Canister Fuel Filters and Heat

Concern has arisen that some filters can be damaged by handling fuel above the temperatures for which they were designed.

Some cartridges produced for the Lucas/CAV/Rotodiesel style 'sandwich' filters, where the filter cartridge is held between the filter head and a metal base, have been found to become unstuck due to heat. This has been observed especially when these filters are heated directly although hot fuel flowing through the filter may cause the same effect.

Coolant heated filter

Examination of a number of filters elements of the 'sandwich' type used in this application revealed two common forms of construction. Both types come as a canister, the filter media being sealed within.

Adhered Type

Knecht (Long)

This filter is one from my converted Land Rover. It was coolant heated, with about five feet of uninsulated heater hose/fuel hosing running to it. You can see from the picture where dirt from the tank has by passed the element once the element had come unstuck from the canister base. Luckily I had an inline filter plumbed after this on the vegetable oil fuel line....

Fram Europe C1191PL (Short)

With this design of filter cartridge the elements are glued into the canister. If they are heated the adhesive becomes soft and with the pressure from the flow of fuel, the element lifts from the base of the canister.


After a similar experience Sebastian Rasch used a 8mm collar of 22mm diameter copper pipe to guard against this. A similar diameter spring would provide a more positive force upon the filter

Fram Europe C1191PL (Short)
Knecht (Long)
Coopers A2F015 (Short)
Motaquip VFF104 (Long)

Rolled Metal Type

The other type of filter cartridge I found, has the element sealed within the canister with a rolled seam holding the metal top. This type would appear to be suitable for use with heated fuels. I have found Mann, Lucas, Delphi, Peugeot filter canisters of this design.

Filter Internal Coating

Some filters have an internal metallic coating that appears to react with the free fatty acids in vegetable oil to for deposits. Oils high in FFAs such as heavily used cooking oil would cause more problems. MANN filters reportedly have this coating.

Lucas / CAV /Delphi / Peugeot filters have a painted/plastic internal coating that appears stable with FFAs.

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