Cobra Outdrive Sucked Up Some Sand

[Nizoj]

Like a lot of sand and shells and debris from running aground. We were investigating a shift issue where the drive came out of gear and couldn’t go back into drive from neutral. Thought we were heading down the bad shift cable adjustment rabbit hole. Instead, we found sand and shells packed in every water cavity in the outdrive. It appeared the cavity between the lower and upper was packed so tight it wouldn’t allow the shift bar to move. Also found water and fine sand in the u-joint bellows.
My question is: What do we need to check/clean/replace? We are assuming we redo all the seals and bellows in the unit. Pulled the prop bearing and checked the gears which look good. Seems like the u-joint had been running with water present for awhile but it appears mechanically sound and has no slop. Nothing else is jumping out as a huge issue. What are we missing here?

 

[Lou C]

Bellows & gimble bearing and check the u joints carefully.

 

[Scott Danforth]

Keep in mind you will have sand and debris in your engine water jacket to

 

[Lou C]

If its that badly packed, you also need to remove the impeller housing and flush it both from the water intakes up ward and from the raw water intake hose backward. With the impeller housing off you can see if water is able to flow from the water intakes to the impeller and from the impeller to the thermostat housing.
You may have to flush the manifolds and engine with the drain plugs out.
All that sand will for sure cause overheating that can/will cause engine damage.

 

[Nizoj]

If its that badly packed, you also need to remove the impeller housing and flush it both from the water intakes up ward and from the raw water intake hose backward. With the impeller housing off you can see if water is able to flow from the water intakes to the impeller and from the impeller to the thermostat housing.
You may have to flush the manifolds and engine with the drain plugs out.
All that sand will for sure cause overheating that can/will cause engine damage.

Thank you very much! I am truly appreciative of your help, both here and on the many other threads I’ve read.
We have the upper and lower unit removed but the gimbal housing pivot housing are still on the boat. I’m assuming we will have to remove the pivot housing to replace the bellows. To flush the thermostat water compartment and impeller intake, can/should I proceed from this position? Should I just spray hose water through the hose to the engine that is now exposed? When you say remove drain plugs, are you referencing the water drain plug screw on the outdrive?

 

[Lou C]

Ok if you have the complete outdrive off, then put muffs on it and flush it with the imeller housing removed so you can see if water comes out of the water port behind it. You will have to change the impeller anyway because it got worn from the sand you sucked up, the wear plate will for sure be scored. Then you can back flush the water hose that goes from the thermostat housing to the transom by disconnecting it at the thermostat housing and putting a garden hose in it, this will flush the power steering cooler behind the engine as well. Normally I'd say put a old towl in the bellows because water will spary around there and can get the gimble bearing wet but based on what you said, you are replacing all that anyway.
You should also pull the thermostat housing and clean out all the ports, put the stat in a pot of hot water make sure it opens and closes. I would also hook up a garden hose to each feed hose for the exhaust manfolds and flush them out, you can leave the drain plugs in at first then remove them to make sure its not clogged inside.
For the engine its more difficult, but you can reinstall the stat housing without the stat, then hook up a garden hose to the port that feeds in raw water, and re-connect the manfold feed hoses. Then remove the drains in the engine block and rod them out with a pick so they will drain.
While the water is flowing, try pinching the manfold feed hoses closed with fingers, this may force more water to go through the block and out the drains. All this is done with the engine OFF BTW.
to replace the bellows the best way is yes to remove the pivot housing, thats how I do it and you can better tell if its seated right. Use only OEM for the bellows and impeller kit. They fit better and last longer.
I found a Volvo spec stat that opens at 140 which works better for my salt water cooled OMC, it runs at a cool 140 all the time now. In fresh water the standard 160 stat is fine.

 

[Lou C]

Also
search on my user name for the steps to properly set up the OMC Cobra shift linkage. Once it is done right, with a good shift cable, with the ESA working, and all adjusted right they shift VERY easily. Mine goes into gear with a nice solid "THUNK" and goes into neutral with 2 finger pressure on the control. But you must follow all the steps, no short cuts.