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2001 Mercury 90hp Lower Unit Vent Tube

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Wolfgang12

New member
I am new to Mercury's, so have a quick question. I just bought a 2001 pontoon with a 90hp Mercury on it and have found a vent tube that has a plastic 90 degree elbow broken off just above the lower unit. The question is what is the vent tube for and where should the hose terminate to as it seems to be cut only about 12 inches above the elbow? Does it terminate inside the cowl? Is there any thing I should check in the lower unit once the elbow and tube is replaced? Thanks for any help.
 
It sounds like you are talking about a pitot tube which is used for a speedometer.

They get water forced in them while underway and the tube goes all the way up to the dash as the feed for the (water fed) speedometers.

With the advent of GPS units these are less and less popular and most guys/gals simply remove them, or do a "poor hatchet job" as it sounds in this case.
 
galamb said:
It sounds like you are talking about a pitot tube which is used for a speedometer.

They get water forced in them while underway and the tube goes all the way up to the dash as the feed for the (water fed) speedometers.

With the advent of GPS units these are less and less popular most guys/gals simply remove them, or do a "poor hatchet job" as it sounds in this case.
Click to expand...

Thanks for the reply.
 
Last edited:
Ok, galamb, you were right. I finally found it on the parts break down and the tube states speedometer pick-up. This boat does not have a speedometer and the pitot tube is not like my pickup on my bass boat. I appreciate the help.
 
90 Merc.jpg

If you are talking about the parts in the yellow circle on the diagram then it really is a feed for the speedometer.

The lower unit has it's own pitot incorporated and the feed comes out as illustrated. There is no vent or other connection between the lower unit and powerhead save the driveshaft, shiftshaft and water tube.
 
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