Mercruiser 5.7 MAG MPI Water Pressure Sensor & Oil Pressure Sensor Interchange/Alternatives + 4 in 1 gauge not showing speed and oil pressure

[mckaras]

Anyone have any luck finding alternatives to those sensors mentioned above?

881879T11 Oil pressure sensor

881879T10/881879010 Water pressure sensor

I have an issue on my Chaparral 236SSX with a 5.7 MAG MPI where the 4 in one gauge is not showing any oil pressure or showing any speed on the gauge. I already have a brand new oil pressure switch 8M0068784 which I'm assuming will show me oil pressure when replaced if the old one is defective?

The only code I'm getting is popping up for Pitot Pressure. It doesn't throw my engine into limp mode at all.

 

[Stinnett21]

You mean alternatives to OEM? I would buy OEM sensors. Aftermarket is asking for trouble.

 

[alldodge]

Part number 8M0068784 is the oil pressure sensor, an I'll bet a beer it's not you problem. Those 4 in 1 gauges are crap and don't last. The oil pressure gauge is not connected to the ECM, another sensor is used for that

The speed not working is most likely the pitot tube is clogged. If you have a Bravo drive there is a small hole on the front edge of the drive. Use a small drill bit and manually clean the hole out, don't use a drill

 

[Scott Danforth]

the gauge manufacturer often supplies the sending units. however SMP (Standard Motor Products), Little River and BWD are OEM tier 1 suppliers.

links to their catalogs are in the electrical stickies.

if 2 or more of the gauges are not reading, my bet is the gauge. is bad. check the grounds and the daisy chained ignition lead

 

[mckaras]

the gauge manufacturer often supplies the sending units. however SMP (Standard Motor Products), Little River and BWD are OEM tier 1 suppliers.

links to their catalogs are in the electrical stickies.

if 2 or more of the gauges are not reading, my bet is the gauge. is bad. check the grounds and the daisy chained ignition lead

The oil pressure on the 4 in 1 gauge is not showing up and the speedo gauge is a separate gauge where I don't have the speed showing up alongside with the Pitot Pressure Sensor fault.

 

[mckaras]

Part number 8M0068784 is the oil pressure sensor, an I'll bet a beer it's not you problem. Those 4 in 1 gauges are crap and don't last. The oil pressure gauge is not connected to the ECM, another sensor is used for that

The speed not working is most likely the pitot tube is clogged. If you have a Bravo drive there is a small hole on the front edge of the drive. Use a small drill bit and manually clean the hole out, don't use a drill

I figured it may be a clogged pitot hole in the bravo drive, it has been a while since I have taken the boat out and it's been sitting winterized. I'll have to check in with gauge saver and see if they're able to repair it. The oil pressure on that gauge itself doesn't even move when it's off or on. You don't think the pitot pressure sensor code I'm getting is related to no speed showing up?

 

[mckaras]

You mean alternatives to OEM? I would buy OEM sensors. Aftermarket is asking for trouble.

Well, alternatives but made in the US. I was able to find on neweagle.net the OEM Quicksilver/Merc sensor for the water pressure for cheap but the oil sensor I had no luck since they're out of stock and only have the 0-150 PSI sensors which have a different plug. Now even the Merc/Quicksilver ones are made in China. I bought two of them off Amazon from Quicksilvers store to save $40 a piece from the marina. Still rang in at $160ish or so a piece.

 

[mckaras]

Part number 8M0068784 is the oil pressure sensor, an I'll bet a beer it's not you problem. Those 4 in 1 gauges are crap and don't last. The oil pressure gauge is not connected to the ECM, another sensor is used for that

The speed not working is most likely the pitot tube is clogged. If you have a Bravo drive there is a small hole on the front edge of the drive. Use a small drill bit and manually clean the hole out, don't use a drill

Is there anyway to check to see if the speedo is working when it's on a trailer? I'm assuming maybe I can use a hose to blast water into that hole on the bravo drive and see if it works?

In regards to the oil pressure I have the smartcraft bluetooth device installed, I'll have to check if it's popping up on there if it has the option.

 

[Fun Times]

Confusing as this may be, you'd have to check and see if the pitot pressure sensor is actually present on the boat and connected to the wiring harness which is usually towards the stern of the boat inside.... If the pitot pressure sensor is not connected then you would normally see a fault code when connected to an engine scan tool as a default but also ignored by way of not sounding a warning horn... If the pitot pressure sensor is there and connected up to be used, then there may be an issue with the sensor or maybe even clogged up with debris somewhere.

To test, you could use a low pressure of an controlled air source and blow some air in the small hole at the leading edge of the stern drive and see if the gauge is working.

There is/should be also a yellow plastic fitting that needs to be installed often left off after drive servicing.

I believe gauge saver in Florida might be able to repair gauges such as yours as most probable it's going to be a faulty gauge vs sending unit,

Mercury 4" - 4-in-1 Analog Device Restoration Services - GaugeSaver

New Lens Replacement: $75.00 NEW Chrome/Black/White Bezel $35.00.

gaugesaver.com

 

[Stinnett21]

I know you want things working but I gave up on the pitot tube system years ago. Block the fault and be done with it. Speed is now measured via GPS. Leave the hole on the lower unit clogged it will create less drag.

 

[mckaras]

Confusing as this may be, you'd have to check and see if the pitot pressure sensor is actually present on the boat and connected to the wiring harness which is usually towards the stern of the boat inside.... If the pitot pressure sensor is not connected then you would normally see a fault code when connected to an engine scan tool as a default but also ignored by way of not sounding a warning horn... If the pitot pressure sensor is there and connected up to be used, then there may be an issue with the sensor or maybe even clogged up with debris somewhere.

To test, you could use a low pressure of an controlled air source and blow some air in the small hole at the leading edge of the stern drive and see if the gauge is working.

There is/should be also a yellow plastic fitting that needs to be installed often left off after drive servicing.

I believe gauge saver in Florida might be able to repair gauges such as yours as most probable it's going to be a faulty gauge vs sending unit,

Mercury 4" - 4-in-1 Analog Device Restoration Services - GaugeSaver

New Lens Replacement: $75.00 NEW Chrome/Black/White Bezel $35.00.

gaugesaver.com

Understood, I may as well just replace it with a new one and check if fixes the fault. The pitot hole on the lower wasn't clogged miraculously. I'm assuming all that's left is that sensor as it was in brackish/fresh water. The manifolds and riser only had 182 hours on them and they were in appearance good but as soon as taking them apart they were terrible. More than likely that sensor is fried or clogged. Luckily I just had a replacement come in.

I'm waiting on gauge saver to give me a call back, I called them a few days ago to fix the digital gauge I have on this boat with a bad LCD. Looks like they'll make a few more bucks with the other gauge I'll send in.

 

[Scott Danforth]

The water pressure sensor is not rated for water. It's an oil pressure sensor. It's been covered before. Search the forums

 

[mckaras]

The water pressure sensor is not rated for water. It's an oil pressure sensor. It's been covered before. Search the forums

Which one? The one I mentioned in the beginning? I'm talking about the one that's on the power steering cooling in the diagrams. 881879T10/881879010

Here's what I'm talking about. https://www.mercruiserparts.com/mercury-mercruiser-71-8m0157742-sensor-p

You did help me just now solve what I was looking for. Google results as always confused the two. I mistakenly ordered the water pressure sensor instead of the Mercury Boat Smartcraft Pitot Sensor 8M0090447...

 

[mckaras]

I know you want things working but I gave up on the pitot tube system years ago. Block the fault and be done with it. Speed is now measured via GPS. Leave the hole on the lower unit clogged it will create less drag.

How did you set up the GPS with the smartcraft gauge out of curiosity if gaugefinder can't fix my gauge? Any idea which NMEA it is 2000 or 0183? I don't have a GPS on the boat but I have seen that it's a possibility to set it up with a GPS puck/receiver.

 

[Scott Danforth]

GM truck oil pressure sensor.

 

[Scott Danforth]

the specific mercruiser part shown in the pictures is a Danfoss HVAC pressure switch.

the 075G1034 is the Danfoss part number

The second number is a specific lot number

 

[mckaras]

the specific mercruiser part shown in the pictures is a Danfoss HVAC pressure switch.

the 075G1034 is the Danfoss part number

The second number is a specific lot number

View attachment 409562

View attachment 409563

Awesome, thank you! The quicksilver one I just got in is identical.

 

[mckaras]

Any of you guys know if there's a place that repairs these smartcraft gauges? The 4 in 1 gauge I have 780903SDFB I cannot find anywhere for the life of me... The ones on greatslakeskipper doesn't have the functions I need, which are oil pressure, temperature, trim, and volts. The ones they have are oil pressure, volt, fuel, and coolant temp... There's one on ebay that has the right ones but they are on opposite sides. would it be plug and play for that gauge or will I need to cut/splice/swap wires around for the plug? @alldodge @Scott Danforth @Fun Times

I also replaced the pitot sensor and blew compressed air into the connected sensor, needle did not even budge on the speedo whatsoever... I'm assuming the gauge is faulty unless I did it incorrectly. Pitot tube itself isn't blocked, I blew air through it. Luckily I found the correct gauge for the speedo in stock.

The code I'm still getting is 451-25. Pitot pressure/The input circuit for the sensor is below the valid limit

 

[mckaras]

Any of you guys know if there's a place that repairs these smartcraft gauges? The 4 in 1 gauge I have 780903SDFB I cannot find anywhere for the life of me... The ones on greatslakeskipper doesn't have the functions I need, which are oil pressure, temperature, trim, and volts. The ones they have are oil pressure, volt, fuel, and coolant temp... There's one on ebay that has the right ones but they are on opposite sides. would it be plug and play for that gauge or will I need to cut/splice/swap wires around for the plug? @alldodge @Scott Danforth @Fun Times

I also replaced the pitot sensor and blew compressed air into the connected sensor, needle did not even budge on the speedo whatsoever... I'm assuming the gauge is faulty unless I did it incorrectly. Pitot tube itself isn't blocked, I blew air through it. Luckily I found the correct gauge for the speedo in stock.

The code I'm still getting is 451-25. Pitot pressure/The input circuit for the sensor is below the valid limit

Update, disconnected pitot tubing from the Speedo... It works but pitot hole is clogged somewhere farther in the drive. I tried blowing air into it and it does not budge at all. At least the speedo issue is fixed after I get this salt/calcium/whatever it is blocking the drive pitot hole out.

I'm curious whether or not I would be able to fix the 4 in 1 gauge myself. I would not know the first thing on where to source parts for it unfortunately. I checked with my Rinda tool and I have oil pressure so I know either or sensors are good.

 

[alldodge]

There's one on ebay that has the right ones but they are on opposite sides. would it be plug and play for that gauge or will I need to cut/splice/swap wires around for the plug?

No idea, but I would not buy anything like this on ebay without a blue ribbon guarantee