How to: SDI cambelt change

[mk2]

Having done a few cambelt changes on the SDI, I thought I'd post a how to. I've had to repair other people's mistakes as it is not obvious like on other Vdubs. There are a few sequences you MUST follow, as some parts overlap or get in the way. If you do it in the wrong sequence you can break something. Take your time. The work is fairly straight forward, but some bits are fiddly, such as the hex bolts on the crank and water pump pulleys. Don't use allen keys- use a proper hex driver attachment to fit your socket set ratchet spanner.

Tools needed:
trolley jack
1/2" metric socket set (to 19mm)
metric spanner set (to 19mm)
stubby screwdriver 8mm flat blade
1/2" drive hex key driver set (to 10mm)
a medium length 1/4" flat bladed screwdriver
3mm allen keys or nails or steel pins
molegrips for the pipe clamps
compact mirror
paint
spray grease
light oil can

rust removal liquid
rag to clean hands and messy bits

 

Start here:

Loosen RHS front wheel bolts.
Jack up front of car, both sides.
Put on axle stands or blocks, wood etc. Both front wheels off the ground.
Remove plastic sump tray (two 10mm bolts and three star clips)- rotate star clips counter clockwise until they come off their threads if they will be reused.
Remove RHS front wheel.
Open bonnet.
Remove engine dressing cover (take care with the clips). If the two studs come away, they will need to be detached and thread locked back onto their pedestals later.

Dismantling:
Unclip air temp sensor
Remove air duct
Remove ribbed belt -14mm spanner- loosen tensioner bar around back of diesel pump
Remove top cam belt cover (don't forget small plastic screw and pipe clip)
Put trolley jack under rhs of engine sump
Remove engine mount top bracket 3 + 1 bolts -jack up engine to take the strain
Loosen engine mount side support 4 bolts- leave in place for the minute
Remove engine mount 3 bolts
Manoeuvre engine mount side support up and out (leaving bolts loose in it)- jack up engine or lower as needed
Remove water pump pulley - no option - this must be done (3 bolts)
Remove the crankshaft ribbed belt pulley (4 bolts)
Remove the lower cam belt cover (3 bolts- yes 3)
Turn engine clockwise using socket on crank until all the TDC marks line up
Put a paint mark on all of the cambelt pulleys and behind them in easy to see positions
Loosen cam belt tensioner nut to allow cam belt to go slack
Remove the mini cambelt idler bearing pulley next to the diesel pump
Ease the cambelt off the pulleys
Fully remove the cam belt tensioner (jack up the engine a bit)
This is the (easy) point to remove the water pump if you are going to replace it
Check condition of pulleys and crank seal, and clean up any gunge- if any.
This is the easy point to check/change ribbed belt tensioner pulley bearing

Reassembly: (raise or lower engine as needed throughout the procedure)
Clean then lightly oil every nut and bolt before reassembly
Lube (spray grease) intermediate slider and spring inside tensioner (they wear out quicker otherwise)
Loosely hang new cam belt on tensioner pulley and slide it back onto the stud (no nut just yet)
Locate tensioner anti rotate peg into slot (important)
Ease the cam belt onto the pulleys, starting at the crank first, just hanging on the pulley edges
Once the cam belt is located in the right timing teeth slide it fully onto each pulley
Check the paint marks are still right and the pulleys haven't moved
Tighten the tensioner nut up to finger tight (don't forget the washer)
Recheck the anti rotate peg is correctly located
Refit the (new) small idler bearing pulley (to the right torque- not too tight!)
Using some makeshift tools tension the cam belt just enough to take out any slack, then tighten the tensioner nut just enough to stop it loosening.
Turn the crank by hand a few times to get the new belt to settle in the pulley teeth and allow it to find its running line.
Using a small mirror, check the alignment of the tensioner marks.
Adjust tensioner so that the marks line up
Turn the crank again a few times
Check and adjust the tensioner again. keep doing it until the tensioner mark stays lined up. Then the tension is perfect.
Note the tension alignment moves with temperature if checking a hot engine (the belt gets tighter).
Tighten tensioner nut to the right torque (not too tight!)

Refit (in this order):
Engine mount side support (the bolts have to be in place before trying to fit it)
Lower cam belt cover
Water pump pulley
Crankshaft ribbed belt pulley
Remaining top engine mount parts in reverse order as removed -don't overtighten!
Top cam belt cover
Ribbed belt
Air duct
Temp sensor (don't forget to plug it in or you'll get a check engine light!)

Final check- make sure you can turn the engine over at the crank before starting

Refit the other bits in reverse order as removed

The timing alignment can be double checked with all wheels on the ground (upper cam belt cover off)-
Put the car in 5th gear, roll forwards inch by inch till the timing marks all line up:
Flywheel check hole (--o mark), cam pulley (dot) and injection pump (holes line up)

pics for reference follow:

 

Here's a link for the very similar polo SDI engine, with some useful diagrams how to change the cam belt.

http://replace-timing-belt.com/how-to-replace-timing-belt-on-vw-polo-6n-1-7-sdi/

Tighten bolts and nuts to the following settings. Notice that they are not that tight, as many threads are cut into aluminium which strips easily. Add a drop of oil to each thread before assembly. Not too tight...

Upper engine mount 3+1 bolts: 30lbft

Engine mount side plate 4 bolts: 30lbft

Cam belt tensioner nut: 15lbft

Water pump pulley 3 hex bolts: 20lbft

Crank pulley 4 hex bolts: 25lbft

Lower cam belt cover 3 bolts: 10lbft

Plastic bolt upper cam belt cover: a bit tighter than finger tight.

Idler pulley bolt: 20 lbft.

I recommend wearing gloves, as knuckles will get damaged during work. There is hardly any space between the body and the engine, so you'll need to raise or lower the engine all the time to get things to fit. Start to finish takes a relaxed 3h. You can do it in about 45 minutes with practice!

Edited April 5, 2020 by mk2
updated with crank pulley fix