trying to decide if my 1976 35 hp johnson is worth sending to the shop.

[rmiddleton]

The outboard is a 35el76g johnson out outboard that i purchased with a boat last year. I ran it alot last summer with no prolems. In fall it started to kind of bog when you idled up and then would kick in. It did this for multiple outings untill now all it will do is just bog along at 1/3 its normal speed. I can take the boat home and it will throttle up to full rpm it sounds in the tank but not on the water. Im an extreme novice with motors so ive done only small stuff.

Ive replaced both coils, installed a fuel filter after the gas tank, replaced gear oil in the lower unit and put on a new impellor.

 

[HighTrim]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

A few tests will narrow your problem down. Sounds like you are dropping a cylinder while under load.

I would first ensure that it is firing on all cylinders, and compression is good. Do you have a inductive timing light? If the spark and compression check out, you may have a fuel delivery issue. Will pumping the primer bulb pick it back up? What about spraying pre mixed fuel into the carb throats while underway?

 

[rmiddleton]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

My only testing tool is a multimeter. I havnt ever messed with motors much but do have aptitude for repairs as im a pool, spa, heater tec

Are inductive timing lights expesive or compression meters expensive? maye available for rent for autozone?

and as far as the bulb its hard when running

 

[HighTrim]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

They are not expensive, and can likely be borrowed in the loan a tool program, but cannot verify that as I have never personally used it.

A simple test to determine if it is firing on both cylinders is to pull the plug boot while underway. Be sure to use insulated/grounded boot pullers or pliers or youll get a shock! If the rpms drop, that cylinder was firing, if there is no noticable change in rpms, you have a dead cylinder and need to investigate further. I personally prefer the inductive timing light, simply clip it around a plug lead and view to see if it is lighting up.

If the rpms pick up while misting a 50:1 fuel/oil mix into the carb throat, a carb cleaning/rebuild is in your future. Also try choking it while underway.

Let us know how it goes.

 

[jasper60103]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

My only testing tool is a multimeter. I havnt ever messed with motors much but do have aptitude for repairs as im a pool, spa, heater tec

Are inductive timing lights expesive or compression meters expensive? maye available for rent for autozone?

and as far as the bulb its hard when running

Yep, free rental of compression testers from autozone. Not sure about the timing light. A spark tester is only about $7.

 

[SparkieBoat]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

get a dva adapter too

 

[dew2]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

get a dva adapter too

Isnt the dva for CDI ignitions??

 

[rmiddleton]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

I got a compression tester from autozone and tested getting 90 psi on the top cylinder and 70 on the bottom. not sure if it matters but this is in 30 degree weather. I dont have a large body of water to test it in atm as far as pulling plugs while the problem is accuring due to ice. I can run it in a stock tank but it seems to run fine that way.

this isnt actually all the prolems with the motor. im pretty sure the starter needs replaced also. it will click for a while until the bendix rises the first time you get it going for the day. I did some testing acording to my seloc manual and determined that the celenoid was good and i was getting proper voltage to the starter.

also the electic chokes linkage and switch have been removed leaving it in the full open position. has been this way since i purchased the boat.

what im looking for out of the motor is a couple more seasons. Not even sure what new four stroke motors are equivlant.

 

[HighTrim]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

Compression is an issue. Wont know how much of one until you open her up.

 

[rmiddleton]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

what would i be opening? the cover plate were the plugs screw in?

are some compression issues in this year/type motor doable without specialized tools?

 

[tx1961whaler]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

Once you are sure that you've done a good compression test and that there is indeed a 20 lb. difference between cylinders, you'd take the cylinder head off and inspect the cylinder for damage and the cylinder head gasket for signs of leakage. Also put the head on a flat piece of plate glass to see if it's warped. If there is no cylinder damage, then you just put a new head gasket on and re-torque the cylinder head. Could just be a leaky head gasket. 15 bucks. No special tools required.

 

[rmiddleton]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

What would the damage look like? and once i take off the head off and look in will i need to remove internal pieces to fully inspect? (ive never looked inside a engine block but) also when you say re-torque do i need a toque wrench and will my selock book have those specs.

and thanks so much for the info everyone. i think ill try to do this myself since ive alot of time atm.

also what would a good test be considered? used fully charged battery with my tester screwed in a cylinder with the other plug in place and turned the engine over at least 6 times until the pressure stopped going off. did this several timeswith each cylinder.

 

[tx1961whaler]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

Damage to the cylinder walls would be pretty obvious. There would be gouges, scratches, chipped out areas, etc. A torque wrench would be required, but those can often be borrowed from an auto parts store. The Seloc book should have the torque specs.

I sounds like you did a good compression test already. I usually have both plugs out when I do the test.

 

[HighTrim]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

You will need a torque wrench for re installation. Once the cylinder head is off, you simply inspect the walls of the cylinder for scores, grooves, etc... Take a pic if you can and post it on here. You will likely be able to tell though by looking. Hopefully it is a simple head gasket job, easy and simple like tx stated.

There is a good thread in the FAQ by JB about performing a compression test. I hope you grounded plug leads, disconnected your ignition system though.

edit: sorry typing at same time as tx

 

[SparkieBoat]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

Isnt the dva for CDI ignitions??

dva adapter is used to test stators, power packs, timer base and rectifier/regulators..if he has a compression problem that needs to be addressed first. do a decarb as listed in the secret files.

 

[rmiddleton]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

Took off the head and their is no damage to cylinders but the head gasket was torn on the lower compression cylinder.
Ordered a new one will test once i put it back together.

 

[dew2]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

You mention the cold weather? where are you? I'm in central Mn and motors just like yours I buy every year for anywhere 100-350,some want more but for me at 350 the motor has to be running and decent condition,Your starter can be rebuilt at a elec repair motor shop I pay 35.00 for those starters to be rebuilt,

Thanks sparkie you have increased my limited knowlege!

 

[HighTrim]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

That is great news. Be sure to torque to spec, which I believe is 14 ft/lbs, need to verify that as Im cluster brained right now, and torque in the proper order, to maintain an even seal. Start in the center, sprialling outwards, like follows. Start with about 10 ft /lbs, through all the bolts, then finish with the 14 ft/lbs.

 

[SparkieBoat]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

yes good news indeed..head gaskets are cheap..be sure to clean everything good before putting it back together

 

[rmiddleton]

Re: trying to decide if my 1976 35 hp johnson is worth sending to the shop.

So i got my head gasket and im wondering do i need to use some type of sealer or adhesive when i put it back in?