Potential oil pressure issues
Discussion
Was driving home last night (bit of backroads, bit of DC, bit of traffic, nothing too hectic or overly long sat in queues just a nice drive) in my Chimaera and the low oil light came on, I stopped, checked the pressure gauge and it was showing 30psi at idle, what it normally does so I figured that it was likely a wiring or pressure switch issue (I've got a new switch ready to go in tomorrow) and drove the couple of miles home gently, watching the gauge all the way (which never dropped below 30psi) and the light, which when I went over a bump went off and then if I hit another came back on, fuelling the faulty switch theory.
Sounds simple replace switch and carry on, however.......
I've been out in it again today and it's obviously quite hot, when I first started the car good pressure on the gauge light goes out straight away, when it got hotter again the low pressure light starts to flicker and then finally stays on, this time i'm watching the pressure gauge as well and that's now behaving oddly with pressure sometimes dropping off at idle to just above 0 on the gauge but coming back up to around 30 when on the move (it never fully dropped to 0 but wasn't far), but it wasn't climbing much higher than 30psi at 2k when driving (where it used to climb to around 45), also it's quite up and down like I hadn't seen before on the gauge slowly crawling in traffic could see 30 but then it may drop to about 15.
Engine is probably 7000 miles old after a total rebuild (ex Belle427 car) and had new oil pump gears then, Oil level is about 5ml off the max and it's running a Kerax 15/50 synthetic race oil with a new Bosch filter. The water temp was around 90 the whole way in traffic. When I got home I let it tick over on the drive for a couple of minutes before I shut down and the gauge sat rock solid at 30psi but the orange warning light was on.
I've got a feeling the replacement switch isn't going to cure the issue now so looking for other suggestions, wondering if my oil choice (Kerax hyperdrive served my well in my tuned impreza) my need revision or could it likely be something more sinister?
Sounds simple replace switch and carry on, however.......
I've been out in it again today and it's obviously quite hot, when I first started the car good pressure on the gauge light goes out straight away, when it got hotter again the low pressure light starts to flicker and then finally stays on, this time i'm watching the pressure gauge as well and that's now behaving oddly with pressure sometimes dropping off at idle to just above 0 on the gauge but coming back up to around 30 when on the move (it never fully dropped to 0 but wasn't far), but it wasn't climbing much higher than 30psi at 2k when driving (where it used to climb to around 45), also it's quite up and down like I hadn't seen before on the gauge slowly crawling in traffic could see 30 but then it may drop to about 15.
Engine is probably 7000 miles old after a total rebuild (ex Belle427 car) and had new oil pump gears then, Oil level is about 5ml off the max and it's running a Kerax 15/50 synthetic race oil with a new Bosch filter. The water temp was around 90 the whole way in traffic. When I got home I let it tick over on the drive for a couple of minutes before I shut down and the gauge sat rock solid at 30psi but the orange warning light was on.
I've got a feeling the replacement switch isn't going to cure the issue now so looking for other suggestions, wondering if my oil choice (Kerax hyperdrive served my well in my tuned impreza) my need revision or could it likely be something more sinister?
The low pressure is very odd, I'd be surprised if 15/50 caused that. I use 20/50 VR1 or Fuchs racing depending on who services it when - I do interim oil flushes between it getting the book service at my local specialist. Never gets below 28 on a hot day after proper thrashings.
That said, best to ask whoever built the engine what oil to use. Dom @ Powers swears by 10/40 for his engines and will only honour the warranty with that oil. Warranty is worth more than PH heresay.
I'd be putting a mechanical gauge on to verify if the sender and switch are correct, or if you have a wiring fault.
Oil filter has a bypass valve, try replacing the oil filter in case that is faulty. Someone else will come and tell me if that would cause 0psiish or not.
switch light on at 30psi indicates a fault to me however with your wiring or your switch
That said, best to ask whoever built the engine what oil to use. Dom @ Powers swears by 10/40 for his engines and will only honour the warranty with that oil. Warranty is worth more than PH heresay.
I'd be putting a mechanical gauge on to verify if the sender and switch are correct, or if you have a wiring fault.
Oil filter has a bypass valve, try replacing the oil filter in case that is faulty. Someone else will come and tell me if that would cause 0psiish or not.
switch light on at 30psi indicates a fault to me however with your wiring or your switch
Agree 100%, get a mechanical gauge to check your actual oil pressure, before anything else.
If that also shows low pressure, you could pull the sump in case some silicone sealant is blocking the pick-up(?).
(Not wishing to cast doubt on the skill of the engine builder, but it does happen).
Is the low pressure accompanied by increased engine noise (it sometimes is)?
If that also shows low pressure, you could pull the sump in case some silicone sealant is blocking the pick-up(?).
(Not wishing to cast doubt on the skill of the engine builder, but it does happen).
Is the low pressure accompanied by increased engine noise (it sometimes is)?
I would verify all the wiring is sound first as both are electrically operated, it may be worth checking the 12 volts and ground at the gauges under the dash is sound.
I would expect some of the other gauges to play up though as they are on the same source.
I did take care when rebuilding the engine and only used a light coating of silicone on the sump gasket, I stuck this to the engine overnight first as to eliminate the squashing out.
I’m no engine builder but I don’t think it would be this, I read the silicone kids threads and it scared me!
I wouldn’t expect it to be the filter, Bosch are normally very good quality.
I suppose if it were me I’d get a new Mann or oe Land Rover filter and put some Valvoline Vr1 20/50 oil in it, I’m not too familiar with the oil your currently using.
I’ve read that hot pressure does tail off with certain oils but maybe not to your extent.
Hope it’s something simple.
I would expect some of the other gauges to play up though as they are on the same source.
I did take care when rebuilding the engine and only used a light coating of silicone on the sump gasket, I stuck this to the engine overnight first as to eliminate the squashing out.
I’m no engine builder but I don’t think it would be this, I read the silicone kids threads and it scared me!
I wouldn’t expect it to be the filter, Bosch are normally very good quality.
I suppose if it were me I’d get a new Mann or oe Land Rover filter and put some Valvoline Vr1 20/50 oil in it, I’m not too familiar with the oil your currently using.
I’ve read that hot pressure does tail off with certain oils but maybe not to your extent.
Hope it’s something simple.
I doubt putting a different oil in will make any difference, if the problem is mechanical.
After all, modern high spec ester, fully or semi synthetic oils are designed to maintain pressure under extreme circumstances, and for extended periods.
I also doubt many road going Chims would push the limits of these decent quality oils (be it 10/40 or 15/50, or whatever) as long as service intervals are maintained.
After all, modern high spec ester, fully or semi synthetic oils are designed to maintain pressure under extreme circumstances, and for extended periods.
I also doubt many road going Chims would push the limits of these decent quality oils (be it 10/40 or 15/50, or whatever) as long as service intervals are maintained.
Sir Paolo said:
I doubt putting a different oil in will make any difference, if the problem is mechanical.
After all, modern high spec ester, fully or semi synthetic oils are designed to maintain pressure under extreme circumstances, and for extended periods.
I also doubt many road going Chims would push the limits of these decent quality oils (be it 10/40 or 15/50, or whatever) as long as service intervals are maintained.
I wasted £75 on expensive oil recommended by a nobody on here and instantly had a rattly engine. Total waste of money. After all, modern high spec ester, fully or semi synthetic oils are designed to maintain pressure under extreme circumstances, and for extended periods.
I also doubt many road going Chims would push the limits of these decent quality oils (be it 10/40 or 15/50, or whatever) as long as service intervals are maintained.
Put the correct grade oil in.
Fully synth hot is like water compared to 10/40 semi.
Tell you what I’ll listen to the engine builders of note!
My point is until it’s on the designed oil grade you can’t be sure what’s going on as thicker oil might add pressure but actually reduce flow rate, thin oil as in fully synth might circulate faster so actually might show lower oil pressure.
If in doubt use a mechanical gauge
All my oil pressure senders showed low pressure when hot,, that’s because it is. There is nothing new in RV8 showing 15psi at idle hot which might show 5 psi on gauge.
Instead of arguing the toss the o/p should use a mechanical gauge on the car as is and find out what it says.
That’s after you are sure the electrics are connected at both senders.
Good luck
If in doubt use a mechanical gauge
All my oil pressure senders showed low pressure when hot,, that’s because it is. There is nothing new in RV8 showing 15psi at idle hot which might show 5 psi on gauge.
Instead of arguing the toss the o/p should use a mechanical gauge on the car as is and find out what it says.
That’s after you are sure the electrics are connected at both senders.
Good luck
Belle427 said:
I researched oil to death when I owned the car, its a debate that never will be answered properly.
2 of the most respected engine builders in the country recommend both 10/40 semi and a 20/50 mineral. (Vr1)
One of life's great mysteries !
Absolutely agree 100%, like you, I have researched oil to exhaustion for many years.2 of the most respected engine builders in the country recommend both 10/40 semi and a 20/50 mineral. (Vr1)
One of life's great mysteries !
Which is why I don’t think the oil grade is relevant to the OP’s issue in this instance.
Oil deliberations aside, and as unlikely as it maybe, it’s possible that the OP’s issue is failure of the low oil pressure switch AND the oil pressure sender.
Hot engine oil, especially once contaminated with petrol hydrocarbons, will eventually perforate a sender diaphragm.
I noticed slightly reduced oil pressure towards the end of last year (although still very good for an RV8) - a new sender unit restored the pressure readings!
Hot engine oil, especially once contaminated with petrol hydrocarbons, will eventually perforate a sender diaphragm.
I noticed slightly reduced oil pressure towards the end of last year (although still very good for an RV8) - a new sender unit restored the pressure readings!
So I've replaced the switch as it was only £7 and took 20minutes. I also removed the ratty old crimp on the sender for the gauge (the switch has nice new wiring and crimps already) and replaced with a new crimp that grips a bit better.
Light straight out and 40psi straight away.
Will give it a try later and if I'm still getting issues a mechanical guage will be ordered to test it correctly.
It's funny that I use cheap fully synth (usually Comma or Carlube 10/40) in my race engines and I've never blown one despite taking them well beyond anything they were ever designed for, RV8 gets grumpy on a hot day with decent 15/50!
Light straight out and 40psi straight away.
Will give it a try later and if I'm still getting issues a mechanical guage will be ordered to test it correctly.
It's funny that I use cheap fully synth (usually Comma or Carlube 10/40) in my race engines and I've never blown one despite taking them well beyond anything they were ever designed for, RV8 gets grumpy on a hot day with decent 15/50!
Out again yesterday and it was fine again.
Gauge is reading slightly higher now with the new crimp (I think I'm going to solder and heatshrink this and fit a modern waterproof locking connector inline as a mod).
Oil light is really squeaky bum time and I guess the gauge had always fluctuated a bit but I'd only checked it occasionally and with the light coming on I was watching it as much as I could and I was just seeing it's normal behaviour.
The LR specialist (Safari Engineering who are only 5 mins from me) told me they sold quite a few pressure switches and the guy just nodded and said they basically all fail the same way when I told him what it had been doing.
Gauge is reading slightly higher now with the new crimp (I think I'm going to solder and heatshrink this and fit a modern waterproof locking connector inline as a mod).
Oil light is really squeaky bum time and I guess the gauge had always fluctuated a bit but I'd only checked it occasionally and with the light coming on I was watching it as much as I could and I was just seeing it's normal behaviour.
The LR specialist (Safari Engineering who are only 5 mins from me) told me they sold quite a few pressure switches and the guy just nodded and said they basically all fail the same way when I told him what it had been doing.
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