Roomster 2014 1.2 TSI (CBZB engine) – Cam chain wear measurement.

[SY-Pete]

I’ve spent a lot of time recently scouring this forum for information as to how you can measure the wear on the cam chain with no success. So, if anybody can point me to an existing thread on the subject, I would be most grateful.

 

I have a 2014 1.2 TSI Roomster (CBZB engine) with 45K on the clock. From what I have read this version should have the beefier cam chain & sprockets fitted as original, but it had the infamous cold start rattle. The dealer (not Skoda) I bought it from insisted that the rattle was normal & nothing to worry about. I had my doubts & investigated this on the web & found you guys. Very interesting reading but, I was unable to find anyone with a detailed procedure to check the cam chain wear. I have been quoted £750 for a cam chain replacement by a Skoda dealer) & didn’t want to shell out that sort of money without being sure it was really necessary. I found one thread that mentioned wear should not exceed 74mm but where exactly is this measured from?

 

I have obtained a new chain tensioner (Febi Bilstein Part No 40379, VW part No 03F 109507 & fitted it myself. An easy job only needing a 27mm socket (& a cold engine!). With this new tensioner fitted all is now quiet. So, the logical conclusion is that the original fitment is either faulty or of poor design. I did measure the overall length of the new part from underside of the sealing washer to the end of the plunger at 76.72mm. the original was 72.07mm. Could this 4mm make all that difference? The other difference I saw was that the end of the new tensioner is much larger than the original. Could this make a significant difference? Going back to the max wear @74mm could this measured from the face of the cylinder head, where the tensioner fits, to the pivoting chain guide?

 

Any help would be much appreciated.

 

[stratosg]

May I ask something? Is it DSG or manual? And if it is manual to you leave  a gear engaged when you park the car?

 

Mainly is a design flaw, as the tensioner is positioned too high.

Edited 9 September, 2020 by stratosg

[SY-Pete]

Hi stratosg,

 

Thanks for taking an interest in my post.

 

It’s a DSG. I did read about the manual version being left in gear & can roll back turning the crank anticlockwise pushing the tensioner back & loosening the chain. Not a problem here.

 

Nice to know you think there is a design flaw in the tensioner, my money was on that. Could you explain further as to why the tensioner is too high?

[stratosg]

I really do not know why they put the tensioner too high. This results the lack of tensioning force. Regarding the parking a manual car with gear engaged leads tensioner to loose the remaining oil thus its tensioning capacity during the first seconds of engine start up. Then this rattle occurs until the tensioner gets filled up with oil.

 

I had never had that rattle noise when I left car parked with neutral and handbrake no matter the level of the ground nor the days left parked, while leaving car parked with gear engaged in many cases led to a rattling start up.

 

I have no idea if you can leave an automatic car parked only with handbrake and if the P selection in DSG means that some gear stays engaged leading the tensioner loosing the oil. 

 

Maybe this is why your new tensioner is a bit longer and maybe this is why 4mm makes that difference. Please keep in mind that I am not a mechanic but just an enthusiast.

Edited 9 September, 2020 by stratosg

[edbostan]

My 63 reg 1.2tsi has done it since new but not on every start-up. Sometimes it does it and sometimes not. If the tensioner tightens with oil pressure then for the first few seconds before oil pressure has built up surely the chain is slack? I can't get my head around it. When it first happened I put it down to possibly tappet clatter but don't know.

Edited 10 September, 2020 by edbostan

[Breezy_Pete]

Not sure if it's similar to the one on the 3-cylinder HTP engines, but those have a spring up the middle of the tensioner that means tensioning push never goes to zero.

[edbostan]

16 minutes ago, Wino said:

Not sure if it's similar to the one on the 3-cylinder HTP engines, but those have a spring up the middle of the tensioner that means tensioning push never goes to zero.

I have not heard it on my sister-in-law's Fabia

[SY-Pete]

Thanks for all your replies. Sorry I’ve been a bit slow in replying but been busy catching up with & visiting family & friends before we go into another lock down!

 

Wino; yes the tensioner has a strong spring inside the piston that, as you say, would always keep some tension on the chain via the pivoting guide arm. I assume this keeps the chain from rattling prior to the oil pressure coming up.

 

Edbostan; your rattle is odd that it only happens from time to time. Does it do it on a cold start but after then is it quiet? From what I have learned so far, and Wino confirms this, the internal spring takes up any slack until the oil pressure comes up. There is no doubt that the tensioner is fed with oil as the oil pressure sensor is in the same oil gallery as the tensioner. My rattle was worst at a cold start & not so noticeable on warm starts.

 

I have some more questions for you all:

·         What material is used to face the chain guides? It’s got to be tough stuff to stand up to thousands of miles of running with a chain sliding over it. Could it be PTFE?  From pics of chain kits, the 2 guides look like they’re engineering plastic. Nothing wrong with that after all the inlet manifold is plastic.

·         Oil filter anti drain back valve. If installed incorrectly surely this would means very little or no oil pressure at all. (Have seen posts about this) Are there preferred brands of oil filters that are more reliable than others?

·         Oil & filter change. I’m a very low mileage user & rarely cover more than 6K miles in a year. Should I be considering an oil & filter change around 3K miles or every 6 months?

 

FYI: I’ve now covered about 600 miles since changing the tensioner & I’ve not heard any rattling noise when starting, hot or cold, like I did before. I did go to my local Skoda dealer for another matter some months ago & as part of their “Health check” they told me that the cam chain was about to fail. They quoted £750 to fit a new chain kit. When I asked if there were any cheaper alternatives & I was informed there wasn’t. It now seems it was a good job I didn’t agree to have the job done when a new tensioner seems to have solved the rattle.

Have a look at these pics & you’ll clearly see the difference between the original fitment & the new one with the larger end section. Can this difference in length stop the rattling?

 

Back to my original question, does anyone have an answer as to how to measure cam chain wear?

[Breezy_Pete]

Some interesting questions there.

I expect the guide rails are indeed faced with a PTFE-like material.  They do still wear though, I changed the chain and associated hardware on our 1.2 HTP mk1 Fabia this summer, and there was wear on all of these plastics. Wear on the guide rail on the driven/taught side of the chain seems most relevant as that probably has more impact on the crank/cam timing correlation than the actual elongation of the chain.

Having said that, the simplex chain on our car seems much more likely to carve channels as there are only two contact points, compared with several on your 'fancier' chain which will load any given point/line on the plastic less.

 

I don't seem to have a photo of the wear on that rail to hand, but here are some channels carved at the point directly opposite the tensioner, on the other rail; probably the highest side loading point. Less significant for cam/crank timing I think

 

Do you have access to VCDS?

I came across some measuring blocks that tell you something about cam/crank correlation, and give permissible value ranges.. I took some data from these before the chain kit change, and the numbers were towards the top end of these ranges, from memory. I've yet to repeat to see if things are now different. 3rd and 4th field of measuring block 12 are specified respectively thus:

 

No. of the crankshaft gear for camshaft pressure change low - high 11) 85…91

No. of the crankshaft gear for camshaft pressure change high - low 11) 25…31

 

Note 11 is defined as: "If the value is outside the tolerance and if fault 16725 or 17748 has been stored in the fault memory, the voltage [sic] of the timing chain must be checked (on engines with high mileage)."

 

I have no idea what those numbers mean in real physical terms. The chain at 175000 miles had very, very little elongation compared with the new:

 

However, when trying to insert the crank locking pin with the cam locking ones already in, it wasn't possible with the chain on, and probing about with an Allen key instead of the locking tool suggested that the slot in the flywheel it's supposed to engage in was about 4 or 5mm advanced relative to where it needed to be for the tool to fit.  That's not necessarily much of an angular error though, as the crank sensor position is towards the outer edge of the flywheel (I've not done the sums on that).

 

I've always tended towards genuine oil filters, as they don't cost significantly more in the grand scheme of things.

With the low annual mileage you do, presumably a good proportion of that is rather short journeys? How short?

 

 

 

 

 

Edited 23 September, 2020 by Wino

[SY-Pete]

Indeed, whatever the facing material is, it will wear. From your photos the facing material looks like a Phenolic resin-based material. Phenolic resin-based materials have been around for years. The best-known one is Bakelite. If it is Phenolic resin based it is most likely the cotton fabric-based version. Very tough & hard wearing. I came across this stuff years ago in bearings used in model plane/boat engines. Standard rivetted or folded cages tended to fall apart rapidly at high RPM. Phenolic caged bearings lasted 5 times plus longer.

I with you on the chain elongation as you photo shows. There’s actually very little load on the chain. If it where a final drive chain on a motorbike it would be significant. I’ve seen elongation of over 20mm & distorted sprockets. I think the wear is in the guides rather than the chain itself. The modified duplex chain used in my engine should last a lifetime and greatly reduce the guide wear.

Sorry no access to VCDS.

I’ve looked at the procedure to change the chain on my CBZB engine & it took me a while to fathom out that there were no timing marks on the crank/camshaft sprockets or keys to positively locate the sprockets. Then came the light bulb moment of realising with the camshaft locked in place & in the case of the CBZB engine a wedge to lock the crank, there’s no need for positive timing location marks. Actually, remarkably simple.  Sounds like your 1.2 HTP engine used the same basic idea.

 

My thoughts on a quality filter & short-term oil changes are as yours for a low mileage user such as myself. Thanks for you input.

 

Don’t forget I’m still looking for an answer to my original question of how to measure the cam chain wear.

 

[xman]

When I checked the chain guides removed from our 2011 73,000mile CZBC engine, with (sometimes massively, ready to climb over sprockets) rattly starts, the guide faces looked like Nylon 66 material, very lightly marked, far far less than 1mm wear just detectable by finger and the inverted tooth chain not obviously sloppy or twistable by much. Removed top sprocket looked fine but I wasnt shown the bottom sprocket as I didnt see it in the box of removed bits or missed it. Apparently its the bottom sprocket that wears when the chain is loose and hangs down a bit. The tensioner appeared to be fully extended and I couldnt push it back (using thumb and forefinger)

 

The latest kit for 2012-  engines and retrofittable to earlier engines has a revised chain design requiring new sprockets of a different profile and dimension to be fitted.

For pre 2012 engines, to measure when chain has stretched is shown in TPI 2037419/9 Metallic knocking after start. I dont have access to this (perhaps try erwin). It involves removing the tensioner and measuring ''how deep the tensioner came out using a sliding gauge". 74mm is the limit that Skoda uses anything more and the chain is stretched and should be changed. In my experience the cold start rattles are present before this limit is reached.

 

Some pictures here and maybe the TPI in another language...

https://a1audiclub.forumfree.it/m/?t=63989251&st=240

 

Edited 30 September, 2020 by xman
Removed reference to teflon

[Breezy_Pete]

I've just dug out the other rail, the 'tight side' one and there's barely any wear at all on it, I guess because there's no equivalent single point where any side force is applied, unlike the tensioner rail. Just a little bit of wear right at the top.  The revised version, as fitted in the other photo is a shade longer, possibly to avoid this 'rattle zone'?

This rail looks to be the same material as the chain-touching insert in the other one, judging by the colour of the two new ones, and has a material ID of >PA 46< *

 

 

*"Stanyl" apparently. Wonder if that was created by Stan? https://plasticsfinder.com/en/application/Valve Train/4GZJv

Edited 30 September, 2020 by Wino

[xman]

Not really that relevant @Wino  1.2tsi use an inverted tooth chain also known as a silent chain which present a  much larger area to the guide opposed to the thin outer plates on a simplex chain and so any guide wear should be insignificant.

 

[Breezy_Pete]

Perhaps the OP was interested? He did speculate on the material not long ago, remember...? Oh, and Teflon isn't Nylon 6.6, I'm pretty sure.

Edited 30 September, 2020 by Wino

[xman]

39 minutes ago, Wino said:

Oh, and Teflon isn't Nylon 6.6, I'm pretty sure.

 

Correct, my mistake.

[Meridion]

On 09/09/2020 at 16:13, SY-Pete said:

I’ve spent a lot of time recently scouring this forum for information as to how you can measure the wear on the cam chain with no success. So, if anybody can point me to an existing thread on the subject, I would be most grateful.

 

I have a 2014 1.2 TSI Roomster (CBZB engine) with 45K on the clock. From what I have read this version should have the beefier cam chain & sprockets fitted as original, but it had the infamous cold start rattle. The dealer (not Skoda) I bought it from insisted that the rattle was normal & nothing to worry about. I had my doubts & investigated this on the web & found you guys. Very interesting reading but, I was unable to find anyone with a detailed procedure to check the cam chain wear. I have been quoted £750 for a cam chain replacement by a Skoda dealer) & didn’t want to shell out that sort of money without being sure it was really necessary. I found one thread that mentioned wear should not exceed 74mm but where exactly is this measured from?

 

I have obtained a new chain tensioner (Febi Bilstein Part No 40379, VW part No 03F 109507 & fitted it myself. An easy job only needing a 27mm socket (& a cold engine!). With this new tensioner fitted all is now quiet. So, the logical conclusion is that the original fitment is either faulty or of poor design. I did measure the overall length of the new part from underside of the sealing washer to the end of the plunger at 76.72mm. the original was 72.07mm. Could this 4mm make all that difference? The other difference I saw was that the end of the new tensioner is much larger than the original. Could this make a significant difference? Going back to the max wear @74mm could this measured from the face of the cylinder head, where the tensioner fits, to the pivoting chain guide?

 

Any help would be much appreciated.

 

Hi Pete, Which dealer did you get that quote from please? Its not too bad considering some quotes I've had haha. Im in leeds so not too far from you

[Aaron1875]

On 09/09/2020 at 16:13, SY-Pete said:

I’ve spent a lot of time recently scouring this forum for information as to how you can measure the wear on the cam chain with no success. So, if anybody can point me to an existing thread on the subject, I would be most grateful.

 

I have a 2014 1.2 TSI Roomster (CBZB engine) with 45K on the clock. From what I have read this version should have the beefier cam chain & sprockets fitted as original, but it had the infamous cold start rattle. The dealer (not Skoda) I bought it from insisted that the rattle was normal & nothing to worry about. I had my doubts & investigated this on the web & found you guys. Very interesting reading but, I was unable to find anyone with a detailed procedure to check the cam chain wear. I have been quoted £750 for a cam chain replacement by a Skoda dealer) & didn’t want to shell out that sort of money without being sure it was really necessary. I found one thread that mentioned wear should not exceed 74mm but where exactly is this measured from?

 

I have obtained a new chain tensioner (Febi Bilstein Part No 40379, VW part No 03F 109507 & fitted it myself. An easy job only needing a 27mm socket (& a cold engine!). With this new tensioner fitted all is now quiet. So, the logical conclusion is that the original fitment is either faulty or of poor design. I did measure the overall length of the new part from underside of the sealing washer to the end of the plunger at 76.72mm. the original was 72.07mm. Could this 4mm make all that difference? The other difference I saw was that the end of the new tensioner is much larger than the original. Could this make a significant difference? Going back to the max wear @74mm could this measured from the face of the cylinder head, where the tensioner fits, to the pivoting chain guide?

 

Any help would be much appreciated.

 

Ho did you replace the tensioner ?

 

can you please guide me through process ?

or send a link to a how to guide ?

 

thanks  

[Meridion]

1 minute ago, Aaron1875 said:

Ho did you replace the tensioner ?

 

can you please guide me through process ?

or send a link to a how to guide ?

 

thanks  

What year is your car? 

[Ootohere]

There are vids on Youtube.

 

 

 

Repair / Replacing  of the timing for the new version of the 1.2tsi Fabia / Polo / Ibiza CBZA / CBZB

 

 

[Aaron1875]

12 hours ago, toot said:

There are vids on Youtube.

 

 

 

Repair / Replacing  of the timing for the new version of the 1.2tsi Fabia / Polo / Ibiza CBZA / CBZB

 

 

Thank the first video halfway through depicts the oil filled chain tensioner. So it looks as though I could get away with just removing the top timing chain cover and wedge the chain to keep tension and unscrew old tensioner from rear of timing case/engine and replace it. 

[Ootohere]

It also looks like you can ba-lls it up without all the gear and just ideas.  All the best with it.

[mikkelvitus]

On 09/09/2020 at 17:13, SY-Pete said:

I have obtained a new chain tensioner (Febi Bilstein Part No 40379, VW part No 03F 109507 & fitted it myself. An easy job only needing a 27mm socket (& a cold engine!). With this new tensioner fitted all is now quiet. So, the logical conclusion is that the original fitment is either faulty or of poor design.

 

I have also bought a new chain tensioner - and just wanna know if you just unscrewed the old one and then torque'de the new one to 60 nm, without locking the camshaft with the "camshaft locking tool" ?
If it is safe to do the operation without locking the cam, that would be the easiest