Re: Johnson 3HP JW-17 Compression woes

[jerry-w-bert]

To Frank R , Thank you ! Yes I cleaned both surfaces very well with acetone. and bolted it down snug… little here ,little there like I would any head . . I too am flabbergasted that the compression dropped so much !! I will be getting to it next week and I’ll keep you posted , I’m going to redo the head using the torque specs and correct sequencing and then try again …

To Fleetwin , Thank you ! It was a year ago but I remember one was an o ring at the top of the drive shaft at the powerhead. There was nothing there . The other was down by the water pump..I think …It was a bugger getting the old one out as I remember. Probably an original seal. Yes it has run, I had used it maybe 8 or 9 times in the past 8 years always started right up and no problems . But it has set unused for 3 years with gas properly drained and run out of carb . It started up fairly easy last year when I was going to take it out and then I noticed the gas leak after pulling it out of the water barrel , and started working on it. Then I got cancer, surgery , ect. so it has set for another year and I’m just getting to it now. Can’t go wrong on the plug wires top one has a metal band on it says top. Yes I pulled the flywheel last year everything looked shipshape in there, no visible cracks ,no evidence of overheating or water ingress. I’m going to check to see if rings are stuck as per Jerry Ahrens . Yes I am new to this engine, this is the first marine engine and the first 2 stroke I’ve worked on. I’m 66 years old and spent 32 years at sea in the Merchant Marine ,but I was in the Deck Dept ,so I didn’t do engine work. But I figure your never to old to learn …,Re: carb I did repair the valve at the gas tank ,had to solder the wing to the valve stem ,this valve is a very pricey item found one valve on line for 98$ …too much for me. Carb seems ok , but may I ask you for the correct initial needle valve settings on the hi and low . Thank you very much for your input I will repost as soon as I get back to it ..hopefully by Wednesday.

To Steve D.My 3rd cousin twice removed is head bag boy at that piggly wiggly…:) I hope you didn’t off him !!

To. Jerry Ahrens Thank you for your input. I will check the rings as you said. I had watched a YouTube video where a guy did a comp test on a similar engine and it had 60 & 60 but wouldn’t start ..he claims he changed the rings and that fixed it .. Hence I bought the rings . I’m going to redo the head again , and if rings are stuck I’ll try the easy fix with a product such as you say , How about seafoam? I have some in the shop and I also have Lucas injector cleaner I use in my Ford 7.3 liter pickup. I really like this little Johnson it works perfectly for my McKenzie wood drift boat . I am going to know this engine inside and out when this is over.

THANK YOU TO ALL WHO HAVE REPLIED , Also thanks for having patience with me … a novice ..Look for a new post/update next Wednesday or Thursday .. Sincerely J.W.Bert