V8 Vantage S low oil pressure warning

[tom-4hcey]

Haven’t used my vantage for a while but started every few weeks and kept on a battery optimiser in the garage. Booked in for MOT tomorrow so went to start it this morning and followed the normal crank for oil pressure procedure but the red oil pressure light didn’t go off. I let the engine fire and it displayed low oil pressure, stop engine. Turned it off straight away. Checked oil level and all ok, no leaks etc. is it likely to be a faulty oil pressure switch? If so has anyone changed one? Or any other suggestions.

Many Thanks

[Calinours]

I’d first check the oil pump is actually working by confirming engine oil is being returned to the stainless tank with the engine running.

If all OK, and no untoward noises then it is most likely to be the switch as you suggest or maybe a corroded connector.

[V8V Pete]

Having just paid to have my Vantage S engine rebuilt, personally, I wouldn't be driving it until I knew it was definitely not true loss of oil pressure. Even if you have a warranty, there are essentially no engines out there to replace it with if you have a catastrophic failure.

[tom-4hcey]

Thanks guys. To check the pump would you start the engine and remove the stainless steel lid on the oil tank?

[LTP]

tom-4hcey said:

Thanks guys. To check the pump would you start the engine and remove the stainless steel lid on the oil tank?

Personally, if you suspected you had no oil pressure and possibly a SNAFU'd oil pump, the last thing I'd be doing is starting the engine again.

I'd be calling for a trailer to take it to the nearest reliable independent/ MD for them to check. The only other possible thing would be to get an OBD reader and check all the fault codes in case it gives you a clue.

Just my $0.05 - you do you.

[tom-4hcey]

Just trying to get my Autel obd reader updated then I’ll plug in to see if I can shed any light. Unsure if it supports Aston Martin. Just seems strange as I started it a few weeks back no problem. It’s covered 500 miles since it was last serviced at main dealer. I suppose the pump or pressure sensor could fail at any time. Think I’ve located the pressure sensor on the back right hand side. Going to be fiddly to remove and replace.

[Cold]

/Side note/
You're doing it no favours by starting it periodically and subsequently not actually driving anywhere. Let it continue to sleep. No wear happens when it's switched off but plenty happens on every cold startup.

[tom-4hcey]

Yea very true but had to start it as been carrying out work on the car since I got it and n feb. New brakes all round , Sub frame removed and powder coated, 4 wheel alignment, ASM hoses, transaxle fluid etc etc. it’s just now I’ve re fitted the bumpers and undertrays etc to take it for mot tomorrow and this has happened. Fingers crossed it’s just the pressure sensor.

[sheepdip]

If you do decide to look for oil circulating in the oil tank I would be taking the plugs out first. I would even think about taking a rocker cover off too.

[IainWhy]

the pressure switch is just a cheap part, i would just replace it, and then repeat the cranking for pressure process. removing the plugs will reduce the load on the bearings and increase cranking speed.

[tom-4hcey]

Thank you. I ordered the pressure switch from Aston Martin yesterday. Going to collect it tomorrow. Also ordered a Foxwell NT530 to see if that gives me any more information. Failing that I’ll get it trailered to my local dealer or Indy.

[tom-4hcey]

Thank you. I ordered the pressure switch from Aston Martin yesterday. Going to collect it tomorrow. Also ordered a Foxwell NT530 to see if that gives me any more information. Failing that I’ll get it trailered to my local dealer or Indy.

[tom-4hcey]

It’s also come up with Low Battery Power Save Mode so makes me wonder if it’s all related.

[tom-4hcey]

Thanks for all your help and advice. Thankfully it was just the oil pressure switch. Part No: 1R12-39-10532 £5.52 from Aston Martin.

[V8V Pete]

tom-4hcey said:

Thanks for all your help and advice. Thankfully it was just the oil pressure switch. Part No: 1R12-39-10532 £5.52 from Aston Martin.

Couldn't have had a better result than that

This time next year that part will be £200 just like the washer pump

[Kengillespie]

tom-4hcey said:

Thanks for all your help and advice. Thankfully it was just the oil pressure switch. Part No: 1R12-39-10532 £5.52 from Aston Martin.

Hi, can you tell me where the oil pressure switch is located on the engine and is it accessible to change out yourself?

[IainWhy]

next to the oil filter, access is not all that huge but should be easily done

[Calinours]

Result. How did you confirm that it was just the sensor? - I presume once the switch was swapped out you held your foot down again on crank (no engine fire) and hoped for the light to go out this time..?

I’d never heard of oil pump failure on one of these dry sumped V8 so was hoping for some sort of follow up on this thread. Thankfully one of those rare fixes that cost pennies (for the component).

I held off further comment after all the advice you received to trailer the car to a specialist etc, and run up a £500+ transport and dealer bill (in absence of any other obvious error codes all the dealer would have done was as I had advised, crank the car and check the oil return line to the dry sump catch can).

With hindsight I should not have said ‘with engine running’ - it was perhaps something of a reaction to OP stating he’d been running the engine each month.

Assuming someone is certain that oil did actually remain in the engine, a no fire crank on that engine with someone else looking for the visible oil return (a bonus on a dry sump car) could not do any harm and would instantly confirm that the oil pump was still functioning. As suggested above, and if you were completely risk averse, then removing plugs and pipetting few drips of engine oil into each bore would reduce risk to zero.

Edited by Calinours on Wednesday 29th November 11:09

[tom-4hcey]

Pressure switch is located just above the oil filter. Pretty easy to change little bit fiddly.

Yes that correct changed out the pressure switch, then cranked for oil Pressure without letting engine fire. Oil pressure light went out straight away, let engine fire, turned off engine and checked oil level, oil level ok, I then confirmed oil was flowing back in to the oil tank by removing the lid/dipstick. Drive the car 20 miles to the MOT and drive like a dream. I just didn’t want to risk damaging the engine incase it was one of the oil pumps.

I have since tested the old pressure switch with a multimeter and put pressure on the membrane and the resistance readings fluctuated as expected but were very intermittent and sometimes worked and sometimes didn’t.

Hope that makes sense.

Thanks again

[Exocet1]

tom-4hcey said:

Pressure switch is located just above the oil filter. Pretty easy to change little bit fiddly.

Yes that correct changed out the pressure switch, then cranked for oil Pressure without letting engine fire. Oil pressure light went out straight away, let engine fire, turned off engine and checked oil level, oil level ok, I then confirmed oil was flowing back in to the oil tank by removing the lid/dipstick. Drive the car 20 miles to the MOT and drive like a dream. I just didn’t want to risk damaging the engine incase it was one of the oil pumps.

I have since tested the old pressure switch with a multimeter and put pressure on the membrane and the resistance readings fluctuated as expected but were very intermittent and sometimes worked and sometimes didn’t.

Hope that makes sense.

Thanks again

Many thanks for your useful post; could I ask if you had to access the switch from under the car?

- I have exact same problem on my 4.7L vantage and it’s currently stuck in the garage with no way to lift and there seems no room to disconnect it from above.

Pretty sure it’s the oil transducer but reluctant to drive to the garage with a warning to stop the engine…