Went through new to me yamaha 30hp 2 stroke and found some things, need advice

[rosscopeeko]

Hello guys. I'm a marine newb and found myself a good deal on a 92 yamaha 30hp 2 stroke. It was a boat package and it was really cheap so i bought it mostly for the motor. Anyways, i drained the carbs last winter and then it sat in my garage until now. I cleaned the fuel filter and got fresh fuel, new plugs, charged the battery and tried to start it. I had it on muffs in my yard. It started right up and reved up a bit at idle. I coaxed it down by manually pushing the throttle return back. Here's one of my issues. It never pumped water out of the tell-tale. I ran it for about 20-30 seconds. Today i removed the lower unit and drained the oil and it was a milky silverish color. A touch of water in there? Which seal should i replace for this? The water pump impeller was in exc shape, no cracks, all there. Next i'll check the thermostat. There was some white goop in one of the passages right by the water pump impeller. Not sure what it is but i'll clean that. Is there a good way to flush the cooling system? Spray water down the thermostate housing? This is my first project to tackle, then i'm on to a new fuel pump diaphram and i'll check the compression. I know the pistons have a lot of carbon on the tops from trolling. I want to test the oil injection system also but i'm scared to not run pre-mix for now. This is the 3cylinder model. Please give me some advice if you can. Thanks,

 

[99yam40]

Re: Went through new to me yamaha 30hp 2 stroke and found some things, need advice

check the tell tail to see if it is plugged.

A new to you motor should have the water pump replaced, and thermostat replaced with new or at least tested for proper operation.
pressure/vacuum test lower unit to see where the leak is or just reseal it all.
I would make sure the compression was good before spending much on it.

 

[rosscopeeko]

Re: Went through new to me yamaha 30hp 2 stroke and found some things, need advice

Ok, thanks for the advice. I have a compression tester. To do this do i just do it cold and run the electric start for a few seconds per cylinder? I'll disconnect the coils so it doesn't fire on the other cylinders. From reading i know i'm looking for even compression accross all cyclinders. What would an acceptable figure be? 120 accross all three?

 

[99yam40]

Re: Went through new to me yamaha 30hp 2 stroke and found some things, need advice

pull all plugs and the kill switch to keep wires from sparking.
Spin over several compression strokes on each cylinder. let us know what you find

120 wold be too go to be true, but who knows what you will find

 

[rosscopeeko]

Re: Went through new to me yamaha 30hp 2 stroke and found some things, need advice

Ok, did the compression test and found 105, 107, 107. How is this? Worth spending a few bucks on? I planned on buying a new tiller arm for about $240, new thermostat, new fuel pump diaphram, new impeller, and fix the leak in the bottom leg. I took a look at the thermostat and it was disgusting. White and green corrosion everwhere. Inside the pocket for the thermostat there is a tiny hole in the bottom of it, about 1/8th of and inch round. Is this normal or has it rotted through? I also flushed water down the thermostat hole and a hole bunch of white gritty stuff was pouring out the bottom. I took a look at the fuel pump and i found tiny particles of fine sand in there along with what looks like a litte red rust. I took some pictures, i'll see if i can attach them. Can you guys give me your insight. The model is an electric start, control type. I need a tiller. Too much to invest or will it be a reliable powerful rig when set up right? It will run on a 14.5ft aluminum.

 

[rosscopeeko]

Re: Went through new to me yamaha 30hp 2 stroke and found some things, need advice

Got a new impeller and thermostat and it's running really well. The bottom leg's fill plug was very loose, so i'm hoping that was my leak. I'm going to take it to the lake and see how it goes. I also got a new fuel pump diaphram. This thing fires right up, idles well, and revs up insanely fast. I'm unsure of the tiller arm conversion. I see a complete tiller arm is listed as buyable, but the piece that joins the throttle controls to the tiller is different on my control motor. I'm not sure where i can buy that. A yamaha mechanic told me the compression is ok and that two stroke outboards don't run high compression.

 

[rosscopeeko]

Re: Went through new to me yamaha 30hp 2 stroke and found some things, need advice

Hey guys, i'm bumping this one up. I need your insight. My compression numbers on this motor are 105, 107, 107. Lower unit might have a leak, not sure after i tightened drain plug and refilled it. I found a hole in the thermostat housing where the thermostat sits. It was at the bottom, and about 3/16" around, looked rusty looking. Is this normal to see in the thermostat housing area, or is it rusted through? I picked up my new aluminum 14.5 and might fix this 30 up if it's worth it. I need to convert it to a tiller. Should i sell this motor and look for another, or fix it up a little. I'm worried about that hole in the water jacket. It's a 92 model yamaha.