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Go Back   SailNet Community > On Board > Gear & Maintenance > Engines > Diesel > Yanmar Oil Pressure Pegged
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Topic Review (Newest First)
07-29-2013 09:35 AM
mark2gmtrans
Re: Yanmar Oil Pressure Pegged

Quote:
Originally Posted by dem45133 View Post
"I have driven for hours with the gauge just above zero and the proof for me that it's the sender is that the buzzer works off a different sender and even when pressure is effectively zero, the buzzer doesn't go off and the engine runs just fine."

Wow... thats pretty risky to me. If the engine is running solid lifters, you may not be able to hear the low pressure indicators (or high pressure limited flow indicators) until its too late and its been hurt... likely catastrophically. I intend to go to a purely mechanical oil pressure and also the water temp gauge when I re-due my console. I've had to replace sensors in a couple vehicles over time... but if the oil pressure gauge or light buzzer does anything out of norm... its always been my practice to shut down.

Also super high pressures generally indicate a blockage... either through a malfunctioning regulation device or an plugged line. Learned this the hard way on Dad's 52 Dodge pickup... it had always run high oil pressure from the day he bought it used... after a couple months it seized. Upon opening up it was totally gummed, crudded up everywhere and had blocked the linage. All the lines had to be opened with wire and pipe cleaners. Turned out upon inquiry that the previous owner (a shoe string relative) had NEVER changed the oil or filter since new... just added oil if the stick said it needed it. Think it had 50000 miles when we bought it... considering its abuse it did well to go that far.

Oil or temp issues... its good practice to always shut down first... well unless you LIKE to buy replacement engines or install head gaskets (smile).

Another idea is two sets of guages... one set electric driven for the topsides console... and a second set of purely mechanical gauges on the engine or in the engine compartment as a backup. Takes nothing to install.

Just my opinion... but I been around and owned a lot of farm, industrial, and regular transportation engines for 45 years.
Exactly, which is something I covered in an earlier post, either here or in one of the other threads, I have a Dodge pickup that was running fine, the oil pressure gauge went low, then returned to normal, then low again. What had happened was that the oil pump drive gear shaft had broken, it is driven off the end of the camshaft in the Dodge engine, and it was seating itself, and then coming unseated, until it quit. The engine never ran even close to hot and the oil pressure would go to zero and then when I turned it off it would come back up to normal for a few minutes. I incorrectly guessed it must have been the sender. I now have a new engine in it, which sucks because I did not want to have to build a new engine for it. The only good thing in that deal is that I built the engine myself, so it only cost me about $500.00 to replace it completely. Most people cannot do that for $500.00, which covered the cost of the complete rebuild kit and having the heads ported and polished in the machine shop.

You can go to a manual gauge on your boat, just make sure the oil line does not have any way to chafe, and cannot get snagged on anything. The oil pressure gauge kits are cheap when you go with a manual gauge, and they are going to work no matter what else is going on. I personally would probably go with a new electronic gauge, in order to link it all together to a chart plotter and systems monitor on a boat over 38 feet, or one which had the option of linking everything together. However, that is my preference and may not be what you would want.
07-28-2013 05:10 PM
dem45133
Re: Yanmar Oil Pressure Pegged

"I have driven for hours with the gauge just above zero and the proof for me that it's the sender is that the buzzer works off a different sender and even when pressure is effectively zero, the buzzer doesn't go off and the engine runs just fine."

Wow... thats pretty risky to me. If the engine is running solid lifters, you may not be able to hear the low pressure indicators (or high pressure limited flow indicators) until its too late and its been hurt... likely catastrophically. I intend to go to a purely mechanical oil pressure and also the water temp gauge when I re-due my console. I've had to replace sensors in a couple vehicles over time... but if the oil pressure gauge or light buzzer does anything out of norm... its always been my practice to shut down.

Also super high pressures generally indicate a blockage... either through a malfunctioning regulation device or an plugged line. Learned this the hard way on Dad's 52 Dodge pickup... it had always run high oil pressure from the day he bought it used... after a couple months it seized. Upon opening up it was totally gummed, crudded up everywhere and had blocked the linage. All the lines had to be opened with wire and pipe cleaners. Turned out upon inquiry that the previous owner (a shoe string relative) had NEVER changed the oil or filter since new... just added oil if the stick said it needed it. Think it had 50000 miles when we bought it... considering its abuse it did well to go that far.

Oil or temp issues... its good practice to always shut down first... well unless you LIKE to buy replacement engines or install head gaskets (smile).

Another idea is two sets of guages... one set electric driven for the topsides console... and a second set of purely mechanical gauges on the engine or in the engine compartment as a backup. Takes nothing to install.

Just my opinion... but I been around and owned a lot of farm, industrial, and regular transportation engines for 45 years.
07-22-2013 01:08 AM
mark2gmtrans
Re: Yanmar Oil Pressure Pegged - Part II

Quote:
Originally Posted by DrB View Post
Okay,

So I went to the boat today. Changed the oil filter, pulled the sender, and put in new oil; in that order. Sender looked fine, not plugged with stuff. I didn't have a mechanical pressure gauge to try, so I reinstalled the sender and jiggled the wire some.

After I turned the key to on, and before I pushed the start button, I looked at the oil gauge and it was pegged, without the motor on. The other gauges hadn't moved. I am more convinced now it is a electrical problem or the oil sensor itself.

Thanks all for the advice.

DrB
If you used anything other than a Yanmar sensor with a Yanmar gauge you have to understand that Yanmar makes theirs where they will not work with other manufacturers senders or gauges, it either has to be both of them Yanmar or neither of them Yanmar. If you have that part right it could be wiring, or the gauge, the only way to know is to swap and test, or at least the only way to easily know.

I personally would have swapped out both the sensor and the gauge for a teleflex gauge and sensor or some other aftermarket set. The Yanmar ones are pricey enough to pay for both pieces with the swap out. You cannot mix the Yanmar sensor with any other type of gauge or the Yanmar gauge with any other type of sensor, they will not work, and will peg the gauge over every time.
07-22-2013 12:31 AM
DrB
Yanmar Oil Pressure Pegged - Part II

Okay,

So I went to the boat today. Changed the oil filter, pulled the sender, and put in new oil; in that order. Sender looked fine, not plugged with stuff. I didn't have a mechanical pressure gauge to try, so I reinstalled the sender and jiggled the wire some.

After I turned the key to on, and before I pushed the start button, I looked at the oil gauge and it was pegged, without the motor on. The other gauges hadn't moved. I am more convinced now it is a electrical problem or the oil sensor itself.

Thanks all for the advice.

DrB
07-17-2013 07:31 PM
mark2gmtrans
Re: Yanmar Oil Pressure Pegged

Quote:
Originally Posted by Omatako View Post
It's almost sure to be the pressure sender. My engine starts at 45 psi cold and when hot drops to nothing. A little rev up and it goes back up and stays then drops again and so it fluctuates.

I have driven for hours with the gauge just above zero and the proof for me that it's the sender is that the buzzer works off a different sender and even when pressure is effectively zero, the buzzer doesn't go off and the engine runs just fine.

I'll get round to a new sender one day . . . .
Would you care to bet an engine on that? I did and lost...
07-17-2013 04:07 PM
Neosec
Re: Yanmar Oil Pressure Pegged

Electrical oil pressure sending units typically work by changing the resistance in proportion to the oil pressure. As the oil pressure rises the resistance, in OHMs, goes up. This change in resistance may not be linear. The path of current is likely from the negative terminal of the battery and negative bus through a ground wire to the engine block. Then through the oil pressure sending unit where the resistance is varied with the change in oil pressure. Continuing out a single wire to the oil pressure gauge and finally out through another wire to the positive bus and to the positive side of the battery. Any poor connections along this route will add resistance to the circuit and show up as a higher then normal reading. This, of course is simplified and your system may be different. Don't be surprised if you remove the sending unit to check the pressure and it is ok, then reinstall the sending unit only to find the problem went away.
07-17-2013 04:39 AM
Omatako
Re: Yanmar Oil Pressure Pegged

It's almost sure to be the pressure sender. My engine starts at 45 psi cold and when hot drops to nothing. A little rev up and it goes back up and stays then drops again and so it fluctuates.

I have driven for hours with the gauge just above zero and the proof for me that it's the sender is that the buzzer works off a different sender and even when pressure is effectively zero, the buzzer doesn't go off and the engine runs just fine.

I'll get round to a new sender one day . . . .
07-16-2013 08:13 PM
mark2gmtrans
Re: Yanmar Oil Pressure Pegged

Your first test is to get a mechanical oil pressure gauge and remove the oil pressure sender and put the gauge in its place. Get a true and accurate reading and then you can go forward.

This little cheap one from Harbor Freight is only $24.99 and it will do you just fine.

Engine Oil Pressure Test Kit



You can see the various little fittings that will include the one you need and you just pull the sender and screw the tester in the place of the sender. If you determine that the pressure is actually high you need to find where the obstruction is before you run the engine too much, check the pressure regulator and hopefully that will be it, also change the oil and filter. Let us know if you have any questions or when you discover the issue and fix it, what it took to get it right. My guess is that it is the sender or the gauge.

Side note, you can replace the original Yanmar gauge and sender with a Teleflex sender and gauge. You do have to replace both, because the sender from Yanmar is proprietary and will not talk to other gauges and the gauges will not talk to other senders. If you decide to replace the gauge and sender with the MUCH less expensive Teleflex unit the cost of the two, sender and gauge will be less than the Yanmar sender alone.
07-16-2013 07:36 PM
Neosec
Re: Yanmar Oil Pressure Pegged

When troubleshooting anything try to split the system in half and isolate the problem to one side (of the half) or the other. In this case the problem could be in the engine that the pressure IS too high, maybe caused by blocked passages? Or, it could be indicating too high caused by the pressure monitoring system (sending unit or gauge, etc.). I'd split the system between those to systems, the engine and the monitor. As stated above, get a mechanical pressure gauge and put it in where the oil pressure sending unit was. if you get the same indication, you know it's in the engine. If your nearly due for an oil change I'd start there though. Or if the problem showed up right after you did one, replace the oil filter (may be a defective pressure bypass in the filter).
What did the pressure used to be? Used to be 55 then dropped to 20 after 5 min? In other words is it a 30 PSI even gain? If so I'd look at wiring, might be getting extra resistance into the monitoring system from a poor connection.
Good luck.
07-15-2013 07:00 PM
dabnis
Re: Yanmar Oil Pressure Pegged

Quote:
Originally Posted by fryewe View Post
I'd pull the sender and clean it as a first step.
If you can get a mechanical gauge as a test you might try that before ripping into the engine pressure relief valve. Some oil filters, maybe all, have pressure relief or by-pass valves. Maybe try a different brand and make sure they meet the engine specs.

Paul T
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