Oil Pressure Sender
Discussion
Of course the easiest solution is...
If you have the later pure white faced 0-90psi oil pressure gauge like this...
You need to select a 0-90psi sender, and there a loads on eBay for around £15 that will work just fine.
And it also looks like the ETB gauge fitted very early Chimaera's was 0-90psi....
On the other hand if you have the mid production Caerbont 0-100psi gauge that came between the early ETB and late model pure white faced 0-90psi oil pressure gauge which looks like this....
You need to select a 0-100psi sender, and for that the Isspro R8917-03 is perfect as I've proved.
In my opinion none of the TVR gauges should be considered precise instruments, if they give you a decent reliable reading within the acceptable operating range we should view this as perfectly acceptable.
But in the end it's just a simple case of selecting the right sender to go with the right gauge.
If you have the later pure white faced 0-90psi oil pressure gauge like this...
You need to select a 0-90psi sender, and there a loads on eBay for around £15 that will work just fine.
And it also looks like the ETB gauge fitted very early Chimaera's was 0-90psi....
On the other hand if you have the mid production Caerbont 0-100psi gauge that came between the early ETB and late model pure white faced 0-90psi oil pressure gauge which looks like this....
You need to select a 0-100psi sender, and for that the Isspro R8917-03 is perfect as I've proved.
In my opinion none of the TVR gauges should be considered precise instruments, if they give you a decent reliable reading within the acceptable operating range we should view this as perfectly acceptable.
But in the end it's just a simple case of selecting the right sender to go with the right gauge.
Paulprior said:
I read 30 psi, hot, cold, tickover or high revs, I assume this can't be right?
You're right it's not, but this is pretty much how these cars came from the factory, well often the gauge would show 15psi at idle rising to an absolute maximum of 35psi at speed, basically it was wrong from day one because while the true idle pressure could be as low as 15psi the higher over 2,00rpm figure should be more like 50psi not 35.Paulprior said:
From the experience of you guys should I target the gauge or sender first?, maybe do a resistance check as detailed earlier on?
It's almost certainly the sender.Paulprior said:
I have the older style as pictured above
There are three gauges pictured above?The oldest type is an ETB 0-90 psi gauge fitted to the very earliest Chimaeras, 1993 - mid 1995, for this gauge you may want try one of the many cheap senders offered on eBay, ideally you need one that operates over a 0-90psi range (6 Bar). The challenge is 0-90psi senders aren't that easy to find as most on offer are either 0-80psi or 0-100psi.
From mid 1995 on the Caerbont gauges were used, these are often an off-white colour (magnolia) but could actually be special ordered in many colours, this is what I have on my late 1996 Chimaera, the Caerbont OP gauge seems to be 0-100psi, I'm using the American made Isspro R8917-03 0-100psi sender which for me gives the correct readings and seems better quality than anything else on the market including the very expensive ones from the TVR parts specialists.
I believe from sometime in late 1998 or early 1999 TVR started to use different gauge sets, they look very similar to the Caaerbont gauges but were often pure white in colour although you could probably order them in different colours as with the Caerbont gauges. If you have these later gauges I believe you're back to looking for a 0-90psi sender because people with pure white gauges have tried the Isspro R8917-03 0-100psi have found it makes the gauge over-read by roughly 10psi over it's full range.
In all cases you are looking for a sender with a 1/8 x 27 NPT thread, but be careful some operate in the 3-160 Ohms range and others over a 10-180 Ohms range, the next difference between senders is their pressure range which you'll need to match to your gauge. Try to choose a sender that has two terminals, but make sure the second terminal is an earth and not for a warning light, with a dedicated earth terminal you can create your own little earth lead from the sender to the earth stud on the O/S outrigger which is more reliable than the original one terminal sender system that earths directly to the engine block through the 1/8 x 27 NPT thread.
The going rate for a cheap Chinese sender from eBay is anything from £12-£20, in my experience they are no worse or better quality than the ones being sold by the various TVR parts specialists for around £65 by the time you've paid the VAT & postage, which quite clearly is a rip-off.
The only one I've been able to find that operates on the less common 0-90psi range is this one...
http://www.etbinstruments.com/index.php?route=prod...
Unfortunately the second terminal is a warning light so you'd just leave this disconnected, the sender then earths directly to the engine block through the 1/8 x 27 NPT thread as per the original, this will work fine, its just not as good/reliable as a dedicated earth terminal/lead setup.
This 0-90psi sender is £33.60 plus whatever they charge you for postage, but that's still likely to give you a useful £30 saving over the TVR parts one.
Alternatively call Speedy Cables on 01639 732300 and discuss your requirements, Speedy Cables have been around for ever, they are not particularly speedy but what they don't know about gauges & senders isn't worth knowing. and they may well have a 0-90psi sender with a dedicated earth terminal if that's what you're looking for.
Using a mechanical gauge and hot oil my car reads 28psi at 3000 revs.
Hot at 5000 revs it barely gets past 45psi.
Below 2000 revs it's 20-15 psi.
Tickover as low as 12 but that was with a low tickover speed of 750.
That corresponds almost exactly to my Tvr ( Powers ) supplied sender and gauge.
My gauge does top out at 30 psi no matter what revs I'm doing so incorrect at those values.
Truth is I've been on track a number of times with this set up and looking at the gauge at 145mph and accelerating is nigh impossible, so you obviously look when your slowing down, idle pressure is what matters to me and my Tvr gauge can be trusted and corresponds to the instant pressure build and drop with engine revs. When I see 10 psi on the gauge it's cos it is.
Compression and individual engine tolerances might play a part but mine never reaches 50 psi at 2000 revs.
Hot at 5000 revs it barely gets past 45psi.
Below 2000 revs it's 20-15 psi.
Tickover as low as 12 but that was with a low tickover speed of 750.
That corresponds almost exactly to my Tvr ( Powers ) supplied sender and gauge.
My gauge does top out at 30 psi no matter what revs I'm doing so incorrect at those values.
Truth is I've been on track a number of times with this set up and looking at the gauge at 145mph and accelerating is nigh impossible, so you obviously look when your slowing down, idle pressure is what matters to me and my Tvr gauge can be trusted and corresponds to the instant pressure build and drop with engine revs. When I see 10 psi on the gauge it's cos it is.
Compression and individual engine tolerances might play a part but mine never reaches 50 psi at 2000 revs.
it's going to be less dexterous at those temps so although may show lower pressure readings the flow of oil is being maintained so still plenty of oil where it's needed. Given the design of an oil pressure relief valve and assuming it is functioning correctly you really should be seeing more or less the same oil pressure from anything over 2,000rpm all the way to the red line.
An oil pressure relief valve is just a spill valve, as the oil pump spins faster it inevitably makes more pressure most of which would be highly undesirable. So as the pressure increases the valve will open more spilling more and more of the oil back in the sump, like I say if it's working correctly (and above 2,000rpm) the pressure in the galleries will be maintained at a constant value irrespective of revs.
This constant value is governed by the force of the oil pressure relief valve spring, to be clear I have the V8 Developments oil pressure relief valve mod on my otherwise original 4.0 litre serpentine engine that has never been rebuilt, and I can 100% guarantee you Alun it makes a genuine and fixed 55psi from just over 2,000rpm to 6,250rpm.
The engine also consumes minimum oil and happily idles just over 30psi, please be aware I run a 1050rpm idle which by itself will give a very differing (read higher) idle pressure than a Chimaera idling at say 900rpm. The V8 Developments oil pressure relief valve mod definitely works, just as it did when I used to put a stronger relief spring in old Fords back in the day.
In many respects the Rover V8 is quite similar to a Chevy V8 which is well documented to make at least 20psi at a 1000rpm idle and 45-50psi over 2,000rpm (all hot figures), and there's an old rule that remains just as relevant on our engines today, that is... minimum oil pressure should be 15-20psi per 1000rpm while never exceeding 65psi at speed.
The other variable to influence oil pressure is of course the weight of oil you choose, for many years I have successfully run my engine on Pernrite HPR15 which is a 15w/60, this and the V8 Developments oil pressure relief valve gives me the following figures on a Sykes Pickavant professional mechanical OP gaauge.:
Cold idle: 40psi
Hot Idle: 33psi
Cold over 2,000rpm: 60psi
Hot over 2,000rpm: 55psi
The Isspro R8917-03 sender combined with my Caerbont gauge shows exactly these figures too.
But as we all know volume is actually more important than pressure which is why Land Rover redesigned the RV8 engine in around 1995 deleting the old gear type pump replacing it with the much higher volume front cover mounted rotor type pump, and so was born the serpentine engine.
An oil pressure relief valve is just a spill valve, as the oil pump spins faster it inevitably makes more pressure most of which would be highly undesirable. So as the pressure increases the valve will open more spilling more and more of the oil back in the sump, like I say if it's working correctly (and above 2,000rpm) the pressure in the galleries will be maintained at a constant value irrespective of revs.
This constant value is governed by the force of the oil pressure relief valve spring, to be clear I have the V8 Developments oil pressure relief valve mod on my otherwise original 4.0 litre serpentine engine that has never been rebuilt, and I can 100% guarantee you Alun it makes a genuine and fixed 55psi from just over 2,000rpm to 6,250rpm.
The engine also consumes minimum oil and happily idles just over 30psi, please be aware I run a 1050rpm idle which by itself will give a very differing (read higher) idle pressure than a Chimaera idling at say 900rpm. The V8 Developments oil pressure relief valve mod definitely works, just as it did when I used to put a stronger relief spring in old Fords back in the day.
In many respects the Rover V8 is quite similar to a Chevy V8 which is well documented to make at least 20psi at a 1000rpm idle and 45-50psi over 2,000rpm (all hot figures), and there's an old rule that remains just as relevant on our engines today, that is... minimum oil pressure should be 15-20psi per 1000rpm while never exceeding 65psi at speed.
The other variable to influence oil pressure is of course the weight of oil you choose, for many years I have successfully run my engine on Pernrite HPR15 which is a 15w/60, this and the V8 Developments oil pressure relief valve gives me the following figures on a Sykes Pickavant professional mechanical OP gaauge.:
Cold idle: 40psi
Hot Idle: 33psi
Cold over 2,000rpm: 60psi
Hot over 2,000rpm: 55psi
The Isspro R8917-03 sender combined with my Caerbont gauge shows exactly these figures too.
But as we all know volume is actually more important than pressure which is why Land Rover redesigned the RV8 engine in around 1995 deleting the old gear type pump replacing it with the much higher volume front cover mounted rotor type pump, and so was born the serpentine engine.
Discopotatoes said:
After a lot of debating which way to go, I bought this one from Merlin, as it's a telemetric and designed for carbont gauges.
I expect it to be of good quality, and although all in was £47 if it works and is accurate that's to less things to worry about.
I'm all ears I expect it to be of good quality, and although all in was £47 if it works and is accurate that's to less things to worry about.
to see how this goes. Fingers crossed
ClassicChimaera said:
Discopotatoes said:
I'll be fitting it Tuesday if it's arrived by then, I know I have 50 psi at idle on a mechanical snap on gauge so I have a starting point to work to
Is that hot or cold? Mines only ever that high at idle cold
Hi all,
after the recommendation in this thread, especially from ChimpOnGas, I decided to give the ISSPRO sender a try. Got the right sender (R8917-03 with Insulated Return) for my '99 Chimaera gauges.
Now the problem: the sender worked well for about 1-2 minutes, then the needle fell below zero as if someone had pulled the wire. Bought a second sender, same behavier. Fitted the wires on the sender vice versa, still the same problem. Waited a few minutes, sender working again, after 2 minutes needle falls below zero. Have fitted the Rover sender again which is working fine.
Is there something I didn't think of?
Stefan
after the recommendation in this thread, especially from ChimpOnGas, I decided to give the ISSPRO sender a try. Got the right sender (R8917-03 with Insulated Return) for my '99 Chimaera gauges.
Now the problem: the sender worked well for about 1-2 minutes, then the needle fell below zero as if someone had pulled the wire. Bought a second sender, same behavier. Fitted the wires on the sender vice versa, still the same problem. Waited a few minutes, sender working again, after 2 minutes needle falls below zero. Have fitted the Rover sender again which is working fine.
Is there something I didn't think of?
Stefan
stefan1200 said:
Hi all,
after the recommendation in this thread, especially from ChimpOnGas, I decided to give the ISSPRO sender a try. Got the right sender (R8917-03 with Insulated Return) for my '99 Chimaera gauges.
Now the problem: the sender worked well for about 1-2 minutes, then the needle fell below zero as if someone had pulled the wire. Bought a second sender, same behavier. Fitted the wires on the sender vice versa, still the same problem. Waited a few minutes, sender working again, after 2 minutes needle falls below zero. Have fitted the Rover sender again which is working fine.
Is there something I didn't think of?
Stefan
Sorry to hear this, I'd say you've got issues that go beyond the sender, my ISSPRO has been perfect offering accurate readings and being 100% reliable.after the recommendation in this thread, especially from ChimpOnGas, I decided to give the ISSPRO sender a try. Got the right sender (R8917-03 with Insulated Return) for my '99 Chimaera gauges.
Now the problem: the sender worked well for about 1-2 minutes, then the needle fell below zero as if someone had pulled the wire. Bought a second sender, same behavier. Fitted the wires on the sender vice versa, still the same problem. Waited a few minutes, sender working again, after 2 minutes needle falls below zero. Have fitted the Rover sender again which is working fine.
Is there something I didn't think of?
Stefan
Good luck with finding the fault but I seriously doubt it has anything to do with the ISSPRO sender, which in my experience is a quality thing.
Dave.
Dave,
I would have also suspected maybe an electrical or gauge problem, would not the Rover sender be working faultlessly in the same configuration.
I don't really expect both new Isspro senders to be faulty, but I'll try to find a way of checking wether they're operating correctly or not.
I would have also suspected maybe an electrical or gauge problem, would not the Rover sender be working faultlessly in the same configuration.
I don't really expect both new Isspro senders to be faulty, but I'll try to find a way of checking wether they're operating correctly or not.
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