Pitot Tube Speedo Problem

[Coral 202]

I have a 2002 225 EFI Mercury. My speedo has NEVER worked correct since new. Here is the mystery. The hole in the lower unit could be completely clean and WOT shows maybe 30 mph on analog gauge. When the hole plugs completely with wood, the speedo reads slightly higher. It seems there is somehow a passage between low water pickup and pitot tube. Even when brand new I could blow air into pitot hole and could hear air coming out low water pickup area. I have just not worried about it for the past 6 years or so but would be nice to see it work. Analog gauges are usually optimistic at anything over 60 . Any ideas on how to fix this? I have had lower unit off and did not really know what to do. I have checked gauge from LU forward and seems to respond correctly. Could the hole coming in from the top into pitot tube be thru? Can pitot tube be replaced?

[ssimpala71]

Just asking here to remove all doubt,, water pressure gauge isnt hooked up to speedo is it? One thing I could see is that the gasket for the shift shaft housing could be blown out and leaking, allowing water pressure to build even though the pitot tube is blocked.--maybe??

[EuropeanAM]

Brian's question regarding the water pressure and pitot tubes "being swapped" is certainly a possibility!

Also possible is that the pitot tube (between the gearcase and powerhead) is leaking.

However.... my "guess" is that you'll find the gasket underneath the "shift shaft cover (seal carrier)" is damaged, causing a leak in the pitot passage.