Low oil pressure in F7R

Level 2 User Joined: 02 Jan 2005 Posts: 45

My new track car has low oil pressure. Around 3 bar at 3k at 20 or less degrees. As it gets hotter, the pressure drops further. Sometimes when very hot, at stand still the oil light comes on. Tests at a garage using a mechanical tester have confirmed the pressure is low.

Question is, whats it likely to be? Engine is on 100,000 so first guess is a worn engine, allowing good flow from the pump but no pressure (resistance to the flow) because of large gaps in the engine due to wear. Do the pumps on these engines fail? Ive been told its unlikely. Car the engine was from was also rolled. So i guess some debris could have been dislodged and is now blocking something?

What about a blocked filter? Is this likely. Ive already changed the oil, and this didnt help. I have a 60k engine i could drop in, but i was hoping to sell this, so be nice to fix this one if its not too expensive.

Cheers

rob

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

my answers not good enough?

If not you better go and pay somewhere as you won;t get a better one.

Level 2 User Joined: 02 Jan 2005 Posts: 45

What makes you think its not just a worn engine / large bearing clearences?

I respect your opinion, but how sure are you. If your wrong its going to cost be 500 quid for a problem i still have.

Mr Quoter-vator Joined: 16 Feb 2004 Posts: 7405

The oil pressure gauge is next in line from the oil pump, so any drop in pressure i would presume be a fault in the pump...whether thats a knackered pump or blocked pickup.

Level 2 User Joined: 02 Jan 2005 Posts: 45

Well my understanding of it is that the pump produces flow. This flow is converted to pressure when the oil flow rate from the pump exceeds the ability of the oil to pass through the clearances in the bearings.

Now if the clearences are small the release valve opens to prevent pressure build up.

You could get a drop in pressure from either large clearances (worn bearings) or a release valve stuck open, thuis preventing the oil flow being converted to a high pressure.

My question is: How do you tell the difference between the fall in pressure from large bearing clearnaces from those of a pressure release valve that is stuck open?

Chris obviously has some experience / knowledge that makes him suspect the former. I jusrt want to know what that information is.

Site Subscriber Joined: 05 Jan 2005 Posts: 569

Would a low oil level give a low pressure reading?

Level 2 User Joined: 02 Jan 2005 Posts: 45

Yes, i believe so. First thing you should check if the oil pressure is low.

Site Subscriber Joined: 05 Jan 2005 Posts: 569

Oh right. Mines just under halfway between MAX and MIN.

I would have changed the oil if the damn filter would come off.

Stupid self distruct Renaults ;mad:

Level 2 User Joined: 02 Jan 2005 Posts: 45

Take it to kwik fit and let them burn their hands and get covered in oil.

Gay Rights Activist Joined: 07 Apr 2004 Posts: 1268

Rob, this is why i was asking how the engine sounds, as it is hard to say if low pressure is to due to an inadequate pump, or excessive main bearing clearance. difference between the two being excessive mains clearance will result in a rumbly sounding engine.

the only other way to tell is to remove the pump and check its tolerances and pressure relief function, or remove the crank and check bearing clearances. i suggest if the engine "sounds" ok, you should start by removing the pump and check that. once you haave established its condition, you can then make an informed decision about the condition of the rest of the engine.

Level 2 User Joined: 02 Jan 2005 Posts: 45

Apart from the low oil pressure and the warning light flickering on at a stop, ther are no other symptoms. The engine is a bit tapetty, but less so with mineral oil in it (did have fully synth in it from previous owner 5w 40). Also the warning light hasnt come on since i put the mineral oil in it (10w 40).

Pressure is 2 bar at motorway cruising speeds and it rises to this between 1.5k and 4k revs. Once here it will rise no further even if you put your foot down. At idle the pressure slowly drops. With the synthetic oil it dropped enough to allow the ligh to come on.

Dont know why as both were the same viscocity at optimum temp. At cold start up the pressure is 3.5 bar at 3k revs. This drops as the oil heats.

There is no smoke, noise or other symptoms atall.

Level 10 User Joined: 27 Apr 2005 Posts: 620

5w40 oil's isnt thick enough for the f7 engine aswell king, when the oil gets hotter the viscosity decreases therefore as its flowing through the engine its like theres actually no oil there because its so thin, 10w40, 10w60, 15w40 are the best oils for it, as far as what your saying id go with the oil pump matey

Level 2 User Joined: 25 Oct 2005 Posts: 55

Sounds a strange one.

As for the oil type....everyone seems to differ in opinion!

I have had experts tell me that fully synth 5w40 is fine in F series engines, and others than 10w40 is the lowest viscosity that should be used.

I only know one thing...that when i changed from 5w40 fully synth to 10w40 semi synth last time i did my oil change the engine got a whole lot more tappety!

Is most fully synth stuff designed to be the same viscosity at 100C anyway, it just is just less viscous at lower temps, allowing better lubrication and will heat up better, saving cold start engine wear?

Interesting to hear u guys speak about using mineral oil Confused

I thought it was the shitty-est stuff you can buy! Rolling Eyes

Level 10 User Joined: 27 Apr 2005 Posts: 620

we'll 15w is the mineral stuf 10w is part sythetic and 5w is fully ive always used part and it does tappet at all gtx maggy isnt the best of oil's as me chris h and a few others have found out but as you say personal preference

Level 2 User Joined: 02 Jan 2005 Posts: 45

Its not the oil. Ive run all different grades and typres in my F7R's and they do have different pressures, but never oil light low presssures.

This is definately an internal engine problem. I just need to be sure what it is before i spend muchos cashus on sorting it out.

Im tempted to just get someone to rebuild the engine. I have the cash it migh be the best solution.

Level 6 User Joined: 16 Dec 2005 Posts: 145

5W-40 gives just as much protection as 15W-40 at running temperature.

5W simply benefits from more protections at cold starts. For this reason i am chaning my oil from 15W-40 (very tappety on cold mornings), to 5W-40.

Level 10 User Joined: 27 Apr 2005 Posts: 620

well for the time being you could wack the other lump you got and have the 1 you got in the car re-built least u still got a motor

as for changing to 5w its not summik id do not even in my 410bhp scoob

Level 2 User Joined: 02 Jan 2005 Posts: 45

Im not the sort of person that really has the ability to just shuffle engines around. Hence i need to find out exactly what the problem is, so i can target my resources correctly when i pay someone else to do the work.

Affiliate Joined: 28 Jan 2005 Posts: 360

As a neutral figure here I have to agree with Laine on the viscosity issue except i'm planning on running a 5w/40 fully synth when the TB's go on. Doll and Lowe and Evis from RSC use it in F7R's without issues so i'm gonna give it a go to. I've also firm believer in the rule of "Start at the cheap and easy items and work through the list to the pricey ones"

If you've got the cash for a full rebuild and you're planning on using this car hard on track then that's obviously the best way to go. Failing that I'd say Stans advice about removing the pump and checking it's tollerence is obviously the short cut and cheaper option but a sensible one none the less and replace the pump is required.

Mick

Level 6 User Joined: 16 Dec 2005 Posts: 145

Ive just changed my oil to 5W-40 and can notice no real change at all. Temp's pressures are all roughly the same.

Im just hoping it makes less noise when i turn it on first thing in the morning.

Failing that im going to get some Wynns hydraulic valve treatment, to try and stop noisy tappets.

Level 10 User Joined: 27 Apr 2005 Posts: 620

liane hows the tappets ? they still tapping