Hello everyone,

I am going to fit new head gasket (and take a look on the valves). The bolt on the crankshaft seems to be incredibly fastened and does not come loose no matter what. So, does anybody here know about some special tricks to undo this bolt? Is it possible that it is reverse threaded?

 

Car: Skoda Fabia 2006 (Mk 1), 1.2 12V 180.000 km

 

Thank you in advance

 

 

I think the trick is just a "big **** off breaker bar".

Turn the engine in the direction of rotation till the breaker bar is locked against the cross member or bulkhead etc then spin the engine very briefly on the starter motor.

 

Unless it is a left hand thread which I have yet to come across and would usually be marked with a groove.

Thank you very much both! I'll try this tonight and report back.

2 hours ago, J.R. said:

Turn the engine in the direction of rotation till the breaker bar is locked against the cross member or bulkhead etc then spin the engine very briefly on the starter motor.

 

Unless it is a left hand thread which I have yet to come across and would usually be marked with a groove.

 

Really? You know the crank gear isn’t keywayed and if the bolt comes loose the timing chain slips right?

The correct (and only way) is to put all your timing pins in and then counter hold the pulley with an appropriate counter hold tool and undo the bolt. 

 

When refitting it’s a new bolt, spacer and o-ring and torque up while counter holding again. 

 

44 minutes ago, Tech1e said:

 

Really? You know the crank gear isn’t keywayed and if the bolt comes loose the timing chain slips right?

 

I didnt and thanks for letting me know, I made a similar mistake on a DOHC Sierra many years back, a mechanic pal was doing the job and having problems aligning stuff, cant recall what I did but it was turning the crank with a spanner IIRC, it all went back together and ran fine but 2 days later the timing slipped and all the valves were bent.

 

I cant recall exactly what caused it, I think the drive key was damaged, too long ago but it was my fault, just my luck to pay someone to do a job and for it to go wrong and be my fault.

 

I cant edit my posting now but hope IWA does not follow my advice.

 

 

Is it the same on the MK1 mechanical injection pump engine?

 

I did the timing belt on that without destroying the engine, perhaps I was lucky.

 

When I come to do it on this BKC engine does the pulley have to come off?

 

If so then I will need to get tooled up before starting, Techie you just might have saved me from myself!

Only relevant to the 1.2 with a timing chain. 

 

You take the pulley off on the BKD but don’t touch the crank bolt other than to turn the engine over. 

Thanks Techie!

Just out of interest and probably not relevant to this engine, but on the 1.4 mpi 8 valve there is a threaded hole normally used to hold the engine speed sensor that you can insert a bolt that has been ground to a point to lock the flywheel.

 

Edited 23 August, 20196 yr by TMB

Thank you all very much for all your suggestions, they are very much appreciated. We managed to remove the bolt by locking the pulley with a special tool and gargantuan force to undo the bolt. We continued to dismantle the engine and remove the head. The head gasket appeared to be OK, however, one exhaust valve was burned and the other exhaust valves were more or less in bad condition. The inlet valves appeared OK. 

 

What could be the cause for the damaged valve? See attachment.

Localised overheating causes the initial damage, you've lost a lump of exhaust valve, no wonder you had compression problems.

On 24/08/2019 at 18:16, iwa said:

one exhaust valve was burned

Looking at your picture, the burnt valve was coked. That caused the localised heating, and hence the dropped valve as pictured.

 

I'd suggest a full decoke, replace any burnt valves, and rebuild.

I’d check the play in value guides too.