Mercury 90hp water pressure problems

tkj1973

Recruit
Joined
Jun 20, 2011
Messages
2
I am having a water pressure problem on a 2007 90hp Mercury 2 stroke. There is little to no water coming out the water outlet. I have changed the Impeller, but that did not fix it. What else should I look for.
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Mercury 90hp water pressure problems

The amount of water out the tell tale has very little to do with the water pressure in the engine. All the water from the tell-tale has to go through a thermostat first. Without an actual water pressure gauge you can't tell what the pressure is.

It's possible at idle in cold water that there would be little water from the tell-tale and it would be normal. Also, it's both possible and probable that bugs have taken up residence in that little orifice and partially plugged it.

Is the tell tale real hot? Is there water flowing out of the prop hub? Are the heads too hot to touch without pain?
 

tkj1973

Recruit
Joined
Jun 20, 2011
Messages
2
Re: Mercury 90hp water pressure problems

Thanks for your reply j_martin. I removed the hose from the inside and sure enough there was something in it. Works like it should now.

I always thought that the tell tale was for checking your water pressure. I always check it to make sure it is running before I take off(just a habit). Exactly what is the tell tale for?

Thanks
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Mercury 90hp water pressure problems

Thanks for your reply j_martin. I removed the hose from the inside and sure enough there was something in it. Works like it should now.

I always thought that the tell tale was for checking your water pressure. I always check it to make sure it is running before I take off(just a habit). Exactly what is the tell tale for?

Thanks

On a Mercury, the tell tale won't put much out till the engine is warmed up to operating temperature. On my bass boat, that tells me the engine is warm enough to not cold-seize when I blast off. Usually takes about 30 seconds.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: Mercury 90hp water pressure problems

I always thought that the tell tale was for checking your water pressure
The proper name is tell tale and it is for visial water pump operation,it has nothng to due with pressure as it will still "p" with a weak impeller. On your motor the tell tale is off the exhaust plate before the t-stat and poppet so "p" will alway be cooler than actual engine temp and have more volume.
 
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