S40 V40: oil light on

[s2000]

Originally Posted by skyship007

Just to confirm the OP did state the oil filter and pressure switch were changed.

Yep the oil filter, oil & switch were changed..

[s2000]

Originally Posted by magnuz

Oil pressure @ idle... 1 bar (14.5psi)
Oil pressure @ 4000rpm...3.5 bar (51psi)

Thanks Magnuz

[Matt86]

Originally Posted by skyship007

Just to confirm the OP did state the oil filter and pressure switch were changed. The garage did some kind of pressue check, so this is probably a sludge case, as it's rare for an oil pump to fail.

The thing I find strange is that there was no flickering light first and the full service history. It's possible that the car did a lot of short tripping and the Volvo dealer was using not using Castrol Edge, as 10K mile oil services can be pushing the limits sometimes.

Ahh ok, Yeah I agree with Skyship then, Reckon it's a pickup problem so you'd need to drop the sump and clean it out and replace the sump gasket when you do it.

[oragex]

while the sump is off, it's good to inspect all o-rings inside and eventually replace them, and also, important to inspect for any play and color change in the rod bearings (when a bearing lacks lubrication because of oil sludge, it gets darker in color). Bearings can only be properly checked with the sump off, a spun bearing will typically get a low oil pressure light.

[s2000]

Originally Posted by oragex

while the sump is off, it's good to inspect all o-rings inside and eventually replace them, and also, important to inspect for any play and color change in the rod bearings (when a bearing lacks lubrication because of oil sludge, it gets darker in color). Bearings can only be properly checked with the sump off, a spun bearing will typically get a low oil pressure light.

Are these the big end bearings on the crankshaft you mean ?

[skyship007]

Originally Posted by oragex

while the sump is off, it's good to inspect all o-rings inside and eventually replace them, and also, important to inspect for any play and color change in the rod bearings (when a bearing lacks lubrication because of oil sludge, it gets darker in color). Bearings can only be properly checked with the sump off, a spun bearing will typically get a low oil pressure light.

I had a look at the Volvo instructions for cleaning a block last year and it did mention checking the main bearings for wear, although if a spun bearing or severe wear was causing a low oil pressure the engine would be rattling and probaby smoking as well.

[cookie]

dropping sump is only a 20 min job, have seen one swapped on a T4, in less than 30 mins, may be sludged up, as often on high mileage cars, oil it taken right to limit as servicing done on mileage, so unless correct oil is used at every service, if something is blocked

something like low oil pressure can be a ticking time bomb, whats going on inside an engine is unknown and having oil light come one would stop me from driving car.

just on a side thought, not sure if yours has grid inside filler neck, if not can you see oil being flicked around with cap off?

[960kg]

Originally Posted by s2000

Hi, The car is quite new to me not had it that long, it has a full Volvo service history so has been serviced once a year, but a service is due now. There was no oil light flicker before this happened & there is no loss of coolant.

Why do owners buy a T4?........to use the performance.

I have never ever heard of a T4 being sludged out!......modern oils do not cause sludge.

The garage must of put a low grade oil in to get extra work! .......you said the oil light never flickered before.

Put some 10W 40 Castrol Magnetec in the engine together with another Volvo filter change and see the difference.

Volvo recommend 30grade only for low mileage motors from new and are no good for 165,000 mile engines.....you have to move up a notch with the viscosity to counteract the wear.

[s2000]

Thank you all for your input, I hope to get on with this tomorrow, I will let you know what I find ?????
I'll be using your comments / advise as my manual !! Many thanks & fingers crossed.....

[skyship007]

960kg: modern oils do not cause sludge.

There is no real difference between an old fashion conventional oil and a modern high tech Synthoil in terms of sludge formation.

Sludge forms when the detergent additives in the oil are used up. There are two main additives based on Calcium and Magnesium compounds that combine with Carbon blowby products and keep them in suspension until the oil is changed (The oil filter will catch some of the sludge). Once they are used up, sludge starts to form. Obviously it forms a lot faster in an old engine with worn rings and a lot of blowby than a new one.

The ability of an oil to prevent sludge formation relates directly to the amount of detergent additives in the oil and that can vary from 1000 ppm for a supermarket oil to 3000 ppm for oils like Mobil 1 0/40 or LM Synthoil 5/40. The actual type of base stock does effect the ability of an oil to clean the block, but makes no difference as regards resisting sludge formation when the detergents run out (In fact a Synthoil will dump sludge slightly faster than a conventional base oil if used past the point at which the detergents are used up).

So it does not matter which oil you use, if it is in use for too long, it can result in some degree of sludge formation. The sludge then starts to obstruct the oil flow by blocking the oil pump intake or restricting the oil passageways, that raises the cylinder heads temp, which in turn results in varnish formation around the top end.

When an engine that has been correctly serviced with good oil sludges out, the culprit is nearly always a very small HG leak that results in anti freeze contamination of the oil. Anti freeze reacts directly with the detergent additives and stops them working (It's an order of magnitude worse than water). So if you get any kind of HG leak, it's essential to make sure the block is cleaned up after the HG leak has been sorted.

There have been a number of Black death epidemics in the past, like the famous Audi one in the US that was caused by the manufacturer recommending a rather long oil service interval in combination with the dealerships not using the recommended oil. That issue of garages and even dealerships using the wrong oil has still not gone away and recent checks done in the US revealed that 20% of bulk oil used was in fact outside the required API specs. I doubt if the situation in the EU is any different.