Johnson 6hp cdl-23e

[wolfebrother]

Hi, I have Johnson 6hp (1960's model) outboard (model number cdl-23e). It was running when it began to overheat and then it cut out. I changed the impeller and while doing that noticed that the impeller key had sheared so changed that too. Now that it's back together it won't start. I had it in neutral when I changed the impeller and had to pull the starter cord a little before the shaft would push back up into place properly. Any idea what might be the trouble and what I acn do to fix it? Any held would be greatly appreciated!!!!

 

[Paul Moir]

Re: Johnson 6hp cdl-23e

If this is the first start since you overheated and cut out, begin with a compression check.
There's not much you can do in an impeller change to cause the engine not to start, especially if the flywheel still turns normally.

 

[wolfebrother]

Re: Johnson 6hp cdl-23e

I was thinking that maybe I had put the timing out or something?

 

[Paul Moir]

Re: Johnson 6hp cdl-23e

That's pretty much impossible. I suppose it's conceivable that the sync is out but that wouldn't normally keep it from starting and it's hard to put out without taking a screwdriver to the engine.

Just as a quick test, pull the spark plugs out, cover one spark plug hole with your thumb and rotate the flywheel. Then try the other one. You should feel the compression on each.

(I think and hope you may have blown the head gasket, which will often happen when you overheat)

 

[wolfebrother]

Re: Johnson 6hp cdl-23e

Do I do this one at a time while leaving the other plug in?

 

[Paul Moir]

Re: Johnson 6hp cdl-23e

No, take both plugs out and set them aside.

Without the plugs in (and without your thumb over one of the spark plug holes) the flywheel should turn very easily with just some resistance and perhaps some squeaking from the impeller.

 

[wolfebrother]

Re: Johnson 6hp cdl-23e

Hi, I did that and there was compression on one plug hole but very little on the other. Does this mean I should change the head gasket? Thanks.

 

[Paul Moir]

Re: Johnson 6hp cdl-23e

Ok, good, that's why it wont' start. It's really hard to start the smaller engines when they're running on one cylinder.

Now it's time to pull the head. Try to keep the head gasket as intact as possible so you can examine it and verify it's blown out. You may wish to remove the thermostat from the head first (under the three screw cover) and repeat the test while listening down there. If you hear the air escaping into the water channels you can be pretty sure it's just a blown head gasket.

While we're on the subject, overheating can damage and vary the thermostat. You would be wise to replace it at this stage. Pick it up with the new gasket - it should only be $10-$15.

 

[wolfebrother]

Re: Johnson 6hp cdl-23e

Ok, I'm going to replace the gasket and thermostat. Many thanks for your help! I really appreciate it. I hope this fixes it!!! Actually I just redid the test as you said with the thermostat out, I couldn't really hear air through water (though I'm not really sure what I was listening for!) but the compression on the lower plug hole seemed to be bit better with the thermostat out.

 

[wolfebrother]

Re: Johnson 6hp cdl-23e

Ok, good, that's why it wont' start. It's really hard to start the smaller engines when they're running on one cylinder.

Now it's time to pull the head. Try to keep the head gasket as intact as possible so you can examine it and verify it's blown out. You may wish to remove the thermostat from the head first (under the three screw cover) and repeat the test while listening down there. If you hear the air escaping into the water channels you can be pretty sure it's just a blown head gasket.

While we're on the subject, overheating can damage and vary the thermostat. You would be wise to replace it at this stage. Pick it up with the new gasket - it should only be $10-$15.

 

[wolfebrother]

Re: Johnson 6hp cdl-23e

Hi, I changed the head gasket and thermostat and now have good compression, I have good spark too, but the engine still won't start, any ideas? Thanks

 

[Pony]

Re: Johnson 6hp cdl-23e

Have you done a compression test with an actual tester yet? I overheated an engine in the past, and it wouldn't start because the compression was so uneven......destroyed one of the pistons in the overheat. For peace of mind sake you might want to test it and get some actual numbers to see how equal the compression it.

If you have spark and compression, then the next thing is fuel. Shoot some premix into the cylinders and see if it trys to start, if it does then that would suggest that you have a fuel delivery issue.

 

[F_R]

Re: Johnson 6hp cdl-23e

This is overly simplistic, but got the spark plug wires back on the right plugs?