Loosing all oil pressure @ full throttle??

kokkolanpoika · Post by **kokkolanpoika** » Fri May 04, 2007 7:47 pm

Hi.

I need some help. My rover 4,6 engine lose now all oil pressure (range rover classick oil pump)up to 4500rpm.
Idle pressure is ok. And 2400rpm pressure is near 40psi..

I have got some cold oil pressure proplems before this proplem starts. And here is the story.
I just clean my oil pump because oil pressure is stedy 30psi when engine is cold, and when it varms then oil pressure go upto 40psi. Then i take off the cover and look at inside the pump, everythink looks good, but valve/piston stick slightly when it is in the bore gable. I clean the piston fine 1000 sand paper, and i clean the bore also with this fine sand paper. Now valve moves casually. (No more cleararance that my another car oil pump just chek it at same time)
pressure spring is ok. same lenght as my another car spring.
I use same oil both cars..
This proplem start after this operation.
Also i have got new oil pressure transmitter.

Question is, is my oil pump caput? Or vill i damage it when i clean valve/bore with this fine sand paper? Everything looks good. Gears are ok, i measure the wear of those gears too, its ok.
Is my only choice buy new oil pump?

ian.stewart · Post by **ian.stewart** » Fri May 04, 2007 7:52 pm

Is the dip stick the right one fot the engine??

kokkolanpoika · Post by **kokkolanpoika** » Fri May 04, 2007 8:47 pm

ian.stewart wrote:Is the dip stick the right one fot the engine??

Yes..

I m drived this (recon/new) engine about 40-50000km without proplem. And oil pump is drived i think near 200000km?
The cold oil pressure proplem start about 3-veek ago.. (and fault is 90% sticking oil pressure valve/piston) And i have got no more cold oil pressure proplem, but full rpm pressure proplem yes..

I just think if the bore gable/piston leak? If the bore gable is too big/wear because i "honed" it?

kiwicar · Post by **kiwicar** » Sat May 05, 2007 12:52 pm

Hi,
Is the oil pick up loose/ bent and sucking itself onto the sump and sealing off the end so that no oil can get into the pump, this could explain both symtoms, when the oil is cold and thick it draws the pick up onto the innerface of the sump and when thin hot oil flows in suficient quantity it does the same (high revs)???

Mike

kokkolanpoika · Post by **kokkolanpoika** » Sat May 05, 2007 4:06 pm

kiwicar wrote:Hi,
Is the oil pick up loose/ bent and sucking itself onto the sump and sealing off the end so that no oil can get into the pump, this could explain both symtoms, when the oil is cold and thick it draws the pick up onto the innerface of the sump and when thin hot oil flows in suficient quantity it does the same (high revs)???
Mike

Hi..

I think 98% its not loose/bent. Engine works fine when hot before i screw the oil pump/oilpressure valve.. And works fine about over 4 weeks ago..
I just send enguiry to RPI from new oil pump..

What about if the oil pressure valve is too loose in its bore at the top of in its bore? And sticks open at full throttle because there is a lot of pressure witch have to be limited..
My theory is when valve open at full throttle and try to limiting a pressure, then it stick in this area, because if the piston/bore clearance is too big, then piston moves/turns slightly at one side, and its stops at this bore wall before when it is in the top of in its bore.

Sorry very difficult explain..

Ian Anderson · Post by **Ian Anderson** » Sat May 05, 2007 6:19 pm

I had something similar on a Vauxhall Carlton (OK only 1800 and 4 cylinders)
at Idle it had oil pressure and when revved tie oil light came on

The oil pickup was clogged with crud and replacing it solved the problem the pump seemend to manage to suck some air due to lack of oil flow than cavitate before managing to get come oil through again

Going by the miles you engine has done I would expect the strainer to be fairly well clogged up - I don;t know if there is an "anti clog"additave you can pu in oil - if so it would be worth a go!

Ian

kokkolanpoika · Post by **kokkolanpoika** » Sat May 05, 2007 7:04 pm

But why my engine gives a good oil pressure at 1000-4500rpm, near/over 40-50psi and when i rew it over 5000rpm, then pressure drops. This happen only if i drive like a racing car.
If i rew engine in place near 6000rpm many times, pump the gas 3000rpm to 6000rpm (car dosen´t move) there is no oil pressure proplem at all. Pressure is over 40psi something like 50++++
Oil temp is about 70C and i just notice that i runt 15w 40 oil, not a 15w50.
Oil pressure proplem start after i screw the oil pump.? And i use same 15w40 oil before i screw the pump, and nothing proplem then...

Post by **katanaman** » Sat May 05, 2007 7:18 pm

I would expect to still see some oil pressure at high revs even if the valve sticks open. It isn't designed and I don't think it can dump all the pressure with the volume of oil pumped at revs.

High revs makes you pump more oil, if for some reason (clogged strainer, air leak at pickup pipe) you cant supply enough oil your pressure will drop like a rock. There is also a lot more oil sitting in the top of the engine so if your levels aren't right again you wont have any oil to pump. You are also using the wrong grade oil but you know that already

kokkolanpoika · Post by **kokkolanpoika** » Sat May 05, 2007 8:20 pm

I dont understand anymore..

Eaven my friends dont understand..

If valve sticks fully open when pressure and rpm is high, then pressure can go to zero? Because there is no more recistive parts?

Is it possible that heat varm up the pressure spring and it slacken when it is hot?

Or is it possible that tolerances is too big in the "pressure"piston/valve vs bore when engine is warm?

How you can explain that when i rew this engine about 1000- 4500rpm many times on road there is no any ensign about this proplem?
And when i rew this engine is my homeyard 6000rpm many times, there is no proplem.

And when i screw this pump, i do it about 2-hours. And then i go to test drive.
I notice that oil press light/ pressure drops above 5000rpm. And i think this pickup pipe cant be slacken in this 2-hours?

Ps: i fill about +6,5litres of oil, inc oil filter/cooler + pipes..

Post by **katanaman** » Sat May 05, 2007 8:47 pm

I don't think the pressure can go to zero at high rpm because the passage for the oil isn't large enough so it will still restrict the flow. You wont get good oil pressure but I believe you will still have some pressure. Generally a stuck valve will stay stuck as well unless you hit the valve to loosen it off. Its possible but I haven't seen it happen that it hangs up on high pressure to release itself on low pressure.
The way I see it you have two options. You can drop the sump and check everything is ok with the pickup pipe. This costs a sump and pickup gasket. Option two is by a new pump base and fit that which costs a lot more. Actually there is a third option, throw the piece of junk original barrel valve in the bin and get yourself a tadpole valve from JE. It doesn't matter what the bore of the valve is like as it doesn't touch it. Even if it isn't the relief valve you have saved a fortune and have a much better valve in place. If you don't know what the tadpole valve is then search the old forum.

GreenV8S · Post by **GreenV8S** » Sat May 05, 2007 10:25 pm

Do you have an electric oil pressure gauge? If so, it's possible that the gauge is lying. This could be a fault in the sender itself, or in the wiring by the sender. Either of these could be affected by the movement of the engine as it is revved, and erratic gauge readings are a classic symptom of this type of problem.

kokkolanpoika · Post by **kokkolanpoika** » Sun May 06, 2007 6:59 am

Yes i have got a electric oil pressure gauge. And loosing the oil pressure is not a only proplem. Lifters also pump up/empty when light go on /pressure drops.. usually about 4800-5000rpm..
When pressure drops/light come on, i always switch off the engine. And i wait about 10-20 second and then i start engine again, lifters say couple of second rak rak, and oil pressure light turn off about 10second and also this oil pressure gauge increase after 10second. Both sensors are almoust brand new.. I dont think its not a sensor/gauge/light fault..

Before this pump/valve operation my engine can run (with same oil) about 6000rpm without pumping up/empty the lifters and also without loosing any pressure..

kiwicar · Post by **kiwicar** » Sun May 06, 2007 3:48 pm

it sounds more and more as if something is blocking the inlet to the pump and starving it of oil, I would review this and make certain it is not the problem before you go any further as starving the engine of oil at high revs will do alot of damage very quickly. a stuck pressure relief valve would still give fair oil pressure at these revs, the bypass passage is too small I can't see this being the problem.
Mike

badger · Post by **badger** » Sun May 06, 2007 11:11 pm

Sump pan too close to pickup, starving pump inlet at high flow??? Oil not returning to sump due to insuficient quantity in engine????

kokkolanpoika · Post by **kokkolanpoika** » Mon May 07, 2007 6:38 am

badger wrote:Sump pan too close to pickup, starving pump inlet at high flow??? Oil not returning to sump due to insuficient quantity in engine????

I think not..

Engine works about 4 years without proplem, and after this (2 hour operation) pump sticking valve operation, this proplem starts..
Nothing proplem when valve stick slightly on its bore top (only stick about 3 week), pressure stays at top near 6000rpm.. and idle pressure is also good.. Now pressure drops, because i screw the pump..?? And my opinion is leaking valve..