solid, extremely comfortable to drive, reliable and easy to repair when required. They are the best for Charter and long distance travel and a true operators dream since they are low cost to keep on the road. But I must say that as a base for a Coach Conversion into a Motor Home they have a serious drawback which is that the only place you have full stand up head room is in the isle, and in the bathroom, which is at isle level. The seats are all on a raised platform so if you merely cover up the isle you end up with about four feet of head room. And that platform is part of the vehicle structure and impossible to remove with out totally rebuilding the structure and rerouting air lines and tanks and equipment under the floor. I've seen that done, and even roof raises done, but I shudder to think of the overall damage these modifications have made to the vast over-engineering and structural integrity of these fantastic buses. Sorry for the digression.  But I still love me my Scenicruiser and look forward to finding a good example and restoring it and keeping it in a charter service configuration as a display and driving demonstrator of what once was.