General: S40 Variable Valve Timing

[Paul Sanderson]

Volvo S40-S (manufactured 2003)
Engine number: B4163358648

The Variable Valve Timing unit (VVT) on the top of the engine makes a very noticeable intermittent chuckling/grinding sound when the engine is at idle. We’ve replaced it with a new unit… but the same thing continues. When both units had the wiring disconnected the noise stopped (though when fired up again the engine did so easily and continued to run smoothly at tick-over).

This suggests that both the old unit and the new unit are in fact OK but were reacting to a bad signal coming from elsewhere.

The car runs OK otherwise. It’s only when the engine is under sudden load and the VVT is needed that the noise is apparent. Typically, this is when pulling away at low revs, and the engine is a bit jerky and likely to stall. One deals with this by raising the revs a bit and slipping the clutch, but of course that’s ‘bad practice’. During normal road running the engine seems OK though the higher engine revs might smooth out any imperfections and also mask any noise – so we don’t truly know if this is happening further up the rev range. I now take particular care to choose my gears carefully – in other words I avoid putting a strain on the engine… and that's how I should be driving anyway!

At the time that this became apparent we’d just had the catalytic convertor changed. The engine warning light is on but that was assumed to be because of the car recognising that the new c/c was not Volvo’s own c/c. The light can be turned off but comes back on again at about 3000 revs, so now the thinking is that it may be to do with the VVT circuit and not the c/c circuit.

Anyone any ideas?

Best regards, Paul Sanderson
sanderson-by-the-sea@hotmail.com

[ITSv40]

You need to get the codes read instead of guessing. The noisy vvt pulley is most likely the solenoid that operates the pulley if both pulleys exhibit the same characteristics.

The engine light coming on could be an inferior cat or it could be faulty sensors., reading the codes is the only way to find out.

[Paul Sanderson]

Now that we know it's not the VVT unit itself that's malfunctioning – just being made to be noisy by an outside cause – checking the codes is indeed the next step. I'm not sure what you mean by 'pulleys'. I know what the word means of course, in a much older car (the ones I'm used to) that's what the fan belt runs around, but I can't see how that would make the VVT unit (nowhere near any pulleys or belt) go noisy. Although this Volvo is 20 years old, to me it's a modern car using technology beyond my knowledge!

[ITSv40]

The 'pulleys' I was referring to are the VVT units. They are normally referred to as cam belt pulleys or cam pulleys - the inlet being the vvt unit, the exhaust just being a plain pulley. Some folks refer to them as sprokets, but technically a sprocket drives a chain. A pulley drives a belt, whether a toothed belt or plain.

[magnuz]

Can you clarify if you have replaced the solenoid ( the bit with the electrical plug) or the VVT pulley/unit ( driven by cam belt ). When you get the noise you described, it's usually the VVT pulley that is the problem. The pulley should only be replaced if you have the cam locking tool, as the pulley is not keyed to the camshaft. Disconnecting the solenoid will cause the EML to illuminate. If the VVT is really badly worn the EML can light up for incorrect cam timing position, but reading the codes may give more clarification ?

[Paul Sanderson]

Just returned from Manchester, so my first opportunity to catch up with the VVT issue. It's clear now that your definition of 'pulley' and mine are the same... and I can say that no pulleys are involved in what I'm describing!

However, since the unit I refer to as the VVT unit is not pictured anywhere, I am, in fact, just guessing that it is called that. Now I suspect that it isn't called that, and that's what's leading everyone astray. I've included a pic from a well-known online auction site. The black part on the right is where the wiring attaches to it. The unit sits fore-and aft on top of the engine, clearly visible when you remove the engine cover. Underneath are various oil ways. It comes with a gasket.

Simply disconnecting the electrical lead from the back stops the noise, but of course the lead is meant to be connected. On the Manchester trip (600 miles round trip) the unit continued to make a noise at idle or low revs but the car performed with it's usual aplomb and economy at speed on the motorways. Most of the journey was at motorway speeds. Photo later.

Although my account settings are set to alert me by email when there is any action on the topic... it doesn't. Hence I may not reply instantly

[magnuz]

The picture that you have posted is of the VVT solenoid, it's basically a valve that diverts oil within the VVT pulley unit to operate it. The usual cause of the noise is the pulley unit as shown here https://www.skandix.de/en/spare-part...tment/1067027/ They are not so easy to get from the main dealers, but there may also be somewhere a bit cheaper than Skandix. I believe it is possible to source some chinese manufactured units, but i don't know how good they are ?.. In fact the one on the Skandix website may even be a chinese one, as the original part is no longer manufactured ?

[ITSv40]

So you have replaced the vvt solenoid and the issue remains. The problem is in the vvt pulley, change that and it will be sorted.

[Paul Sanderson]

Right, just to recap to make sure I've got it right (having got it wrong I need to thoroughly eradicate my own erroneous thinking!).

Although the VVT solenoid (I'd pictured it earlier) on top of the engine is the item making the noise, and which stops being noisy when the electrical lead is disconnected, in fact it is OK and is only making the noise because it is receiving a rogue electrical signal.

That 'bad' signal is generated by the VVT pulley that deals with inlet matters. My understanding (from earlier comments) is that there is also an outlet pulley. An earlier link takes me to a picture of the inlet pulley in question (many thanks for that) but I don't know if the outlet pulley looks the same. If it does, how do I tell the difference on the car? If there is an exploded view of the engine (engine type: B4164S2, possibly “…S3”; it’s hard to read) online, then directing me to that would be a great help.

[ITSv40]

The exhaust cambelt pulley is just a bog standard pulley in looks - it cannot be mistaken for the vvt pulley.

You are approaching the problem from the wrong end. The noise is generated by the vvt pulley when it is controlled by the solenoid. Disconnecting the power supply to the solenoid stops the solenoid from functioning and hence the pulley goes quiet. It is the pulley that is faulty, not the solenoid.