g0gcd
23-01-2016, 06:56 PM
I am trying to solve a cruise control related problem and the investigation has led me to the Camshaft Position Sensor. I have ordered a replacement sensor whilst I trace through the wiring (I hope that it's the wiring!) but should it be the sensor, I can't find any clear guidance as to how the go about changing the sensor.
It looks like it's mounted behind the camshaft drive pulley and that all I need to do is to pop the cambelt cover off and use a socket through the pulley to unbolt the sensor. However, I have read somewhere that the cambelt and pulley need to come off to gain access.
Question is: Can anyone who has actually done the job please advise?
It's the BRT engine, 2.0TDI SOHC.
Many thanks
John
EDIT - I have now eliminated the wiring - definitely the sensor, so here we go.....
EDIT2 - OK, so lesson learned. Check the sensor before installing it.
This is definitely the BRT engine. The label on the timing belt cover says so. It was as I thought, however, to change the sensor quickly, you have to accept cutting the plug off and remaking the wire afterwards. To replace the sensor with the plug, as purchased, it looks like the timing belt and camshaft pulley have to be removed. Guess which one I went for, being electronics oriented....
If you can accept mutilating a perfectly new sensor, then the sequence is:
Engine cover off
Air filter cover off, disconnecting the MAF and air inlet pipe
Upper/outer plastic timing belt cover off (two clips and it lifts off)
Remove the 10mm AF sensor retaining bolt
Cut the plug off the old sensor
Pull the sensor and the cable clear. The sensor is located with a plastic alignment lug into the cylinder head so there's a bit of resistance to begin with
Refit is the reverse, except for making the plug off, rather than cutting it. The bolt might benefit from a bit of screw lock on it.
I used a 'chicken string' on the 10mm bolt. The risk of losing it into the engine was high, so I slackened it off three turns and then put a slipknot of garden twine around the thread, so that if it dropped out of the socket, I'd have it on the string. The bolt can then be removed with confidence and usually you don't then drop it. (Just like having a safety wire when tightrope walking - not that I'd try that!) Likewise, when reinstalling it, the slipknot is on until the bolt is definitely threaded and then by pulling on the tail of the knot, then loop can be slackened and removed before fully tightening it home. Note that there is a washer behind the bolt head, so get the slip knot on the thread below the washer.
The bolt is almost under the belt and there's not a lot of room but a standard ratchet / socket will just squeeze in there to crack the thread. Then the socket and finger can be used to remove it completely. Make sure that all tools/fingers are as clean as possible, because you will be rubbing on the timing belt, which does not like oil/grease on it.
Having completely the exercise, the engine was very sluggish to start. I repeated my checks on the sensor and found that the output signal was reading low, so it's either a faulty sensor or my wiring job wasn't as good as it should have been. Having run out of daylight, I retired to the workshop with the old sensor and connected it up to a 5 volt supply. It worked properly - a small washer waved in front of it caused the output to toggle. However, after four minutes or so, it stopped. Just what my cruise control was doing. SO I'm now really confident that I've found the original fault, I'm just cross that I didn't check the replacement before installing it. (see lesson learned!)
When I get the new sensor working properly, I'll close off the thread. I'm just waiting for the rain to stop to go out and do some proper electrical tests before having to potentially repeat the exercise!
EDIT3: I've reinstalled the old sensor - car now starts properly. The 'new' eBay sensor works, just not on this car. Back to the drawing board
EDIT4: Now I've finished, I find this: How to change a G40 Cam position sensor - 10 minute job (http://www.fixmyvw.com/how-to-change-a-g40-cam-position-sensor-10-minute-job/) Apparently there's a grommet that, when removed, allows the plug to go through. Aaaargh! I didn't need to cut the plug off and resolder it .... Still, when I try the next sensor....
EDIT5: Old sensor started to work properly/consistently whilst off the car. Having now re-installed it, not only does the car start properly, the cruise control now works properly too. Now I just wait for it to break again. I hope that my notes are useful to someone.
EDIT6: The story is now properly closed. I was advised (thanks Dave) to use Intermotor 419 44 0850 and this has worked properly. Alternative, eBay sourced sensors did not and this appears to be due to the colour of the plug. The Intermotor part has a white plug and pulls the sense to 0V when sensing metal. The others, with a black plug, pull the sense to 0V when not sensing metal, i.e. the other way up. Changing the sensor is a 30 minute job and needs some care but is not difficult and does not need any special tools. The Cam Shaft Sensor failing will not show the MIL light, nor restrict the engine revs but will cause cruise control to drop out. An intermittent sensor will cause the engine to be sluggish to start and to feel a little bit lumpy when running....
It looks like it's mounted behind the camshaft drive pulley and that all I need to do is to pop the cambelt cover off and use a socket through the pulley to unbolt the sensor. However, I have read somewhere that the cambelt and pulley need to come off to gain access.
Question is: Can anyone who has actually done the job please advise?
It's the BRT engine, 2.0TDI SOHC.
Many thanks
John
EDIT - I have now eliminated the wiring - definitely the sensor, so here we go.....
EDIT2 - OK, so lesson learned. Check the sensor before installing it.
This is definitely the BRT engine. The label on the timing belt cover says so. It was as I thought, however, to change the sensor quickly, you have to accept cutting the plug off and remaking the wire afterwards. To replace the sensor with the plug, as purchased, it looks like the timing belt and camshaft pulley have to be removed. Guess which one I went for, being electronics oriented....
If you can accept mutilating a perfectly new sensor, then the sequence is:
Engine cover off
Air filter cover off, disconnecting the MAF and air inlet pipe
Upper/outer plastic timing belt cover off (two clips and it lifts off)
Remove the 10mm AF sensor retaining bolt
Cut the plug off the old sensor
Pull the sensor and the cable clear. The sensor is located with a plastic alignment lug into the cylinder head so there's a bit of resistance to begin with
Refit is the reverse, except for making the plug off, rather than cutting it. The bolt might benefit from a bit of screw lock on it.
I used a 'chicken string' on the 10mm bolt. The risk of losing it into the engine was high, so I slackened it off three turns and then put a slipknot of garden twine around the thread, so that if it dropped out of the socket, I'd have it on the string. The bolt can then be removed with confidence and usually you don't then drop it. (Just like having a safety wire when tightrope walking - not that I'd try that!) Likewise, when reinstalling it, the slipknot is on until the bolt is definitely threaded and then by pulling on the tail of the knot, then loop can be slackened and removed before fully tightening it home. Note that there is a washer behind the bolt head, so get the slip knot on the thread below the washer.
The bolt is almost under the belt and there's not a lot of room but a standard ratchet / socket will just squeeze in there to crack the thread. Then the socket and finger can be used to remove it completely. Make sure that all tools/fingers are as clean as possible, because you will be rubbing on the timing belt, which does not like oil/grease on it.
Having completely the exercise, the engine was very sluggish to start. I repeated my checks on the sensor and found that the output signal was reading low, so it's either a faulty sensor or my wiring job wasn't as good as it should have been. Having run out of daylight, I retired to the workshop with the old sensor and connected it up to a 5 volt supply. It worked properly - a small washer waved in front of it caused the output to toggle. However, after four minutes or so, it stopped. Just what my cruise control was doing. SO I'm now really confident that I've found the original fault, I'm just cross that I didn't check the replacement before installing it. (see lesson learned!)
When I get the new sensor working properly, I'll close off the thread. I'm just waiting for the rain to stop to go out and do some proper electrical tests before having to potentially repeat the exercise!
EDIT3: I've reinstalled the old sensor - car now starts properly. The 'new' eBay sensor works, just not on this car. Back to the drawing board
EDIT4: Now I've finished, I find this: How to change a G40 Cam position sensor - 10 minute job (http://www.fixmyvw.com/how-to-change-a-g40-cam-position-sensor-10-minute-job/) Apparently there's a grommet that, when removed, allows the plug to go through. Aaaargh! I didn't need to cut the plug off and resolder it .... Still, when I try the next sensor....
EDIT5: Old sensor started to work properly/consistently whilst off the car. Having now re-installed it, not only does the car start properly, the cruise control now works properly too. Now I just wait for it to break again. I hope that my notes are useful to someone.
EDIT6: The story is now properly closed. I was advised (thanks Dave) to use Intermotor 419 44 0850 and this has worked properly. Alternative, eBay sourced sensors did not and this appears to be due to the colour of the plug. The Intermotor part has a white plug and pulls the sense to 0V when sensing metal. The others, with a black plug, pull the sense to 0V when not sensing metal, i.e. the other way up. Changing the sensor is a 30 minute job and needs some care but is not difficult and does not need any special tools. The Cam Shaft Sensor failing will not show the MIL light, nor restrict the engine revs but will cause cruise control to drop out. An intermittent sensor will cause the engine to be sluggish to start and to feel a little bit lumpy when running....