With respect, not enough info here for us to offer suggestions.
1) Make and model of genny?
2) Fresh water
3) The "tap" is that the cap on the coolant reservoir? Or is that a drain tap at the bottom of the (plastic?) coolant reservoir?
4 Is there sludge in the whole fresh water
NOTE: if your genny has alloy parts
(like the head) doing an acid flush may harm those parts!!!!You really need to check with the manufacturer first!!!!
Without answers to the above, some general comments on flushing
!) If the coolant reservoir has sludge, and if it has a drain at the bottom, you can hose it out with fresh water from a dock
hose while you hold a bucket under the drain. Suggest you do this first.
2) To do a proper clean of your entire fresh water coolant system, you need to use hydrochloric acid. Vinegar is simply not strong enough.
The best way to do this is to set up an active closed-circuit with an acid-proof centrifugal pump
. You add hydrochloric acid to the water in the engine
and circulate it for an hour or so. Then you flush out that water/acid mix. Just filling the engine
with water/acid and letting it sit is the lazy way some people do it, but that will not get all the internal passages clean and remove all the sludge.
If you don't/can't set up an active closed circuit with an external pump
, you could do the system flush by adding hydrochloric acid to the coolant water and running the genny for say 10 minutes. But I suggest you run this past the manufacturer.
Whatever you do, if you do an acid flush, you absolutely have to flush out the whole system with fresh water. To do this you'll need to disconnect 2 of the coolant system hoses and use one to introduce fresh water from a dock
hose while the other dumps the water overside.
Again, without knowing how your genny is setup, its impossible to say which hoses to use for this procedure.