'84 Evinrude 9.9 exhaust- really need help

[mafhuntfish]

Hi All - First, I would like to thank everybody who has helped with my previous questions. I?m still working on a 1984 Evinrude 9.9 -
e10selcra - Yachtwin. I?ve just replaced the powerhead to exhaust housing gasket , the inner to outer exhaust housing gasket, and the driveshaft seal on top of the water pump. The water pump is sealed good and working correctly. My problem is: I have a serious exhaust leak that is starving the motor. It is in the engine compartment somewhere & I?m having a real hard time locating it.
I can run the motor, but when I put the cover on, it looses rpms & sputters. (starving for air) Is there any tests I can do to determine where this exhaust leak is coming from with the powerhead still installed? (ie exhaust cover - bypass cover, ect) There is no water leaking out anywhere, only exhaust. Thanks in advance for any help or tips. Mark

 

[Mas]

Re: '84 Evinrude 9.9 exhaust- really need help

Does it run better without the hood on/off? I'm assuming that your running on muffs. Get a fan and see if you can blow exhaust away from the motor. Maybe it's just drawing in expelled exhaust.

MAS

 

[mafhuntfish]

Re: '84 Evinrude 9.9 exhaust- really need help

It definately runs better with the cover off. No need for a fan - the exhaust leak is extreme and is coming from somewhere in the engine compartment - I just can't tell where. When you put the cover on - it blows exhaust out the top rear vents in the cover and through the holes in the bottom pan.

 

[ezeke]

Re: '84 Evinrude 9.9 exhaust- really need help

It's not uncommon to lose the outer exhaust cover gasket. If you have a leak a little liquid soap should expose it while running the engine. The gaskets are subjected to a lot of stress from expansion and contraction of the covers.

 

[Rick.]

Re: '84 Evinrude 9.9 exhaust- really need help

I would fill a spray bottle with a soap and water solution and start spraying any seals that could be a leak suspect. You will see bubbles right away if you get the solution on the leak. Do you have the air breather (plastic part) in place? Is there a chance that with your upper cowl in place the carb. is air starved and not necessarily sucking in exhaust vapor. Good luck. Rick.

 

[mafhuntfish]

Re: '84 Evinrude 9.9 exhaust- really need help

and actually I'm running the motor in a 30 gal drum.

 

[mafhuntfish]

Re: '84 Evinrude 9.9 exhaust- really need help

I do have the air breather in place and with the cover off - it seems to run fine. Going to get some soap & water right now

 

[mafhuntfish]

Re: '84 Evinrude 9.9 exhaust- really need help

OK - no bubbles that I can see. It seems like most of the exhaust is coming from under the bottom engine pan somewhere around where the shift rod goes down through ????

 

[ezeke]

Re: '84 Evinrude 9.9 exhaust- really need help

Is the rubber seal between the inner exhaust and the gearcase in good shape and sealed?

How about the grommet on the shift rod?

That large o-ring on the top of the water pump housing is the seal for the drive shaft tube.

 

[mafhuntfish]

Re: '84 Evinrude 9.9 exhaust- really need help

Hi - Rubber seal is new - o-ring for pump was in good shape & actually didn't see a grommet for the shift rod. This model has the weird lower unit (25") where the exhaust comes out at the base of the extension instead of the prop. I dropped the lower unit again with the extension still attached and sealed around where the exhaust goes down through. There is a cross member in the casting that I believe was allowing the exhaust to flow into the chamber with the water tube & driveshaft and then out through the mounting bolt areas & up. Going to let the sealant set for 24 hours & see if it takes care of the problem. Thanks again

 

[mafhuntfish]

Re: '84 Evinrude 9.9 exhaust- really need help

Hi again - After much closer examination, I have determined that It?s blowing exhaust up through the shift rod hole in the exhaust housing right below the bottom mounting bracket & coming up through the pilot shaft. I know that there is supposed to be a grommet (which is missing) sealing the shift rod in this hole. My question is - I can?t understand how I?m getting exhaust in this area in the first place. This unit exhausts at the bottom of the extension and through the six holes in the back top of the lower unit - not the prop - so it?s impossible for the exhaust to even go down into the lower unit. I thought I might have blowby in between the exhaust housing & extension so the last time I had it apart I sealed this area with gasket sealer. Unfortunately this hasn?t solved the problem. Is there supposed to be exhaust in the shift rod area that the grommet prevents from escaping? Thanks for any help - this motor is kicking my a**

 

[CATransplant]

Re: '84 Evinrude 9.9 exhaust- really need help

You said you're running this in a barrel. That could be the source of the exhaust gasses. In normal operation, the boat is moving, dissipating the exhaust. In a barrel, it tends to collect around the engine.

The grommet should be there, but I'm betting your problem goes away when you're on the water.