787 engine taking in water

[nikko_m]

i tested a 97 gsx and we found out that its leaking through the carbon seal,so we took it out of the water.i started the engine and seems that it takes time to start,we pulled out the plugs and its wet (mixture of oil,gas and water).so we took the head of and found water on top of the pistons.installed the head and cranked it,after installed a new plugs and it started right away.after did a comp test and it showed 130psi on both cylinders.

now what do we have to check here?and do we need to rebuilt the engine?im worried the water might affect the bearings of the cranks.

 

[Sportster-2001-951C-Stock]

130 psi is lower than it should be, if this number is correct and you tested it using the correct method you should see closer to 150psi but b/c both cylinders are same I have to wonder how accurate your gauge is?

You need to find out how water entered the engine, if the boat was sunk and the water was inside the engine for more than a couple of days the crankshaft bearings are probably rusted. If the water was only in there a matter of hours, try to operate the boat in the water very soon, in order to dry out the inside of the motor so it doesn't rust. Especially prone to rusting if this was salt water.

 

[nikko_m]

yes compression is low,i wa using stanley comp tester.and was really surprised both exactly read 130psi.it didnt sank.but there was water in the hull but basing on it i know its within the safe level.but nevertheless there is water,its fresh water though.how long would you run it in the water to determined the water was flushed out?

 

[Sportster-2001-951C-Stock]

If you are aware of the counterbalance shaft oil reservoir and able to check the contents, you can run the boat about 1/2 hour at planing speed and easily burn most all water from the engine. The key to if the engine will last many more seasons lies in the counterbalance shaft cavity oil contamination. Some later engines have a fill plug on top of the counterbalance gear housing (see link) thus you can check the condition of the oil using a plastic dipstick to slide down inside and take a sample for inspection. Do this after running the engine for a time so that water will be mixed with the oil into a "milkshake".

Here are some ideas:

http://www.seadoosource.com/reservoircheck.html
http://www.seadoosource.com/maintec.html

 

[nikko_m]

i can not open the counter balancer oil cap,it stuck so what i did was to take the cylinders off and saw the rings are sticking to the pistons,but pistons still usable with new rings,can we install sbt rings on oem pistons or it should be oem rings only?

 

[Minnetonka4me]

Next time just get the water out and get it running.

at this point if its going to sit a few days I'd say pour some oil in the crank areas and rotate the crank by hand. That will coat everything good, then suck the excess oil out.

 

[Sportster-2001-951C-Stock]

I think SBT rings should work fine in this case if they are the correct dimensions. You need to measure the new rings end-gap in the cylinder and perhaps adjust by trimming or filing the ring ends as necessary, confirm ring thickness to make sure they fit the piston ring lands correctly.

Of course clean varnish deposits from piston ring lands first, using solvent and visually inspect the piston ring lands for wear. Measure ring to land groove clearance with ring installed in ring land to confirm specification. The original rings may be worn, so replacement is reasonable. I expect varnish deposits are probably causing the rings to stick in the ring lands. Incorrect type of oil will cause these varnish deposits to accumulate there.

 

[nikko_m]

thanks for the tip nick but since the carbon seal is also leaking so i can take it back in the water so just pull out the cylinders and pour more oil for the meantime till ill have time to take the entire engine and just rebuilt it.