Oil light staying on

[scrumpydude]

'lo all. Have a bad feeling about this one.

The truck (3.0) started to use oil a few months ago but this seems to have accelerated over the last few weeks to some interesting times over the last few days.

Current situation is that despite being above the high mark on the dip stick, the engine oil light is staying on. Yesterday morning it came on (first time in 2 or 3 weeks) and it went out with half a litre. However, it came on again in the afternoon after no more than 15 miles of driving. Today, my wife had it come on again.

The oil is Castrol 10W40 SemiSynth and it is being topped up with a GM version of the same type/grade.

Any ideas?

I saw reference to a phrase on a previous oil related thread to (something like) "turbo blow past". A couple of times when pulling onto the road the truck has shot off as if in 'sports mode' and there has been a puff of something from the exhaust. Could this be related?

Either way I'm guessing this is a garage job as I don't have the time myself.

 

[solarman216]

first thing I would do is change the switch, think there are two on the 3 so check which one is the low pressure one, if the turbo is passing buckets of oil then yes this could lower the pressure a lot also it can lead to runaway, you could have experienced this already "truck has shot off" = this, if it does it in neutral then get it in top gear double quick and drop the clutch with foot hard on brake, Rick

 

[solarman216]

forgot to add you must never fill a turbo motor above the full mark, it increases the risk of runaway by loads and will do nothing for oil pressure, Rick

 

[Barrbeast]

I think you could have two separate issues, whatever is causing the random spirts mode and a dodgy pressure switch.

The high pressure switch is the one that usually goes (turning the warning light on) but I've heard of the low pressure one going occasionally. Low pressure is tge easiest to get to as it's next to the oil filter, high pressure one can be got through the driver's side wheel arch on the Terrano (I believe).

High pressure switch on the Trols is harder to get to, I didn't bother, just fitted a pressure gauge and earthed the pressure switch connections so the light went out:thumbs

 

[Blocky10]

This might help.

 

[scrumpydude]

Thanks all.

Hopefully just a pressure switch then. Never known that before. After leaving her stood still for two hours I've just checked the oil and she's above the high mark (about an inch!) so I'm happy she's not out of oil. Light went out when I gave her a rev (don't think I revved her for some reason earlier). Will try an get her into the garage tomorrow.

Thanks for the advice on runaway Rick. Only happened twice when changing from 1st to 2nd IIRC. When I bought here she was well over filled (several inches up the stick). Put her into the garage (for a service where I supplied the Castrol) and she came out more or less the same. Two trips back for them to take oil out. I'll risk her being over filled until the garage has seen her (hopefully her next trip).

One last question. Where are the oil pressure switches in relation to the engine? Have a concern that if one was in the head, could it be showing oil pathways being blocked? If both are in the block then less of a concern. That said, I assume blocking the oil pathways would take some doing.

 

[Barrbeast]

Oil switches are in the block bud.

You don't check the 3.0 oil level cold, get her up to operating temperature and switch her off. Leave her ~2 mins and then check :thumbs

 

[macabethiel]

Beware of too much oil !

On many diesel vehicles you have an oil level too high warning light as at high RPM you can wreck an engine due to internal hydraulic damage.

When carrying out the oil change the fresh oil is obviously cold so if you fill it up to the top mark on the dipstick and then drive say on a motorway in the summer the oil over full light will come on in a big red display. In addition when the oil level is too high oil mist foaming inside the engine will often result in the engine smoking particularly under load at higher RPM.

It is for this reason that many Mercedes Dealers under fill the oil by about half a litre when servicing to prevent this occurring.

 

[scrumpydude]

Well, thanks all for the advice. A new pressure switch (garage believes there is only one - well, that's what their supplier said) and things seem good. I had the oil changed while it was in as I had the oil and filter purchased ready. Came out about 1mm above full but the oil was so clean it was difficult to be sure. That won't last.:lol Ready the owner's manual and it indeed says to measure the oil when warm. You learn something new every day.

 

[jims-terrano]

Erm I'm a little concerned when you say oil level is an inch above max level or did I not read correctly. If so get rid of some oil quick smart.

Check the downloads, sure I remember a how to guide for the oil pressure switch. Yeah I think it's a relatively common issue on 3litres.

 

[Barrbeast]

Older 3.0 engines only had one switch, later ones had two... So the supplier is half right

 

[scrumpydude]

Ah, that's worth knowing.

Sent from my D6603 using Tapatalk

 

[micktheshed]

Oil switches are in the block bud.

You don't check the 3.0 oil level cold, get her up to operating temperature and switch her off. Leave her ~2 mins and then check :thumbs

The most common switch failure is positioned just above & behind the starter motor ie; a right pig to get at & almost invisible. A cheap replacement can be found listed under 'Renault', take your old one to compare. It's smaller a/f hex. & much easier to fit (guess how I know LOL).

I agree with above oil level test. After standing a few hours the oil level will show too high, it must be checked warm & after 1-2 mins. of switching off.

A handy tip worth knowing re diesel contamination of the oil, which some vehicles can suffer from for various reasons (eg. DPF regen). When checking the level as normal this shows as 'overfull', & can be confirmed by wiping the dipstick on an absorbent tissue, the diesel shows as a lighter halo around the oil stain. Yet another thing to worry about.

 

[glanrichbex]

'

The oil is Castrol 10W40 SemiSynth and it is being topped up with a GM version of the same type/grade.

Never mix oils - it may be the same version but they may be made of different ingredients which may react and cause emulsification or complete break down. If you change to a different manufacturer - always do a flush and drain well.

 

[scrumpydude]

Never mix oils - it may be the same version but they may be made of different ingredients which may react and cause emulsification or complete break down. If you change to a different manufacturer - always do a flush and drain well.

Cheers for the advice. To be honest, she was only being topped up because of the 'emergency'. The oil has been changed now and is 100% GM.

 

[scrumpydude]

.....and......
the light came on again on the way home tonight. With the clean oil in it's difficult to see the level but I think it's fine and there is no sign of any leak. Will have to hit the workshop manual and determine if it's a dual sensor engine or not.

If a jobs worth doing .....