I'm starting to gather that my new VDO oil pressure gauge might not be all that great. Tonight (first time out at night) it was reading near 0lbs at idle, but the idiot light was not coming on (dual pole sender). Normally I see somewhere between 7-10lbs on the gauge when hot. My suspicion is that the voltage was lower (at idle) to the gauge because the headlights and what not were on.

I seem to remember RatWell saying these gauges weren't all that accurate, but being off by 10lbs is just silly. Gauge perked right up off idle and gave me well over 10lbs per 1K rpm. Are there any gauges that might be more accurate at the lower rpms than these? Aircraft Spruce is my favorite vendor for this stuff, but nothing they sell has any low PSI resolution in an electric gauge.

I just bought a set of aem electronic gauges for my daily car. They have a digital readout which should be more reliable than traditional styles. Only problem is they are wired from the factory so will need to be cut and extended

One of the VW mags did a gauge comparison and pretty muchevery time, STACK came out on top. They're more expensive, but quality costs.

They have them on Summit, here. This one is $220, but they also have a $77 version although I'm not sure how they compare quality-wise.

The cheaper stack range do not use the stepper motor gauge which is what they are known for. Awesome gauges. Their tachos are meant to be great

(sorry to hijack)

Would you lose the idiot light if you were to use the Stack gauge and sender ???

There's no need to lose the light. Add a tee on the end of the extension hose so both the stock sender and gauge sender can be installed.

Longacre makes stepper pressure guages and tachs well.

http://www.speedwaymotors.com/Longacre-465...CFcuh4AodvVcAtA

They can't be the only ones. They're wonderful IMO. I haven't used one so I don't know if it uses the analog sending unit.

OT Alert: Now, a stepper tach in an 8K motor? Oh yeah. With data-logging. Now that's useful, especially good for spotting secondary overruns (downshift overrevs). DME units have tracked that kind of thing for many years. I don't know if my 1995 unit does.

Make sure you have a good ground from the sender unit to chassis.

Or to be even more accurate, run a dedicated ground from the sender to the gauge, then ground that wire to chassis as close to the gauge as possible. I am building a new harness this weekend, and you just made me decide to add a couple of extra wires just for that purpose.

Stu

https://www.youtube.com/watch?v=SUiOMwF9j_I

Wonder if something like this is the hot ticket:

http://www.powerstream.com/dc12-12-8A-isolated.htm

Expensive, but cheaper than new gauges.

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There's no need to lose the light. Add a tee on the end of the extension hose so both the stock sender and gauge sender can be installed.
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Example of what Chris said in photo.
Click to view attachment.
But, I would be concerned that the idiot light was not triggered by the VDO. Most complaints are that the VDO triggers the idiot light at higher pressure than the idiot would normally trigger on it's own. If your idiot light is not lighting when you crank the car then it's not getting a signal from the VDO. From the installation shown in the photo, you get two independent opinions, one from the VDO sender and a second from the idiot light which is no longer dependent on the VDO sender

I ran into almost the same thing on my little diesel. When Hot the light would come on. I figured it was the sender,changed it and had the same problem. I read the vdo senders came on at 7.5 lbs and stock came on at 5?

So I tested the engine with a manual gage and holly crap 6lbs at idle hot. Not good for a turbo motor. I ended up adding an oil cooler with thermal plate and blue printing the oil pump. (oil temp was in the 230-240 range)

I would recommend seeing if a local hydraulic shop can loan you a manual gage and check at idle. the one i used was like 6 inch dia and only went to 30lbs.


jcl

I think I've managed to confuse the issue... The idiot light didn't come on because there isn't a pressure problem. The idiot light is not affected by voltage variances, where the gauge is. The gauge is basically nothing more than a calibrated volt meter hooked up to a variable resistor. As voltage goes down, be it by the resistor (sender) or by the overall voltage in the car, the gauge will go down - as shown in the video by me turning on the headlights.

I'd either need to stabilize the voltage to get consistent, but not necessarily accurate gauge reedings, or use a gauge that has the ability to use a reference voltage.

I never worried about oil pressure, head temp, etc. until I got gauges.
My VDO does some funny things too. I have good oil pressure on the freeway; 3k rpm and 60psi, but it will randomly drop down to 20psi and then after a minute it will go back to 60psi. It annoys the hell out of me and I just tell my self it's a gauge issue and not a problem with the engine. Not so sure I want to drop $200 on another gauge to eliminate the issue....