Sterndrive Problem - Any Mechanics?

[boatboy50]

Hey Guys,

Have a problem with a Volvo 5.0L Carb engine. It is fitted to a 2000 Glastron GS249 Sportscruiser, in warm climate.

The boat has always been dry stored and flushed regularly, with regular use (500 odd hours).

Had no problems with the rig when it was layed up on the hard for around six months, while it was for sale. It was regularly started with fresh water and run till warm during this period.

Once sold, and on delivery, first time back in the water on trailer during launch, the engine ingested water and hydro locked. Thought it was an isolated incident due to ramp/trailer/piston angles, and cleaned out engine and got going again.

Launched again, put on about six hours with no problems. Third outing since launch, anchored overnight (new owner), and it ingested water again.

Pulled on hard, cleaned out again, got running, then pulled manifolds and risers down for inspection.

All seemed to be in quite good condition, apart from one gasket which could potentially be letting water in. Apart from that, to the naked eye, all seemed reasonable.

On both occassions, water was in all cylinders, but never made it down into the sump.

Apart from replacing manifolds and risers (which we are doing anyway), does anyone have any other ideas on what could be happening to cause this issue.

Last thing we want is to do all that work and find the problem still exists?

All help would be greatly appreciated.

Regards

Darren

[Roughasguts]

All cylinders ! It's got to be water comming up through the exhaust pipe. Is there a flap and S" bend at the rear on the transom wall.

[boatboy50]

Hey Rough,

These engines are apparently not fitted with any flaps, but are set up that the water can't come in. I don't think there is an "S".

It astounds me that the engine did 500 hours without a problem, and now.....

Any other ideas?

Regards

Darren

[Roughasguts]

Hmmmm We got a 21 footer with a Volvo V8 shaft drive 3.6 litre fully alloy every thing. On both sides of the exhaust there is a heavy metal flap which closes off until exhaust pressure pushes it open and vents both water and exhaust. On the Inside of the transom both pipes rise up way above water level and then come down to floor level, through the muffler where the exhaust uses 3 inch rubber pipe until it gets to the exhaust manifolds.

By the way it sounds fantastic these motors idle at 250 Rpm and rev out to over 6k. Wish me outboard would sound that good.

Okay I should say it has never had the heads off in over 40 years but the exhaust has melted due no cooling water getting through at one stage.


But this boat has always been trailered away from the ramp it's never been moored. Mind you nearly sunk many times as shes a timber clinker hull and it can take a while for the boards to swell up and make her water tight again.

But never had water get up in to the block...... Oh hang on ours was a carby model but ordinary choke! Have you got a water cooled carby for the auto choke if it has one that could fill your block with water if shes rusted through.

[Roughasguts]

Got Auto choke on your carby with a water manifold keeping your carby warm ?

[BM]

If its in all cylinders Darren it seems to me like an intake manifold leak. 5ltr Chev yes?

Fresh or salt cooling?

[boatboy50]

Hey BM,

I was hoping you'd catch this thread. Thank you.

I'm sure the engine is a 5.0 Chev based. It is salt water cooled.

We are replacing the manifold and risers which appeared to be in good condition.

I'm just scared that I will still have the same problem.

Is there anywhere else I should look to?

Regards

Darren

[BM]

Water in all pots in my opinion has to get in via the intake manifold. It would be unlikely that it has 2 cracked heads and even if it did the cracks would be to 1 cylinder normally (1 cylinder per head so 2 cylinders with water).

Failing it being the intake then the only other possibility is the exhaust system but then water would only have gone into the cylinders with their exhaust valves open so not all 8.

How much water are we talking per cylinder? Are you sure it didn't get in when you pulled the heads off? Is it ht esame volume more or less in each cylinder?

Cheers

[boatboy50]

Hey Nick,

I'm not all that mechanical so you will have to be patient. I am relaying info from my mechanic here in Qld.

I am told it was about a couple/few litres in total.

The engine definately had water in it before we pulled it down. Twice!

I am sure it is the same amount per cylinder.

Regards

Darren

[BM]

Have the manifolds (intake and exhaust) pressure/vac tested and also the risers. This is the inital step to solving the problem.

cheers

[boatboy50]

Thanks Nick,

I will chat with the mechanic tomorrow and let you know the outcome.

Regards

Darren

[jimbo59]

Hi darren i have a volvo/penta/chev 5.7 injection/vortec here at the moment that has a similar problem with the injestion of water.These motors have a 4 into 1 manifold that can fill more than 1or 2 cylinders if the manifold has worn thru with rust.i doubt that all 8 cyilinders will have the pots full of water.Sometimes when you back off and the flappers are ceased or rusted it can get a gut full of water.I have found the states are the cheapest at 500 for the set(us made)....jim

[Angla]

Is it possibly coming through with the fuel

Chris

[boatboy50]

Thanks Jimbo,

I'll be in touch about the cat soon.

Angla, i'm almost certain it can't be coming in through the fuel. There is far too much for that way.

Regards

Darren

[jimbo59]

darren been thinking bm might be correct with it coming in thru the inlet manifold.That would figure that the 8 pots would be choca block. cheers..jimbo

[Dodgemeister]

I know it should be common knowledge to your mechanic but before you remove the risers, are you draining the exhaust manifolds through the plugs at the rear of the manifolds?