Im about to buy a 1978 140 hp johnson does anyone know if the reliability is good?

Question

have only had mercury in the past just want some info

Answer 1

Johnson is one of the best brands because of reliabilty and if anything ever did have to be worked on ,the parts are probably the cheapest and easiest to find as long as you have a compession test first to make sure its not completely shot ( do that with all motors) it should be one of the best motors youll ever have.

Answer 2

have a comp check done, parts are still available, those are good motors if they have been maintained.

Answer 3

Johnson made a very good engine. That unit is getting up there in age but I’m assuming you’re looking for something less expensive or you’d be looking at new engines. So…

#1 start with a compression check. With the unit warmed up (run it for a few minutes), remove all the spark plugs and disable the ignition system. Push the throttle plates 100% open. Insert a compression gauge into each cylinder and crank the engine over for about 3 revolutions per test. You should see all cylinders within 14 psi of each other. Any more than this and you may have a problem.

#2 check the oil in the lower unit. If it is low or you see water in the oil (a creamy appearance) the lower unit may need resealed. If you find metal particles (large chunks) the gearcase may need rebuilt. Both are fairly costly and probably prohibitively so on a unit of that age.

#3 test run the motor. How does it start?…. How does it idle? Does it have the power you need?

#4 Remote Control (shift) boxes are getting hard to come by for those older models. Dose that one come with the rigging components? Remote? Wire harness? Etc. Or does you’re older unit (the one you’re replacing match?)

#5 if it’s a salt-water motor.. It’s probably corroded beyond repair at this age!

Keep this in mind before you make an offer on the unit. Those were basically very strong units and fairly reliable. Parts are still relatively available (common stuff anyway). And the units are modern enough for most etches to service it no prob.

As far as general reliability on that unit… The only engineering prob. That engine had was a crankshaft which tends to break under VERY hard use or overrev. Not to the point where I would let that affect my decision to buy or not buy it for general use.

Unless the owner can provide service records indicating a recent water pump service (in the last two years). If you buy it do yourself a favor and replace the impeller as soon as you buy it.

Good luck

Answer 4

if it has been in saltwater forget it.

Answer 5

First of all this motor is 30 years old,and has no real value.You should take it to a dealer and pay them to check it out for you,this should not take any more than 1 hr,and could save you hundreds of dollars and untold heart ache.

  Unless you are a marine mech and you have received this engine free,take a pass.

     35 years as a marine tec

Answer 6

Check the out drive out. make sure it starts and the shifter move freely in and out of gear. That the part of the motor if shot will cost the most to replace.

Johnson make a good motor. make sure the guy includes the shifting cables with the motor. Their very expensive to buy .