Mercury 15hp cooler problem

Has anyone out there got any info on why my 2002 Mercury 15hp 4 Stroke will only pump water from the tell tale hole when in gear .In neutral no water pumps out from the tell tale (pee hole).The propeller shaft is new and impeller looks fine .The engine starts and runs fine but without water cooling it, it,s a bit worrying .Has anyone had a similar problem ,and how can I fix it

Re: Mercury 15hp cooler problem

Not completely familiar with your engine, but from my drawings I see that the telltale comes from the bottom of the exhaust cover. That established, you should be seeing water regardless of it being in gear or not...

The first thing I'd be checking is to see if water is actually getting to the engine... With it running and the covers off, check the temperature of the exhaust cover... you should be able to hold your fingers on the cover easily. If the cover is too hot to leave your fingers there, you have a water supply problem.... Who checked that the impeller was fine? Did they make sure the 2 washers were in place, either side of the impeller? There is also a pipe between the water pick up (under the cav plate) and the water pump base, with a rubber seal on each end.. are they in place and sealing correctly? Are the gaskets either side of the water pump base plate sealing properly?

Just a couple of things for you to start with....

If the exhaust cover is cool to the touch, then just get some compressed air and blow the telltale line out. Easy...

Chris...........

Re: Mercury 15hp cooler problem

The mercury outboard I have is a F15S 4stroke .The tell tale (pee hole) is located on bottom cowl off engine head .Having looked at the impeller looked fine pipe running to cavitation plate was unblocked ,the impeller works and pumps water to engine but only in gear.Anyone got advice?

Re: Mercury 15hp cooler problem

Have you done the check I suggested? Fingers on the exhaust cover? I have the drawings for your engine and see that the lower unit is the same as the 2 stroke 15, which I am very familiar with... I have also the drawing of exactly where all the hoses run and where they are connected...

Now, check the exhaust covers.....

Re: Mercury 15hp cooler problem

Many thanks Acris there was a spacer missing from the bottom end of the intake pipe .After running it today it went very well ,with no overheating signs and the tell tale hole pumping water in gear and in neutral ,nice one cheers .