Engine problems in 30 knots - Volvo D55

[Burge]

Hi,

I am hoping to get some helpful advice on diagnosing an engine fault. 2005 Volvo D55 normally aspirated.

Last weekend I went to take my boat out after being overseas since April and as I motored away from my mooring with 30 knots on the nose I started to increase revs up towards 2000rpm and the engine suddenly lost power and dropped revs down to approx 1000rpm.

In my mild state of panic I thought this might be a fuel issue so quickly changed over to full separate tank. The engine was then running ok but as I went to increase revs again it started making a really bad clattering noise so I had to immediately reduce revs and it would then stop clattering.

I quickly picked up another mooring and tried reving the engine out of gear and it didn't clatter even taking it up to 2500rpm. I then stopped engine and double checked oil level which was fine and water intake was clear.

I started engine again and for the first time ever the lower pressure oil alarm stayed on for approx 10 seconds, I then put the boat in reverse and motored against the mooring and the clattering happened somewhere between 1500-2000rpm. With the engine compartment open the clattering was awful and sounded like something was about to go bang.

I stopped and started the engine a few more times over the course of the next hour and the lower pressure alarm sounded each time after starting for 10-15 seconds.

Limped back to my mooring at low revs no problem.

There was no signs of overheating and no smoke out of the ordinary.

It might be unconnected but the last time I used the boat was bringing it back from the boatyard where I had the rocker cover gasket replaced due to an oil leak. It ran ok coming back from boatyard but that was only a couple of miles and probably didn't rev above 2000rpm if that.

Any ideas? I'm now overseas again so trying to figure out what to do?

Burge

[Rickfit]

Gday Burge,
Sounds like you may have mechanical damage to your engine. Replace the engine oil filter , cut open ( if it is a metal case - use a hack saw to cut the case then cut a sextion of the paper filter out) . Once you have a section of the paper filter removed put it in a vice and squeeze the excess oil from it. Inspect the dried paper filter to see if there is any metal in it.If there is you’ve probably done a big end ( big end bearing to crank) . You will be up for a costly engine repair . If there is no metal it means the internals of the engine is ok. I hope this helps

[DougR]

Two things come to mind:
- D2-55 engines had some low oil pressure alarm issues in the early 2000s that were caused by a poorly fitting O ring where the oil pickup pipe goes into the engine block. The oil pump is mounted on the front of the engine block and sucks oil from the pan thru the pick up pipe, past the O ring, and up to the pump. This O ring was a poor fit in its seat, and when the oil got hot and thin it would allow air to be pulled past the O ring, causing low pressure alarms. Normally this would occur when throttling down after long hours at high load, as the oil was very thin. Letting the engine and oil cool down resolved the problem until next time.

I suggest checking the filter as Rickfit mentioned. Also, remove the oil alarm sender and install a mechanical pressure gauge in its place and see what oil pressure you actually have.

Second option - D2-55 engines of that vintage had problems with the two stage torsional damper mounted on the flywheel to transfer power from the engine to the gearbox/ saildrive. These dampers could fail in two or three different modes, all of which sounded like everything was coming apart. (Because it really was)
If everything checks good with the oil pressure try looking here next.

DougR

[MartinR]

Have you inspected your prop?

[Burge]

Thanks Martin, Doug & Rickfit.

At this stage I have organised an oil sample to be tested for metal, water, silicon etc to determine if there is mechanical damage and I will go from there.

Its such a pain being in a different country try from your boat!

Thanks for your advice so far.

I haven't inspected the prop since the engine fault but I did have the prop - prop speeded in April so should be clean.

Burge

[jannw]

Symptoms (awful clattering when revving) are consistent with a fuel supply problem. Did you check (change) your fuel filters and bleed out the fuel system? I'll bet the fuel supply was disassembled when your rocker cover was removed - could there be a small air leak in the fuel system introduced when it was reassembled?

Can't speak for the oil pressure alarm ... are the bolts tight?

[Burge]

Thanks for your thoughts JannW, I would much prefer a fuel problem than mechanical damage.

The oil test came back clear so no evidence of mechanical damage. I have decided to bite the bullet and booked flights back to boat early October and will meet diesel mechanic on site. Hopefully BTS marine, Havelock will be able to figure it out.

Burge