Chimaera oil pressure
Discussion
Hi all,
I’ve recently carried out an oil and filter change. I took the opportunity to also change the sump gasket and re-seal the pressure sender (was a slight leak present). Prior to this work oil pressure was indicating normal (30 psi plus).
On restarting the engine oil pressure was indicating zero. I suspected I’d been over enthusiastic with the plumbers tape and the sender was no longer earthing against the engine block. I removed the sender and re-sealed ensuring not to overdo the tape. Now, as soon as I turn on the ignition (but not starting the engine) the pressure gauge goes straight to maximum 90 psi plus. Once the engine is started it still indicates maximum. I’m happy that the oil is circulating at a good pressure and the problem is with the sender. Any ideas what may be causing these symptoms?
Many thanks
I’ve recently carried out an oil and filter change. I took the opportunity to also change the sump gasket and re-seal the pressure sender (was a slight leak present). Prior to this work oil pressure was indicating normal (30 psi plus).
On restarting the engine oil pressure was indicating zero. I suspected I’d been over enthusiastic with the plumbers tape and the sender was no longer earthing against the engine block. I removed the sender and re-sealed ensuring not to overdo the tape. Now, as soon as I turn on the ignition (but not starting the engine) the pressure gauge goes straight to maximum 90 psi plus. Once the engine is started it still indicates maximum. I’m happy that the oil is circulating at a good pressure and the problem is with the sender. Any ideas what may be causing these symptoms?
Many thanks
The connection to it may need tightening, ie pinched up with a pair of pliers as it does become loose over time. Check it looks clean too.
I suspect it may be the tape hindering the ground but thats just a guess, just make sure no tape is blocking the port, i always try to start any ptfe a couple of threads back to try and avoid this.
I suspect it may be the tape hindering the ground but thats just a guess, just make sure no tape is blocking the port, i always try to start any ptfe a couple of threads back to try and avoid this.
phillpot said:
If gauge is going to max pressure there's no problem with the connection or earth!
Sender unit kaput?
I'll second this. Had exactly the same scenario. One day the gauge was all fine, then the next day on start up the needle went off the scale. No warning or playing around with it. New sender sorted it.Sender unit kaput?
kris450 said:
phillpot said:
If gauge is going to max pressure there's no problem with the connection or earth!
Sender unit kaput?
I'll second this. Had exactly the same scenario. One day the gauge was all fine, then the next day on start up the needle went off the scale. No warning or playing around with it. New sender sorted it.Sender unit kaput?
I have the Ispro sender detailed in the thread recommended above.
It does read closer to actual oil pressure as recorded with a mechanical gauge on my car. Slightly higher if anything.
In truth it reads exactly like the original but just starts reading slightly higher up the gauge so looks good on the dial.
With hot oil at low revs like tickover I’ve come to the conclusion the original which often showed as low at 12-15psi and only about 35 at 3000 revs was actually reading correct with an old engine using semi synth oil.
I feel the Ispro is flattering the engine very slightly.
Good bit of kit and the extra ground can’t be a bad thing which I just tracked to offside Earth point in wheel arch following other wiring route. Black tape and it looks o/e but not strictly necessary and if it fails I’m likely to go back to the cheaper standard one because only using a mechanical gauge to check can give you accurate data you can trust.
As Tvr specialists often ask you when you complain of low pressure ‘ is warning light on’ and if the answer is no they usually shrug their shoulders as they all read low sir. They don’t really read low so much as everyone thinks they should read higher?
The issue is actually the belief the engine should be running 45-50 psi to be considered strong which is slightly incorrect.
Anything over 30-35 using 10/40 semi is high enough pressure on hot oil and in most cases closer to actual pressure.
So in short stick with the original type if you want a fairly truthful reading or use the Ispro to look impressive. Lol .
I’d suggest it’s like wearing a large cod piece, only you know the truth
It does read closer to actual oil pressure as recorded with a mechanical gauge on my car. Slightly higher if anything.
In truth it reads exactly like the original but just starts reading slightly higher up the gauge so looks good on the dial.
With hot oil at low revs like tickover I’ve come to the conclusion the original which often showed as low at 12-15psi and only about 35 at 3000 revs was actually reading correct with an old engine using semi synth oil.
I feel the Ispro is flattering the engine very slightly.
Good bit of kit and the extra ground can’t be a bad thing which I just tracked to offside Earth point in wheel arch following other wiring route. Black tape and it looks o/e but not strictly necessary and if it fails I’m likely to go back to the cheaper standard one because only using a mechanical gauge to check can give you accurate data you can trust.
As Tvr specialists often ask you when you complain of low pressure ‘ is warning light on’ and if the answer is no they usually shrug their shoulders as they all read low sir. They don’t really read low so much as everyone thinks they should read higher?
The issue is actually the belief the engine should be running 45-50 psi to be considered strong which is slightly incorrect.
Anything over 30-35 using 10/40 semi is high enough pressure on hot oil and in most cases closer to actual pressure.
So in short stick with the original type if you want a fairly truthful reading or use the Ispro to look impressive. Lol .
I’d suggest it’s like wearing a large cod piece, only you know the truth
Hi,
I'd read the above thread previously and my only concern is the replacement sender is longer than the original and requires jacking of the engine to fit/remove.
As you've said, it's only indication as they're not calibrated test guages and if the low pressure switch is not active (plus water temperatures are in the normal range), it's just an indication of pressure increasing and decreasing with the engine. I'll continue to try and source a replacement here in Euro Land (1/8NPT, 0-100psi)
I'd read the above thread previously and my only concern is the replacement sender is longer than the original and requires jacking of the engine to fit/remove.
As you've said, it's only indication as they're not calibrated test guages and if the low pressure switch is not active (plus water temperatures are in the normal range), it's just an indication of pressure increasing and decreasing with the engine. I'll continue to try and source a replacement here in Euro Land (1/8NPT, 0-100psi)
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