If it aint broke, fix it 'til it is.

How to: replace a Grand Scenic (k4m) dephaser pulley saving hundreds of pounds

Our faithful Grand Scenic had been making an awful clattering noise on startup for some time. The dephaser pulley is a known fault with the k4m 1.6 16v vvt Renault engine. So I decided to replace it. I bought the dephaser along with a cam belt kit including water pump for around £150.

 

Garages have quoted around £600 to do this job. 

What you will need:

 

  • Engine locking tools (I paid £20 from eBay)
  • Trolley jack and axle stands
  • Ratchet and selection of sockets (I have both 3/8" and 1/2" drive which helped)
  • Torque wrench
  • E12 and E14 sockets
  • Selection of spanners.
Here's what you do:

 

 

 

  • Jack up the front offside wheel and support it on a suitable stand.
  • Open the bonnet and remove the scuttle panel. The passenger side one comes off first followed by the rest (you need to remove the wiper arms but not the wiper mechanisms)
  • Then remove the metal slam panel, there's a section above the air filter that comes off first, then the rest. It's all 10mm bolts. This allows you access to the engine.
  • Next you can remove the pipe from the air filter to the air intake. Slacken the clips and it pulls off.
  • Next the intake manifold. This has four E12 torx socket bolts at the front and three 10mm bolts. There's also a variety of electrical plugs to pop off. The intake manifold will then lift off vertically. Don't forget to stuff something into the inlets to stop you dropping a washer or something in there.
  • Then the engine mount can be removed. First support the engine under the sump with the trolley jack.  Use a piece of wood to cushion it. This job is very fiddly and it's made much easier by lots of raising and lowering of the engine.
  • A 16mm socket will make short work of the bolts on top of the engine mount. Three bolts into the chassis and the whole mount can be removed.
  • Next I removed the offside wheel and wheel arch liner to give access. There's also a large metal plate removed by undoing four 13mm bolts. This allows much better access. I did this in a different order but my getting it wrong gives you opportunity to get b it right. So next slacken off the aux belt tensioner. A 16mm socket (or spanner because there's not much space) turning clockwise on the tensioner will allow you to slip the aux belt off. This will allow you to access a 10mm bolt on the lower cam belt cover (plastic). There are four bolts, one I need each corner.
  • Next there are four 16mm bolts (well, two are nuts) holding the upper cover on (metal). To access them all you'll be raising and lowering the engine and cursing the lack of accessibility, but they will all come off. This will leave you with full view of the cam belt, the cam pulleys and the crank pulley. 
  • On the gearbox end of the head there are two rubber seals over the ends of the cam shafts. These need removing (new ones should be included in your cam belt kit). Stick a screwdriver through the middle and lever them out gently.
  • Remove the E14 bolt just to the right of the oil dip stick. This is where you'll insert your crank locking pin. It screws in to the hole and presses on the crank. It'll lock the engine at TDC and prevent clockwise rotation but not anti clockwise. 
  • Insert the locking pin. If it doesn't go, turn the crank bolt clockwise (18mm socket). When you're able, screw the pin completely in.
  • Once in turn the engine gently until the crank touches the pin. That's your first timing mark.
  • Check the ends of the cams. The slots in each one should be horizontal. Insert your locking tool, it should only fit one way up.
  • This step is personal choice but at this stage I put timing marks everywhere. I marked the belts position with the pulleys and the pulleys position with the block. Up to you but I did. And will again.
  • Before doing any more let's slacken the dephaser. There's an oil cap with a torx bolt. Remove this to give access to the 18mm main bolt. This just undid for me. Beware that none of the pulleys are keyed. As such when you slacken the bolt it will move freely on the cam.
  • Next to remove the crank bolt because you can't get the cam belt off otherwise. On the grand scenic the best way is to lock the flywheel. Under the car near the back of the engine underneath the starter motor you can actually see the flywheel teeth through a gap in the bell housing. Stick a screwdriver into the teeth and wedge it firmly.  Hold it tight while you ask a mate to undo the crank bolt. Make sure the crank is against the timing pin as you do it. Because this will be your bench mark.
  • One the bolt is slack you can slacken off the cam belt tensioner (13mm socket and an Allen key to relieve tension).
  • The belt can the  slide off, leaving your crank in the known tdc position and your cams locked in the horizontal position.
  • Now unbolt the water pump. There are 7 10mm bolts and 1 13mm bolt. Ideally drain the coolant first because as you undo the bolts it'll all spill out all over you.
  • If the water pump is stuck,  encourage it gently with a hammer.
  • Clean up the gasket surface,  use a new gasket and replace with new water pump. The cam belt tensioner bolts to the water pump so I bolted it on before fitting the water pump. 
  • Next replace the roller, that's a torx bolt torqued to 45nm which is about 34ft lbs. Make sure it still rolls freely when torqued, my new one didn't so I checked and reused the old one through necessity. 
  • Now unbolt and replace the dephaser. I used the old cam belt and the timing markings I made to mount it in the same position as the old one. I've no idea if I needed to but I liked doing it.
  • Now on with the new cam belt. I copied across the timing markings from the old belt and started with the cam pulleys, wind it round. It's very very tight when new. I removed the crank pulley,  placed it on the belt then tapped the pulley back onto the crank with a hammer. Not ideal but it's the only way I got it to go on.
  • Once on, lock the flywheel again, refit the crank aux pulley and tighten to 20nm (14 ft lb). Tension the cam belt pulley but turning the Allen key clockwise and tightening the 13mm nut down.
  • Torque the dephaser bolt down to 60 ft lbs. Replace the oil cap. I forgot and it caused me loads of work later.
  • Remove the timing pin and cam tool and turn the crank pulley through four complete rotations (18mm socket).
  • If you can easily reinsert the timing tools then it looks good that the timing is right. 
  • Torque down the crank bolt, 20nm then 130degrees more. Opinion is split here, many people say the timing pin must be removed when tightening otherwise you risk bending it. Others report that renault themselves use the timing pin to torque it down because the pin is loaded down the end, not across it. Whatever opinion is, I used the pin and it didn't bend in the slightest.
  • Now the reassembly, plastic belt cover first, then top one (metal). Then replace the aux belt. Then replace the engine mount. Then reattach the intake manifold and the assorted gubbins.
  • This is the time to add some coolant and test start the engine. I left the wheel liner off, the wipers etc and also didn't replace the rubber bungs at the ends of the cam incase I needed to make adjustments.
  • If it starts and runs, happy days, just the finishing touches of the bungs and replacing some trim.. If not. Back to the timing drawing board.
All in all, not a horrible job. It took me the best part of two days leisurely working through it starting late and finishing early. (Whilst googling and supping tea). Well worth the hundreds of pounds saving.

Happy spannering. 



Contact Us | ©2008 Gaz-racing