Rover P6B Engine Oil Pressure Concerns

Mike Allfrey

Mike Allfrey

Member
Hello,
I have a 1976 Rover P6B, generally in excellent condition, however, I am a bit concerned about the engine's oil pressure. In warm weather conditions (28-35 degrees C, ambient) and in very slow stop/start traffic conditions, the engine heats up to the extent that the temperature gauge indicator needle sits just within the RH end of the green sector. In such conditions, the oil pressure gauge drops close to zero, but the low oil pressure warning light does not illuminate. As the engine's revs increase, the oil pressure climbs steadily to about the mid position on the gauge.
The car has air conditioning and is equipped with automatic transmission. The engine oil is of top quality and of the correct type. The car is regularly serviced and a new oil filter cartridge is installed at every service. A new oil pressure transmitter will be fitted at the next service.
Any thoughts or previous experiences on this concern?
In addition to that one, I am also wondering about the condition of the hydraulic lifters (tappets). Maybe they are a source of oil pressure loss at low idle. The engine does require a great deal of cranking to start when cold, which makes me think that there is a concern with the lifters. For cold starts I have tried leaving the ignition switched on for about 45 seconds for the rear mounted electric fuel pump to get petrol to the engine, but that does not make much difference. The engine is fitted with a new electronic ignition system and, once running, operates very nicely.
Any comments will be appreciated,
Mike Allfrey (Melbourne, Australia) Rover P6B in 'Spanish Olive' and known as Pea Soup!
 
Rover V8 engines are known for running with a low oil pressure, factory spec is 30-40PSI @ 2400RPM HOT, there isn't an idle pressure specified. If you have some sort of reading on the gauge and the warning light isn't coming on personally I wouldn't worry, but low pressure is normally associated with worn main and big end bearings rather than worn lifters. You could fit a high volume oil pump or a kit for yours and that will bump up the pressure a bit and ensure more oil is flowing around the system.
 
Thanks Harvey,
The low oil pressure warning light has illuminated just once in my ownership, recently, that was under an extremely hard braking condition, avoiding a red light runner (quite common here). Probably oil surge into the timing cover area. Until then, I was not fully aware of how effective P6B brakes really are - most impressive!
I will install the oil pressure transmitter and see if that makes any difference. I will also ask the workshop to test the idle oil pressure with a Bourdon tube gauge. Your comment about worn main and big end bearings takes me back to the 1950s and another manufacturer's aluminium crankcase. So far there are no rumbles (mains) or knocks (big ends) that new hearing instruments have picked up for me. Thus, I think matters are sound in that area.
Thanks again,
Mike Allfrey (and Pea Soup).
 
I had those symptoms too in my P6b.More alarming for the driver as passengers would comment when the low pressure came on at low revs. An SD1 oil pump sorted that low pressure reading. Had to swap the P6b gear end over to match the SD1 pump. The correct oil is 20w/50
 
Hi Mike,

There is no guarantee that your oil pressure transmitter is working correctly either. If it is the original, then I can recommend that you keep it rather than changing to the modern replacement. The replacements are extremely unreliable, and will read low and high and everywhere in between, giving no peace of mind.

The oil warning light will illuminate when the oil pressure falls to between 8 and 10 psi, remaining on with falling pressure. Given the light is not illuminated and the gauge displays zero pressure, that tends to suggest that the sender is reading incorrectly. With zero oil pressure, your engine will knock heavily, so that is another indicator that the sender is at fault.

Ron.
 
Hi Ron. I'm currently having the same problem with my oil pressure. Intermittently dropping to zero on the gauge. No oil warning light and no knocking from the engine. I`m sure it is the sender. I tightened the spade clip on the sender itself. no change.

Do you know what the correct sender would be for an 1975 3500? There seem to be a couple of types floating around. Mine has a single terminal on the back of it.

Cheers

James
 
Had the same thing happen on my 2200TC. No knock but zero on gauge intermittently. Changed sender for a NOS and everthing was fine. Oil leaks from the crimped over joint.
 
Within the last year I cleaned the inside of my V8; valley, heads, sump, pickup strainer and tube, and replaced the rocker shafts only. Before this I would get ~30-50 psi most of the time. Now I only get about 30 psi max and maybe 10 psi on startup. I know the rocker shafts were worn and assumed the oil pressure would be higher with these replaced. Maybe cleaning out the gunk has "released the flow"so to speak and now gives realistic oil pressure. Before startup I did prime the pump with a drill, before and after fitting the new rocker shafts and there is plenty of flow there. Never any oil light on though.

BTW sometimes my gauge needles travels backwards! Its a bit of lottery which way it will travel when I start up.

Craig
 
74westy said:
Within the last year I cleaned the inside of my V8; valley, heads, sump, pickup strainer and tube, and replaced the rocker shafts only. Before this I would get ~30-50 psi most of the time. Now I only get about 30 psi max and maybe 10 psi on startup. I know the rocker shafts were worn and assumed the oil pressure would be higher with these replaced. Maybe cleaning out the gunk has "released the flow"so to speak and now gives realistic oil pressure. Before startup I did prime the pump with a drill, before and after fitting the new rocker shafts and there is plenty of flow there. Never any oil light on though.

BTW sometimes my gauge needles travels backwards! Its a bit of lottery which way it will travel when I start up.

Craig
Click to expand...
That is a bummer. Maybe you should remove the oil pump base and take it apart and clean all through, it is possible you have some dislodged crud around the pressure relief valve.
My old very knackered 3.5 ran @ 50psi cold on start up, I built up the 4.6 and it only had 30psi cold, disappointed I investigated the old pressure relief valve and found it had a longer heavier spring, so I put that in the 4.6 and now have 50 psi cold again. I think it is Rimmer Bros that sell the uprated spring.
Edit
Found it here Oil Pressure Relief Valve Service Kit - Uprated - RTC2044AKUR | Rimmer Bros
 
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rottenlungs said:
Hi Ron. I'm currently having the same problem with my oil pressure. Intermittently dropping to zero on the gauge. No oil warning light and no knocking from the engine. I`m sure it is the sender. I tightened the spade clip on the sender itself. no change.

Do you know what the correct sender would be for an 1975 3500? There seem to be a couple of types floating around. Mine has a single terminal on the back of it.

Cheers

James
Click to expand...

Hi James,

The genuine NOS item is 555947. When they crop up, they are exceptionally expensive as this one on ebay illustrates.
NOS Land Rover OIL PRESSURE TRANSMITTER EARLY V8 555947 | eBay

There was a company in the U.K that was manufacturing them with the part number 555947P. They looked virtually identical, and from the information that I have, worked extremely well. There is another replacement that looks quite different, but sadly they are very unreliable.

Ron.
 
Hi Ron. Thanks very much for the information and wow that is rather expensive.

I may have to see if I can find something 2nd hand down here.

Cheers

James
 
I have to do battle with electric senders in my job and I can tell you that the repro ones made by Speedy cables ( Smiths ) are a total bag of S**t, so if I were you I would go to a bone yard and harvest as many old ones from old Brit stuff as I could.

The 1/2 scale gauge uses a different sender to a full scale gauge, it is just a lottery as to which would work with the Rover.

You can however make any gauge work with any sender by using one of these to get you out of a muddle, but it's a bit of a faff.
https://spiyda.com/Link/PicWizard All Pages V4.4.pdf
 
Mark that is good to know. I’ve got to do battle myself at some point with my new gauges and senders, adapting the senders to the engine etc. They’re all part of a Veethree kit so once fitted should just work in theory..
Jim
 
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