Bore wash

[Mole]

I've been reading some old threads that mention "bore wash". What is bore wash and can anyone tell me what causes it - various threads seem to suggest such things as over-rich mixture and detergents in Optimax!

 

Someone enlighten me please

 

SV 52 CAT - the Mole is flying

[Peter Carmichael]

If the mixture is massively over-rich, liquid fuel on the bore walls will wash away the lubricating film of oil at the piston rings and rapid wear of the rings and bore will result.

[Mole]

Thanks Peter - I knew I could rely on you ❗

 

Presumably then this is less likely on injection engines vs carburated? Do you have a view on the likely effect of detergents in fuels such as Optimax - it seems inconceivable that a major supplier like Shell could sell a fuel that would lead to increased engine wear

 

SV 52 CAT - the Mole is flying

[Peter Carmichael]

All road fuels have a detergent package. Optimax is not unbelievably different to anything else. An injected engine with a bad sensor could be fuelled incorrectly enough to cause bore wash.

[Peter T]

It can also happen when you rev your engine prior to switching off, excess fuel is drawn into the cylinders as the engine slows, with no ignition on, no spark occurs and the fuel is not burnt! Really only applies to carbed motors.

 

C7 PWT X-Flow all Steel

Fuel Injected Iron Block

[Rob Walker]

Also sitting blipping the throttle with carbs is bad news, the throttle pump jets squirts neat fuel in which does no good if the engine is not under load.