• WH Allen

WH Allen


Components suitable for WH Allen diesel engines

We have a long standing connection with the WH Allen range of engines, and can source and supply parts for both the S12 (2000) and S37 (4000).

In 1906 the manufacture of W.H. Allen engines began at the engineering works in Bedford. In 1919 crude oil engines were developed, and in the 50s and 60s turbochargers were introduced. In 1989 the company was bought by Rolls Royce, and 2010 it was sold on again.

In recent years the main Allen engines are the S12 (later the 2000) and the S37 (later the 4000) as well as the 5000 (which has a ‘B’ version  developed from a Rolls Royce Bergen engine). The 5000 series was one of the first to use casting simulation to test the quality and integrity of the manufacturing processes. Up until then (late 1990s) finite element analysis had been used to predict mechanical loading and temperature distribution, and engine cycle simulation had been used to predict performance, but there was no way of testing manufacturing quality.

You can see a wonderful old 1935 built Allen engine at the Kew Bridge Steam Museum. It is one of four originally installed there. It’s a three cylinder four stroke engine coupled to a centrifugal pump. It’s remarkably modern in design but it still has an external flywheel. The Allen Diesel Pumping Engine at Kew Bridge Steam Museum


Outline of an Allen engine overhaul:

Allen 2000 (in fact, a broadly typical job)

All cylinder heads were removed, and replacement, newly overhauled cylinder heads were fitted onto new seals and gaskets and torqued according to OEM specifications.

The pistons and rods were removed. The pistons were calibrated and fitted with new rings.

Refurbished connecting rods were supplied and refitted onto new shell bearings. The original big end bolts were also torqued to OEM specifications.

All cylinder liners were removed, and replacement liners were fitted using new O-rings.

The end float of the crankshaft was measured and found within tolerance. The main bearings (incorporating the thrust washers) were removed and inspected. The sprung-loaded LO pump drive was found to have excessive play so the springs were changed for new.

The camshaft bearing clearances were checked as was the  end float. All the lobes were inspected. All the cam followers were inspected in-situ. The cam bays were cleaned.

The fuel pumps were removed and replaced, and the moment of injection set according to OEM instructions. The injectors were overhauled at the site and were refitted with copper washers.

The governor was inspected together with the drive plates. The backlash was checked.

The turbocharger was replaced.

A new lube oil pump was supplied and fitted onto new seals. The size of the drive shaft casing was found to be incorrect – it was replaced.

The jacket water pump was replaced and fitted onto new gaskets, and the backlash was checked.

The pump was stripped and overhauled on site. One of the ball bearings had suffered a collapse by way of the ball cage. It was fitted onto new gaskets and the backlash checked.

The generator was inspected as per OEM instructions.

The main oil filters were removed and replaced. The engine was subjected to an eight hour flushing program using one bank of the new filters. The fuel filters were replaced.