If I can turn the Crank pulley by hand but none of the Pistons move - What has broken?

**zollaf** · 31-05-2017,12:38 PM

timing has been out and you have a bent valve or two.

**Nuggit** · 31-05-2017,12:43 PM

Right. Thank you!

Do you know of a guide that can show me how to inspect this? I mean, I want to learn how to do this, it's either scrap, sell or DIY as money for a mechanic I do not have.

**zollaf** · 31-05-2017,12:45 PM

the tappet that you can push down is most likely over a bent valve. you could do a leak test, connect compressed air to a spark plug hole and see where the air goes. if it is as i suspect then its just a case of removing the head and replacing the bent valve.

**Nuggit** · 31-05-2017,12:48 PM

I have an air compressor, so I can do this.

Okay, so blow air into spark plug hole, and if air comes of through ... the side of the tappet then that is most likely a bent valve?

**zollaf** · 31-05-2017,12:52 PM

ok, so remove the cam shaft by simply undoing the cap bolts one turn at a time until its free, this ensures all the valves are closed. all the buckets shhould be at the same height now. any that are lower indicate bent valves. remove the spark plugs. seal the airline in through the spark plug port with rag and blow down it,. air shouldnt come out through the inlet or exhaust valves, which you will hear in the inlet manifold or exhaust. remove the manifiolds for more accuracy.

**Nuggit** · 31-05-2017,01:00 PM

ah okay! Okay, I'll get on this tonight.

Thank you zollaf and sorry for the trouble earlier.

**Crasher** · 31-05-2017,02:41 PM

The crank will not rotate a full turn as a piston is hitting a valve because this engine depends on valve timing to keep the valves out of contact with the pistons, what the industry tends to refer to as an "interference engine", before you took the belt off, did you check the timing was correct? It is almost certain that you have now bent a number of valves and so the head will have to come off for a rebuild BUT it would be worthwhile putting the belt back on and checking the compression fist as the ABD is THE most simple cam belt engine VAG have ever done. It is not like rebuilding a cam chain engine to check the compressions which is hours of work. In the good old days (when I were a youngun) I could have the head off one off those, stripped and down to the engineers with new valves and exhaust guides by tea break, back up here after lunch and billed and gone by home time. Now the equivalent engine such as a 1.4 TFSI we did two weeks ago is a major 4 day job necessitating a turbo rebuild whilst it was off (rattling wastegate flap) and a new supercharger pulley (i.e. water pump) and belt with a bill well over £3k.....

**Nuggit** · 31-05-2017,03:03 PM

Well, this is good news for me then

More than anything, I'm just happy to be learning about how this all works. I never envisaged it would be in such a damaging way, but hey-ho! I hope it's only as "simple" as replacing the valves, and nothing that is too costly/beyond me, as I want to get deeper into the engine with a good reason. guess I have one.

I have a feeling that zollaf is right, and it's the valve(s) - I've been watching a lot of online vids etc. and learning about what I'm dealing with to give me an internal image of understanding. It only took me 10 mins to get the Cam shaft off yesterday, but if i'd known about the tappets balancing out etc as Zollaf explained then I would already know for almost sure that it's a bent valve.

So Crasher, you say to check the compression with the belt still on, however, zollaf says to do the compression test with the cam shaft out - i.e. no belt on the cam. Is this a different test, or am I mis-understanding?

**FrenchAudi** · 31-05-2017,03:45 PM

Before you tear into that engine any more, I suggest you get a manual for the car and do a little basic study on how engines work. Google is your friend for doing this

**zollaf** · 31-05-2017,03:51 PM

Originally Posted by Nuggit

Well, this is good news for me then

More than anything, I'm just happy to be learning about how this all works. I never envisaged it would be in such a damaging way, but hey-ho! I hope it's only as "simple" as replacing the valves, and nothing that is too costly/beyond me, as I want to get deeper into the engine with a good reason. guess I have one.

I have a feeling that zollaf is right, and it's the valve(s) - I've been watching a lot of online vids etc. and learning about what I'm dealing with to give me an internal image of understanding. It only took me 10 mins to get the Cam shaft off yesterday, but if i'd known about the tappets balancing out etc as Zollaf explained then I would already know for almost sure that it's a bent valve.

So Crasher, you say to check the compression with the belt still on, however, zollaf says to do the compression test with the cam shaft out - i.e. no belt on the cam. Is this a different test, or am I mis-understanding?

crasher is on about a compression test by lining up the timing putting the belt on and spinning it over. i am on about a leak down test byt removing the cam so all valves are closed then putting compressed air into each cylinder to see where it goes. both tests wil work but you mention the engine wont turn and this is probably because a valve is hitting and stopping a piston, so my test is betterer, probably.