Multiple marques - same problem

Multiple marques - same problem

#13 of 37


WO Bentley engine

Hispano Suiza H6C engine

Delage engine

During the past six months we have been privileged to work on and recommission three iconic motorcars of the 1920’s: a Speed Six ‘WO’ Bentley, a Hispano Suiza H6C and a Delage. In every case they were suffering from problems we have seen in hundreds of other cars we have worked on: the consequences of storage with old petrol or coolant in the system.

Modern fuel currently available in the UK has approximately 5% of ethanol added to the cocktail; this is set to increase to 10% in the not too distant future, designated E10. As well as requiring minor adjustments to the mixture, which will be more of an issue when E10 is introduced, the ethanol has a potentially damaging effect if the fuel is allowed to stand for a length of time. Particularly in the case of a petrol tank which is only partially full, moisture in the atmosphere will condense in the tank, mix with the fuel and be absorbed by the ethanol. Ethanol of itself will oxidise over time, and this is exacerbated by the absorption of water. The result is a potentially corrosive fluid which will attack copper and tin, both of which are present in the fuel system of older cars, and are also constituents of brass alloys which are found in carburettor fittings. It will also attack aluminium.

A second problem arising from the introduction of ethanol, particularly in cars that receive little use, is its solvent properties. In a car that is used only occasionally the more volatile constituents of the fuel cocktail will evaporate, leaving behind a gummy residue. With older types of fuel this would generally stay where ever it lodged. However, ethanol will over time dissolve the gummy deposits, which can then block small passageways within carburettors and cause moving parts to seize up.

To overcome the corrosion issue, a number of fuel additives have been developed which will limit the corrosive effects of the fuel. The Federation of British Historic Vehicle Clubs has undertaken tests on a number of these to gauge their effectiveness. This is covered in detail at, which also lists the additives endorsed by the FBHVC.

If cars are to be stored, the recommendation is to either drain the fuel system completely, or else store with a full tank. But better still is to use the car regularly and avoid the problem.

In the case of the many cars we have recommissioned after storage, issues arising from fuel systems problems attributable to the effect of ‘legacy’ fuel were preventing them from functioning correctly, if at all when coupled with other problems that we encountered.

The Speed 6 Bentley required a carburettor overhaul, and attention to both the linkage and the ignition which had been assembled incorrectly before it would run satisfactorily.

The Delage had developed extensive corrosion in the fuel tank which required major repairs. In addition the fuelling system and the carburettor had suffered from both gummy deposits and corrosion, and until these issues had been addressed the engine would not run.

The Hispano Suiza came to us with a main silencer that had blown apart. This was the result of both ignition and carburation problems, resulting in unburnt fuel exiting the engine and then igniting in the silencer. Once again the problems were attributable to the effects of old petrol and incorrect assembly and adjustment of both the fuel system and the ignition.

Having achieved a running engine (with a new silencer) an internal water leak within the engine was found. The cylinder block and head are cast in one in aluminium on this engine, and a water leak into a combustion chamber was identified. It is possible that this is a consequence of the anti-freeze in the coolant not being renewed. In order to maintain the corrosion-inhibition properties in water-based anti-freeze the coolant should be renewed at least every two years. Anti-freeze being cheap when compared to the cost of a new aluminium cylinder head or block we recommend changing it annually. This is something not often taken into account when storing vehicles for a long period; this is understandable as often owners don't anticipate the car being in storage for a long period and so the risk of this won't occur to them. In the case of the Hispano Suiza a new block may be required, with a cost of several tens of thousands of pounds. Ouch!

We strongly advise all owners to consider their storage options carefully, and to speak to your storage provider about how to avoid the issues above. All cars in long-term storage at Fiennes go through a variation of the above processes in consultation with the owner to ensure no inadvertent damage is done to the car when it is not in use.

If you’re interested in storing your car with us, or would like to explore recommissioning one after a period of non-use, contact us on