OMC GM V6 hydralocks at cruise

[jeffmorris]

1996 GM V6 with Penta out drive runs great most of the time but two or three times a year the engine backfires and dies at cruise speed. starter grinds and will not turn over due to water being in the cylinders.

Could this be caused by a manifold exchange leak, melted flapper (cant find info on this possible scenario) or water in the fuel tank.

again units runs great on a weekly basis until boom and were being towed in.

 

[89 VIP Valiant]

Re: OMC GM V6 hydralocks at cruise

Jeff,

My experience with hydrolocking that it happens on start up when caused by the flapper. That is not to say that it couldnt' be for your situation. If they have never been changed, being your boat is 14 years old, and if it has been in saltwater especially, i would start with the flapper. Easy to inspect, easy fix, and fairly inexpensive.

 

[Howard Sterndrive]

Re: OMC GM V6 hydralocks at cruise

risers/manifolds #1 on the list of probable causes.


You need to figure out what you own, though.

don't think OMC had their name on anything in 1996- they were out of the sterndrive business before that

 

[jeffmorris]

Re: OMC GM V6 hydralocks at cruise

You are correct its a 1996 Fourwinns with a GM V6 and a Volvo Pinta Outdrive.

With this being intermittent any suggestions on how to test the manifold riser for leaks on a fresh water (open loop) system?

 

[Bondo]

Re: OMC GM V6 hydralocks at cruise

1996 GM V6 with Penta out drive runs great most of the time but two or three times a year the engine backfires and dies at cruise speed. starter grinds and will not turn over due to water being in the cylinders.

Could this be caused by a manifold exchange leak, melted flapper (cant find info on this possible scenario) or water in the fuel tank.

again units runs great on a weekly basis until boom and were being towed in.

Ayuh,... I donno, you might need manifolds, or not...

My thought is an Electrical Gremlin,...
If the motor just backfires,+ Dies,...
The Rush of water, if at speed, could Easily backwash into the motor...
Volvo dropped using shutters,...
What kinda shape are Your's in,..??
When you Pull the risers,+ elbows, you should be lookin' Right at 'em...

Manifold Failure usually happens at the gasket faces of the manifold/ riser joint...