fbekholden.com

hi guys,
many years ago a couple of guys did a diesel flush on an old gray that was fumey. it stopped the fumes completely
does anyone know how this is done?.
i seem to recall they added about 1-2 liters of diesel, idled it for about 5 mins, then drained, another 1-2 litres of diesel poured in to flush the remains of oil, then filled up with new oil

does this sound right?

tia

cheers

I am sceptical. The diesel fuel would flush remnant oil out of the crankcase. But a fumy engine is caused by worn cylinder bores and piston rings. And I think diesel fuel is a poor lubricant, so I'd be unhappy about running the engine for any length of time with diesel fuel in place of oil.

Rob

ardiesse wrote: Tue Oct 14, 2025 2:28 pm I am sceptical. The diesel fuel would flush remnant oil out of the crankcase. But a fumy engine is caused by worn cylinder bores and piston rings. And I think diesel fuel is a poor lubricant, so I'd be unhappy about running the engine for any length of time with diesel fuel in place of oil.

Rob

Agree. Diesel and lubeoil densities are very similar. Good chance the diesel ends up as a layer in the bottom of the sump, and you initially run the bearings on neat diesel. Diesel is tested for lubricity (it has to lubricate fuel pumps, and low sulphur diesel sometimes needs an additive for lubricity). It is not as good as lubeoil for creating an “oil wedge” under shafts.

Cheers,
Harv

thanks!