Reliability of a 70 horsepower Johnson model# J70ELCTD?

[Big Bubba]

Hello to everyone,
I have a quick question to ask all of you. Have any of you that own a 70 horsepower Johnson model# J70ELCTD have had any issues with your motor. I just bought a new to me 70 horsepower Johnson with model# that I just mentioned above and I like my motor it is on a 1991 Lowes 20 foot Pontoon boat that pushes it at 21 MPH at 5400 RPMs wide open throttle. I was just getting your guys thoughts if you have ever own one and what do you think about your 70 horsepower Johnson outboard? Let me know Bob

 

[tashasdaddy]

Re: Reliability of a 70 horsepower Johnson model# J70ELCTD?

they are a very popular, reliable motor. more bang for the pound. than any other motor. you need to reprop so that you get around 5,800 rpms, wide open.

 

[guy74]

Re: Reliability of a 70 horsepower Johnson model# J70ELCTD?

Are you positive of that model number? I can't find one with a D on the end. It seems to be a 1983 model. Anyway, they are good reliable motors. I have a 1988 60hp (basically the same as your 70hp), I love it, pretty economical to run. The only reason I replaced it on my boat was it wasn't quite enough motor for serious waterskiing. Now I'm looking for a smaller boat to put it on, for cruising around.

 

[JB]

Re: Reliability of a 70 horsepower Johnson model# J70ELCTD?

Had one of those, Bubba. Dang near bulletproof with care.

Only thing I can think of to watch out for is the ground cable connection to the engine block. It is usually bolted with a steel bolt to the steel bypass cover. Electrolytically generated corrosion will create a low resistance connection and prevent starting. Take it off and clean it at least once a year.

 

[jay_merrill]

Re: Reliability of a 70 horsepower Johnson model# J70ELCTD?

Like most OMC motors, that basic configuration (3 cylinder looper) was was made for many years. Properly maintained and cared for, it will last you for a very long time.

 

[Big Bubba]

Re: Reliability of a 70 horsepower Johnson model# J70ELCTD?

Yes, I just rebuilt the 3 carbs in her myself, paid someone 70 dollars to do a lync and sync, replaced the spark plugs with Champion QL77JC4's, and replaced the lower leg unit oil in her. She pumps water really well out of the tale tale and my pontoon boat has a water pressure guage that I will tap intot he main tell tale line so I can use that to tell how the water pump is pumping becuase I can't see the motor when I am driving the pontoon baot and it has a water pressure gauge in it that works. Basically how much pressure should the water pressure guage be reading if the water pump s working correctly? Thanks again, Bob

 

[kynolan2183]

Re: Reliability of a 70 horsepower Johnson model# J70ELCTD?

I own an 1984 70 hp. Very good motor but can be difficult on the link and sync. Design is so good the Yamaha now makes basically the same motor today in their 70 hp carbed motor.
Run it at about 2/3 throttle and your gas will last much longer.
At 2/3 throttle my speed is 26mph but my flow meter shows 3.7 GPH with RPM at 4000

At WOT my speed is 36mph and the flow meter shows 6.9 gph with RPM at 5500

Doing the math WOT is 5 miles per gallon and 2/3 is 7 miles per gallon.

If you listen to the motor you will know where the sweet spot is.
It is just where the motor starts to scream at you and your speed doesn't jump up that much.

Of course mine is on a bass boat and I think you said yours was going to be on a pontoon. Either way your GPH at 5500 RPM will be about the same.
My 70 hp has been the most economical motor I have ever owned in relation to GPH and speed.

Good luck
Kyle

 

[jtexas]

Re: Reliability of a 70 horsepower Johnson model# J70ELCTD?

this is a trick question, right?

1979 vintage, runs as good now as the day she came off the showroom floor.