Oil pressure question...

[chris1972]

I haven't used the car for about three weeks and it has been sat under the cover on my drive.

I eventually got around to fitting new alternator, battery and blown 100A fuse, plus cleaned the stepper motor at the same time. When I started her up and she was rough. I also noticed that the oil pressure took a little time to rise and seemed to be struggling (looked a little inconsistent), whereas she normally pops right up to 30lbs. I got underneath today and changed the oil sender as the existing one has been playing up. I would have liked to have changed the spade connector as well as this looked pretty poor, but had no choice to use the existing one for now. I also tightened up all the bolts around the sump casing which were fairly loose.

Anyway, I fired her up with the new sender and the oil pressure seemed to take ages to rise to 30lbs. The oil light went out a couple of seconds after she was started, so I put this down to the new sender. Once she was warmed up, the pressure sat around 45lbs when gently burbling around and close to 60lbs when given a few more revs. I drove her around a bit and then stopped for five mins before starting her up again. Sure enough, when started, the oil pressure took about 15 - 20 seconds to rise, but was fine again during driving. The new sender has cured my oil pressure dropping to zero on hard revs (previous post in December), but I appeared to have a new quirk.

Can anybody tell me what this slow increase in pressure means? Is it only me that has this? My oil is about half way, so I will top up to max again. Could it be because she hasn't been run in a little while?

Thanks
Chris

[IainGriff]

Chris, my oil pressure is slow to rise also, when cold I have an indicated 35 psi at idle and 30 when hot. I'm afraid I can't shed any light why its so slow to rise, I would suspect the pressure transmitter.

[Alun450]

Could be the gauge, mines newly re built engine max pressure 45, there a low pressure system quite normal to drop down to 10/15 psi on low revs, I've been told even if the gauge says 50 it's bks, they never create such pressure, I can't be sure of this but it makes sence to me. Mine takes 10/15 secs to see the gauge up to speed! It's the cold I reckon. Someone will put me straight you watch. Lol

[Chilliman]

Mine's also slow to rise... as to why...

[MADMAX2]

Chilliman said:

Mine's also slow to rise... as to why...

thats what happens when you get older dude

[chris1972]

Thanks guys... I'll stop worrying! I'll keep an eye on it and see if the speed to 30lbs improves. It seemed to take ages to come off zero with the new sender.

Nest job, coolant flush!

[QBee]

Try a Cabernet Sauvignon flush - so much more fun on a cold winter's evening....

[ChimpofDarkness]

Alun450 said:

I've been told even if the gauge says 50 it's bks, they never create such pressure, I can't be sure of this but it makes sence to me.

Who told you that Alun?

My experience is a serpentine RV8 will easily make 50psi over 2,000rpm if you plumb a decent external mechanical gauge into the mail gallery.

I found my TVR OP sender was not correctly matched to TVR gauge, at best the original TVR set up reads 20psi low, often its more of a discrepancy.

This is worth a read:

http://www.pistonheads.com/gassing/topic.asp?t=984...

My cheapo E-Bay sender not only give a more accurate reading than the TVR original but has proved 100% reliable in the last two years.

I like the separate earth strap as it provides a more reliable ground, it also allows you to use PTFE tape on the thread to create a perfect oil tight seal something you cant do with the original as it earths through the sender body.

Cheaper & more reliable than what TVR used, it also shows you the true oil pressure on the TVR gauge.............

What's not to like?

[Bassfiend229hp]

Mine registers 15 PSI when the ignition is just turned on, 30PSI when ticking over and between 60 and 90 PSI over 3,000 rpm...

[ChimpofDarkness]

Bassfiend229hp said:

Mine registers 15 PSI when the ignition is just turned on, 30PSI when ticking over and between 60 and 90 PSI over 3,000 rpm...

Quality Phil, you're clearly going for TVR originality there

[QBee]

Mine stays dead centre of the dial all the time - not sure it means a lot

[Bassfiend229hp]

ChimpofDarkness said:

Quality Phil, you're clearly going for TVR originality there

I work on the theory "If the gauge moves then there's pressure ... as long as there's enough pressure to turn off the oil pressure light then we're in with a chance."

[chris1972]

QBee said:

Try a Cabernet Sauvignon flush - so much more fun on a cold winter's evening....

Had a Corona flush instead!

[Bassfiend229hp]

QBee said:

Mine stays dead centre of the dial all the time - not sure it means a lot

Just reminds me about the oil pressure and water temperature gauges on the RX-8 which were originally proper analogue representations of the sensor readings but this was a very hot running wankel rotary and the yanks used to complain that the oil pressure dropped at tickover and that the water temerature used to get quite high and that it was a fault so they reprogrammed the ECU to set the oil pressure gauge to a notch *OVER* halfway when it was in the "normal" range, the water temperature gauge to a notch *UNDER* halfway when it was in the normal range and that was that.

[phazed]

Newly rebuilt engine with a mechanical gauge. New oil pump and a tightened oil pick up pipe

Start up from cold, oil light is off in a split second, pressure at idle about 40-50.
Rev it a bit and you can see 60

When hot, idles at about 30 and hits 55-60 from about 2.5K revs.

I wouldn't dismiss your problem without further investigations Chris.

Maybe you need to get to the get together to discuss your problem

[ChimpofDarkness]

phazed said:

Newly rebuilt engine with a mechanical gauge. New oil pump and a tightened oil pick up pipe

Start up from cold, oil light is off in a split second, pressure at idle about 40-50.
Rev it a bit and you can see 60

When hot, idles at about 30 and hits 55-60 from about 2.5K revs.

I wouldn't dismiss your problem without further investigations Chris.

Maybe you need to get to the get together to discuss your problem

Spot on Peter

Thems the pressures I see on mine since the cheapo E-Bay sender & the V8D OP relief spring mod.

All confirmed on a proper external Sykes Pickavant mechanical gauge.

Sounds like you're getting there mate, how's the mapping coming along?

Edited by ChimpofDarkness on Friday 8th February 22:55

[phazed]

I can't believe that I am still solving problems.

A bit more on line remote adjusting tomorrow morning.

If things don't work out, I might just explode

[chris1972]

phazed said:

Newly rebuilt engine with a mechanical gauge. New oil pump and a tightened oil pick up pipe

Start up from cold, oil light is off in a split second, pressure at idle about 40-50.
Rev it a bit and you can see 60

When hot, idles at about 30 and hits 55-60 from about 2.5K revs.

I wouldn't dismiss your problem without further investigations Chris.

Maybe you need to get to the get together to discuss your problem

Hmmm... top end rebuild about 7k ago (2009). A new oil pump is on the invoice. New sender but crappy looking spade connector. Oil light is taking a little longer to come off (seconds). I'll see what it does tomorrow morning. What else would cause this?

[phazed]

If the readings are correct then it's a can of worms!

Oil pump
Front cover
Loose oil pick up pipe
Worn bearings
Lack of oil!

[ChimpofDarkness]

phazed said:

I can't believe that I am still solving problems.

A bit more on line remote adjusting tomorrow morning.

If things don't work out, I might just explode

Drive it to the boys at Lloyd Specialist Developments.

Tell them what you want.

Return to collect your perfectly mapped car with any other related wiring, earth or MS issues resolved.

Drive & enjoy

Job done