help please, oil light flicker at idle

[fylfot]

A couple of times now my oil light has started flickering when the engine is at idle, when i increase the idle a tiny bit it goes out. I don't know if it's doing it because the idle control idle control is faulty, causing the engine to tick over too slow or if the oil pump is going home. What revs should it idle at (2.5v6 petrol manual)? Cheers David.

[Nick Mann]

The VR4 is well known for this issue. I would be amazed if the issue is not the same on the V6 - the block is 99% the same. The issue is just that the pressure switch is getting lazy.

http://www.camskill.co.uk/m22b0s1399...2_5_Twin_Turbo

[fylfot]

Cheers Nick, i got a switch today, whereabouts on the engine is it located? sorry for being a dumb ass, i tried googling the location, but all the images were too vague. Cheers David.

[Nick Mann]

If you take the drivers front wheel off and then the plastic liner between the wheel and engine, you should see the wire to it between the pulleys.

[Nick Mann]

http://www.clubvr4.com/forum/showthr...l=1#post701105
First picture - the switch is above the bottom pulley and slightly higher than the centre line of the main crank pulley. Note that the aircon and power steering should be bottom right too but as the engine is out of the car they are not there.
http://www.clubvr4.com/forum/showthr...l=1#post701713
The engine photos in this post are all from a similar angle and the switch is visible slightly up and right of the crank or below the engine mount bracket.

[fylfot]

thanks mate

[fylfot]

Just to update, changed the switch/sender, problem solved, phew, that was cheaper than oil pump/ big ends etc!

[Nick Mann]

Splendid.

[elnevio]

Great knowledge, cheap fix!

[Davezj]

Glad to see people listening to thee advice given and acting on it and potentially saving massive amounts of money in the process.
Well done all.

[elnevio]

Mine did this for the first time today. The oil may have been a little warmer than usual after I conducted a couple of roofbox speed trials whereby I amused myself at surprising unsuspecting BMW drivers in a family estate with a roofbox on... anyway, I digress! The oil was a little warmer I guess so a touch thinner. But I've never seen the oil light flicker at idle (unless the idle goes really low, like restarting about 30 mins after driving, when usually the other lights come on too as it will nearly stall) before. Gentle few minutes home, and it didn't do it when I stopped on the drive and let it idle.

Maybe the switch is on the way on mine now?

Cheap enough to change anyway - I just wish I'd done it a few weeks ago when I eventually put the driver side splash guard back in place!


Does much oil comes out of the sensor hole? I guess it can be minimised by swapping the new one in pretty quickly.

Also, while I think of it, is the sensor hole the same size as the sensor fitting for normal oil pressure/temperature gauges, and can it be used for them? Just wondering, as I would prefer this to the sandwich plate option.

[Confused]

The standard pressure sensor is quite a large thread, the aftermarket pressure switches (that you fit to a sandwich plate) are usually a much smaller thread.

[Davezj]

Standard oil pressure switch is only a few quid you might as well just change it.

[SEAN-NZ]

Considering the sensor would be somewhere above the sump, I would guess that oil lost wouldnt be much, if the cars been sitting for a while

[Nick Mann]

No, you don't lose much oil. Less than a teaspoon full in my experience, although most of the ones that I have changed have been during a service so there wasn't much oil to drip out anyway!
I have seen one engine with an adapter in that allowed a tee piece to be fitted. I assume that this was used for after market sensors as well as the stock item.

[elnevio]

Now I have all the bits to sort out my snapped alternator tensioner bolt, I have taken the opportunity to get a new oil pressure sensor too, seeing as the same bits will be coming off for me to fit it! Well, today is the plan anyway - my plans have a habit of remaining in a long gestation period...

[elnevio]

Belt, bolts and dipstick replaced.

Old oil pressure sensor eventually removed (the 24mm collar was not as hexagonal as it once was! ). Was intrigued to see that the old one was not screwed all the way in but had been plugged with some rubber sealant or something.

Screwed the new one in as far as I could, with some PTFE tape on the thread, fired it up, and got a nice oil leak - so tried to tweak the sensor a bit more - no good. Removed it with the plan of adding in a washer to help the sealing, and realised that the housing is in fact cracked, as you can see in the picture.



Not sure if it was on its way out before, hence the old sensor not being all the way in, but I'm pretty sure I've only made it worse!

What are my options with this? Chemical metal is my first thought, but that will definitely mess things up if it ever needs removing again, and most definitely if I don't get a good seal and have totally screwed it up! Also, I have never used the stuff, so would want to be sure of what I am doing first.

All suggestions gratefully received!

[Davezj]

i believe the sensor screws into the oil pump, so the last resort is to replace the oil pump but that is major surgery for the engine, and unless you can do the work yourself it will cost you more than a replacement engine. but that absolute worst case.

you could get it welded on the front face and down the side then retap the threads. however to weld the ally it has to be very clean and free from oil and contaminates.

if i remeber rightly the thread for the oil sensor is a NPT or BSP both tapored threads so the sensor is not designed to go all the way in. it is designed to lock and seal in place as the tapored thread bites into the other tapoured thread in the oil pum. if you do it up more and more it act like a wedge and splits the threaded boss in the oil pump as has happened to you unfortunatly.

OK so hear are the cheaper options.

you could just remove the oil sensors and plug the hole completely and perminently. Then fit the pressure sensor in a sandwhich plate by the oil filter.

how you block the hole is up to you, but using an old sensor and liquid metal or RTV sealant or equivalet would do.

or you use a metal adhesive or two part putty or RTV sealant.and put a normal bolt in the hole which will lock up, it will distroy the thread in the oil pump but it should seal the holes.

or find some kind of other bung to plug the hole and fill the crack. whatever you find to fill the hole, the area will have to be completely free of oil or dirt, a good pray with carb cleanrer and rags. but the carb cleaner will get in the oil in the engine so a oil change will be required.

these are some options i am not saying they are best, but off the top of my head these are the bit i thought of.

[adaxo]

That's a bugger, I think it will be hard to fix/seal due to very high pressure. Sorry for not being so optimistic but its a tough one to sort out, replacement of oil pump its doable but not quick or easy, fixing this crack by putty imo is not an option due to high pressure, welding? Then you will need to rethread hole so its a part off anyway.

[elnevio]

Thanks for the ideas! Well I guess it has to be worth a stab at fixing it. May try the blocking up route and using a sandwich plate for the sensor. Just the small matter of what to use and the time! I do have a sandwich plate so can check the sensor fitnent.