3801 (pronounced Thirty-eight o-one) is a C38 class 4-6-2 steam locomotive operated by the New South Wales Government Railways between 1943 and 1974.

[4] When joined by 3802 in April 1943, these engines were allotted to working the Melbourne Limited expresses between Sydney and Goulburn.

It was often used on special services operated by railway heritage organisations, the most famous being a non-stop run from Sydney to Newcastle on 28 June 1964.

[5][6] Just failing to break the two-hour barrier, this remained the fastest journey from Sydney to Newcastle by rail (2 hours 1 minute 51 seconds) until bettered by an XPT in 1988.

In October 1965, the locomotive was found to have serious boiler problems, so was withdrawn and placed in the care of the New South Wales Rail Transport Museum.

During this time, it operated a train celebrating the 25th anniversary of the Newcastle Flyer on 31 May 1969, as well as the Western Endeavour special across the continent to Perth between 22 August and 12 September 1970.

In June 1975, it hauled 5711 and 1905 from Enfield Locomotive Depot to Thirlmere when the New South Wales Rail Transport Museum relocated.

In November 1982, chief executive of the State Rail Authority, David Hill, enquired about the suitability of restoring 3801.

A visit was made to the South Maitland Railways (who at the time still used steam engines) to learn about modern boiler techniques.

More trial runs followed and on 29 November 1986, 3801 headed from Newcastle to a grand ball on the concourse of Sydney Central station.

During the Australian Bicentenary celebrations in 1988, it operated an extensive program across Australia visiting every mainland capital accessible by rail including another trip to Perth in April/May 1988.

3801 was struggling to climb the Cowan Bank (on the Sydney side of the Hawkesbury River) when returning from the Morpeth Jazz Festival when a CityRail Interurban passenger service crashed into the back of 3801's train.

3801 applied sand to the track to assist grip and an investigation into the crash suggested this may have caused the signals to malfunction.

[25] The locomotive continued to haul day trips and longer excursions until withdrawn from service for a major overhaul at the end of 2007.

The contract for the construction of the new boiler was let to Dampflokwerk Meiningen in Germany, while the tender tank was transferred to the Hunter Valley Training Company at Maitland for repair.

Trial fitting of the boiler revealed a number of dimensional, manufacturing and technical issues which made it unsuitable for use.

[31][32] In September 2015, Transport Heritage NSW announced that 3801 would return to service in 2017 with the old boiler to be reconditioned by the Goulburn firm Ainsworth Engineering.

[37] It then undertook two test runs each day from Chullora Railway Workshops to Glenfield before being transferred under its own power to the NSW Rail Museum at Thirlmere on the 25th.

[40] On 15 May 2020, 3801 performed an adhesion test hauling a 318-tonne train in simulated wet weather conditions up the 1-in-40 graded Cowan Bank.