86 Johnson 70HP seized

Author Message   redfish45 Posted on Monday, July 15, 2002 - 02:55 pm:    I have an 86' Johnson 70HP engine that has a major problem. This weekend, I had been running the engine at about 4500 rpm across a saltwater bay flat for approximately 10 minutes and then all of a sudden it would act like it was being starved for fuel. When I backed off the throttle and pumped the fuel bulb it would run normally again. I changed the in-line fuel filter out and it appreared to be dirty with very fine rust particulate matter. The engine ran fine again for about 6-7 minutes when it just slowly quite running and died. The water pump tattle tell was working normally and no overheat horn came on but the engine is barely turnable with the hand crank rope no. The starter will not turn the engine over at all. I took the spark plugs out and it is still very hard to turn over manually without any compression. Could this be a main bearing problem or piston problem?   James King Posted on Monday, July 15, 2002 - 03:23 pm:    probably in the lower unit,just went through replacing the upper bearing in my 75 horse chrysler lower unit and after 3 days it acted like yours,the pressure had pushed the seal out and lost all gear oil.check your gear oil,drain and see if any signs of water or metal. take lower unit off and see if that doesn't free up the motor. be better than a powerhead.Jim King   Redfish45 Posted on Tuesday, July 16, 2002 - 12:25 pm:    James, would the crank still be difficult to rotate when in neutral if the problem is in the lower unit? BTW, It is an 1982 model versus 1986. Red   WALKABOUT Posted on Tuesday, July 16, 2002 - 12:38 pm:    Redfish45, the lower unit drive shaft is always in motion when the engine is running. Bearing sezure in the lower unit can produce the same symptoms as powerhead failure. Pull the lower unit, if it is still siezed up then it is likely a powerhead problem. Pulling the lower unit is the easiest way to eliminate or confirm a problem with the lower unit. Good luck   James King Posted on Tuesday, July 16, 2002 - 01:01 pm:    yeah, when mine went bad it made the worst screeching noise the first time,i pulled the lower unit to confirm if it was lower or upper part. i hope i have my problem solved now but can't get it to the water for a few weeks yet. let us know how it goes.Jim King   Redfish45 Posted on Tuesday, July 16, 2002 - 01:24 pm:    Thanks for the advice. I will pull the lower unit this weekkend and let you know what I find. Red   redfish45 Posted on Monday, July 22, 2002 - 10:23 am:    All; I dropped the lower unit this weekend and it looks like I may have a bad bearing on the drive shaft. However, I hope I did not pull a bonehead move. When I took the lower unit off, the power head would rotate normally and did not seem to be binding up anymore. So I thought I would turn it over a couple of times with the electric starter to make sure I did not have a problem with the powerhead. When I did this it rotated about 10 times and then I heard a a large metalic bang and the engine stopped dead still. Now I can rotate the cam shaft only about 20 degrees back and forth. I feels almost like a piston rod has broken. Did I cause the damage by rotating the power head without the lower unit on? Looks like I am going to end up rebuilding the whole engine!! Help!! Redfish   arnould palmer Posted on Wednesday, July 24, 2002 - 02:53 pm:    that sucks

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