stephen newberg
SHO Member
The display characteristic for my oil pressure gauge has, for the last couple of months, been that it has started reading lower than it should for the driving situation and the corresponding oil temperature. First it started reading about 10 lb. low and did that for a month or so, and then it started reading 20 lb. low. At this point I started getting concerned it might be the oil pump, but the car only has 105,000 km (about 65,000 miles) on it, so this did not seem likely. Kirk had told me he had recently started getting similar readings.
Well, a couple of weeks ago I took the SHO on the first long trip since the strange readings started, and in long highway stretches you could watch it run the indicated pressure down to zero. Since it was obvious by the fact that the car was not dead that, in fact, there was oil pressure, l became convinced that it really was likely the oil pressure sender at this point. A slow decline in a reading like that with no other indications of change is normally the kind of thing one sees in a breaking down resistor or capacitor as heat builds up and it stops providing the correct range of current to the circuit for an electrical sender.
So, I went to the local speed shop to order a new sender. The instrument is an old Borg Warner that I had around when I made my instrument cluster 4 years ago. At the time I had it and another old Borg Warner voltmeter, and I ordered in new Autometer oil temp and transmission temp instruments. Turns out the old oil pressure gauge and its sender have not been made for years. So, with some concern about matching problems, I ordered a sender from Autometer for the same range instrument (0-100lb). Very fast delivery, and I put it in on Thursday. The location of the sender is rather tight, just above the oil filter, but if you can get under the car, there is just enough room to swing an open end wrench.
Of course, there were a different number of connections. The old Borg Warner sender was a two wire type, while the new Autometer was a single wire. So I figured out which was ground and put in a ground connection for that wire to go back to the instrument, while connecting the signal wire to the new sender. And, as expected, the match was not correct. It was a 1-2, so that it read out as 10-60 lbs., instead of 0-100. No big deal, except that it reads in reverse!
Apparently the Borg Warner people were reading on the opposite slope as the Autometer people, so now a declining current is provided rather than a rising one. Pretty strange to watch the oil pressure start at 10 lbs. and, as the car warms up, 'decline' to an operating level of 30 lbs., go to 50 lbs. at idle, and, as you punch the throttle, watch the needle go down rather than up.
Anyway, it is all understandable, in reverse, and I may just get used to it, or it may start to irritate me and I will have to buy a matching Autometer instrument to go with my Autometer sender so as to get the needle moving in the right direction. Funny, eh?
pax, smn
Well, a couple of weeks ago I took the SHO on the first long trip since the strange readings started, and in long highway stretches you could watch it run the indicated pressure down to zero. Since it was obvious by the fact that the car was not dead that, in fact, there was oil pressure, l became convinced that it really was likely the oil pressure sender at this point. A slow decline in a reading like that with no other indications of change is normally the kind of thing one sees in a breaking down resistor or capacitor as heat builds up and it stops providing the correct range of current to the circuit for an electrical sender.
So, I went to the local speed shop to order a new sender. The instrument is an old Borg Warner that I had around when I made my instrument cluster 4 years ago. At the time I had it and another old Borg Warner voltmeter, and I ordered in new Autometer oil temp and transmission temp instruments. Turns out the old oil pressure gauge and its sender have not been made for years. So, with some concern about matching problems, I ordered a sender from Autometer for the same range instrument (0-100lb). Very fast delivery, and I put it in on Thursday. The location of the sender is rather tight, just above the oil filter, but if you can get under the car, there is just enough room to swing an open end wrench.
Of course, there were a different number of connections. The old Borg Warner sender was a two wire type, while the new Autometer was a single wire. So I figured out which was ground and put in a ground connection for that wire to go back to the instrument, while connecting the signal wire to the new sender. And, as expected, the match was not correct. It was a 1-2, so that it read out as 10-60 lbs., instead of 0-100. No big deal, except that it reads in reverse!
Apparently the Borg Warner people were reading on the opposite slope as the Autometer people, so now a declining current is provided rather than a rising one. Pretty strange to watch the oil pressure start at 10 lbs. and, as the car warms up, 'decline' to an operating level of 30 lbs., go to 50 lbs. at idle, and, as you punch the throttle, watch the needle go down rather than up.
Anyway, it is all understandable, in reverse, and I may just get used to it, or it may start to irritate me and I will have to buy a matching Autometer instrument to go with my Autometer sender so as to get the needle moving in the right direction. Funny, eh?
pax, smn
