Member Since: 21 Mar 2019
Location: Solihull
Posts: 13
Questions after timing belt/chain fix...
Hi all,
I'm still a newbie to some of this, and nearing the top (hopefully) of a fairly substantial learning curve; all part of the fun though and I'm still smiling which is always a good sign! Apologies this is a fairly long post, but it seemed best to put it all together.
A bit of context... Long story short, I was starting to see signs of oil pump/pressure issues - oil light taking longer to go off when started and engine starting to sound slightly louder etc. So given that it was due a timing belt I decided to do do that and replace the pump at the same time. All went well (bar the locking pin coming out of one of the cams in my previous post), and drove fine for 50 miles or so with all of my previous concerns now resolved. Didn't think any more of it as whilst it was the new style pump it was at least 7-8 years old (that was when the belts were last done by the previous owner) if not the original (an 08 reg. TDV6 D3).
Feeling fairly confident in it I used it to tow a friends car to be repaired but ironically ended up on the side of the M40 myself, having shredded the timing belt, sheared two bolts on the right-hand cam sprocket and broken rockers on a couple of cylinders. I initially assumed I had over-tensioned the belt, but I checked the photos I took after and it looked fine. Later I found that the chain between the left-hand intake and exhaust cams appeared to have slipped and gone one or two links out of time (but not actually snapped). The tensioners were weak so after a good look round and finding no other major damage, I replaced the chains/tensioners on both banks, all rockers and arms, new timing belt/tensioners/idlers/bolts, and all seals/gaskets. Timed it up and now it runs beautifully with a relative compression test looking fine. Not 100% sure of the initial cause, but it looks to me like the cam chain/tensioner is a possibility, potentially alongside my inexperience having never done a timing belt before... Either way, seem to have got away quite lightly and I'm lucky not to have more serious damage I think.
So not only has it had a new timing belt which was the original goal, it's had the body off for the repair and a bit more TLC whilst I was at it - very much out of my depth, but was able to work my way through it all quite happily with help from the guides on here (shout out to Mikey especially) and a very generous friend that allowed me to become semi-resident in his workshop for a few weeks!
Anyway, I'm left with a few questions:
1. I did notice after putting the new timing belt on and tensioning so the mark is within the window, that as I turn it by hand the mark gradually moves out of the window and then back again by the time I've done a complete revolution of the engine. This implies that the tension is increasing past the mark then decreasing as the engine rotates - I assume it's normal as I've seen/heard this with other cars, but given that I'm still a newbie don't know the cause of the failure for sure I just want to check in case it's about to do the same again...
2. I've had it running for a while and took it for its first drive yesterday - it was driving better than it has since I bought it 2-3 years ago, but parked it up whilst I fetched someone for a celebratory drink and it then got stage fright and refused to start quoting the 'P0342-31 (6C)' error code for a frequency modulation/pulse width modulation failure (no signal) on the camshaft position sensor, implying it couldn't see the cam turning with the crank and therefore refused to inject any fuel. Left it for an hour whilst I went to fetch some tools, then had a look round with an endoscope through the hole in the timing cover for the aux belt tensioner. All looked fine (as you'd expect for <10 miles under its belt if you'll excuse the pun) so turned it by hand with no issues and turned the key. Fired straight up as if nothing had happened and ran perfectly as it had before.
I'm assuming this is likely to be either a one-off with the old fault not clearing properly, or potentially a sensor issue - I'll keep an eye on it over the coming days/weeks, but anything in particular I should be looking at?
3. After I'd put it all back together I had one bit left over (as is always the case) - this bracket:
I can find very little reference reference to it online by googling the part number stamped into it (7H2Q-9B303-AB / W235X), only an eBay listing suggesting it might be a support bracket for some vacuum lines? I'll be honest, I don't remember taking it off, so if anyone knows where it goes so I can put it back that'd be great. Apparently it's less effective sat in my toolbox...
All things considered, just glad to have it back on the road and would like to do what I can to stop it going again. Thanks to anyone that can help or has any more advice!
7th Aug 2022 5:26 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10362
i think the bracket goes on the drivers side head. right at the back.
There are 2 silver transmision breather pipes back there.
You aren't the first to ask
7th Aug 2022 5:36 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10362
Member Since: 21 Mar 2019
Location: Solihull
Posts: 13
Thanks for the quick reply, Pete. Appreciate the help.
I did see that post, but don't think it's the same bracket - don't think I took that one off in the end as I didn't remove the head just the cover. Based on where it was in my pile of parts, I think it came off in the process of removing the right-hand cylinder head cover but I can't see it in any of my photos...
Here's it from a couple of other angles... Any other ideas?
7th Aug 2022 7:16 pm
loanrangie
Member Since: 18 Jun 2017
Location: Melbourne
Posts: 600
Snap, i also have that bracket left over and i believe its for supporting the wiring loom somewhere near the HPFP.
Never bothered to look exactly where it goes but will get around to it one day.
8th Aug 2022 1:23 am
wdavison98
Member Since: 21 Mar 2019
Location: Solihull
Posts: 13
Thanks lonarangie - that's not a bad shout actually.
Heading out to do a few other bits on it at some point soon, so I'll have a look and let you know if I find it
12th Aug 2022 11:34 am
wdavison98
Member Since: 21 Mar 2019
Location: Solihull
Posts: 13
Okay, so an update on this - I've still not found a home for the bracket and it's back to refusing to start...
The faults it had logged against the engine ECU were:
- P007D-17 (28) Active speed control denied because the front smart module actuvity failed - General electrical failure - circuit voltage above threshold
- P0191-23 (68) Fuel rail pressure sensor range/performance - General signal failure - signal stays low
- P0622-29 (68) Generator field terminal circuit - General signal failure - signal is invalid
- P0342-31 (6C) Camshaft position sensor A - circuit low input (bank 1 or single sensor) - Frequency modulation/pulse width modulation failure - no signal
I've cleared these but it's still not playing.
It was running fine with the first two or three, so largely ignoring those for now and focusing on the cam position sensor fault. It did start and run once since this happened initially and I've had the timing cover off to check it so am confident this is electrical not mechanical. I've cleaned the sensor as it did have some metal shavings on it (presumably from where a bolt sheared), but no luck so I guess my next bet it to try and get an oscillocope on the sensor or replace it.
My question now is whether it's common for these sensors to fail (especially 10 miles after a timing belt failure or similar), or if I'm barking up entirely the wrong tree?
12th Aug 2022 7:07 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10362
It’s not common fault but clearly you need to try changing it or investigate
I wonder if the distance is critical on these. Bit sounds faulty or bad contact
12th Aug 2022 8:55 pm
wdavison98
Member Since: 21 Mar 2019
Location: Solihull
Posts: 13
So life got in the way and I've not had time to look at this until today... Long story short, a new camshaft position sensor fixed it.
Having checked the timing and confirmed that there hadn't been any movement, I briefly started it on easy start to confirm my suspicions on the basis that it was unlikely to cause any serious damage. The problem with these engines is that they don't log any fault codes unless the engine is actually running, so troubleshooting a non-starter can be a pain (I don't like easy start, but a light spray here was very helpful). Once it started, the fault code logged against the camshaft position sensor was switching randomly between P3042-31 (no signal) and P3041-29 (signal invalid), which reinforced my belief that this was an electrical fault and not mechanical as it wasn't consistent.
As Pete says, the distance between the sensor and trigger wheel is very important on these and having had the cams out it could easily have been slightly out. However, with the timing cover off I could see it was in the correct position and consistent as I rotated the engine so this was ruled out in my case. This left a sensor, wiring or ECU fault.
An ECU fault was unlikely as it had been running fine, and I couldn't see any obvious issues with the wiring (reseating connectors did nothing). Upon removing the sensor, I found light damage from the previous (broken) timing belt rubbing against it and also some form of (non-electrical) anti-seize within the connector which didn't help. I installed a new sensor, and it fired up despite a fuelling issue making it run rich (the fuel rail pressure has now changed to an 'actuator stuck open' fault and seems to be genuine). I've now just got to fix that, finish putting it back together and take it for a drive
For anyone needing to replace a camshaft position sensor on the TDV6, it is a pain and fiddly but isn't as bad as I've read in some places - if you've got reasonably small hands/fingers there's no need to remove the EGR valve etc. as it can be removed from the front of the engine and took me about an hour once I'd worked it out and tried various different options:
1. Remove the battery and passenger-side battery tray (left-side when looking from driver's seat).
2. Remove the aux belt, tensioner and pulleys, and the timing cover.
3. If by any chance the air-con has been de-gassed then disconnect the two pipes that run alongside the battery tray to get more room, but this isn't strictly speaking necessary.
4. Use a screwdriver to help disconnect the plug on the camshaft position sensor.
5. An 8mm offset spanner can be used to remove the single bolt holding the sensor in place (be careful not to drop it as it can be fiddly). Once removed, the sensor will slide towards the back of the engine and can then be removed.
6. Re-fit with these steps in reverse.
Thanks for everyone's help (on and off the forum) - glad to have it back running again!
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