'87 Johnson 90 clunks (like I hit something) at speed

[dougkeene]

'Just bought a used 1987 90 HP Johnson 4 cyliner 2-stroke oil injected engine. When running in forward, the motor "clunks". The first few times it happened I was sure I hit something. The problem is freqent at higher speeds...about once every 10 seconds when running at top speed, but it will happen at any speed. It's almost like it goes out of gear then back in within a blink of the eye, or that it is missing a powerstroke. I asked the previous owner...he wondered if I was using premium gas (I am running regular) but I don't think that has anything to do with it? I've read on the forum that it might be a "cluch dog". Is that something I can replace myself?<br /><br />Can anyone help sort this out?

 

[diggerdan17]

Re: '87 Johnson 90 clunks (like I hit something) at speed

sounds like the clutch dog to me....but first check to make sure that your cables and or shift linkage is fully pulling the shifter into gear.if you can disconect the shift cable and manually put it in gear and it still has problem then check to see if your linkage going down to the lower unit is properly adjusted.i put a new dog in my self and all i needed was the manual and a few tools.

 

[dougkeene]

Re: '87 Johnson 90 clunks (like I hit something) at speed

Thanks for the help, diggerdan17. You mention that I should check that the linkage going down to the lower unit is properly adjusted...is this adjustment obvious when I get the cover off the motor? I'll first do as you suggested and disconnect the shift cable and manually put it into gear, but it would be nice to know where the linkage adjustment is while I have it in the water. Do you remember how long it took you to replace the clutch dog? Looks like I should get a manual...

 

[diggerdan17]

Re: '87 Johnson 90 clunks (like I hit something) at speed

i,m not familiar with the 90 horse model as far as the exact way to measure the linkage to see if it is properly adjusted.it took me about 4 hours to do the clutch dog because i had never taken the gears out before and only have moderate mechanical ability....the manual is a must ...at least for me it was.

 

[dougkeene]

Re: '87 Johnson 90 clunks (like I hit something) at speed

THE ANSWER: I took the advice of diggerdan and disconnected the linkage from the shift lever, then shifted manually. THe engine didn't miss a beat. I reattached the linkage, and it slipped gear several times as it did before. I adjusted tbe linkage, effectively making the cable shorter (to the end of the adjustment) and ran it about an hour with no further problems.<br /><br />Many thanks for the advice! <br /><br />Doug

 

[diggerdan17]

Re: '87 Johnson 90 clunks (like I hit something) at speed

glad to help a fellow boater.