Warning lights come on at idle.

[harbourseal]

Today I drove around a bit with my project.
Sorry haven't decided on a name yet.

But after some time when I come to a traffic light and apply brakes the warning lights for the oil pressure and temperature come on.
They stop burning when I ever so slightly push the excelarator.
The oil level is ok. Do I have a broken oil pump or must I look elsewhere?

This only happens when the engine is at working temperature.

 

[André4Renaults]

The oil and temperature lamps are wired in such a way that BOTH light up when the oil pressure drops to a pre-set level. What oil grade have you in the engine? How old is it? Are there any other noises from the engine? Low oil pressure can be caused by a number of factors, including the wrong grade of oil, worn big end bearings, a worn oil pump or a pressure overload ball bearing being set at the wrong pressure. I'd start by changing the oil & filter and ensuring the correct grade of a good-quality oil is put in the sump. While the oil's out check that the oil pressure release valve is functioning properly and give it a clean.

Good luck! More help available is needed!

 

[harbourseal]

The engine is a rebuilt.
Filter is new.
I'll try some better quality oil first. There is 10w/40 in it now. Any suggestions on what to use?

 

[André4Renaults]

Mmmm.... I'd have thought 20w/50 would be more suitable for an engine of this age, but I stand to be corrected. What grade do Renault recommend?

 

[benchseat]

10/40 is far too thin. At working temperatures you're risking oil pressure loss and also possibly the oil bypassing the piston rings. The recommended oil is 20/50.

The reason why the lights come on is presumably a combination of low oil pressure due to using the wrong grade, plus the oil surging to one end of the sump when you decelerate (again, the thinner it is, the more will be this effect). When you press the accelerator the increased engine R.P.M. raises the oil pressure to a bit nearer normal.

 

[harbourseal]

The greedy Dutchman stands corrected

I could not find the right grade so I went for the oil that was available at the time.
I should have looked further.
First thing tomorrow I'll buy the right grade oil at a good supplier.
Whatever it will cost.
Thank you for this lesson.

 

[Azazello]

Renault recommends 15w40 or 20w50, but I've used several times 10w40 in the past without any kind of problem and noticing no differences between 10w40 and 15w40 (the one I use now). Funny thing I used 10w40 initially with an old engine and 15w40 now that the engine is freshly rebuilt.
I suspect that when instructions for this kind of engines were written 10w40 oil did not exist or was far too expensive to be adviced on these cheap cars...

 

[André4Renaults]

10/40 is far too thin. The recommended oil is 20/50.

Renault know best! Change the oil and filter and then report back....

 

[mr-reno-139]

Had the same problem on the Dacia Shifter I worked on recently needs 2050 on all old cars
might be worth fitting a new oil pressure switch as this may be giving you a false reading on any other car I would have suggested screwing an oil pressure gauge in but there is no easy way of doing that on an R4

 

[harbourseal]

Just now I changed the oil to 20w/50 the engine runs smoother now and no warning lights on my way home.
I didn't change the filter because I used the car for only 50 km since the rebuild of the engine And I changed the filter when I did the rebuild.

Thanks for educateting me.