1994 Johnson 15hp

[nabiul]

My latest acquisition. Is the motor supposed to make a whooshing noise like hoot hoot hoot when you crank it?

http://i.imgur.com/j32tpGB.jpg

Everything on the motor looks alright except for these head bolts which were loose and have paint coming off in areas. Is this an indication of anything?

http://i.imgur.com/vFCJ1fk.jpg

http://i.imgur.com/jbXMOS7.jpg

The motor starts and runs at medium speed but won't idle at all. Reading about 100 psi on both cylinders in two or three cranks, good spark on both.

Going to try some seafoam.

 

[flyingscott]

If the head bolts were loose enough the sound you heard could be the compression leaking out. Replace the head gasket and torque the head

 

[oldboat1]

^^or a plug, I guess. Also, with plugs out, I would spray in some 2-cycle or fogging oil and turn it clockwise by hand (or spin is slowly with the cord). Think I would hold off on seafoam unless it's really carboned up.

 

[nabiul]

The plugs were loose initially, like finger turning loose, but tightening them didn't help with idle. I adjusted the low speed needle, put some seafoam inside and now she starts with one pull and idles really nice. Still kind of concerned because leeroy's site mentioned a setting of 4.5 turns out for the low speed needle and I think I have double that.

I used seafoam any ways because I put a bore scope inside and the piston heads were completely carbonized.

Is there any way to know if the thermostat is working properly without removing it? The motor doesn't get warm at all on the test stand.

 

[Calibra]

Last year I rebuilt the same engine due to failure. Mine doesn't make a whooshing noise
My low speed needle is about 6 screw turns. Another lower and it didn't idle​

 

[oldboat1]

sounds like progress, nabiul. That setting you and Calibra describe is startling (I'm used to the old ones). Have to believe the mix isn't really any richer than the old ones, but just the mechanics of how the carb is engineered(?) Interesting.

I take it the noise is gone. Don't think I have a good answer on the t.stat question. I think the only way to check it is...to check it. If the motor was used for trolling (the heavy carbon), a PO might have run it without the thermostat, so might find none in there. I think the motor has been running cold, though, for whatever reasons -- like you are finding (again, the carbon build up). If it's a saltwater motor, the t.stat might be stuck open. If a salty, though, there's additional reason to pull it out and at least check it. There's likely to be salt build up in the housing, and will want to clean that out.

 

[nabiul]

I forgot all about the noise when it started firing normally. :lol:

It doesn't appear to have been used in salt water, but I'll take a look any ways tomorrow.

 

[nabiul]

It makes the hoot hoot hoot noise when I crank it with the cover off; I think it's coming from the intake silencer. You guys sure that noise isn't normal?

 

[nabiul]

This is what came out of the thermostat housing, clearly something is missing here.

http://i.imgur.com/GwC8cHn.jpg

http://i.imgur.com/jbQoqFM.jpg

Part number 19 is the actual thermostat right?

https://i.imgur.com/8qUsEOf.gif