View Full Version : No forward speed on Mercury 402 (1972)

07-23-2001, 12:48 PM
I have replaced both oil seals in my lower unit to fix an oil leak. The leak is fixed and I have reassemble everything back together. Now when I put the motor in forward gear (mercontrol single lever), the gear engages but I can't make it go faster (even at full throttle). If I put in in reverse there is no problem, it feels like the motor could climb up inside the boat.
What did I do wrong? Can anyone help me?

07-24-2001, 12:49 AM
Sounds like you have some of the gears meshing slightly out of alignment. If you don't have a shop manual then get one fast. You are going to have to take it apart and try again. Check and make sure that you have not missed a washer or shim or put a shim in the wrong place. The shop manual should advise you as to the assembly sequence as well as the torque and any required torque sequence. Note that all torque values are with lubricated threads and if the manual recommends a specific lube, use that lube. It can make a difference.

Gordon Bartlett
07-24-2001, 06:24 AM
My guess is that the shift/throttle linkage is not adjusted correctly. There are typically two safety features built into these linkage assemblies. One prevents the motor from being started unless it is in neutral which in turn prevents the boat from accelerating unexpectedly (with all sorts of horrible results) upon startup. The other prevents the throttle and ignition timing from advancing unless the motor is in gear. This prevents the motor from being blown from overspeed upon startup. This is where I believe your problem may be.
When you engage reverse gear everything is ok. But when you engage forward gear the linkage still "thinks" the motor is in neutral so it doesn't allow the throttle and ignition timing to advance. Remove the cowl from the motor and watch closely while someone else sits at the control and shifts it into forward and reverse. It is usually not hard to see what adjustments are necessary.
Good luck,