T4 ACV 2.5 TDI injector pump errors

[fargo]

Yep I was unsure if I went past the time mark so I loosened the tensioner & rotated in the direction to start the tensioning process again, being a little softer when the marks aligned.
I get a little confused with all of the naming conventions on here. By " pulley on the end that you have just been working" Im guessing you mean the cam "sprocket"? I refer to anything with teeth as a sprocket. Or is there another "pulley" somewhere that I need to loosen?

[jets]

Sorry for any confusion. Yes it probably closer to call it a sprocket. The sprocket you used to alter the pump timing will need to be removed to set the camshaft position.

[fargo]

I was pretty lucky with the timing I think.I made a custom edge & got the pump sprocket mark lines up with the pump body mark bang on. it has never startedor ran better. No moving the cam sprocket at all. I bought a USB ebay lead to have a crack at VCDS lite but could not get past the cable detection setup. So id didnt bother registering.

[Seano]

After all, if the pump belt fails it doesn't wreck your engine.

Err...I recall hearing/reading on the UK forum of a couple of instances where it actually did cause engine demolition due to the belt piling up/jamming and slowing the camshaft that powers it which had fatal implications for the valves. It's rare and perhaps unlikely but seemingly not impossible...

[fargo]

Does a belt actually snap? Seems to me from reading that the tensioners are what generally fails(or tension) & that creates a situation where the belt would just get its teeth chewed out & then slips & then stops . Even if the belt did snap at high revs & speed, it would stop near instantly. The timing belt is of a real concern though.

[jets]

Does a belt actually snap? Seems to me from reading that the tensioners are what generally fails(or tension) & that creates a situation where the belt would just get its teeth chewed out & then slips & then stops .

I don't really know, I can only speculate. If the insides of the tensioner is damaged during installation or is of faulty manufacture & becomes very tight & jams, that could rip teeth off. The bearings could also wear out or be made without enough grease. I would think that the area of the belt would be protesting with lots of noise.
On my first T4 I could hear a slight noise from that area & decided to change the belt, idler & tensioner. One of the bearings was a little dry [can't remember which one] & new parts eliminated the noise.

[Umai Naa!!]

Yeah, belts do snap.

I've got a similar van to yours sitting here waiting for collection after the belt snapped and the valves met the pistons.

[jets]

Yeah, belts do snap.

Just to clarify, are you referring to the cam belt or the pump belt?

[Umai Naa!!]

Both, I'm afraid.

[jets]

I tend to skip through the T4 Forums every few days & I have read many reports of broken cambelts but the ones with broken pump belts
I haven't registered in my mind. Here's one of probably many threads.

t4 2.5 fuel pump belt snapped...Please help! - VW T4 Forum - VW T5 Forum