From February 1944, a device called 'Fuchsgerät' was installed in new Tigers. It could also be retrofitted to old Tigers. The device allowed a cold engine to be heated for starting.
The Fuchsgerät (Flue Equipment) was installed in the engine compartment, to the lower left of the engine. It allowed the engine's cooling water to be heated by a standard German blowtorch, like these ones.
The engine had to be 'turned over' to make the water flow through it, so the Fuchsgerät was used in conjunction with mechanical starters.
The flames were directed through a new port in the tank's rear wall. The port was normally sealed with a steel plug. In this photo, the port is indicated by an arrow.
These diagrams show the cover for the port.
It was held by two conical-head bolts, as drawn here.
The Fuchsgerät equipment included a folding sheet-metal tray that could be attached to the open port. The blowtorch could be left running on it while the crewman tried to start the engine.
This is the open port as seen from the outside, with original German dimensions [4, see page 72] .
This is the inside of the port, with all equipment removed. We are in the Sturmtiger at Munster museum. [3] . The welded ring has two large holes for attaching the cover, and four holes for attaching the heater device.
[1] Survey of vehicle 251114, at Saumur, by Jean-Charles Breucque
[2] DW to Tiger 1
[3] Survey of Sturmtiger at Panzermuseum Munster, by Rob Veenendaal
[4] Der Panzerkampfwagen VI und seine abarten, Walter J. Spielberger, Motor Buch Verlag