What is the process for changing the cam pulleys?

If you can lock the pulleys you can use the air impact gun to loosen the cam pulley bolt but, make sure the pulleys are locked tight. And of course, the other way is to remove the cams.

 

I had no problem, holding the pully with an old cam belt in my bare hand and "hitting" the bolt with the impact wrench.

Came right out and I am not a BIG guy with vice grip hands.

 

that can work and I've done it myself, however the risk is high of valve damage if the pulley slips, I'd loop the belt around a single pulley at a time and hold the looped end. impact gun is going to be the easier then trying it by hand. also make sure the lock tab washer is bent back out of the way.

first things first, bring the engine to TDC, then start the job. helps to have everything lined up first, once the belts are off there is no turning the engine unless you take the cams out.

I didn't catch the model, but the QV and 328 cams should come out to the job as the seals are retained in place by cams on those models.

 

I find this information very useful.
Are the pulleys keyed onto the cams so that they can only go back in one position, or is there any sort of vernier adjustment that requires specialist gear to refit them in the correct position?
Leading on from that, if they have adjustment is it recommended to ever check this?
If so how is it done?

 

There are multiple key hole on the pulley for setting valve timing. It's best to mark the hole before removing the pulley.

 

Also, if you don't have an impact wrench, they can be done manually, but it really requires two people to be secure ----- one with an open-end wrench (long with lots of leverage) holding the camshaft at the cast-in hexagonal lugs near the outboard, cog-side, end to prevent rotation .....and, the other with a fairly long breaker bar / socket on the pulley bolt to unscrew it.

 

I had the cams out when I did this, so one at a time and no risk to valves.

The point I was making was the bolt is not that tight (normally), but too tight to try/risk a cresent wrench.

My Bad.




The more I think about leaving the cams in place, the more I fret over the possibility of damaging the bearings, cam seals or the valves. Probably just best to remove them unless a PRO here has a fail-safe method not yet mentioned.

 

Removed mine by first removing the camshafts. I was able to hold the cam steady by wrapping the old timing belt around the pulley and holding the belt halves together with vice grips and using an impact wrench with the other hand.

Then if you really feel lucky, reuse the timing belts. ; )

 

The PRO way, take out the cams.

You must be a He-man as the TQ value is 100Nm for those bolts, the cylinder heads are the same TQ-spec, only a handful of others top that like ring nuts on the drop gears 180~200Nm etc.. I've not been able to remove those bolts by hand without damaging the plastic pulleys, the steel ones I have a V jaw with pins to keep it from rotating that will allow the use of a loooooong breaker bar. just easier to hit with the impact. And hope some fool hasn't put loctite on the threads in the past.

 

The crank layout is a flat crank, so at TDC piston 1&4 are at TDC and 2,3 are BDC with 5-8 at mid stroke. the risk of valves hitting pistons is on 1&4, once the belts are off the cams are no longer timed of course and any rotating the engine will risk bending open valves. due to the helical gear used in the timing case to turn the drives it's not a good idea to rotate the engine about as a CCW rotation will disrupt the timing and need to be taken out by a full CW rotation, which can't be done if the cams are in. So if the cams are in place they get locked at TDC.

next up is the pin to set the pulley on the cam...

 

Everyone is saying to set the engine to TDC. I wouldn't. First I wouldn't do it in the car, I would loosen them outside, but if I did I would set the crank to 90 degrees before or after TDC. With the flat plane crank all of the pistons would be half way up the bore and none of the valves could hit any of the pistons. Intentionally moving the pistons into position for maximum valve contact if something goes wrong seems crazy to me.

 

but how does the timing get checked to make sure it's right? It'd work if you were ok with the timing as it is or know that it's good, but in my opinion it's not a good idea. In all honesty the cams should come out, set it to TDC pull the cams remove the pulleys then re-install the cams, install the pulleys and set the timing. short cuts always end up taking more time with these engines.