9.9 evinrude - disassembled and ready

Hello all. Haven't been on here for a couple of days because i've been tearing down my 9.9. First i want to thank all of you for your help. As a result of the info i got on this board i ordered a manual and disassembled my engine. I now have it in a million pieces but the good news is they all look pretty good. I do have a couple questions if anyone wants to tackle them. <br />1) I had a lot of water in the lower unit, fortunately nothing was damaged. The gears all looked great and the bearings were in tact. I am going to change the water pump although it appeared to be brand new. Where am i getting water from? I can't find anyplace except for maybe around the water pump. <br />2) As my partner stated in another post the tops of the pistons had some carbon deposits on them but overall were in good shape. They have some discoloration down the sides of the pistons but they are not damaged at all. I am replacing the rings but i was wondering about the carbon deposits. What causes and is it bad thing?<br />3) Any idea how i'm losing compression on my top cylinder (which is still about 120). <br />Thanks for everything. Please help where you can, much appreciatted.

Re: 9.9 evinrude - disassembled and ready

Hi Stream Fisher<br /><br />Good to hear. The carbon deposits are normal, both on top and sides. It will be reduced by decarbonating. I think, if you are lucky, the compression will be more even when you decarbonise, carbon around rings can reduce compression. Most Evin/Johns have backpressure rings. They are squesed against cylinder walls when piston travels, and compression appears, look at the upper edge, it is not rightangeled. The ring compartment in piston should be clean and clear, allowing the rings to work. Be aware, there is a little key where the ringends meet ! Water in lower unit usually gets in, around propeller shaft or drive shaft. Seals both places are interchangeable. You will end up with a very fine motor!

Re: 9.9 evinrude - disassembled and ready

G Dane: <br />Thanks so much for the info. I have picked up nearly all the parts to completely overhaul my engine but i'm still waiting on the seals for the lower unit and a set of rings for the pistons. They had one set, still waiting on the other. I hope the rings fix the problem because i have no other ideas. How to decarb? and can i, or should i, clean the pistons while out of engine and what with? Thanks

Re: 9.9 evinrude - disassembled and ready

It would have been nice if you had decarbed the engine before disassembly.<br />Best way to clean pistons is in a carb cleaner solution which typically comes in a 5 gallon pail. Do not clean on a buffing wheel!! Gently clean ring grooves free of carbon. Some people use the end of a broken ring as a cleaning tool. Just be carefull not to remove any metal and beware of the ring dowel. If the skirt(sides) of the pistons are scored, you can lightly smoothen them with crockus cloth. Even though the manual allows the use of a wire brush, I recommend it be atleast a brass brush. Wet the brush with clean varsol.<br /><br />Be sure to rinse the pistons and rod spotless and blow clean several times. (put your cigarette out first!!!!)<br /><br />*it is better not to clean, than to have cleaned improperly and caused damage.....<br />Careful when re-installing pistons. Ring ends must stay inline with dowel as gdane says or the rings will break. Lube the pistons with a generous coat of 2-stroke oil before installing.<br /><br />my humble opinion....Good luck

Re: 9.9 evinrude - disassembled and ready

Streamfisher, your lower unit problems may be the result of bad seals, or gaskets on the vent/fill screws. Easy to diagnose with a pressure test. I still don't understand why the motor is in a million pieces. Your compression was good but uneven, however a simple spray-in decarb may have solved that. Did it have other terminal issues like scored cylinder walls? I've tried to glean what I can from all the posts you and your partner had out there. I may well be missing some vital data, but what exactly was the reason to disassemble?

Re: 9.9 evinrude - disassembled and ready

We tore the motor down to give her a complete rebuild. We figured it was worth it since we really didnt know the history of the engine and it was nearly twenty years old. It seemed that this was the best approach to take care of any leaks and to find any problems that may have been hidden by previous owners. Thanks for your help

Re: 9.9 evinrude - disassembled and ready

My partner tackled the question of disassembly in a politically correct manner and attempted to justify our destruction but honestly it had just as much to do with curiosity as anything else. We are the type of people who have to know how things work, plus i come from a background of people who fix their own stuff. My dad and brother both own(ed) coal trucks and you have to service your own equipment to even come close to being successful. <br /> He was also right however, that the engine did probably need a rebuild and we wanted to make sure there wasn't any problems inside the engine that we didn't know about that could cause problems later. And it turns out that it was a great learning experience for the both of us and now i can tackle any problems we run into with confidence. Partly because of the wonderful advice i have recieved on here and partly because of the experience of destruction. Thanks