K series VVC Cambelt change questions...

[Peter G]

A couple of questions before I set to on changing the cambelts, firstly is there more than one type of belt tensioner on this engine? If there are options, how do I know which one to get? (I remember on my 1.6K there were 2 options)

Secondly, whats the best way to change the rear belt? When I did it last time the engine was out of the car and we removed one of the pulleys, as there's a lip on one of the pulleys, obviously to stop the belt coming off.

Thanks all, I've got the pulley lock for the front end, and doing the job should be ok, having done it twice before, apart from now having to do the job with the engine in.

 

[revilla]

All VVCs use a MANUAL tensioner.

 

You will need to remove one rear pulley as you say to change the rear belt. If you use your cam lock on the front, that will lock the (solid) exhaust cam. Easiest option is then to remove the rear exhaust pulley with the lock inserted at the front.

[revilla]

Biggest difference doing it in the car is ... you can't get your head in to look straight on an the rear pulleys so it can be hard to judge the timing mark alignment. The marks are on the outer edges of the pulleys and align with the marks on the cover which is at the inner edge of the pulleys so parallax comes into play. Two suggestions i) use a mirror or mobile phone to get a straight view ii) look where the marks are on the outer edge of the pulleys and follow the ribs back to the inner edges, then judge the alignment using the corresponding rib positions at the inner edges.

[Peter G]

Thanks Andrew. Should get it done next week as long as parts arrive ok.

[Wrightpayne]

When removing the rear pulley / belt does the inlet split camshaft move? Does this have any bearing on which pulley you remove?

Ian

[revilla]

It can, you need to be careful.

If you remove the rear inlet pulley instead, there's no way to lock the cams at the rear. You have to use something like a motorcycle pulley holder on the pulley with one hand with a breaker (removing) or torque wrench (refitting) on the other. It's awkward and there's quite a potential for it to slip doing damage (most probably to your hand!).

If you're careful and everything is aligned at safe position when you remove the belt it probably won't move, but it does tend to be very close to the point where it wants to flip round on the valve springs. If it does move you'll need to find some way to grip the pulley to turn it back against the valve springs to get the alignment right.

At least removing the exhaust pulley you can lock the one you are applying torque to.

[john milner]

Something like this can be used on the rear pulleys while unbolting but it is more of a holding in place tool rather than a something you would exert a lot of force on. It also helps keep some of the torque off the cam lock at the front which I suppose could damage the cams:

https://www.ebay.co.uk/itm/MG-Rover-MGF-MGTF-Cam-Pulley-Gear-Wheel-Holding-Tool-F-TF-ZR-ZS-ZT-16V-K-Series/293417553969?fits=Car+Make%3AMG%7CModel%3AMGF&epid=647742241&hash=item44510c9031:g:yKAAAOSwrklVCa99

 

From my personally written idiot guide which avoids any cams spinning around under tension. Followed it to the letter twice and the engine still works:

Remove rear belt

Mark rear belt and pulleys with Tippex 180 degs from factory timing marks (i.e. outwards). Due to engine alignment this is awkward. Alternatively you can count the number of teeth between factory and Tippex marks to ensure exactly 180 degs.

Take photo.

Mark FRONT pulleys with Tippex 180 degs from factory markings. This should be easier than the rear and is easy to see when turning the crank.

Rotate crankshaft clockwise until timing has moved 180 degs (rear pulley Tippex marks facing inwards & factory outwards). If they were done the Tippex rear belt marks should align with factory pulley marks.

Double check using crank and FRONT pulley Tippex markings.

If practical check alignment with a straight edge. All markings should align.

Take photo.

Insert cam locking tool between front pulleys.

Take photo.

Hold rear exhaust pulley with tool (this might not be essential but as it keeps stress off of the cam gear at the other end is worth doing).

Remove bolt (17mm) from centre of rear exhaust pulley.

Remove rear timing belt. A wide flat screwdriver may be needed to slide the belt off.

Inspect belt for signs of damage such as rubbing. This belt is probably in much better condition than the front.

Fit rear belt

Copy Tippex marks from old to new rear belt. By whatever it is done there should as a minimum be two Tippex marks equidistant apart. Very important this part as it makes things a lot easier to line everything up.

Align inlet cam (should not have moved much as off load).

Put new belt on inlet pulley.

Tippex belt mark should align with outward factory mark.

Slip belt over exhaust pulley. Note that pulley has not been fitted yet.

Tippex belt mark should align with outward factory mark.

Loose fit exhaust pulley using bolt (factory marks out, Tippex in).

Check alignment with straight edge and teeth count if in doubt. Do again if required.

Remove exhaust pulley bolt (17mm). The pulley should stay in place.

Apply threadlock cement to exhaust pulley bolt and refit.

Check alignment with, Tippex, straight edge and teeth count if in doubt. Do again if required.

Check front pulley lock has not moved.

Tighten exhaust pulley to 65Nm using wrench and pulley tool.

Check alignment with, Tippex, straight edge and teeth count if in doubt. Do again if required.

Remove cam locking tool from between front pulleys.

Rotate crankshaft clockwise three times. This will turn the cam sprockets 540 degrees to show if there any problems with slack and align marks for the final time.

Check front and rear alignment. All factory marks should be aligned.

Fit rear timing belt cover. Four 8mm x 1” – 10Nm.

[oilyhands]

Fully agree that using marks 180 degrees from the factory marking when fitting the rear belt makes life a *lot* easier as you are not fighting valve spring tension on the rear VVC mech. I *always* use that method. You only have to loosen the rear exhaust pulley and tilt it to get the belt on and off.

Oily

[oilyhands]

Fully agree that using marks 180 degrees from the factory marking when fitting the rear belt makes life a *lot* easier as you are not fighting valve spring tension on the rear VVC mech. I *always* use that method. You only have to loosen the rear exhaust pulley and tilt it to get the belt on and off.

Oily

[Englishmaninwales]

#7 Thank you, John. I can see that will make the task much easier.

Malcolm

[Peter G]

Thanks again gents, much appreciated, garage tasks have been lowered down the list of other "projects" for a while, hopefully next week to get this done.

[Peter G]

Thanks for all the pointers everyone, belts all changed and all seems good, but before I fire it up, how is the tension on the manual belt tensioner set? The spring I have with it doesn’t seem to move the backing plate much and it’s leaving the belt loose in my view, any ideas?

[SM25T]

Spring hooks on bolt you fit in hole above tensioner. With both tensioner bolts loose, it pulls the tensioner to the required level. However, I dont like/trust it either. I move the tensioner with a finger until long strand of belt feels right. Mid span, can't quite twist it to 90 degrees. Then torque up both bolts ... with a spot of loctite. Turn engine over 720 degrees with a ratchet on the crank bolt. Then check tension again. Do remove the spring and bolt.

[Peter G]

I ended up doing the first bit and it felt a bit tighter, and when it fired up the lower section of belt below the water pump was moving around quite a bit, I realise the longer length from the exhaust cam to the crank pulley is in tension, but I couldn’t see that with the bottom cover on. I’ll leave it for now it’s still worn till June 1st, so I’ll give it a gentle run and then have another look and if needs be put a bit more tension on it. Thanks Ian.

[revilla]

You'll find the belt on the VVC engine runs quite a bit looser than on other engines, this is to protect the front VVC mechanism main drive bearing. If you tension the belt as far as you would on other engines the bearing will wear prematurely. There is a different part number for the tensioner spring for a regular K and a VVC.

[Peter G]

Cheers Andrew. After I posted I went back out and i could see the spring working this time so left it as intended. It seemed to be sticking earlier so perhaps something was out of line. Thanks again.

[SM25T]

You mean you slackened off the tensioner bolts this time :-)

[Peter G]

Dodgy eyesight probably.....