vr6 suspected misfire after head gasket replacement

[sean-ff 10]

Hi all im rather new to this forum although iv had my corrado for over a year now.

 

Iv recently had to replace the head gasket on my vr6 as the gasket was cracked on piston 1 causing it to blow and lose compression.

This is the first head gasket that iv done and major work on one of these engines however i stripped it down sent the head off to be pressure tested, skimmed, new valve stem seals and had the valves re seated, along with all new genuine vw head gasket, head bolts, gaskets, top guide rails and tensioner bolt.

 

All seemed to of gone well and all back together and started first time however i think i may have a slight misfire but im not 100% at the moment as iv got a blow on the manifold from where one of the studs snapped on the downpipe.

however im planning on getting that sorted one evening this week so i can start her up again and have a better listen to how its running.

 

Now if i have got a misfire could the timing be one tooth out?

i fitted new plugs and leads while doing all of the work and i turned the engine over by hand numerous times before starting and all the timing marks lined up and the cam locking plate fitted back in place.

 

Any help would be much appreciated, thanks

[Kevin Bacon 5]

You can be up to 2 teeth off before things start clouting each other, but it won't misfire. It just feels a bit flat until you reach the higher rpms. It wouldn't hurt to double check it though. There's an excellent chain replacement guide on here, which shows the all important timing procedures.

 

Maybe the misfire is caused by a dodgy HT lead or a fouled spark plug?

[sean-ff 10]

Thanks :) il double check the timing while im doing the manifold.

All the plugs and leads are new but yes there could be a dodgy one there, what would be the best way of checking the leads?

 

it was the guide on here that i followed, very helpful!

[rickdonald 10]

I'd have a look at the coil-pack as well(if its a coil pack version). I went through two when I had my VR, I think the heat used to kill the plastic and eventually it would break down enough and you could see the arcing.

[Kevin Bacon 5]

Yeah /\ that too!

 

Wait until it's dark and spray some water on the coilpack / HT leads at the head end. Any weaknesses in the HT system will reveal themselves immediately!

[Dox 22]

 

One man method of finding a non spark using a jump lead - the other end of the lead is earthed on the engine block.

 

[sean-ff 10]

hi all i apologise for the delay in reply been a busy week.

 

however iv sorted out the manifold and started it back up and sounded much better, cleaned all the plugs and checked all the leads and its running fine however i do have a bit of a oil leak from where gearbox mounts to the engine block so iv taken the dust cover off, tightened the bolts on the sump and still leaking so im guessing it must be the crank shaft oil seal or the lower timing chain cover.

 

iv also noticed a slight tapping noise coming from the top end is this a common issue?

 

many thanks for your help so far :)