Customer bought in a Mercury 2.5hp 2 stroke which was well maintained but had not been flushed since last use late last year and although starting and running well there was no water coming from the tell tale. The Outboard engine tell tale is blocked.

The tell tale on these engines comes from the top of the water jacket via a small tube and exits via the tube under the power head.

I tried blowing compressed air and pushing some strimmer wire into the water exit port on the cylinder jacket but it was well and truly blocked.

Removed the fuel tank and then powerhead from the engine.

Turned the engine upside down on the bench and took a look.

There was obvious salt build up so using a solution of wessex proflush marine engine descaler I introduced the descaler into the ports which feed water into and out of the cylinder head area, circled in red in the picture below.

I use a 20ml syringe to fill up the jacket and a few tips with proflush marine engine descaler is that it works just as well if not better diluted about 50% with fresh water and it will continue to bubble away and do its work for a long time. Every now and again when the bubbling slowed, I would drain out the descaler and add a fresh mix until the bubbling stopped (overnight).

Eventually I had a clear passage between the 4 ports circled in red below and the tell tale port which has a short tube and syringe attached in the picture below.

Flush the engine through with clean water, reinstall powerhead onto engine and all works a treat.

Back off to Force 4 Marine Chandler – Plymouth  to pick up another litre of Wessex Proflush Marine Engine Descaler

If you have an issue wth your outboard engine tell tale being blocked please Contact us