View Full Version : Outboard exhaust from plug for shift shaft port

Loren Block
09-28-2015, 01:20 PM
We recently installed a water pump kit on a '98 Mercury 2-stroke 5hp outboard. The motor runs fine and the cooling water flow is good but there is some exhaust spurting from the side of the plug that covers the port giving access to shift shaft clamp. Is this normal? :confused:


09-28-2015, 06:57 PM
Nothing to worry about. That grommet is located on the exhaust housing (leg, driveshaft housing are other names for the unit).

When the motor is running, behind that (plug) you have water, exhaust, burnt/unburnt oil/gas etc - any of those getting past that little plug will not make any difference to the operation of the motor nor is it detrimental in any way. You could run without it in place and all would be fine.

If it really bugs you that seal, cover, plug (Merc calls it a grommet) can be replaced for under 7 bucks.

Loren Block
09-28-2015, 08:07 PM
Thanks for your answer. We will proceed to run the motor in a barrel for an extended period but I now think our water pump kit installation was good. Actually the only problem we had was getting the shift shaft through the upper opening in the shift shaft housing. Then we realized the shift was in reverse and the gears were in forward - it pays to read ALL the servicing instructions.

By the way, Mercury Marine just provided the following response: "If the exhaust is cooling water that sounds normal. If it is just exhaust this does not sound normal. Mercury recommends having a dealer look at the motor to confirm."

On reflection we think it was probably both exhaust and water. I suspect lubricating that plug (grommet) with 2-4-C caused the problem and so I will replace it.

Thanks again Graham!