Oil Pressure Sender
Discussion
spend said:
Thanks Spend.Just to be 100% sure I have understood you correctly, if I order the following item from greengauges:
Oil Pressure Transducer, 1/8 x 27 NPT, 140psi or 10 bar
It will definitely be the correct one for my 1996 serp Chim with Caerbont white gauges?
If so, we have a winner at £47.09 including VAT & carriage.
A saving of £15.67 over the cheapest TVR parts supplier I could find.
Dave.
phillpot said:
Ebay 
....... any good ?
Thanks Phillpot, I did look at that one but without knowing the resistance its hard to say if it will give the correct reading........ any good ?To me an oil pressure sender like this should cost about £20, being forced to pay in the region of £50.00 seems a rip off.
The Ebay one comes in a £13.90 so if it works its ideal.
Certainly the thread looks to be correct (1/8 NPT) but it's unclear if it's going to be an acceptable match to my gauge.
I've read a lot about how unreliable the TVR sender is, mine didn't take too kindly to the extra oil pressure generated by the recent double oil pressure relief spring mod.
Spend kindly linked me to one from Greengauges that has a resistance range of 10-180 Ohms.
If the original sender paired with the Caerbont white gauge genuinely works at a range of 10-180 Ohms Spend's one is a good option.
However if the Ebay one works at 10-180 Ohms would be a real bargain.
Has anyone measured the resistance of the original Caerbont white gauge sender?
If so please share, your results would be really helpful to us all.
I will contact the Ebay seller to see if I can get the resistance range on the £13.90 option.
In the mean time if anyone has found a good value sender that definitely works correctly with the white Caerbont oil pressure gauge can they please let us all know the details.
Thanks everyone, Dave.
Its just struck me that the Greengauges sender operates from 0-140 psi.
However my white Caerbont gauge reads from 0-90 lbs.
There seems to be two common PSI ranges on the market:
1) 0-140 psi
2) 0-80 psi
They all seem to operate on the 10-180 Ohms range, so as long as I get the right thread (1/8 x 27 NPT) its just a case of whether its a 0-140 psi or a 0-80 psi pressure range sender.
To me a 0-80 psi sender would be a closer match to my gauge that reads 0-90 psi?
In which case something like a single terminal VDO Oil Pressure Sender 80psi / 5 Bar would be the one to go for?
Thoughts?
However my white Caerbont gauge reads from 0-90 lbs.
There seems to be two common PSI ranges on the market:
1) 0-140 psi
2) 0-80 psi
They all seem to operate on the 10-180 Ohms range, so as long as I get the right thread (1/8 x 27 NPT) its just a case of whether its a 0-140 psi or a 0-80 psi pressure range sender.
To me a 0-80 psi sender would be a closer match to my gauge that reads 0-90 psi?
In which case something like a single terminal VDO Oil Pressure Sender 80psi / 5 Bar would be the one to go for?
Thoughts?
Edited by Chimpafrolic on Wednesday 30th March 00:50
spend said:
VDO & Smiths senders are the two main different standards for TVR gauges. VDO is what is needed for the early ETB instruments, and Smiths for the CAI gauges.
Your gauges will not be calibrated if you use the sender with the wrong range, hence I suspect many posts about how inaccurate gauges are....
Well I have taken a punt on this one for £15.90 all in.Your gauges will not be calibrated if you use the sender with the wrong range, hence I suspect many posts about how inaccurate gauges are....
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&am...
I know it does not earth through the body of the sender like the original, but I actually prefer the idea of separate live an earth terminals.
I will run a separate earth wire from the sender to a known good earthing point, I am thinking the earth point on the chassis diagonal should be perfect, its where the engine earth strap is attached after all.
This allows me to use some PTFE tape to ensure a good seal without risk of loosing the earth as you would with the original earth through the body of the sender type.
After a lot of research it seems the gauge manufacturers all pretty much use an industry standard resistance range on oil pressure senders of 10-180 Ohms.
The big difference seems to come in the pressure ratings, the two common pressure ranges are:
1) 0-140 psi
2) 0-80 psi
My understanding is that the true oil pressure on an RV8 is nearer 60 psi, not the 30 - 35 psi most of us seem to see on our 0-90 psi TVR gauges.
I wonder if this is because TVR used a 0-140 psi sender on a 0-90 psi gauge?
Anyway for less than £16.00 I thought I would take a punt and see what readings the gauge gives.
At the end of the day even when it was working I never considered the oil pressure gauge in my TVR as offering anything more than a general indication of pressure.
I will report back on the results of my cheapo Ebay gamble once it's fitted.
Who knows it could even give a more realistic reading than the original, and at a third of the cost?
Or it may just be another piece of Ebay rubbish that goes straight in the bin
I think you may find that the sensor you found on ebay earths through the body, I think its a two in one sensor, one connecton point is for the oil pressure reading and the other is a connection for a low oil pressure warning. I have the ETB gauges and the original sensor has the two connection points but only one is connected to the engine wiring loom.
[quote=Ozstyle]I think you may find that the sensor you found on ebay earths through the body, I think its a two in one sensor, one connecton point is for the oil pressure reading and the other is a connection for a low oil pressure warning. I have the ETB gauges and the original sensor has the two connection points but only one is connected to the engine wiring loom.
[/quote]
Hmmmm, good point
Could be either really, its not 100% clear is it?
I guess it doesn't really matter in terms of operation in my application, but I will need to know before I wire it up.
It wouldn't be a great idea to wire the live warning lamp feed directly to my chassis would it
So thanks for pointing this out Ozstyle, on the back of your comments I sent the seller this question:
"Dear Sir,
Can you confirm if the sender earths through the body of the unit or the second terminal?
Some senders with two terminals use the second terminal to turn on a warning light, this type earths through the sender body.
In other types the two terminals are the live & earth connections.
The problem is both types often look exactly the same, and it is not clear in you Ebay ad what type it is..
Can you tell me the earthing arrangements of your sender is please?
When I fit the sender I don't want to make the mistake of running a live warning light signal direct to a chassis earth.
Many thanks, Dave"
Lets see what I get back?
]I think you may find that the sensor you found on ebay earths through the body, I think its a two in one sensor, one connecton point is for the oil pressure reading and the other is a connection for a low oil pressure warning. I have the ETB gauges and the original sensor has the two connection points but only one is connected to the engine wiring loom.[/quote]
Hmmmm, good point
Could be either really, its not 100% clear is it?
I guess it doesn't really matter in terms of operation in my application, but I will need to know before I wire it up.
It wouldn't be a great idea to wire the live warning lamp feed directly to my chassis would it
So thanks for pointing this out Ozstyle, on the back of your comments I sent the seller this question:
"Dear Sir,
Can you confirm if the sender earths through the body of the unit or the second terminal?
Some senders with two terminals use the second terminal to turn on a warning light, this type earths through the sender body.
In other types the two terminals are the live & earth connections.
The problem is both types often look exactly the same, and it is not clear in you Ebay ad what type it is..
Can you tell me the earthing arrangements of your sender is please?
When I fit the sender I don't want to make the mistake of running a live warning light signal direct to a chassis earth.
Many thanks, Dave"
Lets see what I get back?
Ok, the sender turned up today, looks fine to me, I just need to find some time to fit it.
The following marks are stamped into the casing:
Terminal 1: S
Terminal 2: W.L./G (this also has a G printed in ink over it)
The stamped marking W.L./G on terminal 2 is confusing me slightly?
As we know there are two types of twin terminal sender, one where the second terminal activates a warning light (W.L), & one where the second terminal is the earth (G).
Could it be the manufacture saves costs by using the same stamped casing, ie it's stamped with both options (W.L./G)
The manufacturer then just puts what type it is in ink over the top of the stamped markings, on my sender they marked the second terminal G in ink indicating its the earth?
Is this a fair assumption?
Or it could be the warning light operates with a permanent live on one side of the bulb and the sender only completes the earth to the other side of the bulb through terminal 2 when the pressure is below 5 psi thus lighting the bulb?
If this is what it's saying then the unit earths through the sender body.
I guess the the safest thing to do is fit it without an earth wire to see if it works, if not then fit the earth wire and watch the needle?
Thoughts?
The following marks are stamped into the casing:
Terminal 1: S
Terminal 2: W.L./G (this also has a G printed in ink over it)
The stamped marking W.L./G on terminal 2 is confusing me slightly?
As we know there are two types of twin terminal sender, one where the second terminal activates a warning light (W.L), & one where the second terminal is the earth (G).
Could it be the manufacture saves costs by using the same stamped casing, ie it's stamped with both options (W.L./G)
The manufacturer then just puts what type it is in ink over the top of the stamped markings, on my sender they marked the second terminal G in ink indicating its the earth?
Is this a fair assumption?
Or it could be the warning light operates with a permanent live on one side of the bulb and the sender only completes the earth to the other side of the bulb through terminal 2 when the pressure is below 5 psi thus lighting the bulb?
If this is what it's saying then the unit earths through the sender body.
I guess the the safest thing to do is fit it without an earth wire to see if it works, if not then fit the earth wire and watch the needle?
Thoughts?
phillpot said:
There was a thread quite recently on S Forum where a guy fitted a sender "same" as this and he connected second terminal to earth.
I'd try it without earth, if doesn't work try an earth wire!
Found it, thanks Phillpot.I'd try it without earth, if doesn't work try an earth wire!
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Looks promising
There is another link to the S owners site, it looks like he took a punt on the cheapo sender just like me and he got lucky.
Scroll halfway down to the date 23-May-2009 on his site here:
http://deadpineapple.net/tvr/diary/2009.php
The photo shows the exact same sender I bought from EBay, obviously its going on a Chim not an S but I am encouraged by what I reading.
Reading the post & website makes me think the second terminal is more than likely an earth.
As Spend suggested, I will test it with a meter first though.
Edited by Chimpafrolic on Thursday 31st March 19:01
UPDATE>
Fitted the cheapo Ebay sender today and guess what?
It works perfectly
In fact I have never seen the needle rise so quickly and give such a solid & consistent reading.
The best I ever saw on the gauge with the old sender was about 38 lbs, and it often fell to 20 lbs when the oil got really hot.
The new sender shows a rock solid 65 lbs.
What killed my tired old sender was the double oil pressure relief spring mod by V8 Developments, I'm sure it was on it's last legs & the extra oil pressure just pushed it over the edge.
The second terminal on the new sender proved to be an earth, a simple fly lead from the earth point on the chassis diagonal to this terminal was all it needed.
I actually prefer a separate earth rather than relying on the unit to earth through the body of the sender as the original does.
Oh, & you do need to change the terminal on the existing live wire from the standard female spade to a ring terminal.
I just made a little 2" converter lead with a male spade at one end and a ring terminal at the other, this way I didn't have to cut the original female spade off.
If I ever need to go back to a TVR sender with it's male spade its just a case of removing my little converter lead.
So if your oil pressure sender is dead or on the way out, you don't need to pay the £50.00 - £60.00 for one advertised specifically for TVR.
Pay £16.00 for this one:
http://cgi.ebay.co.uk/OIL-PRESSURE-Sender-Sensor-f...
Fitted the cheapo Ebay sender today and guess what?
It works perfectly
In fact I have never seen the needle rise so quickly and give such a solid & consistent reading.
The best I ever saw on the gauge with the old sender was about 38 lbs, and it often fell to 20 lbs when the oil got really hot.
The new sender shows a rock solid 65 lbs.
What killed my tired old sender was the double oil pressure relief spring mod by V8 Developments, I'm sure it was on it's last legs & the extra oil pressure just pushed it over the edge.
The second terminal on the new sender proved to be an earth, a simple fly lead from the earth point on the chassis diagonal to this terminal was all it needed.
I actually prefer a separate earth rather than relying on the unit to earth through the body of the sender as the original does.
Oh, & you do need to change the terminal on the existing live wire from the standard female spade to a ring terminal.
I just made a little 2" converter lead with a male spade at one end and a ring terminal at the other, this way I didn't have to cut the original female spade off.
If I ever need to go back to a TVR sender with it's male spade its just a case of removing my little converter lead.
So if your oil pressure sender is dead or on the way out, you don't need to pay the £50.00 - £60.00 for one advertised specifically for TVR.
Pay £16.00 for this one:
http://cgi.ebay.co.uk/OIL-PRESSURE-Sender-Sensor-f...
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