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Another oil pressure thread


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My oil pressure gauge has always been above 40 & operates between that & 80. Suddenly today it is operating between 10-40 psi. The manual says 6-40 is normal. If that is normal why was it higher before? I replaced the sending unit over winter, I still have a new oil pressure sensor I need to slap on. But the boat ran fine, no issues, temp was normal. Checked oil, that was fine. Has me paranoid though?

Edited by racer808
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Hey 808!

Is the gauge bouncing around with no real rhyme or reason?

My gauge will work fine one day, then bounce around randomly the next, sometomes hitting 0, but bouncing right back up.

I am told this is usually a issue with the cannon plug that connects the wire harness to the engine.

Have not tried to fix it yet, but it is scary the first couple of times it happens.

Anyone else?

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No, no bouncing. I replaced the sender unit. It just all of sudden starting operating below 40, it used to always operate above. But everything seems to be running fine. Where is the canon plug?

Edited by racer808
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No, no bouncing. I replaced the sender unit. It just all of sudden starting operating below 40, it used to always operate above. But everything seems to be running fine. Where is the canon plug?

Could somebody take a pic of the canon plug Please.

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I can't, I don't have a boat. But I can tell you it looks like a canister that 35MM film came in. About that size. Usually held together with a hose clamp. So a 35mm film canister with a hose clamp around it. Real close to engine ECM. It's where the wiring of the engine by Indmar 'ends'.

Hope this helps...

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Thanks guys, as soon it dries a lil here this morning I am going to go check that out. My ADD screws me again, I have an oil pressure problem so when we get home from the lake I tear apart my amp rack so I can install the new ones & put a sub in. Priorities......

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Be careful to mark the plug and receptacle so that you can plug it back in the same way it comes out. Mine did not have a guide to prevent it from being plugged in differently

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You have a Monsoon, right? Then you have two oil pressure sensors. One sends signal to the gauge on the dash, the other sends signal to the ECM. The one that feeds the guage is the one with a single (brown, usually) wire going to it. They are both down by your oil filter.

Didn't know if you were aware of this or not.

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Mine has always been nuts(really high readings). Also goes crazy when the heater gets turned on along with the temp guage. I have checked all grounds,etc. I pretty much ignore it now.................I will check the plug.........

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You have a Monsoon, right? Then you have two oil pressure sensors. One sends signal to the gauge on the dash, the other sends signal to the ECM. The one that feeds the guage is the one with a single (brown, usually) wire going to it. They are both down by your oil filter.

Didn't know if you were aware of this or not.

I have the 5.7l, I think it is the monsoon. Yes I have two sensors, I replaced the signal send to gauge. Would the pressure sensor itself affect this? If I have no changes with pressure, what else do I check or when do I worry since it is running fine?

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No...the sensor feeding the ECM says YES/NO to the ECM as to whether or not you have 4 p.s.i. of oil pressure...or some number like that. Thats why the boat beeps when you turn the key on and have not started the engine yet.

I would put amechanical gauge on the engine, get a feel for the oil pressure, and not worry about it too much any more. It is sooo rare that an oil pump on your engine would ever fail, and the 'backup' sensor feeding the ECM would give you warning if it did. So, if a mechanical gauge shows good pressure, stop staring at the gauge on your dash and go have fun.

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  • 1 year later...

The pressure won mine 2010 With base engine, starts to have a lower pressure after about 30 hours from an oil change. Once I change the oil it is fine. This engine seems to,be pretty sensitive to fresh oil. Lucky changing the oil is a piece of cake if you have an extraction pump.

Kris

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I have the 5.7l, I think it is the monsoon. Yes I have two sensors, I replaced the signal send to gauge. Would the pressure sensor itself affect this? If I have no changes with pressure, what else do I check or when do I worry since it is running fine?

Yes, the sensor you changed is what the gauge uses to know what the oil pressure is. This is assuming you change the gauge sending unit (larger one) not the ECM sending unit (smaller one). I would have to double check (look at bakes resource center) but if i recall correctly the gauge sending unit works off of resistance. A certain resistance equals a certain psi of pressure. Your MDC takes that resistance and converts it into a code that the gauge uses to move the needle.

Two things to keep in mind.

1. the resistance measured is the resistance between the wire that connects to the sending unit and ground. When you put a new sending unit on you may have given it a better ground and that may have affected it. I don't remember the exact ohms and resistance for the oil sending unit off the top of my head. If you need more info let me know.

2. If you really want to make sure your safe then I would put a mechanical gauge on the motor and see how the mechanical gauge compares to the boat gauge.

Honestly your probably fine and it sounds like the new sending unit is a bit more accurate than the old one. Just my thought based on the limit number of boats I have been in with the monsoon.

Sent from my iPhone using Tapatalk

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Yes, the sensor you changed is what the gauge uses to know what the oil pressure is. This is assuming you change the gauge sending unit (larger one) not the ECM sending unit (smaller one). I would have to double check (look at bakes resource center) but if i recall correctly the gauge sending unit works off of resistance. A certain resistance equals a certain psi of pressure. Your MDC takes that resistance and converts it into a code that the gauge uses to move the needle.

Two things to keep in mind.

1. the resistance measured is the resistance between the wire that connects to the sending unit and ground. When you put a new sending unit on you may have given it a better ground and that may have affected it. I don't remember the exact ohms and resistance for the oil sending unit off the top of my head. If you need more info let me know.

2. If you really want to make sure your safe then I would put a mechanical gauge on the motor and see how the mechanical gauge compares to the boat gauge.

Honestly your probably fine and it sounds like the new sending unit is a bit more accurate than the old one. Just my thought based on the limit number of boats I have been in with the monsoon.

Sent from my iPhone using Tapatalk

Thats an old post, it was a loose ground

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My boat is a 2005 with the 320 engine. Instead of the dual sensor setup it has a single sensor. The "no pressure" started over a year ago but cleared up once the air temp warmed up. This year it hasn't so I t'd in a mechanical gauge which shows 50 psi at idle. I've searched for the 3-wire sensor and the only one that shows is at Bakes and it references an 1/8" connection, mine is 1/4". Does anyone have experience with this set up? With the 3-wire sensor I get the impression that the gauge reads voltage (https://www.m2omarine.com/resources/IndmarOilSensorVoltsVSpsi.pdf) not resistance.

Thanks

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