apw3
Well-Known Member
Hello all. We have anengine issue that is a mystery to us but probably isn't to you guys.
Volvo Penta AQ171C petrol job attached to a 290 stern drive.
Had boat hauled out for stern drive service (removal and check) by a reputable yard well known to this forum and anti foul. Engine running sweetly.
Took her out for a sea trial before the 10 miles trip back to her berth. Hit max revs at 20 knots for 10 minutes.
On return, engine was fine but traces of oil around outdrive. Engineer reckoned it was just oil from exhaust and would clear itself.
Made the return trip at 10 knots ok. Once berthed we noticed continuous traces of oil around the stern drive again. There was also a white residue around the heat exchanger pressure cap. The heat exchanger was full of coolant. Took her out to check the systems and within a few minutes the temp gauge climbed in to red. Limped back to berth. On going into reverse the outdrive kicked up and white exhaust smoke from the top of the outdrive appeared.
In the engine bay we had water weeping past the pressure cap and a few bubbles appearing after running the engine with the cap removed.
So, checked seawater pump (recently reconditioned) and the impeller was fine. Tested the thermostat and it opens at the right temp. Replaced the cap for a new one at the right psi.
Ran engine and had coolant dripping quickly from bottom of heat exchanger but not past pressure cap. At this point the seawater pump also started to drip (not coolant).
The engineer returned and diagnosed a loose exhaust bellows that explained the exhaust smoke. He also thought that the head gasket had gone and recommended new gaskets for head and heat exchanger.
A week later there is still oil appearing at the stern.
Before we get the spanner out, what do you guys think?
I can go with the engineer up to a point but I don't understand how the engine overheated when there was coolant being cooled. Alternator belt is new and correctly adjusted.
Are we dealing with one original issue that then had knock on effects or might the series of issues just be coincidental?
Thanks in advance for your wisdom.
Volvo Penta AQ171C petrol job attached to a 290 stern drive.
Had boat hauled out for stern drive service (removal and check) by a reputable yard well known to this forum and anti foul. Engine running sweetly.
Took her out for a sea trial before the 10 miles trip back to her berth. Hit max revs at 20 knots for 10 minutes.
On return, engine was fine but traces of oil around outdrive. Engineer reckoned it was just oil from exhaust and would clear itself.
Made the return trip at 10 knots ok. Once berthed we noticed continuous traces of oil around the stern drive again. There was also a white residue around the heat exchanger pressure cap. The heat exchanger was full of coolant. Took her out to check the systems and within a few minutes the temp gauge climbed in to red. Limped back to berth. On going into reverse the outdrive kicked up and white exhaust smoke from the top of the outdrive appeared.
In the engine bay we had water weeping past the pressure cap and a few bubbles appearing after running the engine with the cap removed.
So, checked seawater pump (recently reconditioned) and the impeller was fine. Tested the thermostat and it opens at the right temp. Replaced the cap for a new one at the right psi.
Ran engine and had coolant dripping quickly from bottom of heat exchanger but not past pressure cap. At this point the seawater pump also started to drip (not coolant).
The engineer returned and diagnosed a loose exhaust bellows that explained the exhaust smoke. He also thought that the head gasket had gone and recommended new gaskets for head and heat exchanger.
A week later there is still oil appearing at the stern.
Before we get the spanner out, what do you guys think?
I can go with the engineer up to a point but I don't understand how the engine overheated when there was coolant being cooled. Alternator belt is new and correctly adjusted.
Are we dealing with one original issue that then had knock on effects or might the series of issues just be coincidental?
Thanks in advance for your wisdom.
