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Oil Pressure Gauge Install

14K views 7 replies 6 participants last post by  shadowman  
#1 · (Edited)
For those of you who have asked about my oil pressure gauge, here are a few pictures of the install.

First, the sensor end. The gauge is an Autometer 4353 full sweep electric gauge, and this picture is the sensor install. The sensor requires an M12x1.5 adapter to the 1/8NPT sensor. You also have to rotate it with an elbow because it will hit the side of the valve cover if you don't. If you disconnect the stock idiot light sender, you don't get a code but the light stops working. Watch the guage when you start the engine.



Second, getting the wire through the firewall. There's a rubber boot for the clutch fluid line and I just pushed a piece of 1/8 plastic hose through it (oil sampling hose) to act as a conduit for the wiring. The harness is long and has the gauge connector on one end and the sensor connector on the other. I cut the gauge wiring harness in the middle so I could put it through the small tube, and then reconnected it under the dashboard.



Third, the view from outside. The picture quality sucks but it gives a sense of what it looks like from outside. If I was to do it again, I'd put some sleeving on the wires so they weren't visible from outside.



Last, the driver's view (there's only one guage - the upper one is just a reflection caused by the camera flash on the inside of the windshield). Again, the picture isn't the greatest, but you can see what I see. Very visible, but out of the way. The guage is the same color as the dash instruments so it's ok visually. If I was to do it again, I'd pick the "ultra-lite" series of instruments - the lighting is better. It works fine as it is.



The guage is attached to the A-pillar cover (easy to remove, drill and reinstall - just keep the bolts as far forward as possible - you CAN clear the airbag very easily) and the wiring just runs around the edge of the dash by the door, and goes underneath the dash. The light wiring and the switched power and ground are available off the back of the combined instrument by tapping into the wires on the connector closest to the door.

Installing this is not a job for the uninitiated - it takes some courage and the tools and skills to lie upside down and solder wires together and shrink-wrap the result. That said, it's not complicated. The wiring to the instrument panel is the trickiest, and the Bently 5 series manual is handy for the wire colors to pick.
 
#2 ·
Nice. Thanks.

What pressures do you see at, say idle, 3k and redline- all at operating temp? What oil??

VDO makes a sender that has a pressure switch contact... anyone know what the pressure is for the stock contact?


A
 
#5 ·
Thanks for the feedback!

- I'm not sure about the VDO install - the gap between the fitting on the oil filter and the side of the valve cover isn't very big. If the sender's too tall, the engine will hit it, and that's bad. Also, the VDO guage has a 90 degree sweep and the one I chose has a 270 degree sweep. I've installed it so that 60 PSI is at the top and the needle sits straight up most of the time.

- I've tracked the pressure with different viscosities. Viscosity doesn't make a big difference, if any at all. Operating temp is far more important at idle. Once the oil's over about 70 degrees Celsius and you're off idle, it doesn't matter - the pressures stay within the range below. If there is a viscosity effect, it's that thicker oil yields a lower pressure for a given RPM, but the effect is small.

The curve with a fully warm engine is an envelope that looks like this:

18 to 22 PSI - idle
60 PSI - 1800 to 2200 RPM
70 PSI - 4000 to 5000 RPM
80 PSI - 5500 to 6000 RPM

The oil pressure tops out at 80 PSI, plus or minus a pound or two.

Cheers
JJ
 
#6 ·
Great info JJ. I need to get busy on this myself. Thanks for posting the thread and your info on this. Interesting note about pressure vs viscosity.
Mike

jaj said:
Thanks for the feedback! - I've tracked the pressure with different viscosities. Viscosity doesn't make a big difference, if any at all. Operating temp is far more important at idle. Once the oil's over about 70 degrees Celsius and you're off idle, it doesn't matter - the pressures stay within the range below. If there is a viscosity effect, it's that thicker oil yields a lower pressure for a given RPM, but the effect is small.

The curve with a fully warm engine is an envelope that looks like this:

18 to 22 PSI - idle
60 PSI - 1800 to 2200 RPM
70 PSI - 4000 to 5000 RPM
80 PSI - 5500 to 6000 RPM

The oil pressure tops out at 80 PSI, plus or minus a pound or two.

Cheers
JJ
 
#7 ·
270 deg sweep with an electric gauge is kick ***...

jaj said:
Thanks for the feedback!

- I'm not sure about the VDO install - the gap between the fitting on the oil filter and the side of the valve cover isn't very big. If the sender's too tall, the engine will hit it, and that's bad. Also, the VDO guage has a 90 degree sweep and the one I chose has a 270 degree sweep. I've installed it so that 60 PSI is at the top and the needle sits straight up most of the time.

- I've tracked the pressure with different viscosities. Viscosity doesn't make a big difference, if any at all. Operating temp is far more important at idle. Once the oil's over about 70 degrees Celsius and you're off idle, it doesn't matter - the pressures stay within the range below. If there is a viscosity effect, it's that thicker oil yields a lower pressure for a given RPM, but the effect is small.

The curve with a fully warm engine is an envelope that looks like this:

18 to 22 PSI - idle
60 PSI - 1800 to 2200 RPM
70 PSI - 4000 to 5000 RPM
80 PSI - 5500 to 6000 RPM

The oil pressure tops out at 80 PSI, plus or minus a pound or two.

Cheers
JJ