PSA DV6 Y655 1.6l Diesel timing issues

[dennis_f]

Hi everyone!

I have a Mazda 5 with a DV6 8v engine that suffered a timing belt break.
I bought a used cylinder head (complete with camshaft, valves etc) and all the other stuff i needed and tried starting it today.
Unfortunately its not going my way, the engine wont start, its like the timing is off (i checked it multiple times and the pins fit in the timing holes every time).
When i crank it and it fires its like its firing to early and the engine stops the starter from turning it.
I have no fault codes.

Could the camshaft lobes have spun on the camshaft i got with the cylinder head? How can i measure this? Or could it be something else?
The engine also doesnt sound "right" when turning over, its like the cylinders have different sounds (different compressions).

[Arkis]

Hi,firstly I would start with the easiest out of checklist: Check crankshaft position sensor. It's located next to the belts and torn belt can easily brake it or shift out of position. Without this sensor the engine will not start because it doesn't know the timing.

If the lobes were spun, it would be on your old head. And even so it is very unlikely. Lobes spin really rarely. New head is likely fine. You can check it easily by finding top dead center and checking how the valves are opening. But I wouldn't bother with it at this point.

What I would do is trying to spin the engine with a ratchet and try to find a spot of resistance. If it is out of time, you will feel resistance/sudden stop as the valves hit pistons. Usually you can even hear as the metals contact. If it is spinning fine, then I would do compression test. When the valves hit pistons, the piston may crack or a rod can bend.

But I really hope that it's just shot crankshaft position sensor.

[dennis_f]

But I really hope that it's just shot crankshaft position sensor.

Wouldnt a broken sensor (or magnetic wheel) set a fault code? What is the correct way of checking the sensor?

The valves are not touching the pistons at any time, the engine cranks over fine both with a wrench and with the starter.
but if its just slightly out of time the valves wouldnt touch the pistons anyway i guess?

[RichardW]

You need live data from a scan tool to see if there is a crank signal, and if the cam / crank are synchronised. If it sounds wrong when cranking, then chances are it is somewhere. Sometimes the hydraulic tappets on these engines cause problems after rebuild and don't let the engine breathe properly.

.. And even so it is very unlikely. Lobes spin really rarely.

On this engine the lobes are pressed on, and they almost always spin when the cambelt breaks, but it usually saves the valves from bending. Probably new rockers and cams and the old head would have been OK.
However, the OP doesn't know the history of the head, it may have had a cambelt break, and someone has replaced the rockers but not the cams....

[dennis_f]

I will check the live data to se if i get sync. I am getting fuel from the injectors and no fault codes and i would think that indicates good sync?
The revcounter goes up to about 400 rpm when cranking.

The old head unfortunately had bent valves and a piece of aluminium made a lot of marks on the piston and head in one cylinder (i changed the piston for a new one).

I will try and put the engine at TDC and try to measure that the valves open at roughly the right times (is there any specifications on the cam at what degrees the different lobes should be?). I will also remove the cam and check that the tapets to make sure they move freely.

But its hard to understand what would cause the injector to fire early and make the engine work against the starter motor while cranking (perhaps i will put it together enough to film it tonight)