roaring in airbox

[Burnerman]

Its certainly worth checking the valve timing, but this noise in the air box area really has me stumped.
Maybe the throttle body has a problem but I would have expected idling issues if it has.
I wouldn't expect any valve wear either, without one hell of a racket.
John

 

[Mursal]

Where did the misfire come from, I thought the air box was noisy?

Had a crankshaft sensor that failed at 2500 RPM and it wasn't showing a fault code. The engine had like a flat spot if you tried to rev any harder, was fine up to 2500

How did you get on with the EGR valve and the tin can?

 

[jctilingservices]

Where did the misfire come from, I thought the air box was noisy?

Had a crankshaft sensor that failed at 2500 RPM and it wasn't showing a fault code. The engine had like a flat spot if you tried to rev any harder, was fine up to 2500

How did you get on with the EGR valve and the tin can?

the misfire is what I originally called a roaring in the airbox lol, although the noise does come from the airbox live feed reading is showing a misfire. Blanked off with tin can and still the same, renewed the egr and still the same. today I exchanged the coil pack off my wifes, but still the same, now the puzzler.

timing belt top cover off, jacked up and in gear, turn the wheel to line timing marks, if I have the correct mark on crank it appears the valve timing is out by about 1-2 teeth ALSO I noticed that when turning the wheel to line the marks, there are stages where I can actually take hold of the longest run of belt and wobble it, I don't mean twist to get deflection, I mean wobble it towards say the water pump and back, also its as though I can lift it off the first 2-3 teeth of the cam, but upon turning the wheel around further, the belt tightens up. Should this happen or do I maybe have a stretched belt or faulty tensioner ????

 

[Belle427]

you should be able to twist the belt roughly 90 degrees when you grasp it with finger and thumb on its longest run, it sounds as if you have jumped a couple of teeth

 

[jctilingservices]

you should be able to twist the belt roughly 90 degrees when you grasp it with finger and thumb on its longest run, it sounds as if you have jumped a couple of teeth

when the belt is tight ( car in gear and turn wheel so many degrees ) I get roughly 1/2 deflection, but as I turn wheel further degrees, watching cam wheel come around there are times when the belt goes slack, i.e I can take hold of the belt and lightly wobble it, also if you follow the run of the belt up to the cam, the belt can be lifted slightly off 2-3 teeth, should never be able to do this I don't think, or should I ?

 

[Mursal]

OK, so you are turning the engine clockwise, yes? Line the marks up and take note of any discrepancies (cam shaft lagging where it should be). Then turn the engine 2 complete turns and the marks will line up again, or not.
If you are still "out" the same amount, you have a problem. Any slack on the back of the belt (next the drive) is of little interest, until you are putting it back. This slack will not have any influence on the running of the engine, if all marks are lined up. Just readjust if you want too.

Just double check that you are using the correct marks on the pullies and reference marks on the block. A few teeth is quite a chunk on the running of the engine.

If you go adjusting the timing (jumping teeth), turn the engine over at least 2 full turns with a spanner to ensure all is well, before going for a start.

 

[jctilingservices]

OK, so you are turning the engine clockwise, yes? Line the marks up and take note of any discrepancies (cam shaft lagging where it should be). Then turn the engine 2 complete turns and the marks will line up again, or not.
If you are still "out" the same amount, you have a problem. Any slack on the back of the belt (next the drive) is of little interest, until you are putting it back. This slack will not have any influence on the running of the engine, if all marks are lined up. Just readjust if you want too.

Just double check that you are using the correct marks on the pullies and reference marks on the block. A few teeth is quite a chunk on the running of the engine.

If you go adjusting the timing (jumping teeth), turn the engine over at least 2 full turns with a spanner to ensure all is well, before going for a start.

when both cam marks are aligned, the 2 marks below, pointer on casing and notch in crank pulley are approx. 1" apart, if I line those crank marks up, the cam marks are approx. 1" apart, I have gave the engine quite a few turns, and these marks are never all aligned at the same time. but surely the timing belt should never go as slack as it is doing, I can test for deflection when the belt is tight, approx. 1/2", but when slack I can actually wobble the belt and could probably manage to pull it off the cam wheel by hand, using a bit strength obviously.

 

[Mursal]

If you have a Haynes manual or go onto the Vauvhall site to double check your marks with an actual diagram of the pullies.

The belt might be slack, put will not cause any problems at the moment if the marks were lined up. So don't go off on a tangent, concentrate on double checking the correct marks.

When you have established the correct marks from a diagram, reset the timing if necessary and re=tension the belt. If you go moving the timing, turn manually with a spanner, before starting.

But the slack belt, would allow the camshaft to jump back anticlockwise, it cannot jump forward.

 

[jctilingservices]

If you have a Haynes manual or go onto the Vauvhall site to double check your marks with an actual diagram of the pullies.

The belt might be slack, put will not cause any problems at the moment if the marks were lined up. So don't go off on a tangent, concentrate on double checking the correct marks.

When you have established the correct marks from a diagram, reset the timing if necessary and re=tension the belt. If you go moving the timing, turn manually with a spanner, before starting.

But the slack belt, would allow the camshaft to jump back anticlockwise, it cannot jump forward.

Hi, I have taken my marks from the Haynes manual, as you say cam could jump backover, when crank marks aligned, the cam would have to come forward ( clock wise ) about an inch to line it up with the cut out mark. That's why I think the belt has slipped, but looking at the teeth when crank is aligned, it appears the cam is about 3 teeth out, would this not stop the car starting normally ?
and cheers for replying, appreciated

 

[Mursal]

You would think it would.

But as long as you are sure of the marks just move it forward. And try it, as my last post, double checking after 2 full turns with the spanner.

If you have any doubts, leave it as it is, until you have double check the marks from another source. Because its not a life or death problem, just noisy.

If its an interference engine and the valves hit, you have real problems