Classic Rover V8 oil light problems

jolly-109 said:

I know this isn't a Range Rover but I also know there are some really good engine guys who look at this section as I have a Suffix A and they have been helpful in the past plus the engine is the same

The series 3 I recently purchased has a rover V8 transplanted into it and it's been a wiring nightmare as it was never completed by the previous owner.
One of my last issues is the oil light will not go out (at all) so I have a few questions.
It looks to me that the switch is "closed" on start up and then goes open circuit when pressure is reached is this correct?
Switch is on the earth side is this correct?
Is there any way of testing the switch?
I have not changed the oil or filter and car not not really been run for a few years but does start and run fine, oil looks lovely and clean plus filter doesn't look old BUT neither does switch so I think previous owner has changed it..
Any help much appreciated as usual.

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Saint.V8 said:

This is as close as I have to the oldest Classic wiring diagram (1986) Shows the switch is Made when the pressure is low and when pressure rises the switch breaks turning the lamp off.

Testing it...hmm, Oil pressure is around 30-45psi, so maybe rigging up something from a tyre (usually around 30-36psi) and using some tubing to the switch in some fashion, then a multimeter to check the switch state!!!!

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jolly-109 said:

Makes sense with the wiring, closed circuit until pressure is made then goes to open circuit to switch light/bulb off. Maybe i will tr and rig something up to test the switch as you suggest.

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wammers said:

Oil lamp should go out when pressure exceeds 15 PSI or so maybe a bit less.

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jolly-109 said:

OK, new gauge fitted with T piece and pressure switch and new mechanical gauge all fitted and working. Light now goes out and gauge reads around 35-40 psi (revving it in the garage). I have two questions now:-
What pressure should I get on rover v8?
When I do an oil change in the future do I have to remove oil pump and pack with vaseline again or should I be able to just fill the filter back up?

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tomcat59alan said:

You shouldn't need to prime the pump, just drop the oil, change filter, start it up and watch for the oil light to go out then check for leaks. From memory 40 psi sounds right.

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wil2813 said:

+1 alan but in the past on more than one occasion removing the pump & packing the gears with the old vaso has been the only option to get rid of the glowing red light

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jolly-109 said:

When I do an oil change in the future do I have to remove oil pump and pack with vaseline again or should I be able to just fill the filter back up?

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classic kev said:

Always a bit of a lottery. Would suggest drop oil and re-fill then remove ignition feed to coil and crank engine, if you're lucky the oil light will go out while cranking in which case all is good, if it doesn't then you'll have to prime the pump, I've always used the drill on the pump drive method as it is easier to pop the distributor out rather than dropping the pump and faffing about but just a heads up I did once have an issue where I couldn't get any oil pressure.

I checked and re-checked everything, I ended up dropping the sump, checked pick up pipe and strainer, used an oil syringe to pump oil in to the pump and all sorts and still had no pressure. Then an older and wiser friend of mine suggested putting the old oil filter on it, did that (after putting it all back together of course!) and straight away good pressure! - the new oil filter was faulty and wouldn't allow the oil to flow, never seen it before or since but something I won't forget. HTH.

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Grrrrrr said:

That's a good point. Any o-rings on the oil strainer pickup or similar too.

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