Lurching at 1750 rpm

Taxidriver · 17-04-2007, 14:02

Hi all,

I have had the cambelt and tensioners replaced on my superb 19td1 130 (05) at 80,000 miles and all appeared to be ok. I was aiding the mechanic on this job and we used the lock down tool and 6mm dowel as stated in the VW haynes manual.
Genuine parts were used and the job went without any problems..great. But not long after when driving I noticed a slight hesitation in 2nd gear almost like a very brief interruption in the fuel flow. After a while I noticed that it was at the same rpm of about 1750 that this would occur in whatever gear I was in although it was more noticeable in 1st - 3rd. If I power through the rpm range its does not seem to do it only if I am holding the power or powering very lightly through the rpm range of 1750rpm. Would this have anything to do with the belt or the way the belt was fitted?. Apart from the belt being a tooth out (although we both made sure this did not happen as the lock down tools stayed in place) is there any other form of adjustment to the cam timing I should check. Other then that the car drives fine in all other respect its just annoying to feel that slight lurching.

Thank you for reading this

Laurence (Taxidriver)

rotodiesel · 17-04-2007, 15:04

This does sound like a timing problem. How does the position of the 3 camwheel retaining bolts compare with the original (the ones in the slotted holes)? I would check this very carefully before going in too far.

Out of interest, did you change the water pump and if so, did the original have a plastic impeller? Mine is due a belt change soon and I'm looking into getting a pump with a metal impeller - I think GSF may sell them.

rotodiesel.

Taxidriver · 17-04-2007, 16:45

Hi Rotodiesel,

When you say how does the position of the 3 camwheel retaining bolts compare with the original do you mean the bolt marks left on the camwheel after I slackened them off?. I also checked the water pump for wear, granted externally and it seemed fine so I left it.

Thanks for reading

Laurence

rotodiesel · 17-04-2007, 23:13

Yes, I did mean the marks left on the camwheel. The idea of the vernier adjustment on the camwheel is to allow the belt to be tensioned without any locked in torque from the valve/injector springs and also to allow the camshaft timing position to be precisely set rather than to the nearest tooth. It's a good system (copied from PSA) but if the 3 camwheel bolts on your engine are now in a substantially different position, you may have a problem.

Keep a sharp eye on the waterpump - the plastic impellers have been known to disintegrate on this engine, jamming the pump and throwing the belt off. At best, a broken impeller causes overheating which is hard to trace if you have not met this problem before.

rotodiesel.

Taxidriver · 18-04-2007, 10:50

Thanks Roto for the advice

. I will check the bolt marks later this week and hopefully rectify the problem. I assume that if the marks are slightly out all I need do is slacken the tensioner off and adjust the cam wheel and re-tension?.

Cheers mate

Laurence

rotodiesel · 18-04-2007, 12:59

Erm.. No you can't. The crank has to be locked at the toothed belt wheel using tool T10050 which fixes it at TDC. The camshaft (not the camshaft wheel) is locked with a 6mm pin (I use a drill shank). With the three camwheel bolts slackened, the belt is tensioned, ensuring that the pointer aligns with the notch behind the tensioner wheel if you have the later tensioner without the hydraulic damper. Only then can you tighten the camwheel bolts, rotate engine a couple of turns by hand and then finally check the relative positions of the crank, camshaft (not wheel) and tensioner pointer.

If any of this is wrong, you must do it again. In your case, if the bolts are now significantly differently positioned in the slotted holes, you've probably got it wrong. The actual position is not important - my car has the original belt, runs fine and has the bolts positioned near one end of the slots. This is just the result of normal tolerances, which the slots are there to take up.

rotodiesel.

Taxidriver · 18-04-2007, 13:36

Ok I see what you are saying. I will show this to the guy that did the job with me and we will recheck the cam timing. We have the lock down tool and I also used a 6mm drill for the camshaft. I will post back with the results as soon as the jobs done and hopefully this will cure my problem.

Thanks for your time Roto

Laurence

17-04-2007, 14:02	#1
Taxidriver Briskodian Join Date: Apr 2007 Posts: 11 Members Car: Thanks: 0 Thanked 0 Times in 0 Posts	Lurching at 1750 rpm Hi all, I have had the cambelt and tensioners replaced on my superb 19td1 130 (05) at 80,000 miles and all appeared to be ok. I was aiding the mechanic on this job and we used the lock down tool and 6mm dowel as stated in the VW haynes manual. Genuine parts were used and the job went without any problems..great. But not long after when driving I noticed a slight hesitation in 2nd gear almost like a very brief interruption in the fuel flow. After a while I noticed that it was at the same rpm of about 1750 that this would occur in whatever gear I was in although it was more noticeable in 1st - 3rd. If I power through the rpm range its does not seem to do it only if I am holding the power or powering very lightly through the rpm range of 1750rpm. Would this have anything to do with the belt or the way the belt was fitted?. Apart from the belt being a tooth out (although we both made sure this did not happen as the lock down tools stayed in place) is there any other form of adjustment to the cam timing I should check. Other then that the car drives fine in all other respect its just annoying to feel that slight lurching. Thank you for reading this Laurence (Taxidriver)

17-04-2007, 15:04	#2
rotodiesel Briskodian Join Date: Aug 2006 Posts: 669 Members Car: Thanks: 5 Thanked 83 Times in 74 Posts	Re: Lurching at 1750 rpm This does sound like a timing problem. How does the position of the 3 camwheel retaining bolts compare with the original (the ones in the slotted holes)? I would check this very carefully before going in too far. Out of interest, did you change the water pump and if so, did the original have a plastic impeller? Mine is due a belt change soon and I'm looking into getting a pump with a metal impeller - I think GSF may sell them. rotodiesel.

17-04-2007, 16:45	#3
Taxidriver Briskodian Join Date: Apr 2007 Posts: 11 Members Car: Thanks: 0 Thanked 0 Times in 0 Posts	Re: Lurching at 1750 rpm Hi Rotodiesel, When you say how does the position of the 3 camwheel retaining bolts compare with the original do you mean the bolt marks left on the camwheel after I slackened them off?. I also checked the water pump for wear, granted externally and it seemed fine so I left it. Thanks for reading Laurence

17-04-2007, 23:13	#4
rotodiesel Briskodian Join Date: Aug 2006 Posts: 669 Members Car: Thanks: 5 Thanked 83 Times in 74 Posts	Re: Lurching at 1750 rpm Yes, I did mean the marks left on the camwheel. The idea of the vernier adjustment on the camwheel is to allow the belt to be tensioned without any locked in torque from the valve/injector springs and also to allow the camshaft timing position to be precisely set rather than to the nearest tooth. It's a good system (copied from PSA) but if the 3 camwheel bolts on your engine are now in a substantially different position, you may have a problem. Keep a sharp eye on the waterpump - the plastic impellers have been known to disintegrate on this engine, jamming the pump and throwing the belt off. At best, a broken impeller causes overheating which is hard to trace if you have not met this problem before. rotodiesel.

18-04-2007, 10:50	#5
Taxidriver Briskodian Join Date: Apr 2007 Posts: 11 Members Car: Thanks: 0 Thanked 0 Times in 0 Posts	Re: Lurching at 1750 rpm Thanks Roto for the advice. I will check the bolt marks later this week and hopefully rectify the problem. I assume that if the marks are slightly out all I need do is slacken the tensioner off and adjust the cam wheel and re-tension?. Cheers mate Laurence

18-04-2007, 12:59	#6
rotodiesel Briskodian Join Date: Aug 2006 Posts: 669 Members Car: Thanks: 5 Thanked 83 Times in 74 Posts	Re: Lurching at 1750 rpm Erm.. No you can't. The crank has to be locked at the toothed belt wheel using tool T10050 which fixes it at TDC. The camshaft (not the camshaft wheel) is locked with a 6mm pin (I use a drill shank). With the three camwheel bolts slackened, the belt is tensioned, ensuring that the pointer aligns with the notch behind the tensioner wheel if you have the later tensioner without the hydraulic damper. Only then can you tighten the camwheel bolts, rotate engine a couple of turns by hand and then finally check the relative positions of the crank, camshaft (not wheel) and tensioner pointer. If any of this is wrong, you must do it again. In your case, if the bolts are now significantly differently positioned in the slotted holes, you've probably got it wrong. The actual position is not important - my car has the original belt, runs fine and has the bolts positioned near one end of the slots. This is just the result of normal tolerances, which the slots are there to take up. rotodiesel.

18-04-2007, 13:36	#7
Taxidriver Briskodian Join Date: Apr 2007 Posts: 11 Members Car: Thanks: 0 Thanked 0 Times in 0 Posts	Re: Lurching at 1750 rpm Ok I see what you are saying. I will show this to the guy that did the job with me and we will recheck the cam timing. We have the lock down tool and I also used a 6mm drill for the camshaft. I will post back with the results as soon as the jobs done and hopefully this will cure my problem. Thanks for your time Roto Laurence

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