What is this noise coming from my VR6?

[diggerbucket 0]

I am getting a loud rattly noise coming from what sounds like the head on my VR6, sounds like it's coming from the rear at the drivers side. Anyone any ideas what it might be?

 

Video sound file is here - http://loader.sc0rian.com/users/diggerbucket/MVI_1103.avi

 

The sound is actually harsher in real life, I can hear it when driving around.

[Mr Sands 0]

Asking the bleeding obvious: have the chains and tensioner been done?

[Jim 2]

Hm.. it doesn't sound rattly / metallic enough to be the chains.. thats what I thought it'd be before watching the video, but it sounds just TOO noticable for that?

[diggerbucket 0]

Yep - done just a month ago! The noise is coming from the other side of the engine anyway....

[Mr Sands 0]

Righto, that's the obvious promptly ruled out!

[Critical_Mass 10]

Similar noise on my VR, ill be watching this thread closely. Could it be the valves? :oops: (dashes for door).

 

Is that the BMC CDA filter making the whooshing noise?

[dinkus 10]

Yeah, doesn't sound like the chains, but god knows what it actually is. Will have to wait for someone that knows what they're talking about to come along :)

[Critical_Mass 10]

:lol: probably for the best.

[diggerbucket 0]

That's what I'm hoping for too dinkus :lol:

[eatthis 0]

sounds very tappety

[DierWolf 0]

WEll being a car buff and working on may engines (American cars) sounds like Valve tap and really bad too...

 

Did you do timing lately? If a tensioner is week it can also jump a tooth and create the same situation...

 

If i were you i would have that checked immediately. doesnt matter that the chain tentioner is on the other end, point

is its a valve tap and that could only mean off timing causing the valve tap.

[Critical_Mass 10]

WEll being a car buff and working on may engines (American cars) sounds like Valve tap and really bad too...

 

Did you do timing lately? If a tensioner is week it can also jump a tooth and create the same situation...

 

If i were you i would have that checked immediately. doesnt matter that the chain tentioner is on the other end, point

is its a valve tap and that could only mean off timing causing the valve tap.

 

(looks smug)

[dr_mat 0]

I think all VRs sound a *little* like that, but that's pretty loud - though it's hard to say if that's just because the mic is making it sound worse than it really is.

I reckon it's tappets, as said. Take the car for a really good thrash (having double checked the timing.. ;) ) to pump some good hot oil into the tappets and if it's not cleared up you probably need to look closer ..

 

** Apparently "the book" says that to sort out noisy tappets you should hold 3k rpm on a lightly loaded engine for five minutes .. It actually says while the vehicle is stationary, but I can't see any *really* good reasons why just taking it for a thrash won't do the same thing.

[peanut 0]

hmmm....sounds like sticking tappet. Check the breather valve that comes off the back off the head is in good condition. Has it had correct viscosity oil? Obvious Q but has it got oil in it? any blue smoke coming out the back when driving, especially on overrun? Does sound like one of the tappets isnt filling up properly. Is the noise defo coming from that side of the head and not the tensioner side and trasnmitting down with vibration? to check this get a screw driver and place it against where you think the noise is coming from, put your ear to it.

Keep us posted

Gav

[diggerbucket 0]

Well - it made the same noise before it went in to get it's chains done and I was hoping it was chain related and would disappear, however it's still there. I can't see the timing being wrong both before and after the chains were done surely? And it was done by a VW specialist with a good reputation round here.

 

dr_mat it's had a few good thrashes and it never gets any quieter. It has been getting worse over time.

 

peanut - oil is fine, no blue smoke at all, noise is defo coming from that side of the head. I'll check the breather when I have time. How noisy can shagged tappets get?

 

How hard is it to change tappets?

[diggerbucket 0]

Oh and - are they adjustable?

[dr_mat 0]

They're oil filled, or they're supposed to be. If you have sufficient oil pressure, they will stay pressurised and keep the valve gap down reducing clattering.

Do you have an oil pressure problem?

[Supercharged 2]

What oil is being used?

[StuartFZR400 0]

dr mat - does the VR use a similar system to the 16v? ie I think the 16v has hydraulic tappets, meaning they self adjust - as you say. (Didnt realise they had tappets on the C until recently).

 

Without going into tappets DIGGER, its most likely to be one single tappet. To quote Wikipedia "On a V6 engine, the failure of one tappet is often noticeable, as the engine is not as responsive." But yours may not have completely failed just yet. You also want to ensure the oil is working properly, ie you are using clean (recently changed) oil of the correct weight - VW's own oil is very good and popular - the Semi-synth (SILVER) should suffice. I hear that oil additives for the 16v are bad news.

 

Basically the valve that gets pressed by the cam has a little cap on the end of it to help with a few things (stability of the valve etc) - this is called a tappet. The tappet can wear on the head face, but the slack should be taken up by the Hydraulic system. Then you can also get wear on the side of this tappet too. Theres a great working picture on Wiki of a 4 stroke in action, showing the valve and tappet moving.

 

Tappets are not too expensive, just the labour can be.

*** Has anyone had them replced recently? Maybe at Stealth? ***

 

Side note to anyone who knows: Im curious to know the relation between the location of the spark plug and the tappets; one of my plugs seems to have a seal worn within the head - is there any chance that oil leaking here can also leak from the feed into the tappet? Just a long shot.

[dr_mat 0]

I don't know of a car built in the last twenty years that DOESN'T use hydraulic tappets .. do you? (Apart from maybe the 950cc mini engines ..!)

 

Generally tappet problems can be caused by blockages in the oil lines or low oil pressure. The tappets themselves rarely fail, they just become blocked - they should self adjust for wear as you say.

 

More than that, I'm not sure on ...

[diggerbucket 0]

I'm gonna try a bit of ATF in for a few miles then change the oil, it's been about 4k since it was last done.

 

Is it easy to check the oil pressure? What should it be? It's never shown up any lights or anything.

[Kevin Bacon 5]

ATF as in Auto trans' fluid? In the engine? I wouldn't.....

 

Oil pressure is 4 bar at idle cold, and 2 bar hot.

 

6-8 bar on a cruise cold, 4 bar hot.

[diggerbucket 0]

Aye, half a litre of ATF added to the oil for 100 miles or so then an oil and filter change, the detergents in the ATF clean everything up nicely.

[StuartFZR400 0]

mat, never had to strip a car motor before. These stupid bikes yu see, they're old tech', lol (not really any more, they can be sophisticated stuff now - just an old one we had to work on). Wonder what the old mkII rocco had.

 

You'd suggest pressure is the key here then. Just you hear so many people here replacing tappets. I have no idea how well the tappets wear - but guessing from other cars, they should last well over the 100k mile mark?

Thanks for the hints mat, that might narrow things down for me too.

 

Do you know the last time your C had an oil change Mr BUCKET? Oil and filter are cheap , as said.

[dr_mat 0]

Could be pressure yeah. There's been a number of cases of VR oil pumps failing prematurely (not a vast number, but some), and there's cases of oilway blockages in the head (or the return valve), or of tappets failing due to bad oil or overheating and bad oil or whatever.

Anything that prevents the head from getting full oil pressure could potentially cause a seepy tappet to become noisy where otherwise it would be nice and quiet. And by this I mean full oil pressure when hot - because obviously although pressure is higher when the engine is cold, it's also harder to get it into those tight oilways in the head.

That's another reason why old engines always seem to run better after a bloody good thrash in nice cold air at high revs and full engine temperature... :)

 

I believe Mr Bucket (sorry Bouquet) changed his oil 4k miles ago ..