High Oil Pressure

[ianc1200]

Anybody willing to offer advice?

On the return trip from the East Coast to the upper Thames last October, one of the crew noticed the oil pressure guage was stuck at the top end of the scale. I duly reported this to the boatyard engineer, and it was left (unfortunately) to be resolved when the boat was relaunched. The engine is a 5 cylinder Nanni/Kubota just still in warranty, 3 years old. We didn't use the boat again after the return, and when relaunched went for a trip up to Goring, and returning was approaching Whitchurch lock, there was an odd noise in the engine, followed by an ilregular loud tappett sort of noise. We got back to Hurley, and the warranty service was done after finding that a valve had dropped, but from the noise of running the engine, no damage done. However, a mechanical guage was put on the block and the oil pressure was put on the block and the reading was off the scale, more than 100 PSI. An oil pressure relief valve was ordered and put on this morning, but no difference. Peachments/Nanni were phoned, and the advice was to replace the oil filter as that has another relief valve, so the one put on last week was replaced with a new new filter, no effect. The conclusion is that it appears to be a blockage somewhere, but the oil is perfectly clean, the engine has done 550 hours, and there are mutterings now about it being an engine out job etc.

Any other reason for such high oil pressure that anybody can think of?

regards

IanC

 

[Andrew_Fanner]

May be a little flippant but do you trsut your gauges? I ask because my pressure gauge reads fine but the warning light is on. As the gauge flips up to pressure smartly on startup and the light came on just after that, or didn't go off, not paying attention there! I plan to check the state of the wring from the sender this weekend.

 

[PCUK]

Feed to the rocker assembly causing a valve to seize?
You make the valve "dropping" sound like a minor problem, I would be shouting about a new engine at this stage, very serious problems with this engine that will likely plague you forever unless you sort it now.

 

[oldgit]

Both the boat and mechanical test gauges are giving high readings!

 

[Lakesailor]

As both pressure relief valves have been replaced and there is no difference there must be a blockage or stricture between the pump and the first pressure relief valve. Were it after the valve then pressure would be relieved, although the starving of oil feed would still occur. This relies on the pressure reading take off being before the 1st relief valve as well. Which in most cases I can think of it would be.
I would agree that a warranty claim should be lodged within the warranty period, in writing, just to cover your back in case it becomes a big problem.
Whatever the cause, there will be some downstream problems as evidenced by the valve problem.

 

[ianc1200]

Hi all and thanks for the thoughts. I visited the boatyard on Sat morning, and discussed another thought; I had laid up all Friday night worried, whether an engine out/ summer no boating was in prospect. I had come to the same conclusion re the position of the blockage as had the engineers, but I wanted to try something else. With their agreement, I ran the engine artificially hot, and immediately noticed the pressure coming down. The engine, a Nanni 5.280 HE, seems to run very cold (about 60 C) particularly on the upper Thames, less of a problem at sea. After adjusting the seacock so the temperature, under load, was about 90 C, the pressure was dropping towards 40 PSI. On this basis, we decided to go on out trip, which was from Hurley to Bradwell on the Blackwater. We left at 2pm Saturday, got to Teddington at 1:30am Sunday, left again 5am and arrived at the Bradwell entrance last night at 9pm, but couldn't get in because of LW, so anchored in the river and entered at 5am this morning. It was F6 overnight, which meant I didn't sleep for the third night on the trot (we had drunken louts in the dinghy at Teddington at 4am, ruining the 3 hours of sleep we had planned). The pressure stayed about 65 C, as I didn't close the sea cock fearing damaging the pump on such a long trip, which could also have had a disastrious effect. Having rested this morning, we looked for the thermostat to see if it was working, but there wasn't one in the housing we suspected should contain it. I will ask the Tollesbury Nanni agent to look and see if there is a thermostat problem and discuss his comment last year that there was a mod Nanni had done because these engines don't heat up the calorifiers very quickly. Anybody know where to buy a workshop manual for these engines?

Re the dropped valve, our Hurley engineer says it was definitley not a dropped valve, and I have forgotten the term he used, but said had it of been there would have been damage, perhaps major damage.

Re the high pressure readings by the local Henley area Nanni engineer, we certainly did not get anything off the scale over 100 PSI, and noticed; idle, 45 PSI, running about 5 knots, 65 PSI, but putting the engine under more load, about 6.5 knots, the pressure dropped to about 55 PSI. I wonder whether he was testing the engine very cold?

Anyway, we got there, and for an elderly motor cruiser (built 1951) she weathered the baddish weather we had running up the Blackwater, and the conditions when anchored, rather well.

Thanks again for your thoughts

IanC

 

[Lakesailor]

[ QUOTE ]
the reading was off the scale, more than 100 PSI.

[/ QUOTE ][ QUOTE ]
we certainly did not get anything off the scale over 100 PSI,

[/ QUOTE ] Make up your mind

 

[ianc1200]

The difficulty is I can't make up my mind!

However, the first post related to the Nanni engineer putting a mechanical guage on, whilst I wasn't there. The second post relates to what I observed on the dashboard pressure guage on the trip over the weekend.

I can't relate the two readings. The Nanni engineer wasn't exgerrating, he was concerned. However, we did not see anything like his reading, which would have manifested itself as being at the top of the guage, which I believe goes up to 80 PSI.

Sorry I should made that all clearer.

IanC

 

[Lakesailor]

If it's still a warranty claim and their man is concerned, I'd go along with them.

 

[Dave_Snelson]

I had both senders fail erratically on mine Andrew. Most disconcerting at 25 kts and bleedin miles from port. Needle jumping all over the place, then no pressure, then high pressure. Then to cap it all both guages were doing it (twin engine). Turned out to be the sender units themselves (known problem on GM V6 block). New senders, no problem.

 

[Dave_Snelson]

If still under warranty - back to the dealers with it.

 

[Andrew_Fanner]

Worth knowing Dave.

Dunno where the senders are on an AD41 and even the workshop manual is of no especial help, just tells you to take the things out, clean the ends and stick 'em back in.

Guess its a rummage in the hole some time soon.