Performance change after cam belt replacement?

[gldgti]

No No No No No.

Preen is right - as long as there is enough clearance - and there isnt.

As Jarred said, you can't just go "1 tooth out" on these diesel engines. The valves and pistons WILL hit each other. Changing the belt involves using locking tools for the camshaft to ensure its in exactly the right position and furthermore, the cam sprocket is adjusted on its taper to allow for the difference in belt stretch between the old belt and the new one. Herein lies the possibility for the cam to be less than one tooth out and still work. There of course is a margin to work within, and its feasible that you could notice it.

Please don't anyone put their diesel engine 1 tooth out and lunch you engine.

[Julian Edgar]

So, as a result of my complaint, when the cam timing is re-checked by the company that did it, the marks should line up exactly? And if they don't, there is sufficient adjustment in the taper to ensure they do?

(The performance curve has clearly been moved upwards, and the fuel economy in cruise is also clearly worse than it was previously - have now done a lot more kilometres.)

[brad]

Please don't anyone put their diesel engine 1 tooth out and lunch you engine.

I don't think anyone was suggesting the engine should be mis-timed deliberately. I certainly wasn't. What I was saying is that 1 tooth out is a distinct possibility.

[brad]

So, as a result of my complaint, when the cam timing is re-checked by the company that did it, the marks should line up exactly? And if they don't, there is sufficient adjustment in the taper to ensure they do?

(The performance curve has clearly been moved upwards, and the fuel economy in cruise is also clearly worse than it was previously - have now done a lot more kilometres.)

They should line up IAW whatever the manual says. It will be quite specific & there will be pictures for them to look at.

This any help?

[Transporter]

I don't think anyone was suggesting the engine should be mis-timed deliberately. I certainly wasn't. What I was saying is that 1 tooth out is a distinct possibility.

Me neither, and certainly the slots in the cam gear are wide enough, so they could move by 1 tooth on the cam without the pistons hitting the valves. It would be interesting to know what reason they will give.

[Julian Edgar]

They should line up IAW whatever the manual says. It will be quite specific & there will be pictures for them to look at.

This any help?

Thanks very much.

[Julian Edgar]

It's going back to the workshop this Friday. It will be interesting to see what they say.

[Julian Edgar]

Workshop that did the cam belt change says the marks line up exactly.

Perhaps the original cambelt had stretched a little and the custom dyno reflash (done at around 90,000km) was matched to that (presumably retarded) state of cam timing?

I might have a go at moving cam timing a little within the range provided by the slotted holes and see what happens.

Performance and fuel economy are just unacceptable - considering what it was like prior to cam belt change.

[Preen59]

It shouldn't have made that much difference mate. Altering the cam time by a couple of degrees moves the torque curve a few hundred RPM at most.. There's got to be something else wrong.

[gldgti]

OK, so I see the new engines have done away with the sprocket on a taper for factory adjustable cam gear.... same effect however.

Because of any belt stretch, unless the position of the camshaft with respect to the sprocket is checked to be correct (the "torsion" value in that writeup) then it may not necessarily be in the right place.... the thing to ask is if they adjusted the cam sprocket or not.