K series VVC belt change- hiccup.....

[timb2117]

Ok -I know - feel free to start any reply with "Tim You're an idiot..." 

REAR 2 sprocket VVC belt, took the left exhaust sprocket off having carefully white paint pen marked both sprockets, to a fixed point, and marked the belt to the sprockets, with white marks and counted teeth etc As soon as I popped the sprocket off, the inlet spun about 180 degrees! - That'd be why all the manuals say anchor them down FIRST........

The Q? is - I realigned to the marks (hoping I turned the inlet sprocket the correct way backwards) fitted new belt with all lines lined up. then turned engine manually multiple times and it turns clean and smooth however - have I c***ed it up? As the VVC only works at 4000 rpm plus I'd hate to find out at those revs.....Any ideas would be gleefully appreciated - even if they start with "Tim You're an idiot"

In anticipation thanks heaps.

[Wrightpayne]

Hopefully Revilla will be along shortly to advise!

[SM25T]

Andrew is the man !

[revilla]

Was the engine in the"safe position" with all of the factory timing marks aligned at the point you took the belt off? So long as it was there or thereabouts, the pistons would all be close to the half way point and well clear of any possible valve contact so you won't have done any harm, so long as you're sure you've got it all aligned properly now. By the way you can't really lock the rear inlets so this is quite normal, with the engine at the timing point the inlets are right on the edge of a kick. Some people find it easier to rotate the engine through another 360 degrees, leaving crank timing marks aligned again but the cam timing marks directly away from each other, rather than directly towards each other, when removing the rear belt, as the inlets are slack then.

[timb2117]

Sorry no it wasn't in the safe position - however does this look about right or could I be off still? (the photo is angled a bit, looking square on they are perfectly in line) If I take the front cover off now should all the timing marks be lined up? - If thats the case then I will double check it then hopefully sleep soundly :)

thankyou.

[revilla]

That looks about right.

It's always difficult to look at it "straight on". The easiest thing is to note which tooth the timing mark is on on each pulley and then trace the teeth back to the back (as you look at it, front of the car!) of the pulley by eye and see how they line up. Just to add to the confusion, they can often be a good half a tooth out due to inaccuracies in the drilling of the timing pin holes in the ends of the cams, play in the mechanisms etc.

But from the look of that picture I'd say it was right, assuming you've got a stock VVC engine and no DVA-style offset timing dowels?

The issue is however, if it wasn't at safe position when you took the belt off, there's the possibility that it could have slightly bent a valve. You should ALWAYS make sure that th engine is safe before removing the belts, precisely to allow for the fact that the cams can kick round on the valve springs like that.

Having said that, it's unlikely to have done any damage. The firing order is 1-3-4-2. So the two rear inlets fire one after the other in the order 3-4. All of the valve movements for these two cylinders will follow the same sequence. And you know that one of the cylinders much have been at peak lift since it kicked as the valve wanted to close. If it was No 3 that was open and it kicked round in the forwards direction, it could start the No 4 valve opening with some force behind it, but in that case the cam would click round by 1/4 turn and then lock, as moving in either direction from that point would be fighting a valve spring. If it was No 4 that was open and it kicked round in the forwards direction, all the valves would close and the pulley would be free turn turn for a bit less that 3/4 of a turn, at which point it would hit the No 3 valve spring and come to a stop harmlessly. If it kicked in the reverse direction, just swap No 3 and No 4 in the above description.

From your description, you said the cam went round a good half turn? In which case it kicked away from the other valve and everything should be fine. I presume you then turned it back to the correct position in the opposite direction to the initial kick, retracing its path as it were, rather than forcing it to go right around?

Even if it had kicked in a most unfortunate direction I think you'd still have to have been fairly unlucky to do damage.

[revilla]

[timb2117]

Thankyou very much Revilla I am always impressed by your knowledge and depth of understanding, oh and patience with the partly informed (me!) 

I did indeed turn it back in the direction it came so fingers crossed, thanks again I really appreciate your time.

[revilla]

You're welcome. Let us know how it goes in testing!