The V8 Owners Forum -

hello all,

How long does it normally take for the rover 4.6 crank driven oil pump to prime, when starting the engine first time?

I've ran mine on the starter a few times with no plugs in, then fired it up for very short period...…

But I'm not seeing the oil pressure gauge registering anything.

How long can the engine safely run with oil pressure from start.

Baring in mind the engine has been newly rebuilt.

thanks

scott

I'd not start the engine at all if no pressure when cranking. With an unworn engine, I'd expect the oil pressure light to go out when cranking.

It took me 3 minutes to get pressure cranking on the starter then firing it up before I got pressure. Make sure the oil filter is filled and I pumped a lot of oil in through the oil pressure switch pressure hole. On my engine, there is also an access port on top of the oil cooler so I also pumped in lots of oil there before firing up.

Yes is very concerning how long it takes.

Garry

now I'm getting worried…..

I've spent all afternoon trying things.....and still no oil pressure.

Removed the oil pressure sender and filled the passageways full of oil.

removed the pressure valve & spring, it wasn't stuck and came out freely, filled the passageway full of oil and replaced the valve & spring.

again plugs out and turned it over on the starter, oil pressure gauge isn't showing anything...….

anywhere else I could try and fill it from?

Always thought the serpentine oil pumps primed quicker than the older dizzy driven ones.

cheers

scott

What sort of gauge? Are you sure it would show cranking pressure? I'd remove a rocker cover, and see if oil is being pumped up to them,

I have a feeling that the crank driven pumps don't prime until the engine fires up. I notice that my Rangey immediately runs to 1500rpm before dropping back.

When I start my next engine I am going to be faced with this problem, so I am going to force oil through the pump and oil galleys from the oil cooler ports first, making sure that oil comes out of the rockers. Then I'll start it and hope!

Chris.

As I said above, mine did not get pressure on cranking - not until it fired up - make sure your sender etc works first.

Could you pack it with Vaseline - same as you do with the old one?

Most serp trochoidal style pumps prime soon as the engine fires/runs (new builds) unlike the earlier gear type pumps , I have managed to prime the later serp system on a new build RV8 with a packed with bearing lube/guard mounted on the engine stand and no cylinder heads fitted just by slowly rotating crankshaft but I had brim filled the filter etc cranking alone even with no plugs seldom make pressure on a previously opened up oiling system on a serp

Overfill it to the level of the crank and it should prime quickly.
Then, drain it back to run the motor.

As mentioned above crank driven oil pumps don't normally prime when cranking, need to be started! This can be quite nerve wrecking, from memory mine took about 5 to 10 seconds for the oil pressure to build, but his feels like an eternity.
It's actually more damaging to your cam to do prolonged cranking so best to just start and keep an eagle eye on your pressure gauge/light.
When the light goes out, take a rocker cover off and with the engine running check you have oil weeping out the rockers, this will take a little longer still.

Tom.

thanks everyone, always good to know its not just me.....

I finally got some oil pressure after quite a few short busts a cranking with no plugs in, then finally firing it up...…

The oil pressure now does sometime go off the scale on the gauge, but so does the fuel tank gauge, so i'm also thinking theres a short somewhere to under the dash.

regards

scott

I think the Thor oil pump runs over 50psi which is epic.

Chris.

ChrisJC wrote: ↑Fri Jul 27, 2018 3:56 pm I think the Thor oil pump runs over 50psi which is epic.

Chris.

True. But no RV8 is prone to running big end bearings, so the original pump more than adequate? Interesting that few cars are fitted with an oil pressure gauge these days.

There is no such thing as a Thor oil pump - that is an induction system. All 4.0/4.6 engines Gems or Thor or whatever have the same oil pump - it runs about the same pressure as the old camshaft driven pumps - about 30 -35psi when warm on a good engine.

Garry