The V8 Owners Forum -

Normally my RV8 (from TVR Griffiths 500) runs circa 30psi. Water temp runs 85 - 90 and rarely exceeds that as fan brings temp back very quickly.

Yesterday as a birthday treat for my son he had an IAM Skills Day at Thruxton. It was hot (obviously) and when on the track he once thought the water temp hit 120c. OK, my car was the fastest there! He did not really notoce the gauges anyway as concentrating! On the last lap we think there was a small splat of water from the header tank that hit the windscreen. (Did do once many years ago when I had a blocked rad.) I thus assume water pressure caused this but not no signs of any escape of water anywhere. Oil temp was showing 90c which is hotter than normal which is circa 80c

At the end of the last session I drove home but on starting I immediately noticed oil pressure was 60psi. All else seemed fine but drove slowly. Oil pressure stayed around 60psi for a few miles and then on A303 at 50mph it came down a bit then fluctuated between 30psi (normal) and 60psi. Kept going as all seemed OK and within 20 mins psi stayed more often at 30 but short periods at 50. After about 45 minutes psi was normal at 30. the rest of the journey the psi stayed at 30. water temp was normal all the way home at 85 - 90c.

Any ideas why pressure so high?

I'd guess the only possible cause ( or causes ) are a faulty gauge, or sticking oil pressure relief valve.

In this instance stuck closed, as opposed to stuck open.

Intermittent fault on either gauge or sender?

Huge fluctuation in battery voltage causing gauge to read wrong

Ian

Ian Anderson wrote: ↑

Tue Jul 12, 2022 9:07 pm

Intermittent fault on either gauge or sender?

Huge fluctuation in battery voltage causing gauge to read wrong

Ian

Dunno about all, but the SD1 which has an electric gauge has a voltage compensating winding built in. IIRC, essential with a moving coil meter. And you need a moving coil meter to react quickly enough for an oil pressure reading.

I think I will go for a temporally stuck PRV. All other gauges workd fine so tends to rule out any voltage fluctuation and I think the gauge or sender would often read wrong if faulty.

Checked water levels and I used a minimal amount at less than a half pint.

Obviously did not like the very hot day!

It would be worth pulling the PRV just to see how free it is.

It would be much worse if it stuck in an open position

Must admit to surprise that a fully hot RV8 could make 50 psi even with the valve firmly shut.

stevieturbo wrote: ↑

Wed Jul 13, 2022 9:01 am

It would be worth pulling the PRV just to see how free it is.

It would be much worse if it stuck in an open position

May do this just to see if obvious. Thanks.

Having just said this ...
Q1. Is it best to simply replace spring, etc, with a kit?
Q2. Anyone got a link to showing its removal as I need to see if I can get at it all (easily).

(Serp engine.)

Not familiar with the Serp setup myself.

viewtopic.php?t=6315

https://landroverforums.com/forum/disco ... lve-87547/

https://www.roversnorth.com/category/60 ... i_oil_pump

Not sure if they're showing new and old parts with the 2 springs and plungers, or if there is actually 2 installed ?

Thanks. I think I'll get a repair kit - O ring + circlip - plus a spring and see what happens when I try to fit them. It's not exactly clear and I've searched arund as well.

Since the relief valve must have been sticking closed, I'd expect a good clean to sort it?

So I had a good look around underneath and could not see the PRV - looking for a circlip and cover. Presumed it was located where it is impossible to get to without taking off whole side panel and exhaust too.

Went to Somerset for the 250 mile weekend trip and oil pressure all perfectly good. No issues a none neither with water temp.

Thus decided to leave it alone. Trip to Telford coming up so that should prove it too.

richardpope50 wrote: ↑

Mon Jul 25, 2022 2:42 pm

So I had a good look around underneath and could not see the PRV - looking for a circlip and cover. Presumed it was located where it is impossible to get to without taking off whole side panel and exhaust too.

Went to Somerset for the 250 mile weekend trip and oil pressure all perfectly good. No issues a none neither with water temp.

Thus decided to leave it alone. Trip to Telford coming up so that should prove it too.

The oil pressure relief valve circlip is just above your oil filter.
Remove, clean, check your spring length and then re-build - maybe a job for the winter if its working ok now?
Oil pressure relief valve - inspection
1. Clean relief valve components and piston bore
in timing cover.
2. Check piston and bore for scoring and that
piston slides freely in bore with no perceptible
side movement.
3. Check relief valve spring for damage and
distortion; check spring free length:
Spring free length = 60.0 mm (2.4 in).

Oil pressure relief valve - refit
1. Lubricate new ’O’ ring with engine oil and fit to
relief valve plug.
2. Lubricate relief valve spring, piston and piston
bore with engine oil.
3. Assemble piston to relief valve spring, insert
piston and spring into piston bore.
4. Fit relief valve plug, depress plug and fit circlip.
5. Ensure circlip is fully seated in groove.

stevieturbo wrote: ↑

Sun Jul 17, 2022 5:36 pm

Not familiar with the Serp setup myself.

viewtopic.php?t=6315

https://landroverforums.com/forum/disco ... lve-87547/

https://www.roversnorth.com/category/60 ... i_oil_pump

Not sure if they're showing new and old parts with the 2 springs and plungers, or if there is actually 2 installed ?

There are 2x springs and plungers.
One is the oil pressure relief valve from the oil pump.
The other I think is to do with the oil cooler from memory.