# 1967 Evinrude 9.5hp Exhaust Leak



## wmk0002 (Apr 11, 2016)

I have a 1967 Evinrude Sportwin 9.5 hp which I believe has an exhaust leak and I was looking for some help on the matter. This motor is new to me and this is my first time working on this particular model. I have a running post on the matter on another forum but it has fallen through the cracks to the knowledgeable members. I was thinking plenty of guys on this board would have the same model motor due to it's suitability for small jon boats. Any help is appreciated.

*What I know about the motor:*
The motor has 65 psi in each cylinder. New and properly gapped spark plugs. I cleaned and gapped the points and the spark jumps well over a 1/4" gap. The LU is good and has fresh oil. The impeller is new and it is pumping good water. The thermostat is functioning per a bench, err... stovetop, test. I cleaned and rebuilt the carb. New fuel line from fuel pump to carb. 

*How it performs:*
The motor starts and runs well in a barrel or on a boat with the cowl off. I water tested it last weekend and, with the cowl off and low speed needle at about 1 1/2 turns out, it ran about 15 mph and was turning about 4800 rpms (WOT range is 4000-5000) so it seems that it is running like it should. 

When I put the cowl on it would not idle down very low without dying. It accelerated pretty good though and did push the boat about 13 mph but it was only turning about 4000 rpms and it seemed to fluctuate a little more than it should. The farther in I turned the low speed needle, the better and faster it ran. With the low speed needle all the way in, it was running about 14 mph and turning maybe 4400 rpms. For most motors, any less than 3/4 turn out is too lean so I only did that briefly.

*Questions:*
Am I correct to believe that this is likely an exhaust leak? A previous owner had drilled a bunch of holes in the cowl directly above the carb to likely try correct the same issue. But there also appears to be ample ventilation spots for fresh air to come in, primarily around the sides of the front plate where the pull starter handle, choke, and low speed knob is. This leads me to believe that it is getting fresh air but that it also has contamination from exhaust gasses present. 

If it is a leak, I am aware of the 4 potential locations. So far I checked the seal on top of the water pump which looked good and attempted to check the shift rod boot. I say attempted because I couldn't figure out how to get the retaining plate off as the bend in the water tube prevents it from sliding down and off the shift rod. Would this require powerhead removal? If so, I will just go for it and replace it plus that other large main seal between the powerhead and case while at it. I also haven't check the overboard water tube yet, which is the easiest, so I will do that in the meantime.

Thanks in advance for any advice you guys can give!


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## wmk0002 (Apr 11, 2016)

And who doesn't love a good video.

https://youtu.be/gMLELpgE_bo


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## lckstckn2smknbrls (Apr 11, 2016)

Could be.
It's a pain to pull the power head on the 9.5 motors to replace the gasket.


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## wmk0002 (Apr 11, 2016)

lckstckn2smknbrls said:


> Could be.
> It's a pain to pull the power head on the 9.5 motors to replace the gasket.



Well the good news is that I have a couple other motors to use in the meantime. I'd like to fix this one to either sell or to keep as a portable motor for smaller boats due to its low weight. So I have the time.

BTW, were you just referring to that primary seal around the powerhead/exhaust leg or were you talking about the shift rod boot replacement requiring powerhead removal?


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## SumDumGuy (Apr 11, 2016)

Read through these links when you get a chance....

https://www.leeroysramblings.com/OMC_9.5.htm

https://www.tinboats.net/forum/viewtopic.php?f=4&t=25392


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## wmk0002 (Apr 11, 2016)

SumDumGuy said:


> Read through these links when you get a chance....
> 
> https://www.leeroysramblings.com/OMC_9.5.htm
> 
> https://www.tinboats.net/forum/viewtopic.php?f=4&t=25392



Appreciate it. I am familiar with Leroy's Ramblings. I don't think he specifically addresses the shift rod boot issue but his site has been helpful to me and if I do any powerhead dis assembly, his page will be very helpful I believe.

I think I may have read that other tinboat thread before too. Not 100% sure but I know I have seen the graphic from cajuncook1 before. That was where I first heard mention of a leak from the waterpump seal. I was actually hoping cajuncook1 would reply to this. I have watched his youtube videos and read his posts on other forums and he is one of my favorite posters due to his thorough explanations and clear communication.


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## wmk0002 (Apr 12, 2016)

I fiddled with the motor again this evening. It seemed to be running hot (head getting up to the 170's on my IR thermometer) so I rechecked the thermostat and it wasn't opening until about 165 deg on the stove but stayed open until it got back down to the 140's. It doesn't have a temperature marking on it so I just ordered a new one. 

While testing how cool it ran with the thermostat removed, I began to search for exhaust gases coming from up inside the lower cowling. There was definite exhaust coming up from the front side of the powerhead. I could see where the shift rod went down inot the leg and didn't see any distinctively coming from that opening. It appeared to me that the main powerhead seal was leaking towards the front. 

I should be getting my new boat this week sometime so I don't plan on messing with it any further anytime real soon. I need to focus more on the 9.9 and 15 hp Evinrudes I have and probably need to keep this one intact to carry with me on boat tests of the others as a known working backup.


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## wmk0002 (Jul 12, 2016)

I'm bumping this because I am going to try to go ahead and fix the exhaust leak and sell this motor.

Does anyone know where I can get the main exhaust seal and the shift rod boot for this motor at a reasonable price? They both are discontinued. I seem to remember cajuncook posting a link to a site that still had some ONS. Any leads would be appreciated.


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## cajuncook1 (Jul 14, 2016)

Here is the link to shift rod boot. Part number 309631

https://nymarine.ca/grommets.htm

Nymarine home link:

https://nymarine.ca/

Nymarine parts link:

https://nymarine.ca/parts.htm


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## wmk0002 (Jul 15, 2016)

cajuncook1 said:


> Here is the link to shift rod boot. Part number 309631
> 
> https://nymarine.ca/grommets.htm
> 
> ...



Thanks! You are exactly who I was waiting on to chime in.


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## cajuncook1 (Jul 15, 2016)

Yes, the 2 main culprits of the exhaust leak would be the exhaust housing seal and the shift rod boot. I thought that Nymarine made both the shift rod boot and the exhaust housing seal. The exhaust housing seal can deformed from the years, so it allows exhaust gases to travel up. Usually less noticeable when on the lake because most of the exhaust gases and water go out near the foot. Slow trolling or in a barrel is where the issues tend to be worse.

You will have to remove the tiller and its pinion system and the shift lever and the bell crank system. IT is easier to work and get to different parts if the flywheel is removed. I highly advise using zip lock bags to label and separate the various parts groups that you will taking apart. There are a lot of little parts that can easily get lost. Please please take plenty of digital pictures as you go. It will help tremendously. Pay special attend to the tiller and pinion system removal and set up.

The exhaust housing shell will ultimately have to be removed to get to exhaust housing boot and the shift rood boot. It is a bit of work, but it can be done if you take your time and stay organized. 


If you PM me your email address, I can send you a digital service manual specifically for your motor.


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## wmk0002 (Jul 15, 2016)

Thanks cajuncook! I will take lots of pictures and try to be as organized as possible. I'll post some of the disassembly on here for reference to others with the same problem in the future.

And thanks for the offer on the manual. I sent you a pm with my email.


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## cajuncook1 (Jul 16, 2016)

Did you receive the manual?


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## wmk0002 (Jul 16, 2016)

Yes, I got it. Thank you for the help.


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## Pappy (Jul 17, 2016)

Is your upper mount still intact and working or broken like most of them are? Makes a big difference in how long that seal will last. Grab the flywheel and see if you get a bunch of fore and aft movement.


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## wmk0002 (Jul 18, 2016)

Pappy said:


> Is your upper mount still intact and working or broken like most of them are? Makes a big difference in how long that seal will last. Grab the flywheel and see if you get a bunch of fore and aft movement.



The upper mount is still good. I can actually visually see where the exhaust leak may be when I first crank the motor and it has a slightly richer burn. A tiny bit of visible smoke comes up from the front area either from a leaking main seal or up from the shift rod location. I was actually wondering if running the motor and shooting some seafoam in the carb to richen it up may help me find it a little better.


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## wmk0002 (Aug 10, 2016)

I separated the shell over the weekend and have the powerhead removed. The main exhaust seal looks more like the culprit now as it seems bent down in the front which is where I believe the leak was coming from based on the puff of smoke I saw coming from that location after a choked/rich startup. That will be a straightforward repair after I find a good deal on a seal.

However, I am hung up on removing the shift rod. The manual acted like it could have been pulled out before removing the powerhead all of the way but that is not possible. Will I have to separate the exhaust leg from the powerhead to do so?


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