1987 johnson 70 problems!

[bt16ft]

ok i have a 1987 johnson 70. There are several problems with it. First of all there is a horn that sounds whenever we go fast. it stays on for about 5-10 mins, steady when the key is on. i have felt the heads when it goes off and its not really hot. i have also disconnected the brownwire coming out of the block and the horn stopped. <br />second, the motor cranks realllllllllly slow, sometimes. i have a brand new batt. i took the batt home put it on charge and the charger said it had a full charge.<br />Lastly there is a oil leak which squirts oil from the bottom of the black carbureator cover. i want to disconnect the oil tank and mix the gas . what do i have to do to do this>? also the 2 wires on the oil tank are disconnected should they be connected??<br />any help would be gladly appreciated.

 

[JB]

Re: 1987 johnson 70 problems!

Howdy, Bt16ft. Yep, you have more than one problem, but maybe only one fault. Let's hope there is no serious damage.<br /><br />The continuous horn warns of overheat. Believe it.<br /><br />The disconnected wires at the oil tank power another, intermittent horn which would warn of low oil or insufficient oil flow to the VRO pump.<br /><br />What is possibly happening is insufficient oil mix, therefore insufficient lubrication, overheat and high friction when attempting to start it with dry cylinder walls.<br /><br />Leave the wires off the oil tank. Disconnect the oil line where it goes into the VRO pump on the side of the engine; plug the nipple where you took the oil line off. Feed the engine 50:1 premix and hope your cylinders haven't been scored.<br /><br />If my speculation is correct all three symptoms should go away: No overheat, easy starting and no oil leak.

If I am wrong, what I have told you to do will do no harm. Good luck and let us all know how it turns out.<br />JB

 

[bt16ft]

Re: 1987 johnson 70 problems!

Thanks for the response. That sounds logical, ill try that when i go down tomorrow. However when we launched the boat we ran it on 50:1 plus the oil tank. we did this for a precaution since we disssconnected the tank in the winter. Any other ideas??

 

[bt16ft]

Re: 1987 johnson 70 problems!

Thanks for the response. That sounds logical, ill try that when i go down tomorrow. However when we launched the boat we ran it on 50:1 plus the oil tank. we did this for a precaution since we disssconnected the tank in the winter, and it went off after a few mins. Any other ideas??

 

[JB]

Re: 1987 johnson 70 problems!

Hmmm. That kind of blows my theory. Go ahead and disable the VRO anyway. <br /><br />When it exhibits the "sloooow start" behavior, is it only after it has tooted the overheat horn? You didn't mention whether the telltale stream was good, or how warm it felt. You may have a water pump impeller that has gotten soft and is losing grip on the walls at high speed. It is never a bad idea to replace an impeller.<br /><br />Let us know the results of disconnecting the VRO and, if you decide to do it, replacing the impeller. That OMC 3 cylinder 70 is a terrific engine and it's worth fixing.<br /><br />Standing by.<br />JB

 

[Paddling]

Re: 1987 johnson 70 problems!

Hey bt16ft, I don't know if the smaller hp omcs are the same but my 150 evinrude warning horn system has a fuel pressure sensor that detects low fuel pressure in the vro. It also detects high heat from 2 sensors in the block and the low oil sensor in the oil tank. If there is any restriction in the fuel line that blocks fuel flow or an air leak, the horn will sound continuously. I recently had a primer bulb check valve come apart on me and the pieces turned sideways in the bulb so that idle speed fuel flow was good but on any attempt to accelerate there wasn't enough gas. Just a thought from my un lucky experience.

 

[bt16ft]

Re: 1987 johnson 70 problems!

fuel restriction was a thought of mine. so i went out and bought a new fuel filter,and water seperator filter. ill check the fuel lines too. There is always a strong stream of water coming out that feels cool. also the water coming out of the 2 holes in the back is pretty cool too. The motor always cranks slow not just after the horn.My friend went down to the boat and he said with the spark plugs out it cranks fine. so ill replace them too. any suggestions are welcome.

 

[bt16ft]

Re: 1987 johnson 70 problems!

when putting a head on how many lbs do you use?

 

[bt16ft]

Re: 1987 johnson 70 problems!

when putting a head on how many lbs do you use on a torque wrench?

 

[JB]

Re: 1987 johnson 70 problems!

18 to 20 ft. lb. Start with the ones on either side of the middle cylinder and work alternately toward the top and bottom of the head.<br /><br />JB