speedometer hook-up on a 89 70 Merc??

[BOONEX]

hey all just switched my 82 90hp for a 89 70hp everthin hooked up the same execpt for the speedometer the 90 used a small hose tha ran down to the lower unit didnt see any such thing on the 70 would i have to tke the lower unit off to look or total waste of time??

 

[ricksrster]

Re: speedometer hook-up on a 89 70 Merc??

You can attach one of these on the bottom of your transom so it sticks in the water. It should be at least 12" from your motor to avoid turbulence:
http://www.iboats.com/Pitot_Tube/dm...2144132--**********.535680018--view_id.169185
Instructions:
http://www.downloadingfiles.co.uk/teleflexfiles/library/instructionmanuals/99511.pdf

 

[BOONEX]

Re: speedometer hook-up on a 89 70 Merc??

hey thanks for the reply ...i was aware of those pitot tubes although wasnt aware they were so cheap nor the proper name. still not sure of correct pronouncation...the reason i was askin about the one in the leg although i have no clue how it worked in there it seemed to be a safer set up and was bang on by GPS a all speeeds

 

[jebeebe]

Re: speedometer hook-up on a 89 70 Merc??

Hi,
On the lower unit just above the gearbox there should be a tiny hole in the front of the houseing that picks up water when underway. The force of the water coming in creates pressure in the tube leading to the speedometer, thus causing the dial to rotate. If someone had removed the hose coming out of the lower unit, you will have to remove the lower unit to replace it. There is a 1/8-27 national pipe tap fitting that excepts a 1/4 plastic hose that exits just above where the lower unit goes back together. This hooks up to the speedometor tube................Jerry

 

[BOONEX]

Re: speedometer hook-up on a 89 70 Merc??

thanks jerry i has assumed it worked somthing like that and it looks like my engine has the hole for the speedo tube to go in but it isnt there ..i was wondering was it ever there or did some one pull it out while removing the outboard at some time ...my father has a 98 60hp mariner bigfoot he said he had noticed a small black tube in the same area on his but never knew what it was for..hes a commercial fishermen and uses that outboard without controls on an 18' open fiberglass

 

[jebeebe]

Re: speedometer hook-up on a 89 70 Merc??

thanks jerry i has assumed it worked somthing like that and it looks like my engine has the hole for the speedo tube to go in but it isnt there ..i was wondering was it ever there or did some one pull it out while removing the outboard at some time ...my father has a 98 60hp mariner bigfoot he said he had noticed a small black tube in the same area on his but never knew what it was for..hes a commercial fishermen and uses that outboard without controls on an 18' open fiberglass

I had a 89 150 xr4 that came on the new Lund with a sensor sender mounted on the hull but when I got up to 55 mph it flipped up from the pressure and I had no speedometor, so I hooked it to the engine tube and that solved that problem. It kind of created another though. When you hit a log in the water it plugs the little hole in the lower unit and you have no speedometer, untill you stick a drill bit in the hole and clean it out. Don't happen that often though. Mine came out of the box with a piece of tube zip tyed to the motor. I would say someone removed yours...................Jerry