New one on me

[bullie]

A fellow brought a 1976 Evinrude 25 hp to me to see if I could get it going for him. It had good spark and compression in the mid 90s. Anyway, I put a new impreller and a carb kit in it. I got it running but no water was exiting the leg at all. I dropped the LU again and used my drill to check water pump function. It pushed water high enough to get me pretty wet so that was good. I then hooked up a hose and couldn’t push any water through the motor that way either. I decided next to pull the thermostat cover to see if water was getting that far. Water was pushing that far but there was a plug in the smaller hole on top. I thought it might be a piece of the old impeller but it almost seemed to be made to plug it off? Maybe I should have gotten a picture of it too. Anyway, the tube running down the back of the head was totally clogged with grass or moss or whatever that stuff is in the picture. I was able to get a good deal of it out but things are still plugged up.

I guessed the next course of action would be to pull the cylinder head and clean all the passages out? What else should I do?

[chris-p]

NO sign of anything when you did the water pump? In any of the passages.

You will not have to ensure that all passages from the pump to the exhaust are clear.

You have some fun ahead of you! Always the jobs for friends that I find major problems lol.

[bullie]

quote Chris_P:

NO sign of anything when you did the water pump? In any of the passages.

You will not have to ensure that all passages from the pump to the exhaust are clear.

You have some fun ahead of you! Always the jobs for friends that I find major problems lol.

Nothing at all in the water pump or in the copper pipe going up the leg. I thought it was very strange that the grass/moss was downstream of the thermostat. There was nothing at all in or around the thermostat either.

[outbdnut2]

Could small insects have crawled up there and made a nest? I’m seeing more and more insect and/or rodent-related stuff in motors lately., including a full mouse nest in the lower cylinder of a 1958 35 Johnson.
Dave

[frankr]

One of the two water passages leading to the thermostat cavity is pretty narrow. You’ll see it when you get the head off.

[frankr]

Is the screen in the main water intake aft of the prop? Is the bypass cover in place on the side of the gearcase? Crud of that size shouldn’t be able to get through those two items.

[bullie]

quote FrankR:

Is the screen in the main water intake aft of the prop? Is the bypass cover in place on the side of the gearcase? Crud of that size shouldn’t be able to get through those two items.

I will take a look and let you know. I didn’t notice anything missing.

I thought it was weird that the tubes were clear til downstream of the thermostat. Maybe bugs have it clogged from the bottom up. I donno.

[bullie]

quote FrankR:

Is the screen in the main water intake aft of the prop? Is the bypass cover in place on the side of the gearcase? Crud of that size shouldn’t be able to get through those two items.

Everything is in its place and looks good FrankR. The really weird part is that the crud was only in the pipe running down the rear of the head. Nothing anywhere else. Not even one strand of grass. Absolutely clean. I blew out all the passages I couldn’t see with compressed air. Air was passing through everything well. From both directions.

Oh, the plug of grass/crud that I blew out was about 2x the size of the one in the pic. Glad I didn’t have it the hole pointed at my face. I wasn’t able to dig it out but 110 lbs of air sent it flying. Hit the ceiling of the garage.

[bullie]

Now the bad news. There was a little water in the bottom cylinder when I pulled the head. There is no evidence, that jumped out to me anyway, that water had been in there before. The cylinder walls were smooth, no scoring. No obvious old rust.

But, the clean combustion chamber says water was there when it was running? Right?

Shot of the cylinders.

I put water hose pressure from the bottom up and from the thermostat down trying to blow out the clog. I don’t know if that matters.

[frankr]

Did you have it upside down or something, while you were squirting water around? Or, if you squirted it up the exhaust housing, it could go in through the ex. ports.

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