gauges working properly

[shirleymac]

What is the best way to check that the oil temp and oil pressure gauges are working correctly?

I have VDO gauges and the oil temp does not move off the peg even after the engine has been run. My oil pressure gauge shows around 50 lbs at idle. I read the section on oil pressure in the Getting Started in Formula Vee book said that good pressure at 3000 rpm's should be 25 + lbs.

I let the car run today for about 5 minutes it was idling at 2,000 rpm's and the temp gauge did not move. I've run two solo events and noticed that the temp gauge was not reading a temp. Before my next time out I want to make sure everything is working correctly. Any suggestions on troubleshooting?

[Dietmar]

It would be safe to say that you should have at least three wires at the back of the gauge: one is marked "G" or "S" for sender , the second is a "+" for power, and the third a minus for ground. There could be a 4th terminal for a lamp inside the gauge, but that is of no use and therefore does not need to be connected. When you turn on the ignition switch, the needle should jump just a bit off zero and then return to zero.
5 minutes at idle and you should see some temps

Oil pressure according to VW is 27 # at 2700 RPM with the engine warm (can't remember the exact temp), but that is after the pressure relief valve opens. It is not unusual to see 50-60 # at idle depending on your plumbing arrangement and then it drops to 40 once the relief valve opens and even to 30 when running warm (hot) oil.
Hope this helps
Dietmar

[smsazzy]

Boil some water and put your temp guage in it......

[FVartist]

Check for continuity at the gauge. Make sure you have a good ground, make sure there is power to the gauge and that there is no open between the gauge and the sending unit. If all is good disconnect wiree from sender and with power on ground wire, the gauge needle should go all the way over, if it doesn't the gauge is bad, if it does the sender is.

[shirleymac]

Thanks for the information. I'm still trying to find the time to check everything out, but I did go out and tried turning the ignition on and the needle did jump and go back to zero. When I disconnected the wire from the sender and grounded it to the frame the needle jumped all the way to the left. So I'm assuming that the sender may be bad. I'm going to try the boiling water next to see if that shows anything.

[SR Racing]

If it's more convenient, you can just warm the sender with a lighter or benzomatic type torch. That will tell you if it's working at all. For calibration the water works best. IE At full boil it should read ~212F

Jim

[Lynn]

The boiling point of water decreases by about 0.95 degree F for each 500 feet in elelvation above sea level. That could be important if the tester is in Colorado Springs, Flagstaff, etc.

[shirleymac]

Well I finally had a chance to check the temperature sender--I tried the lighter method. With heat on the sender for a couple of minutes and the gauge not moving off the peg, I'm assuming the sender is bad. My next question is does SR Racing carry a replacement that will work on my car? The sender has these marking on it VDO, 12 93, 6 24V, 150ºC, 801/9/1. The car is set up with a slide-on type electrical connection.

As far as calibrating the gauge, since I don't have any manuals for them is there somewhere on the internet to get that information?

Thanks for all the help.
Tony

[SR Racing]

Yes, we have the correct sender for you..

Jim
SR
859-252-2496