oil pressure light/alarm 3gm30f

Engines, Drive trains, Propellers, Steering, Ground Tackle and other mechanical system
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daletournier
Posts: 181
Joined: Wed Aug 18, 2010 6:25 pm

oil pressure light/alarm 3gm30f

Post by daletournier »

Hi, over the last 3 days I've experienced a intermittent oil pressure light/alarm coming on, very slowly at first then building. I motored 140nm over three days, first day really pushed engine along (2850rpm) for 8 hours straight, then on the 3rd day 16 hrs motoring at approx 2600 Rpm. Late in both days alarm started making its noise, at first very lightly ( no light ) and then gradually becoming louder until light come on. I would reduce rpm which would make alarm and light fully come on before disappearing. On the first day, after reducing rpm and light/alarm going away I increased rpm and it was fine for the rest of the day. Last day I would do the same only this time after sometime light/alarm would slowly start to come back on and Id have to repeat the process all over again. Engine temperature was fine and engine sounded good.
I've just reached Puerto Galera Philippines, I think the first step is to find a pressure gauge and test pressure.
Has anyone experienced this before? Yanmar 3gm30f 4100hrs.
Didn't get into Anchorage until midnight so as yet haven't put alot of thought into it, I'm hopeing that when I awake the forum has spun it's magic and the answer miraculously appears on my smart phone ( simple answer).
Thanks in advance, Dale.

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Robert
Posts: 43
Joined: Thu Dec 04, 2008 9:44 am
Location: Arapahoe, NC / Norfolk, VA

Re: oil pressure light/alarm 3gm30f

Post by Robert »

Check your oil. Do you seem to have more than the last check?

If so, the diaphragm on the mechanical fuel pump has ruptured and diesel is getting dumped into the oil pan and thinning the oil.
Robert

s/y 'Magic' - 1985 Hoyt F32

jdpandlp
Posts: 65
Joined: Mon Dec 08, 2008 8:59 am

Re: oil pressure light/alarm 3gm30f

Post by jdpandlp »

Had the same problem you describe on a 4jhe, it was the sender. Check to see if you have oil on the sender which would indicate leakage by the spring and diaphram inside the switch.
In my case it only happened after everything got hot and the oil got thin. Then a small bit of oil would show on the sender screwed into the block.

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1980raven
Posts: 101
Joined: Mon Feb 15, 2010 8:50 pm
Location: Warwick Cove, Rhode Island

Re: oil pressure light/alarm 3gm30f

Post by 1980raven »

On mine 2QM I was getting an intermittent alarm. Turns out the wire to the sender was loose. It may not be your problem but its easy to check.
Freedom 28 CK Hull# 14, centerboard, wrap around sails with WB booms
Narragansett Bay, RI

daletournier
Posts: 181
Joined: Wed Aug 18, 2010 6:25 pm

Re: oil pressure light/alarm 3gm30f

Post by daletournier »

Thanks for the replys. The mystery to me is why it's happening after 10 plus hours of running. Oil didn't smell like it had diesel in it, and sender dosent seem to be leaking. I'm check wiring thoroughly as it is getting old. I'm going to buy a new lift pump, sender and oil pressure regulator valve. I'll be in some places this year where I don't want mechanical problems. Better safe than sorry.
Cheers Dale.

midnightsailor
Posts: 140
Joined: Thu Aug 06, 2009 1:21 pm
Location: Greenport, New York

Re: oil pressure light/alarm 3gm30f

Post by midnightsailor »

I agree with Robert SV Magic. You need to check your oil and make sure it is getting thinned out by diesel fuel ,either from crack in fuel lift pump diaphram or possibly by blowing past rings after so much running at high rpm. Not sure on this motor but on some it can also leak diesel into crankcase via seal in injector pump (ex. Perkins 4108) At any rate, an oil change may help. Perhaps it could also be that the oil pressure sender is faulty. I take it you do not have an oil pressure gauge ,just the idiot light and buzzer? Good luck, and have fun!
1982 Freedom 33 Cat Ketch, Hull # 53, Standard Booms, deep keel ,tall rig
An armed man is a citizen, An unarmed man is a subject. George Washington

daletournier
Posts: 181
Joined: Wed Aug 18, 2010 6:25 pm

Re: oil pressure light/alarm 3gm30f

Post by daletournier »

Hi, the diesel in the oil seems like the most likely suspect. I'm not sure as I changed the oil the next day. It did seem abit high but I may of overfilled it a little when I last changed it. Also I did think as I was changing it that it was abit thin, but once again I can't be sure. There was no diesel smell to the oil, should there be? If the lift pump had a hole in the diaphragm would it weep out the bottom of pump? Does it have a weep hole? Yes, only have the idiot light. I don't believe there is any sort of mechanical oil pressure problem ( ie bearings etc), engine sounds great when cold and starts instantly. Blow by the rings is a possibility due to the high rpm over a whole day, but I believe the compression to be very good by the way it starts. No sign of oil weeping from oil pressure sender. I'm thinking ( hoping ) a oil change has solved it but are going to buy a lift pump just in case. It's the longest I've run the engine continously at such high rpm therefore I believe it's related. Last time I try to keep up with a 300hp trawler in order to go diving!
Once again thanks,
Cheers Dale.

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