1970 Johnson 9.5 no power w/cover on

[jahughes]

Johnson 9.5HP, model 9R70C which I show as a 1970, runs great with cover off, put the cover on and it bogs down badly.<br /><br />I'm figuring either air flow blockage or exhaust gas getting loose under the cover, but I'm not sure how to troubleshoot this.<br /><br />There is about a quarter-sized hole on the front bottom half of the powerhead cover/clamshell, this appears to be the only air inlet.<br /><br />There is an exhaust overflow/water outlet tube from the rear of the powerhead to to rear bottom half of the clamshell cover (the non-removable part).<br /><br />This tube is rubber, appears to be in good shape and not leaking, but can't really tell for sure...<br /><br />Any advice on how to approach this problem is appreciated, or other ideas on what could be happening to bog it down when I put the cover on will be much appreciated, thanks!<br /><br />Jason

 

[fireman57]

Re: 1970 Johnson 9.5 no power w/cover on

You have an exhaust leak between the power head and the lower unit. The engine doesn't run well on it's own exhaust. Just replace it. This does involve removing the powerhead but what else are you doing in January with all the rain that you have been getting?

 

[Dhadley]

Re: 1970 Johnson 9.5 no power w/cover on

On those motors the common cause is the rubber doughnut is leaking and letting exhaust back up under the cover. To replace it you have to disassemble most of the motor. For years I've wondered about using something like spray foam to shoot down there to seal it up. I'm sure someone has tried it.<br /><br />I believe there should be an air intake under the hand hold on the cover.

 

[bubbakat]

Re: 1970 Johnson 9.5 no power w/cover on

Got one of those punkin heads myself and it ain't no problem to change that seal out.<br />You are gonna need a manuel though.

 

[King P.V.]

Re: 1970 Johnson 9.5 no power w/cover on

You are, to put it bluntly, screw'd!!! Maybe not completely, but 4 the most part, limited to options. The shift rod slides up and down and utilizes a rubber bellows that moves, like an accordian, so it moves with the shaft but seals out ezhust. I would tell you, forget trying to fix it and instead, consider drilling a big hole on the top of the hood and installing a scoop for air!

 

[jahughes]

Re: 1970 Johnson 9.5 no power w/cover on

Thanks y'all, sounds like you've put me on the right track, I'll break out the book collection and see if I have the manual for this "punkin head". Hee-hee, I like that.<br /><br />Funny you should mention that air scoop King P.V., that's actually the first thing that occurred to me as a workaround! Great minds think alike I guess...<br /><br />--J

 

[rolmops]

Re: 1970 Johnson 9.5 no power w/cover on

Fishwish,if you think along the lines of drilling a big hole in the engine cover,you might want to consider putting a bicycle frame on your boat and hooking the chain up to the flywheel.That would solve all your problems with the California clean air laws.While at the same time stopping the carbon monoxide cloud around your engine while trolling.<br />Sitting in the back of a little boat in a carbon monoxide cloud while fishing is not my idea of a good time.

 

[jahughes]

Re: 1970 Johnson 9.5 no power w/cover on

Rolmops, I was "mostly" joking.<br /><br />The idea did occur but I wasn't really seriously considering it. Your advice is well taken though, fishing in a toxic cloud is one angle that hadn't occurred to me and is a good image to put in the mind of anyone who might read the thread and have a (somewhat dim) bulb go off over their heads.<br /><br />I think if I was going to go purely human powered though, I'd definitely go paddle wheel. Time tested, classic design, aesthetically pleasing and sure to spark innumerable dockside conversations. Even legal on those pesky 2 stroke limited lakes, not to mention the healthful aerobic benefits!<br /><br />;-)<br /><br />--J

 

[King P.V.]

Re: 1970 Johnson 9.5 no power w/cover on

I, however, was not joking. Attempting to repair what is surely the tiny exhust bellows/sleeve, will convinse you in short order that unless you can find a dealer who can repair the motor AND is willing to charge you a price you can aford, that Plan "B" is in order. A scoop will be the most economical way to keep this motor in service!!!!! Or.... throw it away!

 

[bubbakat]

Re: 1970 Johnson 9.5 no power w/cover on

King why are you so negative about him doing this. My self I have one and I have replaced th seal and sure its a chore but it is not impossible.<br /><br />I love running up on people that don't like putting a little effort into a motor this way I can get some good deals.

 

[jahughes]

Re: 1970 Johnson 9.5 no power w/cover on

I don't mind giving it a try, it's just something I have knocking around the garage anyhow.<br /><br />Down to brass tacks though, I found an exploded diagram for a '69 in my Old Outboard Repair Vol 1., is this accurate for this year 'Punkinhead'?<br /><br />If so, is it the big oval seal around the top of the exhaust housing I'm looking at or is it the little one down around the bottom of the shift shaft, or both?<br /><br />Thx guys, appreciate _all_ the advice, whether it be accompanied by "go for it!", or by "run for it!"...<br /><br />;-)<br /><br />--J

 

[rolmops]

Re: 1970 Johnson 9.5 no power w/cover on

Fishwish,not to worry.Those pesky little engines are small wonders of engineering and they respond real well to good treatment.Before you take off the exhaust housing,you may want to check the sound insulation on the inside of the cowling.Sometimes it loosens up and causes this sort of trouble.

 

[King P.V.]

Re: 1970 Johnson 9.5 no power w/cover on

The very first 9.5 hp Johnson I ever work'd on that had the afor-memtione'd exhust boot problem was a salt water motor (as is, I suppose, this one). After hours (and hours) of diss-assembling linkages, upper mount hardware, side covers, etc... AND then when the exhust boot and plate were exposed, attempting to remove (read "drill-out the three corrodded screws", located up inside the exhust housing approx. 8" , finally succedding, I think! AND THEN, attempting to get everything back together again...... It was a heck of a way to learn HOW to do so...<br />Well, my thought is that where you HAD a motor that just needed an alternate method of fresh air but instead.... you now have a motor in a million pieces ... in a box. BTW, the exhust housing has been obsolete for at least a decade... and go ask a old time OMC mechanic when he last did this repair, what he would charge and IF you agreed to the repair. would he do it?. Most OMC mechs. who HAVE previously been around these engines (and these are good motors when they don't have THIS problem)will tell you the same thing as I, ... "Are you SURE you want to get intimate with the inner workings of this motor? If you do, I wish you well, and ... would you be so kind as to let us all know the joy you had doing it??? We'd like to know if you were successful, still have that dog you love or if the wife kick'd you out of the house after this repair. I used to work for the largest Johnson dealer west of the Mississippi (Seattle) and we serviced many of these motors. The local Thunderbird class of sailboats used these motors as they were very low profile and fit with-in the "engine box" the boats had. After the salt water problems destined the motors to Davey Joneses Locker, most of the "T-birds" moved on to Honda 7.5 hp. THEN the salt problems really started hapening. So, you may think of me as negative, but I choose to think of it as realistic! Good luck! I'd go talk to a local OMC mechanic and ask him his opinion , see what he says!

 

[rolmops]

Re: 1970 Johnson 9.5 no power w/cover on

Happy new year.<br />The '69 and '70 are identical engines.Make sure that the '69 is a johnson because there may be some differences in the cowling setup.The best way to find out where your exhaust leakage is from is by doing a bubble test.Make some soapy water and while the engine is running(with the earmuffs on so it pumps water)just pour soapy water over the suspect areas and where it makes bubbles, is where your leak is.

 

[MCM]

Re: 1970 Johnson 9.5 no power w/cover on

Fishwish, for accurate exploded diagrams and parts lists for your motor visit this site.<br /><br /> http://epc.brp.com/default.aspx?brands=ej&lang=E <br /><br />If its not working which sometimes happens, visit iShopMarine.com, they also have the same diag. and parts lists available

 

[andy6374]

Re: 1970 Johnson 9.5 no power w/cover on

rolmops-<br />Give her the ol' bubble test you say . Sometimes the simple ideas are the best.

 

[jahughes]

Re: 1970 Johnson 9.5 no power w/cover on

Good tip on the sound insulation rolmops, there was already a patch removed above the carb, I enlarged it a bit just in case, but no change.<br /><br />I tried soapy water down in the well under the powerhead, can't see any bubbles, I think it's burning off too fast from the heat to make bubbles, but that's gotta be the problem area. When I lift the cover about 2/3 off it can breathe again and perks right up.<br /><br />King P.V., I'm lucky on this one, looks like a freshwater motor, so no rusty bolts to sweat over.<br /><br />I am actually trying to think of a way I might be able to try out Dhahley's original thought about sealing the area off without doing a disassembly.<br /><br />I can't find any high-temp spray foam referenced anywhere, just lots of warnings about the nasty gases spray foam gives off when heated, so that's out.<br /><br />I was wondering if hosing it down with Permatex and then filling the well partway with high temp silicone might work. Seems the biggest problem would be to get the silicone to flow down/around everything. Worst case is I have to pull it all out if/when I do have to disassemble.<br /><br />Any thoughts on that approach?<br /><br />And as always, thanks!<br /><br />--J

 

[jahughes]

Re: 1970 Johnson 9.5 no power w/cover on

Hmm, I think I can now recommend against this approach. I haven't tried to run the motor, but it was dang near impossible to get any sealant down there, if I did manage to plug the leak it was more luck than anything else, so looks like I'll be taking it apart.<br /><br />Oh well, nothing ventured, nothing gained...<br /><br />Thanks all for the good advice, I'll update when it's finished to confirm what the problem was.<br /><br />--J

 

[fireman57]

Re: 1970 Johnson 9.5 no power w/cover on

The main thing to remember is don't get in a hurry, don't force anything, and don't have too many cold ones while working on it. Have them after you become frustrated, walk away from it, and return later. Don't let anyone scare you just take your time and follow the manual. Good luck.

 

[tashasdaddy]

Re: 1970 Johnson 9.5 no power w/cover on

fireman. that's the best advice i've heard on a long time. everybody wants to get back on the water in a hurry. i've got a 4.3L i/o i've been working on for months, and will be for several more. everytime is get frustrated i come back and read the sites.