oil pressure gauge problem

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S

Sanders LaMont

I'm looking for advice on what I need to do to repair/replace my oil pressure gauge on my Yanmar 30. The gauges are located in an aft-facing panel below the companionway door, and the wiring drops down into the engine compartment to the sensor. The gauge failed initially by pegging off the chart, often resting in the middle, and being completely inconsistent. (The warning lights/buzzer did not go off). I tried cleaning contacts, but it did not seem to help. The engine was checked and is workng fine, but the gauge is almost. but not completely, dead. How do I determine if I need to replace the entire gauge, wiring and sensor, or just one piece of it? The other gauges (temp, tach, voltage) seem to be fine. The panel, and instruments are about 20 years old, behind glass outside but easily accessable from the rear. I would appreciate suggestions, including a step by step explanation of how to isolate ther problem. I assume I can find the parts through Yanmar once it is identified. Thanks Sanders s/vGood News H37cutter
 

Rick D

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Jun 14, 2008
7,186
Hunter Legend 40.5 Shoreline Marina Long Beach CA
LaMont, I Have One

That is, an oil pressure guage from a 1994 Hunter. Check with some other Hunters of that vintage to see if it's the same. If it is, its yours. However, I replaced mine only to find the new sending unit that was installed previously was defective. Another sending unit fixed the problem. You can send me an e-mail through the owners' directory. Rick Dinon
 
E

Ed Schenck

VDO?

My panel and gauges are from VDO('79 H37C). I checked their site once and found prices to be very reasonable. I think you would want to get a new sender unit from Torresen or Mack Boring. But only if Rick's freebie doesn't fit. A 3QM30, right?
 
E

Ed Schenck

VDO?

My panel and gauges are from VDO('79 H37C). I checked their site once and found prices to be very reasonable. I think you would want to get a new sender unit from Torresen or Mack Boring. But only if Rick's freebie doesn't fit. A 3QM30, right?
 
S

Sanders LaMont

thanks rick and ed

Thanks a lot. I will check the boat in about ten days and get the specifics I need to respond to your suggestions. I am poretty sure they are VDOs but want to check and make sure. Is there a way to test if it is the sender or the gauge itself? Thanks again, S.
 
S

Sanders LaMont

thanks rick and ed

Thanks a lot. I will check the boat in about ten days and get the specifics I need to respond to your suggestions. I am poretty sure they are VDOs but want to check and make sure. Is there a way to test if it is the sender or the gauge itself? Thanks again, S.
 

Rick D

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Jun 14, 2008
7,186
Hunter Legend 40.5 Shoreline Marina Long Beach CA
LaMont, I wish I Knew

The best way is to have someone check it with a mechanical guage. Since I replaced the wrong thing first, I am no good reference. However, the sending units typically go out first. Rick D.
 

Rick D

.
Jun 14, 2008
7,186
Hunter Legend 40.5 Shoreline Marina Long Beach CA
LaMont, I wish I Knew

The best way is to have someone check it with a mechanical guage. Since I replaced the wrong thing first, I am no good reference. However, the sending units typically go out first. Rick D.
 
R

red coles

DIY

If the guage is electrical, you can make a simple resistance test of the sender unit. At the sender unit, remove lead from meter. Hook up an ohmeter with one lead on ground and the other on on the sender terminal. With engine running, start on a high scale and reduce scale 'till you get close to mid range reading. Throttle the engine up and down and the meter reading should change, more or less linear. If it doesn't change sender. If it does, remove test leads, reconnect sending wire and move test leads to other end of wire at the guage. If OK here also, replace meter. Good luck red
 
R

red coles

DIY

If the guage is electrical, you can make a simple resistance test of the sender unit. At the sender unit, remove lead from meter. Hook up an ohmeter with one lead on ground and the other on on the sender terminal. With engine running, start on a high scale and reduce scale 'till you get close to mid range reading. Throttle the engine up and down and the meter reading should change, more or less linear. If it doesn't change sender. If it does, remove test leads, reconnect sending wire and move test leads to other end of wire at the guage. If OK here also, replace meter. Good luck red
 
F

Fred

oil pressure gauge

On an electric gauge you can tell which part is not working by; turning the key to the on position, take the wire off the sending unit, ground the wire to the engine(where there is no paint like a bolt). The needle on the gauge should go all the way to the right(highest pressure). This indicates the gauge is OK and the sending unit is bad. In replacing the sending unit it must match to the gauge by brand. If the wire is bare and touching a ground, it will give false readings(most common problem). Another solution is to get a manual gauge and use small copper line to feed the gauge. These are bullet proof and last forever. Fred
 
F

Fred

oil pressure gauge

On an electric gauge you can tell which part is not working by; turning the key to the on position, take the wire off the sending unit, ground the wire to the engine(where there is no paint like a bolt). The needle on the gauge should go all the way to the right(highest pressure). This indicates the gauge is OK and the sending unit is bad. In replacing the sending unit it must match to the gauge by brand. If the wire is bare and touching a ground, it will give false readings(most common problem). Another solution is to get a manual gauge and use small copper line to feed the gauge. These are bullet proof and last forever. Fred
 
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