Oil pressure gauge working backwards
Discussion
Well I have just fitted a new oil pressure sender to replace the old one that had fallen apart, and it seems to work fine although backwards!
With the ignition on it shoots to 90psi, then when starting the engine returns back to the middle of the guage and gets lower when revving
At least I have an indication of oil pressure now but does anyone know how to fix this? Its an aftermarket sender with its own earth and I have tried swapping the cables but to no effect.
With the ignition on it shoots to 90psi, then when starting the engine returns back to the middle of the guage and gets lower when revving
At least I have an indication of oil pressure now but does anyone know how to fix this? Its an aftermarket sender with its own earth and I have tried swapping the cables but to no effect.
It could be that the sender has a low oil pressure warning switch output. This might explain why you see full scale and then a measured value once running.
Try connecting the usual sender wire to one terminal on the sender and leaving the earth wire off as it may earth through the sender body.
Did the supplier confirm that it is directly compatible with an original gauge.?
Try connecting the usual sender wire to one terminal on the sender and leaving the earth wire off as it may earth through the sender body.
Did the supplier confirm that it is directly compatible with an original gauge.?
No its an eBay special so no big loss if I have to try a different one. Its the only one i could find though that actually had the correct resistance range for the TVR gauge after reading through the other threads about them.
This is the one:
http://www.ebay.co.uk/itm/171235774056?_trksid=p20...
Just had a thought, It has an external ground but maybe i should try fitting it without PTFE on the threads. If it does ground through the body maybe I have screwed that up
This is the one:
http://www.ebay.co.uk/itm/171235774056?_trksid=p20...
Just had a thought, It has an external ground but maybe i should try fitting it without PTFE on the threads. If it does ground through the body maybe I have screwed that up
Seem to be notoriously unreliable
One in my last car used to tick over nicely and rise a little on revs BUT when you came back to a tickover the pressure used to hit the top (90?)
Return on revs to a more likely pressure.
So I bought an ebay special
Was even worse than the original
Current car works ok though.
One in my last car used to tick over nicely and rise a little on revs BUT when you came back to a tickover the pressure used to hit the top (90?)
Return on revs to a more likely pressure.
So I bought an ebay special
Was even worse than the original
Current car works ok though.
I'm very new to the site, so my apologies for late comment. The "Oil Pressure gauge Working Backwards" problem occurred on my boat - I eventually found the problem. The sender was fine (Not "duff" - as a previous respondent suggested. Indeed, if the meter reading varies at all, the sender is - by definition - working); and the gauge was fine. BUT, it took a long time to discover is that US gauges and Euro gauges work on different protocols. Euro Gauges work on ASCENDING electrical resistance as the oil pressure increases; USA gauges work with DESCENDING resistance as the oil pressure increases. The gauge is in essence a resistance meter - hence the "back-to-front" reading. So, the sender may be fine, and the gauge may be fine, but they must both be either Euro or USA.
And you get a similar issue with US and Euro temp gauges. Both work with decreasing resistance as the temperature rises; but with differing values (USA - 100 deg F = 450 ohm; 175 deg F = 99 ohm; Euro - 40 deg C = 281 ohm; 80 deg C = 68 ohm). Again, the sender and the gauge need to be the same protocol, otherwise there's a false reading.
Hope this all makes sense!
Cheers
And you get a similar issue with US and Euro temp gauges. Both work with decreasing resistance as the temperature rises; but with differing values (USA - 100 deg F = 450 ohm; 175 deg F = 99 ohm; Euro - 40 deg C = 281 ohm; 80 deg C = 68 ohm). Again, the sender and the gauge need to be the same protocol, otherwise there's a false reading.
Hope this all makes sense!
Cheers
AndrewPoole said:
I'm very new to the site, so my apologies for late comment. The "Oil Pressure gauge Working Backwards" problem occurred on my boat - I eventually found the problem. The sender was fine (Not "duff" - as a previous respondent suggested. Indeed, if the meter reading varies at all, the sender is - by definition - working); and the gauge was fine. BUT, it took a long time to discover is that US gauges and Euro gauges work on different protocols. Euro Gauges work on ASCENDING electrical resistance as the oil pressure increases; USA gauges work with DESCENDING resistance as the oil pressure increases. The gauge is in essence a resistance meter - hence the "back-to-front" reading. So, the sender may be fine, and the gauge may be fine, but they must both be either Euro or USA.
And you get a similar issue with US and Euro temp gauges. Both work with decreasing resistance as the temperature rises; but with differing values (USA - 100 deg F = 450 ohm; 175 deg F = 99 ohm; Euro - 40 deg C = 281 ohm; 80 deg C = 68 ohm). Again, the sender and the gauge need to be the same protocol, otherwise there's a false reading.
Hope this all makes sense!
Cheers
There are numerous different specs for senders - even "Euro Standard" temperature senders have high and low range variants! It's a bugger finding the right ones...And you get a similar issue with US and Euro temp gauges. Both work with decreasing resistance as the temperature rises; but with differing values (USA - 100 deg F = 450 ohm; 175 deg F = 99 ohm; Euro - 40 deg C = 281 ohm; 80 deg C = 68 ohm). Again, the sender and the gauge need to be the same protocol, otherwise there's a false reading.
Hope this all makes sense!
Cheers
Phil
The answer is in the ebay description.
Yours is 10-180 Ohms.
They then list.
We also have the following type:
0-100psi,240-33 ohms output;1/8"-27NPT;
0-100psi,240-33 ohms output;1/8"-27NPT;low 11psi alarm/warning switch;
0-150psi,10-180 ohms output;1/8"-27NPT;low 11psi alarm/warning switch;
So you need something like the first one of the options where the resistance is falling rather than rising.
However, you do need to make sure the sender psi/bar rating matches your gauge. I suspect it is Caerbont so contact them/speedy cables and get them to tell you/sell you the right sender.
Steve
Yours is 10-180 Ohms.
They then list.
We also have the following type:
0-100psi,240-33 ohms output;1/8"-27NPT;
0-100psi,240-33 ohms output;1/8"-27NPT;low 11psi alarm/warning switch;
0-150psi,10-180 ohms output;1/8"-27NPT;low 11psi alarm/warning switch;
So you need something like the first one of the options where the resistance is falling rather than rising.
However, you do need to make sure the sender psi/bar rating matches your gauge. I suspect it is Caerbont so contact them/speedy cables and get them to tell you/sell you the right sender.
Steve
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