Here's a question which I am having difficulty getting an answer to (which may be due to my inability to explain it clearly): When an Evinrude E-Tec engine is not running, i.e. in storage, parked in the yard, doing anything but running, is there a relatively large open channel from the outside atmosphere to the engine combustion chambers and pistons? if so would this be from the exhaust outlets on the outside of the engine, through the exhaust channel to the exhaust ports in the chamber and then (if the piston is in a certain position) into the combustion chamber? Seems like a simple question to which I'm having a hard time getting a straight answer.
Thanks for your help!
when either a 2 or 4 stroke engine is stopped thier is always a possibility of having an open port or an open valve. it is a game of odds as to where the pistons stop. so may i ask why the worry?
The worry is an insect (mud dauber wasp) can evidently enter the exhaust outlet, make it's way to the cylinder exhaust port and enter the cylinder, build a nest, seize the engine and create an $800 repair bill. 2016 Evinrude 105 Jet with 53 hours on it. Will be plugging the exhausts when not in use.
Dealer had never seen it before but that didn't ease the $800 pain
Thanks for the reply.
06-06-2017 11:21 - edited 06-06-2017 11:23
On all multi cylinder engines from cars to piston engine airplanes to both inboard and outboard motors at least one cylinder and possibly several can be open to the air through the intake or exhaust passageways. It doesn't matter if the motor has valves or piston ports, some cylinders can be exposed.
Like the others told you, I have not seen mud daubers build a nest inside a cylinder. I did find a small dead lizard blocking the water tube from the pump to the engine block once and mice have built nests inside of air silencers and carburetor openings.
Thanks for the reply.
Have devised a system to plug the exhaust outlets with a medium weight foam (cut from a pool float) that fits loosely in the outlets. Will attach a pink ribbon to remind me to remove but even if I forget they are loose enough they should blow out when engine starts. Also will put a drop of peppermint oil on the foam, mud daubers evidently hate it. Mechanic took pictures of the smashed nest and am pretty sure it was mud dauber wasp. Lots of dirt and larve pieces. I have seen the mud nests in the shed but never thought they could (or would) make it inside a cylinder. But the unit runs great again so only damage is to the bank account, the solution to most boat issues = $$$$.
I did something similar and other pilots do too keep birds from making nests in the cylinders on a small airplane. We put ribbons on the foam plugs plus we secured a large red ribbon to the steering yoke to remind us to remove them before starting the engine. You can do the same around the steering wheel.