Driveshaft Issues?

[Challenged Chsllenger]

Took her out today and ran great for a bit then the starboard engine stopped suddenly. No loud noises, just stopped. Tried restarting and just clicked wouldn’t turn over. Got her out of the water inspected the impeller (stuck). Took off impeller and spun freely. Looks like the driveshaft is stuck. Pistons looks good (I can freely spin shaft about 3/4 and then it stops but I can move it 100% by applying force/so I can see the pistons move up/down.
Question: what could be causing the driveshaft to only turn 3/4?

 

[Spider4real]

If you are turning it by hand with the spark plugs out (and pump out) it should turn freely 360 degrees. If it is not, then something mechanical is going on with the engine. You can start by pulling the carbs off and seeing if the rotary shaft is still spinning and not jamming on anything. If it looks fine then maybe pull the head off and look at the top of the pistons for any signs of damage. But I fear you will have to pull the engine to get to the bottom of your issues.

By the way, what year and model are we talking about? Could be other things depending on the engine. Rave valves broke and entered the combustion chamber. Counter balance shaft failure.

 

[Challenged Chsllenger]

Pistons look fine. If the driveshaft bearing seized would that cause the engine to stop?
I recently had an issue with the oil injector so I bypassed and now run 40:1.

How difficult is it to remove the driveshaft?
1997 Challenger 1800 (787).

 

[Spider4real]

This has notthing to do with the driveshaft. Driveshaft has no bearings. You should have a carbon seal.

What issue did you have with the oil pump and what did you do other than add oil to the gas?

 

[Challenged Chsllenger]

Oil fitting broke and filled the hull with oil.
From previous experience with 2 strokes I just decided to bypass and use an oil/gas mix. It runs rich but I know it is lubricated. I always have an extra set of plugs.

Would a worn carbon seal cause the engine to stop suddenly?

 

[Spider4real]

Which oil fitting broke? On the oil tank? DId you leave all the oil lines in the boat. There are 2 big lines connected to the engine that should be filled with oil (hopefully still there with oil) and one smaller line connected to the oil filter then to the oil pump?

No, you have a problem with your motor.

 

[Challenged Chsllenger]

I left all the lines in place. And the res has plenty of oil. Pistons are fine (I can get them to move up/down) but driveshaft is sticking in 1 area. What between the impeller and crank could seize?
I don’t want to remove the block if I don’t have to but I know the inevitable is just around the corner.

 

[Spider4real]

The drivehshaft is not physically connected to anything. It is just floating through the carbon seal. SInce you have not told me where the leak was I suspect you killed the rotary shaft gear when you had your leak. Or worse the crankshaft needs to be rebuilt. Are you just looking at the pistons through the spark plug holes or do you pull the head off?

Google carbon seal removal, there are lots of videos on them. They are the same in the skis and boats so it does not need to be specific to your model. Once you undo the carbon seal you can pull the driveshaft out then pull the engine. You will need to reinstall the pump to undo the clip that hold the carbon seal in place.

 

[Challenged Chsllenger]

Pulled off the head and examined the piston and all looks good. The leak was at the injector pump (fitting where the oil line goes in). Looks like it is just a press fitting and for some reason it just popped.

Rotary shaft gear makes sense… I will post post repair! Thanks for your insight.

 

[Spider4real]

If the leak was at the injector pump, i would be leaning more towards crankshaft issues.

But, to start I would pull the carbs off and inspect the rotary valve and see how that looks. If the gear is shot then it likely will not be spinning smoothly, if at all.

 

[Challenged Chsllenger]

If the leak was at the injector pump, i would be leaning more towards crankshaft issues.

But, to start I would pull the carbs off and inspect the rotary valve and see how that looks. If the gear is shot then it likely will not be spinning smoothly, if at all.

I took out the rotary valve (looked fine) but now I can turn the engine by hand about 95% of the way then it stops. At this point I can complete the turn by tapping a wrench.
The good
- rotary valve is ok
- pistons look good

The bad
- turns over with starter but locks up

The ugly (unknown)
Crank?
Rods?

Engine rebuild might be in the future

 

[Spider4real]

I think at this point you really have no choice but to remove the engine and split the case unless anyone else has some suggestions or ideas.

I suspect you ran it with no oil (or reduced oil before the fitting detached) so the crank was not being properly lubricated.

When I had an oil issue the pistons gave it up before the crank, Seems like the reverse may have happened to you, which sucks because a top end rebuild is easier than the bottom.

 

[mikidymac]

Did you ever pull the pump and driveshaft to rule that out?