100hp confusion

[wayneduncan]

i hav a 1975 100hp johnson. this boat ran great for years but got tight all of a sudden.. it turns over but very slow with the starter. taking the heads off it doesnt free it up any.. still just as tight.. the cylinders are clean and in good shape so its not the rings. the thing that confuses me is that it turns over fine when you spin it backwards with your hand.. then turns over fine forward for about 1/4 a turn then gets tight again.. all of this is without the heads on it.

its a V4 btw. any ideas?

 

[Pokertrampp]

Re: 100hp confusion

have you pulled the leg, if not I would try that and see if the problem goes away.

 

[wayneduncan]

Re: 100hp confusion

leg? i have the bottom of the unit off.. with the shaft pulled also.. so i think anything that could be in a bind is off of the engine?? so idk if thats what you mean

 

[emdsapmgr]

Re: 100hp confusion

Has the engine been sitting for a long time? Removing the heads relieves the compression on the firing side of the powerhead. The reeds create/control the compression on the intake side of the powerhead. Do the reeds seem to be flexing-permitting air to enter the crankcase? Low battery voltage, corroded battery connections, a bad starter solenoid and old starter brushes will all contribute to low starter rpm's.

 

[wayneduncan]

Re: 100hp confusion

the motor had been sitting a few weeks when it tightened up. I dont think its a battery connection problem because when i have the heads off of it, its nearly impossible to turn it clock wise by hand, but the engine turns nearly free in reverse by hand. it feels to me like something is binding up. this is an electric shift unit. could it be stuck in gear or something. i noticed that the shaft that runs into the lower unit was very rusty at the top if that means anything. could the gears in the trans be binding up? its possible that my step dad could of improperly winterized the lower unit and maybe screwed something up. im lost here. Im going to pull the engine completely off the lower unit and try to determine if its a transmission problem or a bearing failure.

 

[emdsapmgr]

Re: 100hp confusion

Pulling the lower unit off is a good way to further isolate the problem area.

 

[F_R]

Re: 100hp confusion

Wayne, If I read this thread correctly, you already have the lower unit off. So that eliminates all the gears, electric shift and everything else outside the powerhead.

I have two suggestions:

1. Remove the flywheel and make sure something hasn't come loose in there.

2. If it still turns hard with the flywheel off (turn it with a wrench on flywheel nut screwed onto shaft), then you have a bad bearing in the powerhead. That's bad news, requiring a total teardown and rebuild of the powerhead. When you do rebuild, be sure to locate the problem that caused the bad bearing. The bearing is a symptom, not the cause. Probably getting water into it.

 

[wayneduncan]

Re: 100hp confusion

took the flywheel off. theres 3 small screws that hold the timing pully to the flywheel.. all of them were loose and one of them was rubbing the engine around the shaft. motor got tight 7 years ago and no1 would even begin to work on it.. i had the flywheel off in 15 mins.. put the flywheel back on it, timed it, fresh gas.. now its running.. thanks for the help

 

[boobie]

Re: 100hp confusion

I'm really confused. If you would, please post the exact model number of the mtr on this forum. Thanks.

 

[wayneduncan]

Re: 100hp confusion

on the title is says its a 1969 johnson 100hp V4, lower unit is an electric ****. its the original engine to the boat.1969 18ft Stamas

 

[boobie]

Re: 100hp confusion

There should be a model # & serial # on port side stern bracket or maybe strb side. Could you post that? For what your saying it is, it doesn't show up in BRP's parts break downs. Thank you.