2000 Johnson 70 hp Powerhead

[sprigs68]

The dealer replaced the powerhead on my 2000 70hp. I have about 6 hours on the new powerhead and have noticed that it doesn't perform close to the level of the old powerhead. The old power heat had a WOT at 6,000 rpm, the new powerhead tops out at 5,500 rpm. Is it possible that the dealer installed a 60hp instead of 70hp?<br /><br />The powerhead is still under warranty - but I'm not sure if this is a warranty issue. Any help is greatly appretiated.<br /><br />Thanks, Sprigs

 

[marinemech]

Re: 2000 Johnson 70 hp Powerhead

60 and 70 blocks are the same so thats not the problem<br />have your dealer check timing and linkage adjustments<br />i'am assuming noone changed props

 

[sprigs68]

Re: 2000 Johnson 70 hp Powerhead

Thank you for clarifying the block size. Does a typical powerhead replacement, include the reuse of same carbs, etc... Is there any chance something like that could have gotten switched around? What tags or identification can I check?<br /><br />No change in prop. The new engine runs great - it just doesn't wind-up like the old one. Could this be a break-in issue, or can an engine run fine and still need adjustments in timing and linkage to make it run faster?<br /><br />Thanks again,<br /><br />Sprigs

 

[angus63]

Re: 2000 Johnson 70 hp Powerhead

Sprigs<br />Recommended breakin varies, But:<br />1) You should be using a 25:1 fuel ratio for at least the first 10 hrs.<br />2) Should avoid WOT for first 5 hrs (3k rpm max) and not remain at any single rpm for more than 5 min. (vary speeds).<br />3) Limit wot to short bursts until 10 hrs is complete.<br />4) Return to 50:1 fuel ratio after 10 hrs, check head bolt torques, and verify sinc-and-linc and WOT timing.<br /><br />After all that, remove plugs and clean them (replace if necessary), and then compare wot to previous powerhead.<br /><br />If still below previous motor, explain to tech the procedure you followed, the results, and lean on them to repair or justify difference.<br /><br />Be sure boat is loaded similar to previous motor, bottom of boat is clear of plant life, prop is undamaged, and verify motor height and trim is same as before.<br /><br />Good luck and let us know what happens.....

 

[reeldutch]

Re: 2000 Johnson 70 hp Powerhead

are you still using the same prop?

 

[sprigs68]

Re: 2000 Johnson 70 hp Powerhead

Same prop as before.<br /><br />Thanks for the reply angus63. I have been quite particular to the break in proceedures as you have described. I'll continue to break it in within the next couple of weeks, then have the dealer check it out. <br /><br /><br />Thanks, again

 

[marinemech]

Re: 2000 Johnson 70 hp Powerhead

usually carbs ignition electrical are original<br />yes motor could run fine but still require adjustments<br />if timing and carbs are set properly motor should run at least as good as before rebuild<br />have your tech verify timing sync etc also verify all cylinder are pulling (cylinder balance test)<br />was motor removed from transom? was it put back in same mounting holes

 

[Dhadley]

Re: 2000 Johnson 70 hp Powerhead

I would suspect the installer set the timing back. That usually means he doesnt know what caused the first failure and is trying to not let it happen again under warranty.