VVC 160 Rattle

[garybee]

I've recently bought a low mileage MG ZR 160 with a view to upgrading my S3.  The engine appears to be pretty healthy (the ZR went well) and I'll give it a thorough inspection at some point but it does have a bit of noise from the VVC mech.  As I understand it this is not unusual for this engine but despite being perfectly acceptible under the sound deadened bonnet of a FWD hatch I suspect it could get annoying in a Caterham.

I realise that I could remove the VVC mechs and go solid cams but this would turn what is at the moment a free performance upgrade into a fairly expensive exercise.  Is anyone aware of a place to buy these at reasonable cost (not worried about wear occurring again, think I did 100 miles last year) or even if anyone has started to remanufacture the bearings which appear to be the problem.

Thanks in advance

Gary

[revilla]

Hi Gary,

I run a VVC 160. I've also got two spare engines, both of which I have run on test rigs. I've also been through the process of trying to eliminate VVC rattle by swapping the mechanisms on two of the engines.

I think there are two different kinds of rattle you can get from the VVC. One is a sort of cam-like chattering, not loud but clearly there, a sort of mechanical whirring which it idle sounds almost like somebody knitting under the bonnet. Sounds a bit like the kind of noises you can get with pushrod engines. The other is a pronounced diesel-like knocking known as the "death rattle".

In the case of the second, the most likely cause is failure of the main drive bearings. The mechanisms were made by Airtex but they shut down production with the demise of MG Rover. The drive bearings were made by SKF but are no longer made. The MGF Centre claim to have them in stock for £75 here, although they are press-fitted into the drive unit casings and I'm not sure of the practicality of swapping them, it would certainly be a specialised job using a hydraulic press at best. If you do get a "death rattle" type failure, I think you're best replacing the drive units.

In the case of the more gentle chattering noise, to be honest I've come to the conclusion that it's just normal and something you live with. I've stripped down several units that were chattering and they have been indistinguishable from other units that were not chattering. You do get a bit of pitting of the rotor bearing surfaces but I think most of the noise is generated by the running clearances of the sliding-block units within the slots in the rotors which can be felt as a bit of play in the cams when the engine is examined. The bushing where the inner concentric cam runs through the outer cam of each pair can also wear a little. On my previously installed engine I replaced the rear VVC unit which was particularly chattery with one that I had stripped and inspected and which was pretty much perfect and it ended up sounding just the same. Another possible cause from what I have read is the oil feed to the VVC units which are right at the end of very long narrow drillings. Ensuring that you have good oil pressure can help. The other thing worth mentioning is that the VVC ECU measures the oil temperature and uses an internal map to convert this to viscosity to predict how rapidly the VVC hydraulics will deploy when the solenoids are activated; for this reason it is best to use 10W40 oil in a VVC as this is what the ECU mapping is calibrated for, and the VVC mechanisms themselves are much happier on Semi Synthetic than Fully Synthetic. Castrol Magnatec 10W40 keeps my VVC mechanisms happy and they are noticeably less chattery on it than on say 5W50 Motorsport Oil.

There's a full set of almost new VVC mechanisms on eBay for £200 at the moment here. I've talked at length the the gentleman selling them in the past and he seems very knowledgeable; he told me that had the facilities to reproduce most of the part in the correct alloys if required although I haven't tested that.

Dave Andrews may also have a few sets lying around as he hates the things and keeps taking them off to go solid cams.

If all you are getting is the light chattering and whirring, in all honest my advice would be to just live with it. The VVC does sound different to the standard K Series as the VVC system is a complex little mechanism with lots of moving parts that are constantly accelerating and decelerating. I know how you feel and that it can be irritating at times, but I don't think you will eliminate it entirely without going for solid cams. It's part of the charm of the engine. Anecdotally, the mechanisms were usually quiet when supplied from the factory on a new engine but each one settled down to its own individual characteristic noise after not many miles and then pretty much just continued to sound like that for the rest of its working life. I'd only worry if it starts getting rapidly worse and knocking like a diesel.

Andrew

[garybee]

Thanks very much for taking the time to type that.  That confirms pretty much everything I've read and adds quite a bit too.  It appears that you've spent some time looking into this.  Talking with Dave sounds like a good shout, It hadn't occurred to me that he will be removing these regularly.

I would rather stick with the VVC for the moment so it's good to hear that you've found the noise can be reasonable in a Caterham.  The info about the oil is interesting.  I'm obviously going to have to give the engine a good service and see if this has any effect before doing anything too drastic.  I would describe the noise as being alike to a stuck hydraulic tappet, certainly not the death rattle/diesel knock that I've read descriptions of and you mention above.  It's a very subjective thing to describe of course.  For all I know you might listen to this one in horror and I'd think yours was silent (aircraft engineer that's spent too much time crouched within 1' of running jet engines).

I do feel better about dropping it in the Caterham now though.  I was a little worried that I might regret it as the current engine is so quiet.

[revilla]

Are you sure the noise is coming from the VVC mechs? Might be worth probing around a bit with a stethoscope or taking the cam cover off and having a prod at the lifters. Just thinking that if it sounds like a sticky lifter, it might of course be a sticky lifter. Does the noise vary much warm vs cold? Is it just there at idle or low RPM or does it still sound noisy as you rev it?

[TomB]

Just press the right pedal harder and you wont hear it

[garybee]

I haven't yet done any investigation.  At the moment the engine is still in the MG so I'll drop the oil, clean the sump out, remove the cam cover etc. when there's some nice weather on a weekend.  It would be nice to completely sort it before removal from the donor of course.  From what I've read and some use of the old 'screwdriver/stethoscope' I strongly suspect I'll be coming back to the VVC mechs though. 

[garybee]

The thought did occur to me that I am making work for myself that has no real benefit here.

[SM25T]

Fuel injectors click quite loudly. Also .... are you running the VVC engine on 10W-40 oil. That is apparently what the VVC mechs were calibrated with.

[SM25T]

Wear good ear defenders while driving. You won't hear it. Ian (VVC engine SV now on 84k.)

[Mankee]

Gary, if you are fitting the big metal VVC plenum and don't already have a VVC right-hand engine mount bracket that is lower than the standard bracket to clear the bonnet, Julian H may now have one spare:

http://www.lotus7.club/forum/techtalk/jenvey-airbox-installation-problem-questions

[garybee]

SM25T - If if all disappears when I give it a good service with fresh (correct) oil I'll be a happy man.  It is louder than fuel injectors though and a bit too noticeable to just ignore.

Mankee - Thank you for the tip.  I will be keeping the plenum, at least at first, so will ask if it's going spare.

Edit: Looks like he needs a standard one, of which I have at least two spare.  Could be a fix for everyone here.

[SM25T]

Must look at my engine mount. Assume it is the correct one. Ali plenum just clears / kisses the bonnet.

[Julian H]

Thats the same as my XPower was Ian, sounds correct.