Paul von Fange
May 30, 2023

Repeated and Extraordinary Mechanical Failures (Senicruisers)

Editor’s Note: This article was extracted from Paul von Fange’s book, Scenicruising: The Greyhound Scenicruiser Story, and was reprinted with his permission.  

Six months into Arthur Genet’s term as head of Greyhound, his frustrations became public. On July 25, 1956, thirteen days after the last Scenicruiser was shipped, he announced in a press conference that the company planned a multimillion-dollar lawsuit for damages against GM. This was for “repeated and extraordinary mechanical failures” on Scenicruisers. Specifically, Genet said that each of the first 570 coaches had to be repaired in company shops because of issues “in the transmissions and clutches due to lubrication.”

The annual report for 1955 had revealed the resolution of this issue to the stockholders, saying, “Starting with the delivery of the 571st Scenicruiser (of the 1,000 on order), a considerable improvement in mechanical performance has been indicated. Scenicruisers delivered previously are undergoing basic changes, which, as of this date, are nearly completed.”

What was the problem? What were the repeated mechanical failures? Most people familiar with Scenicruiser history believe the primary problem was the twin 4-71 diesels conjoined by the fluid couplings. But initial indications pointed elsewhere. It’s noteworthy that Genet’s complaint was not engines, but “lubrication failure affecting transmission and clutch forced Greyhound to spend millions on extra maintenance and repair, disrupting schedules, suffered losses on expensive advertising and promotion campaign.” Had the primary issue been the conjoined engines, as most believe, it’s not clear why neither Genet nor Greyhound nor the press failed to mention it in this context, and why only the transmission and clutch problems were. Had the mid-1955 “fix,” starting with chassis 571, failed? Was it still a problem? Did Greyhound bear the brunt of the costs?

It’s clear that multiple known issues were part of the “repeated mechanical failures.” The transfer case was replaced in mid-1955 with chassis 571 (and retrofitted to the previous coaches) and the clutch issue had already been addressed twice. In early 1956, about the time Genet was talking to GM, the decision was made to move to a traditional manual clutch actuation and the expense of retrofitting 900 coaches in the field. 

According to Genet, he had approached GM executives as early as February 20, 1956, seeking resolution of the issues that had cost Greyhound money and business embarrassment. On May 12 Genet then advised GM of the plan to sue, but not yet having reached a settlement, he resorted to the press conference. Plans were still pending on where and when to file suit.

Whether or not this technique was effective is known only to the participants. As late as September 12 Genet commented that the complaint and summons were soon to be completed and filed. Nonetheless, within three months of the press conference, on October 11, 1956, Greyhound reported the settlement of their dispute with General Motors without a lawsuit. In addition, Greyhound made a 17-million-dollar order for new buses from GM. Genet also noted that with the Scenicruiser joint-development efforts, “bugs can develop on the road which the best engineers cannot foresee during the experimental phase.”

But there was an occasional mention of the engines once the issue was settled. A Greyhound spokesman referred to the “difficulties with the transmissions and motors of Scenicruiser busses bought from G.M.” Compounding the task of understanding exactly what the problems were was a baffling remark attributed to the Greyhound President: “All the Scenicruisers have been repaired by Greyhound by using a two-engine operation instead of the single motor system which has been used, Genet said.” It is not clear at first what this sentence means, since the major issue was not the engines, and the Scenicruiser, built with two engines, had never used a “single motor system,” whatever that meant.

A clue to the dilemma comes from comments in The New York Times article: “The independent single engine operation feature required by the specifications is being abandoned. Improvements developed as Scenicruisers were produced as well as other changes designed to improve the operation and performance of these coaches are being incorporated in all our Scenicruisers.” This may be the evidence that links the transmission, clutch, and engines together, that explains why the engines have traditionally been perceived as the major issue, and why the articles consistently refer to transmission, clutch, and lubrication rather than engines.

“The independent single engine operation feature required by the specifications is being abandoned.” The original engine/drivetrain design required that either the left or right engine be able to operate the coach alone if necessary. Given the complex hydraulic mechanisms and procedures necessary to run on one engine independently, this may have been related to, if not the root cause, of the lubrication, transmission, and engine failures. Thus, Genet’s comment “using a two-engine operation instead of the single motor system” could mean that the ability to run the coach on a single engine was removed from the Scenicruiser, and only the two-engine approach would work. This would fit the other remark that “the independent single engine operation feature required by the specifications is being abandoned.” The load on a single 4-cylinder engine moving a coach to the nearest shop might be one reason why a number of engines failed and thus the enduring focus on that particular issue. And, as seen earlier, beginning with chassis #571, the engine transfer case, which coupled the two engines together, along with many other parts, was changed for the subsequent coaches. And, by 1957, the run-on-one-engine capability was gone.

This is confirmed after reviewing the changes in the operating manuals. By 1957, with the X-5723 edition of the operator’s manual, the one-engine operation was put to rest, and that probably has much to do with the lingering opinion that a Scenicruiser couldn’t run on one engine. No fewer than eight changes were made in the later 1957 manual from the original 1954 operating manual on the “one-engine” topic:


“In cases of emergency, either engine can be operated independently as explained later under “Emergency Conditions.” p. 7

“Refer to EMERGENCY CONDITIONS later in this manual for instructions regarding … actions to take when necessary to run on one engine.” p. 8

Emergency Use of One Engine
“Provisions are made to operate on one engine in emergency if either engine fails. Procedures outlined under “Emergency Conditions” (page 35) must be followed in exact sequence outlined.” p. 11

“Left side closure door must be opened for access to engine control valve lever (page 36), oil pressure gauges…” p. 33

[1954 Rear Switch Panel]
p. 33

“Either engine can be started separately at the rear for checking and testing purposes, or to operate one engine in the event of failure of either engine.” p. 35

Emergency Use of One Engine p. 36-37

“Vehicle can be moved to point of service with one engine, if necessary, as described on page 37.” p. 38


“In case of emergency, call nearest supervisor.” p. 7

“Refer to EMERGENCY CONDITIONS on page 33 for instructions regarding starting engines at rear.” p. 8


“Left side closure door must be opened for access to oil pressure gauges…” p. 30

    [1957 Rear Switch Panel]
p. 35

“Engines can be started at rear for checking and testing purposes.” p. 35

“The safety control relay alarm system can be overruled as explained on page 10.” p. 3

Presumably the elimination of the one-engine locomotion capability from serial #571 and on provided some relief from the powertrain issues plaguing the early Scenicruisers; “Starting with the delivery of the 571st Scenicruiser (of the 1,000 on order), a considerable improvement in mechanical performance has been indicated.” The first 570 coaches were also retrofitted: “Scenicruisers delivered previously are undergoing basic changes, which, as of this date, are nearly completed.” This may have been done while engines modules were swapped out during maintenance over time, since six months had elapsed since #571 and the date of that annual report. Since engines would last longer, however, the work was probably done as special projects. No documents exist yet regarding GM’s role in fixing and paying for the change. So, while Al Meier’s contention that the PD-4501 could not run on one engine alone was incorrect for the first 570 coaches, it was true thereafter or certainly by 1957 – with one important detail.

It was the drivers who could no longer operate the coach on one engine, even though it was still possible! Recall that during the two-week delay after coach #570 shipped, there were more than two dozen parts changes associated with this “fix.” While drivers could no longer switch to one engine by 1957, as seen in the complete elimination of instructions in the operating manual, the coach could still be run on one engine. Without the engine control valve lever, some hydraulic hoses had to be disconnected and connected elsewhere. Some jumper hoses had to be added to reroute fluids. The 1958 maintenance manual gave complete instructions on how to do this, depending on which of the two engines had failed. Why this “manual” capability was documented is unclear, but it was probably for maintenance personnel to operate and move a coach between locations if necessary. Clearly the drivers could not follow these procedures.

This significant change must have been difficult for Caesar to see and for Greyhound to approve, since single-engine locomotion to reduce bus breakdowns on the road was one of the reasons for the dual engines. Within a few years, however, a whole new powerplant option would be pursued, the new V8 engine from General Motors Diesel.

Article written by Paul von Fange

Paul von Fange unexpectedly discovered the Greyhound Scenicruiser in 2009 and has been on a quest for its story ever since.

He has ridden thousands of miles on these buses, attending the 2010 Scenicruise in Amarillo, Texas, the 2011 Scenicruise in Grand Canyon Caves, Arizona, the 2011 Gathering of Buses in Hibbing, Minnesota, the 2013 Ghosts of Highway 61 in Blytheville, Arkansas and the 2017 Busboy Rally in Evansville, Indiana. He served as a volunteer at the Minnesota Transportation Museum, working to restore Scenicruiser PD-4501-739.

His Scenicrusing videos can be found on YouTube by searching for “paulmontry.” Any additional evidence for the Scenicruiser history can be sent to him at His books and more links are available at

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