Geisler

[Geisler]

could not get motor 20001 Johnson -70 HP-started this spring
properly winterized and was fine when I took it out of the water last fall
less than 200 hours on it

Motor has been at the marina service department for over a month and they are returning it,without fixing it, as they are stumped
there is no compression in the top cylander
will run at full speed but stalls when speed is reduced
carbs starter etc are all new

does anyone have any ideas

 

[archcycle]

Re: Geisler

I'm guessing the marina being stumped translates to big scary $$$

Don't worry Geisler, no compression is not a head scratcher. What will take some time is figuring out what caused it so that after you fix it it doesn't just die again, but that can wait right now.

Odds are that your top cylinder will have to be rebuilt. The only way to find out what's going on in there is to take off the head. It's just a few bolts and a $30 gasket to put it back together afterwards if you were to like what you saw in there.

Remove the head and take lots of pictures and post them.

If there is a lot of damage in there then the cylinder will have to be bored out by a machine shop and you will have to install a new piston.

 

[Geisler]

Re: Geisler

Thanks for your advise I will try this weekend

 

[ONERCBOATER]

Re: Geisler

suggest you have manual ordered for engine in meantime. and also suggest as you remove each piece you take 2 to 4 pictures from at least two angles... it will provide direction and peace of mind when putting it back together. BTW i am totally unimpressed with a shop that is "stumped" on compression loss.... pretty simple there are very few options for no compression... piston/rings, head,valves(if 4 stroke), crank,connecting rod, cylinder wall. I must assume not connecting rod or crank...as I assume starter engages on top of engine , connecting rod I would also bet against cause it would have made a very audible sound. it ran fine when you put it away.... so.... what can happen during storage? how about minor head gasket failure leading to water intrusion to cylinder sticking rings? thats about the worst i can think of between storage of fine running engine and restart months later. Now if it has one injector/carb per cylinder.....or oil injection that is cylinder specific.... i can for see other possibilities. That you might not have noted while on water that last good running day.
Bottom line, the guys on this site will help you get to the bottom of it, and should you choose to repair it they will be able to give you sagelike guidance and suggestions to let you do as good a job as most shops... and likely better than your shop that can't find a loss of compression (still unimpressed with that shop)