UK-POLOS.NET - THE VW Polo Forum

Hi Everyone, this is my 1st post, so I am pleading for some advice before splashing out on some head work.

I just bought a cheap 90k 1.2 6v Polo knowing it had a misfire, I am aiming to do the dismantling and reassembly my self but before I send the head off for the repair to the seals and valves could someone please advise if in your opinion it's definitely the valve seals and damaged exhaust valve issue.

I enclose pictures of the compression tests and plugs 1,2 & 3 (the black fouled one)

1 = 200 ish
2 = 150 ish
3 - 100 ish

I have cleaned the throttle boddy and also put new coil pack on 3 but the P0303 fault and engine warning lights remain.

Any advice really welcome.

Without stripping the engine you will never know what is causing the low compression but
Worn valve guides ,burnt vales are more common than you think on these engines. That’s not to say worn rings or a broken piston is not the cause,but you have to start somewhere.
Remove the head and send it for a full recon to a reputable engine builder hopefully the head is salvageable that would be my advise

Thank you for the advice. I am planning stripping the head this weekend and I have already tee'd up a local firm that can refurbish the head for £150, new Valves, guides and re facing. I only paid £150 for the car knowing it had engine problems so its more of a learning exercise for me, and I hate seeing things that can be fixed sent to the scrap heap. So if I can get it fixed for another £150 plus chain kit and gaskets then it saves it from the scrap heap.

Took the head off today, not a pleasant job. Just take a look at those valves.

One more question if anyone has had experience of doing this before, the camshaft appears to have a notch where it mates with the cog but there appears nothing there to lock it in position, does it just rely on the pressure applied by the bolt? or has something sheared off mine?

A picture of both items would help, thanks

You can see the notch in the crankshaft but no key to the sprocket. I mean why put a notch if it’s not used? Seems like it’s built to slip, could this be why these engines fail? Timing goes out because of cam slipping?

On other engines I have seen a locking pin.

It’s probably correct and something to do with the installation procedures to lock the crank and cam but be able to spin the chain to get even tension like some belt driven engine’s.
I expect the bolt is a use once and replace,torque and angle type fixing which is tight enough to hold this without turning but you will have to look this up in the tech specs.

Usually it’s chain stretch or a failed tensioner because of poor maintenance ie over due oil changes that cause problems

Thank you for all the advice