The amount of time varies upon how much deposits there are on the engine.

Usually I place the engine in a small plastic pan and then cover it with DPD.

I let it sit for 5-15 minutes then use a metal brush on it to loosen the stubborn stuff.

Again I cover it with the Dissolver and let it sit longer.

On occasion I will rinse it in HOT water ( Yes I know... ) and reapply as needed.

Once the engine is clean I first flush it out with hot water, followed by a generous amount of WD 40... and then it is in turn flushed with alcohol followed by glow fuel to get out any vestiges of remaining moisture.

I let it sit for a day, then I flush it out with more glow fuel...


I've even used DPD on the interior ( cylinder head open and removed ) of a few old second hand engines to get out some stubborn build up. The engines have run well after the rebuild.