Evinrude 35HP too many exhaust ports?

[johnny whaler]

I have this 1976 Evinrude 35HP long shaft. There are the normal 2 exhaust ports that are on the aft side of the shaft that blow out the water. It exhausts through the prop as well but there are 2 "exhaust ports" that face the transom out of the back of the shaft about 1/2 way up. The sound coing out of there is loud and the fumes rise up into the intake. Are these 2 holes supposed to be exposed or are there supposed to be gromets in there?

The reason Iask is that the engine is considerbaly louder than most other outboards and when I put simple Duct Tape over the two holes the engine runs better and I don't need to take the engine cover off and it's much quieter.

Just wondering if exhaust should be coming out of these two holes. When I block them with my fingers I see the exhaust coming out by the prop as it should. Did something break or am i missing caps there or something? What si the purpose of these two extra holes? Keep in mind, they are on the front side of the engine pointing towards the transom.

Thanks....Johnny W

 

[Texasmark]

Re: Evinrude 35HP too many exhaust ports?

Only thing there would be the shock mounts on the lower end of the clamp bracket and down in the lower unit, maybe a drain hole; not that familiar with OMC any more. Drain hole would be around 0.100 inch in dia. and located around (above) the protrusion that encompasses the gear box.

The exhaust is out the prop as you say with pressure relief ports above the water line (hence pressure relief) at the upper aft part of the mid section, usually 2 side by side.

i think you are correct in that they don't belong there, unless a drain as I said, but the question then becomes, what are they and where did they come from?

I do have a (another) question however: if the engine were on the boat and in the water, would the holes be covered by water?

Mark

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

The holes would be out of the water. This is a long shaft motor on a short transom. I am going to lift it with a mini jack plate once I get it runnign right. The holes are one on top of the other about .50" they are the same size as the exhaust / water ports on the aft side of the shaft where the water pumps out. I can fel the drive shaft spinning when I tried to cover them up with my fingers. I have a feelign they are relief ports that should have a rubber stop or cap that may have just rotted away being 30 years old?

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

can anyone explain what these two holes are? SDhould they be capped?

 

[F_R]

Re: Evinrude 35HP too many exhaust ports?

Whatever you do, DON'T cap them. They are drain holes for water that excapes out the top of the water pump impeller housing. Plug them and the water will rise up to the level of the powerhead and wreck the lower main bearing seal. After that is gone, the water will get into the crankcase and destroy the powerhead.

You are getting the exhaust and noise because the spacer tube that goes between the water pump and exhaust housing is probably missing. Or at least the o-rings that go on the tube. Long shaft and short shaft take different tubes. See it at the exploded parts view at http://epc.brp.com/default.aspx?brands=ej&lang=E

BTW, the missing tube also allows exhaust to come in contact with the forementioned lower main bearing seal, which will also accelerate the damage. Get that tube back in there.

 

[steelespike]

Re: Evinrude 35HP too many exhaust ports?

Two things bother me about these being drain holes
1 He says they are about the size of the exhaust ports
and he says it is louder than other motors.
2 With the holes covered He says it runs better and he doesn't need to take off the engine cover.Something is odd here.

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

The BRP link must be down. Can you suggest the best place to buy parts for an older outboard? Thanks for the help. I knew something was unusual with this.

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

They are the exact same size as the ehaust ports. But one on top of the other. They are just below the pivot point of the top of the lower unit. The are very big and don't look like they would be drain holes but there is lots of sound coming out of there. If I plug them with my fingers or just duct tape the engine sounds normal and I see the exhaust forced out the prop as it should be and my cover problem is gone. No more fumes directly below the intake. I can try to figure out how to post a picture on this site....Jim

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

My apolofies, they are just ABOVE the pivot. I will try to attach the picture now.

 

[xtraham]

Re: Evinrude 35HP too many exhaust ports?

got to have an exhaust gasket blown if exhaust is getting in the drive shaft tube...........

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

my pics are too big, i'll try again

 

[xtraham]

Re: Evinrude 35HP too many exhaust ports?

johnny, you have to host your pics photobucket.com works pretty good, then click on the yelow icon above the reply box and paste the url of your pic in the box click ok

 

[xtraham]

Re: Evinrude 35HP too many exhaust ports?

is this it

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

YES!!!! that is the spot....what is it?
Thanks!!!

 

[F_R]

Re: Evinrude 35HP too many exhaust ports?

Those holes are the ones I was talking about. They are drain holes for water that escapes out the top of the water pump. Read my earlier post. That's my story and I'm sticking to it. It runs better with them plugged because the exhaust coming out them is not going up and being sucked into the carb intake. I'll bet a dollar toward a dead donkey that the tube is missing off the top of the water pump.

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

It sounds logical to me. what would be the cause of the exhaust coming out through there? isn't the tube on the top of the water pump pumping water only? I'm Still trying to figure out how the exhaust travels.

So pretty much rop the lower unit and either the tube is missing or the grommet is shot.

Thanks a million for the help.

 

[johnny whaler]

Re: Evinrude 35HP too many exhaust ports?

Those holes are the ones I was talking about. They are drain holes for water that escapes out the top of the water pump. Read my earlier post. That's my story and I'm sticking to it. It runs better with them plugged because the exhaust coming out them is not going up and being sucked into the carb intake. I'll bet a dollar toward a dead donkey that the tube is missing off the top of the water pump.

I'm thinking here...if the tube on the top of the ater pump is missing then how is the water pumping out the back two exhaust ports? Isn't that tube the only way for the ater to travel out? There is little to no water coming out of the transom side holes, just exhaust gas for the most part. The flow of water out the rear two ports is heavy and normal.

 

[F_R]

Re: Evinrude 35HP too many exhaust ports?

The drive shaft normally runs in an isolated chamber, the tube being part of that chamber. Without the tube, the chamber is no longer isolated from the exhaust and exhaust gets into it and blows out the drain holes. See if this picture posts ?

 

[F_R]

Re: Evinrude 35HP too many exhaust ports?

Guess I don't know how to post pictures

 

[F_R]

Re: Evinrude 35HP too many exhaust ports?

To clarify, we are talking about the aluminum tube, approx 1 inch in diameter with and o-ring on each end which surrounds the drive shaft. Not the copper water tube which carries cooling water. Anybody want a picture, e-mail me at gatorsnfrogs@verizon.net and I'll send it to you.