Oil pressure

steven 90 · Post by **steven 90** » Sun May 06, 2007 8:15 pm

When the camshaft on my 3.5 was changed to the one from a 3.9 the oil pump was "boosted" (i mean the spring was reinforced to give more pressure).
I always had 2.5 bar at idle and 3.5 a high rpm.
After a couple of months my oil pressure gauge broke,so instead of replacing it i waithed until i had to open the oil pump anyway.(to prime it with vaseline)
The oil pump gears and spring and spring piston are al brandnew.
So i replaced the sender it was faulty,now i had 2.5 bar at idle when testdriving it peakt until almost 4 bar and then droped to 1.5.
I changed the cable from the gauge to the sender and it now has 2.5 at idle and when reving the engine up it peaks to + 4 bar and then drops until 2.5.
Is this because the oil pressure relief valve opens ??

Regards Steven

jonnyboy · Post by **jonnyboy** » Mon May 07, 2007 8:28 am

One thing to watch out for is that the piston can stick in the cylinder. A higher pressure spring might cause that problem to get worse. I have heard of a using a "tadpole" valve in race V8's that stops this problem happening.

The green bible states that, when warm and at 2400 rpm, the pressure should be 30 to 40 psi. Thats about 2 to 2.5 Bar. The rover V8 has a low pressure high volume lubrication system and I have my doubts about the benefits of increasing the pressure. If you hitting 4 Bar then thats aprox 60 Psi.

Just my thoughts.

Andy Dawe · Post by **Andy Dawe** » Mon May 07, 2007 8:37 am

Has anyone tried to buy a Genuine oil pressure sender unit recently. Well the one shown in the book has been replaced with Pt No. 555947 0-60psi. Super that will be £135 please. However Rimmer Bros do a pattern part 555947P for £35. still expensive. may have to look at the capillary route at some time.

steven 90 · Post by **steven 90** » Mon May 07, 2007 8:38 am

Thanks for the reply,

I have heard about the "tadpole" in belgium aparently nobody uses them.
I did had the problem of a sticky cilinder this is the reason i put in a oil pressure gauge.I was thinking with the new big end bearings i also would increase the pressure.The problem is that i don't know if the gauge is very accurat.Just a new cable from sender to gauge gifs me an increase of 1 bar.
Also i don't know at max rpm how much the pressure schould be.

Greetings Steven

steven 90 · Post by **steven 90** » Mon May 07, 2007 8:45 am

Andy Dawe wrote:Has anyone tried to buy a Genuine oil pressure sender unit recently. Well the one shown in the book has been replaced with Pt No. 555947 0-60psi. Super that will be £135 please. However Rimmer Bros do a pattern part 555947P for £35. still expensive. may have to look at the capillary route at some time.

I know my sender know is made in italy

it costed about 50 €
The one before after some months didn't do anything.
I know that rimmer bros has a set to place a "real hose" and a gauge that is filled with oil in the dasboard this is probaly always right.
My local parts supplier did not recomend this because with a other brand of car he went for a drive and the hoses inside the daschboard came of

steven 90 · Post by **steven 90** » Mon May 07, 2007 9:02 am

I was thinking about placing in a hose with a gauge where the oil temperartur sender schould be.
However is this a good place to measure the pressure ??
The thing a hate is that every time you open the pump you have to use vaseline to prime it.I was told that people driving offroad competion in the uk had a special "tool" to prime the pump when for example it has done a rollover

.
Don't know if this is true and how they do it

Greetins
Steven

jonnyboy · Post by **jonnyboy** » Mon May 07, 2007 11:00 am

When priming a pump I use a drill with an extension bar and a 7/16" socket. I pull out the distributor and the socket fits onto the top of the pump.

steven 90 · Post by **steven 90** » Mon May 07, 2007 11:03 am

jonnyboy wrote:When priming a pump I use a drill with an extension bar and a 7/16" socket. I pull out the distributor and the socket fits onto the top of the pump.

Do you also fill the pump through the distribitor hole ???

Larry · Post by **Larry** » Tue May 08, 2007 1:32 pm

I had a problem some time back with the piston sticking. The oil light flickered faintly when it did this. Overhaul kit fixed it, but there must be tight tolerances in there as the old one didn't look too worn at all.

I've got a tube type oil pressure gauge that I never got round to fully fitting (its in the dash, but not connected!). I haven't really looked into it, but was told that you needed an adaptor or different housing to get the feed for the gauge off the pump. What do you need to do to fit either type? It does sound like a useful bit of kit to have.

steven 90 · Post by **steven 90** » Tue May 08, 2007 8:20 pm

The piston was not worn with me but there where some metal particels jamming it open.
You have 2 connections on the pump they are both plugd
1 for the temperatuur sender
1 for the pressure gauge.
I think that the biggest one is for the temperatuur (i am not sure thoug).
Just remove it and then screw in the one you have got and perhaps use some other kind of connector.
Use vaseline to prime however i think you know this..

Larry · Post by **Larry** » Wed May 09, 2007 2:58 pm

Cheers for that. What sort of pipe should be used? I'm presuming that fish tank plastic tubing would not cope!

steven 90 · Post by **steven 90** » Wed May 09, 2007 4:25 pm

Larry wrote:Cheers for that. What sort of pipe should be used? I'm presuming that fish tank plastic tubing would not cope!

I buy muy hoses in al local parts shop,use the one resitant to oil and fuel and nothing else

If in doubt i have the plug i removed somwhere in my shop so i can measure it to now if you got the wright one

Steven

steven 90 · Post by **steven 90** » Sat May 12, 2007 6:14 pm

jonnyboy wrote:One thing to watch out for is that the piston can stick in the cylinder. A higher pressure spring might cause that problem to get worse. I have heard of a using a "tadpole" valve in race V8's that stops this problem happening.

The green bible states that, when warm and at 2400 rpm, the pressure should be 30 to 40 psi. Thats about 2 to 2.5 Bar. The rover V8 has a low pressure high volume lubrication system and I have my doubts about the benefits of increasing the pressure. If you hitting 4 Bar then thats aprox 60 Psi.

Just my thoughts.

Today i removed the spring and the nut placed behind it to "boost" the pressure.There where also 2 washers that i left in to gif and extra bit of pressure
Now i have when starting up 2.5 Bar it then drops until about 0.8 kg at iddle and when driving it gives sometimes 4 bar,then drops until 0.8 then 2.5 anyway i think something is still faulty.
It gives me i "creepy" feeling that mabay perhaps the oil pressure realy drops until 0.8 when driving but i still think it is the sender unit.

Regards S

steven 90 · Post by **steven 90** » Tue May 15, 2007 3:29 pm

I changed al the connections,check everything from the fuse to the sender unit.Still nothing
Drove to my parts supplier and fitted a new sender unit,problem solved

for now
So i rebuilded a hole engine and then had the bad luck that the faulty sender unit a replaced with a new one that was also faulty

Thanks for the advice to everyone.

S

onno wielinga · Post by **onno wielinga** » Tue May 15, 2007 6:39 pm

you're not the first one this happened to!
i know a well known garage-owner that restored a three door range rover ans also reconditioned the v8 engine.
ran it; no oil pressure. took the complete engine apart, checked bearings, o.k. put it back in the car. ran it, again no oil pressure.

he was going mad! the wife came in and he told her about this problem.

he did not trust the landrover oil gauge so for the checks he had a professional test unit fitted. the wife said maybe your gauge is wrong. he did not believe this could be right, but desperate, he fitted a new gauge.
you should have seen him and you should have seen the wife when the engine was fine but the gauge was wrong!

this story is sometimes mentioned at his or her birthday for a bit of fun