Timing Belt Adjustment

[ukguy]

Hi all,

I have found out through the use of Vag-Com that my injection timing is out on my Golf mk4(A4). I have read the guide that relates to adjusting the injection timing but just need to clear up the following please.

When I loosen the 3 bolts holding the injection pump sprocket, how do I exactly rotate the injection pump? Do I just take a wrench to the central nut and adjust this

Or would doing this cause other problems. I have never got involved in the timing belt before, but don't want to take it to the place where I had the timing belt done as they don't have diagnostic equipment!

Any help would be appreciated before I attempt this.

Thanks,

Adam

 

[cattlerepairman]

[...] but don't want to take it to the place where I had the timing belt done as they don't have diagnostic equipment![...]

I second that decision. Without diagnostic equipment one cannot even verify the injection timing after the TB job...which means such a place should perhaps not even be trusted to do the TB change in the first place.

You do not say what year your Golf is; the early MkIV have stretch bolts at the pump sprocket that need to be replaced when you correct the timing. Check this post with pics: stretch bolts

For the procedure..you got that right. You do not loosen the centre nut, but you can use it to assist in rotating the injection pump that tiny little bit that it takes to get the timing right.

If you found the write-up, you are all set!

It will take you a number of tries to get it right (even if you do not want to, you will move the pump too much in the beginning).

 

[ukguy]

Thanks a lot for the info' there. Is rotating the injection sprocket a little 'ok' using the centre bolt? I would presume it is well torqued up to prevent me loosening inadvertently whilst adjusting the pump timing

I have a '99 model Golf, thanks for the heads up on the stretch bolts, looks like I'll be needing them afterwards aswell.

One thing, I understand the top timing belt cover is easy to remove by removing 3 clips. Can this be done with the power steering pump, water bottle in their original positions? Do I need to remove them all to adjust the injection timing only or is it very easy to do without all doing all these extra things.

I prefer to know what mechanics are doing and to make sure they're doing it right! And it gives me greater piece of mind and satisfaction when I do the jobs myself, not to mention saving money

Thanks again,

Adam

 

[Powder Hound]

A timing adjustment can be done without removing anything else except the top cover. Pop the clips, the cover is off, and you are ready to work.

Have fun as the adjustments necessary are very small. Remember, the movement on the pump sprocket has an effective rate double that of crank degrees. In other words, since the pump sprocket is driven at half the crankshaft speed, a 1 degree movement at the pump produces a 2 degree change in timing.

Just be ready to move it just a tad, check it, move it back a little, check, move, check, move, check, move, check...

And be patient, because you will eventually get it right.

Cheers

 

[ukguy]

Excellent stuff, thanks for the very helpful advice. I see there is some clearance there to loosen the nuts when the top timing cover is off. Just need to get some new nuts now.

Whilst I have the top cover off, I noticed what looks to be a 5cm long, 2cm width chunk of plastic missing from the inner cover at the side of the tensioner! I'm not overly concerned right now as it's not causing any problems, but with time I can see dirt and allsorts getting into this gap. I would presume it's not meant to be there

I think I'll try some duct tape just to keep the dirt out, it may do the trick.

Thanks again, your help is appreciated.

Adam

 

[ukguy]

Hi there.

I am now looking to put in replacement bolts after adjusting the injection pump. The original bolts are the stretch type. Can they be replaced with the non stretch type at all? The guy at the dealership wasn't sure as he said the different bolts he showed in the system fitted different parts!

I think fitting the non-stretch type would be far more beneficial for future maintenance but would like to make sure I can use them with my early mk4 golf tdi.

Thanks,

Adam

 

[MOGolf]

Yes, you can and VW has a service bulletin about it from years ago. After you get the timing set properly, just remove 1 and replace it with a new non-stretch type. Then repeat for the other 2, doing 1 at a time.

 

[ukguy]

Excellent stuff. Thanks very much for the information, much appreciated.