miket
regular
Reged: 21/06/2001
Posts: 1457
Loc: N Hampshire
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Any thoughts form those of you with engineering knowledge appreciated.
1981 Freeman 33. 2 x BMC 2.5 litre diesels.
Start of a weekend cruising on the upper Thames and after about 10 minutes cruising noticed no oil pressure on stbd. I would normally scan dials on start up but can't swear to it on this occasion.
For some obscure reason I didn't stop engine. Cruised 10 minutes back to base with no oil pressure. Engine sounds normal.
Engineer called.
Dial checked and working (electronic not capillary tube).
Sender checked and working.
Sender from port swopped and still no oil pressure.
Sender removed and finger inserted over orrifice. No pressure felt.
Oil pump is internal and will require engine removal to remove.
Oil pressure release valve still to be checked.
Oil is fairly clean.
I suspect a blockage somewhere but stumped as to further checks excluding engine removal.
Help!!
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MustangTom
regular
Reged: 15/07/2002
Posts: 2458
Loc: Faversham,Kent
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You can try and get some flushing stuff and change filters run till warm
and new oil and filters change again
Worth trying before removal?
Tom
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timtap
regular
Reged: 28/06/2008
Posts: 279
Loc: Paignton Devon
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Before the drastic engine removel route have you taken the oil filler cap off and looked to see good oil flow through the tappet gear or even loosened the oil filter a little with a clear plastic bag over the unit and check pump flow.
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In a recent survey it was discovered that 3 out of 4 people make up 75% of the population
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KevB
regular
Reged: 04/07/2001
Posts: 5496
Loc: London
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Quote:
Oil pressure release valve still to be checked.
I had an old rootes car many years ago, a Humber Scepter. it was dogged with low oil pressure and on 2 occassions I had to rebuild the bottom end. Turned out the cause of the problem was a £4 oil pressure release valve which sat on the side of the engine and took about 5 mins to replace. 
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Nirvana
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volvopaul
regular
Reged: 01/04/2007
Posts: 842
Loc: midlands
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Take the filter off and crank the engine over with the stop lever in the stop position, if no oil flows its the pump, could just be the pump drive gear thats sheared off, if its got a vertical injection pump the drive gear from distant memory is under the injection pump you may be able to remove the injection pump then withdraw the drive gear.
Its not a diy job unless your really handy as the inj pump and drive gear need to be timed up after, i suspect though a sticking relief valve, if you have an oil cooler i would check that for integrity too as the oil may be being pumped out with the raw water, after 10 mins running i would have expected some expensive noises by then!.
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burgundyben
regular
Reged: 28/11/2002
Posts: 1961
Loc: Hamble
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I'd check the oil pressure relief valve, you need to measure the free length of the spring that holds the plunger into its seat, compare the free length with the other engine.
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burgundyben
regular
Reged: 28/11/2002
Posts: 1961
Loc: Hamble
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is there absolutely no oil pressure?
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jfm
regular
Reged: 16/05/2001
Posts: 7740
Loc: London/Antibes
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I dont know that engine so the following might be a bit too general
Is the wiring ok between sender and dial? I'm kinda guessing you eliminated that, but your post doesn't specifically say. To test/eliminate this, take the wire off the port sender and connect it to the starboard sender
The sender is normally located in the pressure gallery right at the output of the oil pump, hence blockage seems unlikely. When you said you removed sender and put finger over hole and no pressure felt, did no oil come out? If so it does seem a knackered oil pump.
Does the sender hole and geometry of pump body allow you to stick a piece of coat hanger wire or plactic drinking straw in and feel the pump working/spinning as the engine turns? Is stbd stopped and port feelable as spinning?
What drives the pump? On some engines you can get to the drive gears at end of the engine, and if it is these that have failed rahter than pump itself you might be able to replace without removing engine
Sorry, these are longshots. Alas I fear a new pump is needed
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LittleShip
regular
Reged: 21/07/2003
Posts: 2801
Loc: In the water .... most of the ...
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After 10 mins running with no oil pressure you would be hearing some very drastic noises coming from the engine. I tend to lean on an electrical fault even though you have swapped the sender it could be something as simple as a broken wire.
The advice of removing the filter and turning the engine over is a quick albeit messy check.......... plastic bag, old towels or a bucket before you do it. If there is no oil being pumped I will be very surprised. I have never had an oil pump fail.
Good luck but try a capillary gauge before you take the engine out.
Tom
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I wish I'd been born rich instead of good looking ?
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Steveu
regular
Reged: 02/12/2003
Posts: 43
Loc: London
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armchair diagnosis is difficult but I'm with the pressure relief valve camp. When the engine starts from cold the pump can't push the cold oil through the bearings so it overpressures & activates the relief valve, releasing oil back into the sump. If the valve sticks open as it sometimes does (due to a build up of dirty oil jamming it) then as the oil gets warmer the pump is still pumping the oil back into the sump....the valve could be jammed completely open or only partially open, allowing some oil pressure but not much.
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