50ESLB Johnson 50hp 1975 -- Engine dies when hood is on.

Hi all -- Thank you in advance for your help.

I just had my outboard serviced. 1975 Johnson 50HP, 50ESLB. He had it running great when the hood was off, but when he put the hood on the engine would die. He said it was because of an exhaust O-ring that is not made anymore causing dirty air to get into the engine instead of clean air. He drilled some holes in the hood so clean air could get in and it runs great. What I'm curious of, is, what is this part? Is anyone making it? Please help. I would rather have it fixed right, if it can be.

Thank you,

Josh

Exhaust O Ring? There is no such item.

There are a few heavy duty rubber exhaust housing seals, depending on which model you have... 313655, 315955, and 315956, to name a few of their part numbers, all of which are stll readily available.

Running normally with the hood off but not running properly when the hood is on indicates that the exhaust is being pulled into the carburetors.

Now, if this took place when actually running down the water way, then yes the engine has an exhaust leak somewhere and it is your job or the mechanics to pinpoint from where.... and be advised that it could be an expensive fix.

However, if the engine was running in a test tank of some kind... there is no way you could run it with the hood on in the first place as the exhaust fumes are directly under the engine and would be pulled thru the air opening directly below the bottom carburetor into the carburetors. There is also (usually) a air vent opening in the rear hood hand hold opening which comes into effect when under way BUT would prove ineffective when the engine is being run in a test tank/barrel, whatever.

Drilling holes in the hood may allow water vapor to enter the powerhead area... really not the way to go.

He test ran it by backing it down into the water. He didn't run it across the lake though. In other words, it would have just been idling at the boat ramp. Does this change anything?

If I want to double check it -- Could I just get on the lake and duct tape over the holes and see what happens as I go across the lake? Then see if it dies during idle? If it works fine, I could just get a new hood -- otherwise, there must be an expensive fix that he just didn't want to do.

Thanks!

Go the duct tape route on the holes and water test the rig. Let us know what you find.