tudorsailor
Well-known member
I have a Yanmar 4JH3-HTE installed 2001. It has done 6000 hours. It is not particularly noisy or smoky. It has been serviced annually and filled with Yanmar oil
Last year the oil pressure gauge stopped reading and the local team put in a gauge from another boat and the pressure then read normally.
This year, my wife commented that the red oil pressure warning light was staying on longer after starting the engine than normal. It does go out, but sometimes only after a minute
I then noticed that the pressure gauge was reading maximum as soon as the engine was given 12v and before it was actually running. I assumed that the gauge was faulty
The boat is now in Murter Croatia where there is an authorised Yanmar mechanic
He installed a new Yanmar Pressure sender. It registered no oil pressure. He checked by grounding etc that the gauge and wire was OK
He then measured the oil pressure with a mechanical gauge and it was unrecordable both at the hole for the pressure sensor and then also at the hole for the pressure switch that activates the red warning light. He double checked with another mechanical pressure gauge, still unrecordable
He then removed the block that is under the oil filter (with great difficulty as the screws were stuck) to checked the pressure relief valve. He found no problems
He put everything back together and the oil pressure dial still read zero and then when rev'd the engine to over 3000 rpm - which is not something I ever do - the red oil pressure warning light came on
So it seems that there really is minimal oil pressure.
The engineer's opinion by a process of elimination is that the oil pump has failed. He plans to remove the engine and fix whatever is necessary. Obviously not a minor thing
Are there any other possibilities that he has not thought of for low/no oil pressure?
When the engine is on the bench what things should I expect him to do to "recondition" the engine? I did ask about the crankshaft and he said he would replace the bearings if necessary.
All rather stressful.................
Tudorsailor
Last year the oil pressure gauge stopped reading and the local team put in a gauge from another boat and the pressure then read normally.
This year, my wife commented that the red oil pressure warning light was staying on longer after starting the engine than normal. It does go out, but sometimes only after a minute
I then noticed that the pressure gauge was reading maximum as soon as the engine was given 12v and before it was actually running. I assumed that the gauge was faulty
The boat is now in Murter Croatia where there is an authorised Yanmar mechanic
He installed a new Yanmar Pressure sender. It registered no oil pressure. He checked by grounding etc that the gauge and wire was OK
He then measured the oil pressure with a mechanical gauge and it was unrecordable both at the hole for the pressure sensor and then also at the hole for the pressure switch that activates the red warning light. He double checked with another mechanical pressure gauge, still unrecordable
He then removed the block that is under the oil filter (with great difficulty as the screws were stuck) to checked the pressure relief valve. He found no problems
He put everything back together and the oil pressure dial still read zero and then when rev'd the engine to over 3000 rpm - which is not something I ever do - the red oil pressure warning light came on
So it seems that there really is minimal oil pressure.
The engineer's opinion by a process of elimination is that the oil pump has failed. He plans to remove the engine and fix whatever is necessary. Obviously not a minor thing
Are there any other possibilities that he has not thought of for low/no oil pressure?
When the engine is on the bench what things should I expect him to do to "recondition" the engine? I did ask about the crankshaft and he said he would replace the bearings if necessary.
All rather stressful.................
Tudorsailor