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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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2005 Volvo Penta D2 55 C in a Bavaria 42 Cruiser.Up to 1500

Customer Question

2005 Volvo Penta D2 55 C in a Bavaria 42 Cruiser.Up to 1500 rpm fine with reasonable amount of water out of exhaust, taking above 2000rpm , steam in exhaust becoming thicker followed by overheat. Impeller is fine. Looking at anti syphon piping, lots of air in the water- no evidence of leakage of water into engine compartment & inlet filter clean
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Marine Mechanic should be aware of?
Customer: Not that I am aware of!
Submitted: 8 months ago.
Category: Boat
Expert:  Jason replied 8 months ago.

Hello my name is ***** ***** am I speaking with?

When was the last time the impeller was changed?

Customer: replied 8 months ago.
Hi Jason, Sorry for delay in reply, out & about with work. This is Roger.
Impeller changed at the beginning of the year & taken out & checked when this overheating problem began. It is in good condition. Cross checked with friend on his 78HP Volvo for air visible in his pipes, whilst he has some, nothing like as much as I see when running my engine.
Expert:  Jason replied 8 months ago.

Hi Roger,

What do you mean by air visible in the pipes? Did you replace the black hoses with clear tubing for testing?

Customer: replied 8 months ago.
No , piping is as when we purchased the yacht three years ago & is the same as on friends 3 year old Bavaria 42. It is the piping up to/from the 'vacuum valve' which is mounted to rear of the engine. They are reinforced piping as normally seen on these engines. They were loose when I closely inspected them, but I have tightened them now, but the problem is still there.
Expert:  Tan replied 8 months ago.

Hello. My name is Tan. Lots of air in the discharge can be caused by an air leak on the suction side of the raw water pump. Check that the gasket or o-ring are making a good seal on the raw water strainer.

Did you inspect the water pump housing for grooves in the pump housing and the cover plate? Is the raw water pump dripping when the engine is running?

Customer: replied 8 months ago.
Hi Tan,
Raw water strainer seems fine, pipe from that to impeller is harder to view, but I don't think there is any evidence of air in that section. Pump housing for impeller & cover plate seemed fine on inspection & certainly no drips from that area. Could it be a problem with the vacuum valve? That said, air is visible both sides of the vacuum valve. I have to head off to work now, so unavailable for around 12 hours. Thanks
Expert:  Tan replied 8 months ago.

Is the vacuum valve on the suction side of the raw water pump?

Ok talk later.

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