V8 oil pressure...

G

grifterkid

Member
I'm sure this has been covered on here but it's just a quick one... What should my oil pressure be showing on my 3500 auto' at tickover...? At the moment it is showing approx 40-50 psi which I assume is correct as the thing seems to be running very well indeed...! It rises to 60 psi when the throttle is used...
 
With a new engine oil pressure at idle whether hot or cold should see at best 30psi. Over time as the engine wears pressure will drop so 20 to 30 psi is normal. Many engines will see 10psi at idle and still run fine.

40 to 50psi is well and truly excessive and off idle 60psi and over...expensive... :shock: Reason being the skew gears,..the camshaft gear drives the distributor which in turn drives the oil pump. Excessive load on these gears, such as the oil pressure that your engine is showing and / or high rpm will see them rapidly wear away. The result being total engine failure as the distributor and oil pump stop working.

So...how many miles has your engine covered? What grade of engine oil are you using? What brand of oil pressure transmitter is fitted to the oil pump? Is it the original Smiths or a replacement made by BMI?

Ron.
 
My car has not been used for approx' 18 months and will be going into the garage this week for a very (very, very...!) thorough service... The mileometer is showing approx' 60,000 miles but there is no history to verify this, however the car is in exceptional condition and runs superbly so I believe this to be correct... I don't know the oil grade used but what should I ask for when the car is serviced? WIth regards to the other info' I really do not know but I assume everything is original...!
 
A full mineral oil, 20W-50 grade such as Penrite Classic 20W-50.

With a nominal 60,000 miles up and all engine parts original, oil pressure should be closer to 20psi at idle. When you remove the oil filler cap off the O/S rocker cover, what colour can you seen both under the cap and inside? When cold and prior to starting the engine, where is the oil level on the dip stick?

The only way the oil pressure would read that high when up to normal running temperature is either the oil pressure transmitter is faulty, or the wrong grade of engine oil has been previously used, such as a 40W-70 grade on a tight engine. With a worn engine, heavier grade oils such as 40W-70 can be used without problem.

The oil pump front cover incorporates an oil pressure relief valve which will open should oil pressure exceed a nominal 55psi, thus preventing any further pressure increase. If the valve were to be stuck in the closed position, that would not have any effect on the idle pressure that your engine is registering.

Ron.
 
Hmmmmm... I will most certainly look at these items that you mention... Rest assured, when it gets serviced this week I'm going to instruct my mechanic to have a look at these points in the hope that any potential problems will be rectified! Thanks for your help, I cannot believe I'm getting advice from a person the other side of the globe...!!!
 
The other thing it could be is given that the car has not been used for at least 18 months, (and when was the oil last changed?) there could be sludge forming in the engine... :shock:

Ron.

P.S : Yes it's 10:55pm here in Sydney on Tuesday, but being a fellow Rover P6B owner, I am more than happy to assist if I can.. :D
 
This maybe a silly question, but something you said made me question it:

Is your oil pressure gauge the 0 - 30 - 60 variety (correct one) or the 0 - 50 - 100 variety which is the 2000TC version.

Just to eliminate if it's also the gauge that was changed for the wrong one at some point.

Bri.
 
Brian-Northampton said:
This maybe a silly question, but something you said made me question it:

Is your oil pressure gauge the 0 - 30 - 60 variety (correct one) or the 0 - 50 - 100 variety which is the 2000TC version.

Just to eliminate if it's also the gauge that was changed for the wrong one at some point.

Bri.
Click to expand...

It's the correct 0 - 30 - 60 dial...
 
SydneyRoverP6B said:
The other thing it could be is given that the car has not been used for at least 18 months, (and when was the oil last changed?) there could be sludge forming in the engine... :shock:

Ron.

P.S : Yes it's 10:55pm here in Sydney on Tuesday, but being a fellow Rover P6B owner, I am more than happy to assist if I can.. :D
Click to expand...

It's a small world... :D I think that a good engine drain and the use of the high quality oil you reccomend will be the solution as under-use is often the classic cars worst enemy...! When I burried the pedal on the motorway (on collection this weekend) a puff of black smoke came out of the exhaust so I can only assume that the old beast was clearing its throat due to being idle for a while and having old fluids in its system... I just hope that a thorough service is the answer...?!
 
Hello,

just wanted to mention that i have the same readings on my 3500. Very high oil pressure according to the instrument, never lover than the middle, goes as high as 55 approx under load. The engine has run 56.000 confirmed kilometers and is an absolute beauty to drive. Oil was changed two times since the car did not run too much the past 5 years. First 500 km with 20w40 to flush and then 20w50 for normal operation. I must say that on top of that my temperature gauge barely touches the green line and always stays on that line, never even comes up to the middle green section. Funny behaviour, i think. Either the whole system is extremely healthy, or something is terribly wrong...
Is there anything you would recommend to check? There are absolutely no problems visible with the engine so far.

CU Olaf
 
oport said:
Hello,

just wanted to mention that i have the same readings on my 3500. Very high oil pressure according to the instrument, never lover than the middle, goes as high as 55 approx under load. The engine has run 56.000 confirmed kilometers and is an absolute beauty to drive. Oil was changed two times since the car did not run too much the past 5 years. First 500 km with 20w40 to flush and then 20w50 for normal operation. I must say that on top of that my temperature gauge barely touches the green line and always stays on that line, never even comes up to the middle green section. Funny behaviour, i think. Either the whole system is extremely healthy, or something is terribly wrong...
Is there anything you would recommend to check? There are absolutely no problems visible with the engine so far.

CU Olaf
Click to expand...

I would check to see if you have a thermostat.

If you (or rather your car) has had an upgraded oil pump fitted, then those are the pressures you can expect from a healthy engine.
 
This is a peculiar request but can anybody put any pictures of their oil pressure gauges (whilst engine is running) up on here so I can see how they vary...? Much obliged...
 
Here's mine





These are with the engine at normal operating temp ie 85. When it's been running for a while this will sit on 30 at idle.

Not sure if this is good or not but I hope it helps.

Dave
 

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Hello Dave3066,

Those are very healthy oil pressure figures that your engine is displaying. My engine runs similar figures. Is your engine fitted with the original Smiths transmitter or the current modern replacement?

Ron.
 
Hi Ron

I've no idea which type of transmitter is fitted. I understand that one is all metal and the other is part plastic :?: :?: :?: Do they look the same?

It started working intermittently a few weeks ago, which I put down to dirty connectors. A good clean and it works fine now.

I'll have a look tomorrow when I wash the car and see if I can figure out which one is fitted.

I seem to have got myself a pretty good engine I think. I changed the oil and filter about 1200 miles ago (I intend to change it every 3000 miles) and whilst checking the oil yesterday it was still pretty clean on the dipstick. I run the car daily and do about 3-400 miles a week.

Dave
 
Further to my last post, it looks like my oil pressure transmitter is of the all metal construction.

Dave
 
Hi Dave,

thank you, saves me the trouble of making pictures while driving. My engine produces more or less the same numbers according to the instrument, with a cold engine even higher. Seems to me i have some fine engine running in my P6, on the other hand it better runs well with only 56000 Km on the whole car. With the V8 that's a barely run in engine, i assume....

CU Olaf
 
Dave3066 wrote,..{quote] my oil pressure transmitter is of the all metal construction[/quote]

Hello Dave,

That should be the original type transmitter manufactured by Smiths Industries. You won't see them anymore. The current replacements by and large are of extremely poor quality from leaking oil through their construction to incorrect readings, either too low or too high with subsequent total failure due at any time.

Ron.
 
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