78 merc 260 engine hydrolocked

[Cabozone]

Having trouble with hydrolocked engine, but it only happens after I drop the boat on the launching area. Compression is fairly even and there's no water and oil mixture. The engine starts just fine when it's on the trailer on level ground. I'm dumb founded? Any ideas and suggestions?

 

[HT32BSX115]

Re: 78 merc 260 engine hydrolocked

Howdy,


You may have some pooled water in the riser that gets tipped into an area of the riser gasket that is leaking that doesn't get there when the boat is relatively level.

If you haven't pulled your risers and inspected them and the sealing surfaces in a few years, now would probably be a good time.....


You also could be "pushing" water up into the exhaust manifold when you back the boat into the water. (check your exhaust "shutters")







Regards,


Rick

 

[Blk-n-Blu]

Re: 78 merc 260 engine hydrolocked

Have a look here for some basics.
http://www.marinemechanic.com/Workhorse/index.htm
Click on "Motor" on the left and scroll down to "water in cylinders or oil"

 

[Cabozone]

Re: 78 merc 260 engine hydrolocked

changed stbd gasket, i will try the port.i dont have water shutters installed on the boat, I already tried starting the engine with just the impeller pick up in the water and still gets hydrolocked. is it possible for fuel to fill up the cylinders when im on the launch ramp? i was going to try to install a fuel shut off valve and see?

 

[Blk-n-Blu]

Re: 78 merc 260 engine hydrolocked

Hyrdolock is water on top of the cylinders not letting the starter motor turn the engine. Is that what you are experiencing?

 

[Cabozone]

Re: 78 merc 260 engine hydrolocked

yes, the last time it happened, a bunch of fluid sprayed out when i cranked it over with the spark plugs out. the thing is it smells and feels like fuel not water? is it possible for fuel to flood the chamber while im trying to launch the boat?

 

[Blk-n-Blu]

Re: 78 merc 260 engine hydrolocked

I might suspect a faulty fuel pump "dumping" fuel due to a bad diaphram. Have you checked the sight line from the pump to the carb / intake to see if it has fuel in it.

 

[Cabozone]

Re: 78 merc 260 engine hydrolocked

if its a bad diaphram would the pump still work? or should i try installing a fuel shut off valve and keep it closed during launches?

 

[Blk-n-Blu]

Re: 78 merc 260 engine hydrolocked

The pump might still work if the diaphram is bad, but it will still dump fuel into the carb/intake when it is running. It is a safety feature to keep you from "Blowing Up"
Check the tube for gas, and fix it if it has gas in it. May also want to check the oil for a gas smell.

 

[dingdongs]

Re: 78 merc 260 engine hydrolocked

a cheap syringe with a small tube down the spark plug holes may tell you if its water or fuel.a bicycle pump with a small tube able to fit down the spark plug hole may also be a viable solution.empty into a glass to check.flaps are a must if your suffering from water intrusion and also check your exhaust manifolds are not shot.(leaking water into exhaust chamber)5 years in salt water usually is enough for them and if there not emptied or flushed after use a lot sooner.

 

[Cabozone]

Re: 78 merc 260 engine hydrolocked

will try it today, ill let you how it goes. thanks