Oh cock! Melted a plug!

[Robin]

hi i know this is a bit off topic but im interested to know something. i,ve seen inside quite a few g40 engines now and all of them seem to have the edge of the pistons washed clean {the edge nearest to the front of the engine} why is this? is it oil washing past the piston rings and washing the edge of the piston clean?

This is the thrust face of the piston.

[supercharged spaniel]

The plugs bosch make for VW may be to a slightly better standard than std aftermarket ones with their name on. As they are roughly the same price I know where I will be getting a set from.

Pete, why has No. 1 got the least efficienct exhaust port ?

cant agree with this.... bosch plugs are surely bosch plugs wether you buy them from gsf or vw..no drop in quality..thats the way i see it anyways.

Yoof.   do you prefer the ngks over the w5dpo's?  or just in extreme tuning cases like yours? personally i cant fault the w5dpo's but then im not running masses of power.

[Robin]

The plugs i used were genuine Bosch W5DP0's but i didn't get them from the UK, i ordered 12 of them from the US as they worked out to be half the price of over here (when the dollar was good rates).

My theory is that it was a crap plug.

[Andy]

The plugs bosch make for VW may be to a slightly better standard than std aftermarket ones with their name on. As they are roughly the same price I know where I will be getting a set from.

Pete, why has No. 1 got the least efficienct exhaust port ?

cant agree with this.... bosch plugs are surely bosch plugs wether you buy them from gsf or vw..no drop in quality..thats the way i see it anyways.

Yoof.   do you prefer the ngks over the w5dpo's?  or just in extreme tuning cases like yours? personally i cant fault the w5dpo's but then im not running masses of power.

Of course a Bosch plug is a Bosch plug, but the part you buy from your motorfactors is not necessarily exactly the same part that Bosch will supply to the vehicle manufacturers. E.g. VW W5DP0s are VAG branded.

It's not uncommon for the OEMs to really screw down their supplies on price - so it's not necessarily true either that VW W5DP0s are better than GSF ones, it's equally plausible that the opposite is true! I don't think it's something to loose any sleep over either way.

As Yoof's already said, the Bosch plugs really don't like nitrous - and we've both found the NGKs to be equally long lasting and as hardcore as the Bosch, but at a more competitive price. In addition the newer Bosch plugs are now WR5DP0, i.e. resistor plugs. We both found this kept popping the existing supression resistor in the rotor arm - no such issue with the non-resistor NGK.

Barring some speshness in the head, I'd agree that this was possibly a dodgy plug - especially given that it was showing either a fairly lean burn or no combustion in that cylinder before. Perhaps the plug had been dropped, damaging the electrode?

[Dan]

The reason I say the W5 DPO's could be better from VAG is because OEM manufactured parts, even when manufactured along side aftermarket parts, can be to slightly different manufacturing standards. OEM standards are much stricter and there is usually less room for quality issues as this would obviously give them a bad name. Not saying Bosch would make crap plugs for one second, but aftermarket parts normally tend to have a shorter life as the cars may be serviced more etc.

Anyway, getting away from the point. I'm not sure I would buy some if they were cheap and intended for the US market. Hindsight is a wonderfull thing though...

[Robin]

Hindsight is a good thing dan.

The plugs were bought under the impression that because they are genuine i had no reason to doubt their quality as they were new and also genuine bosch W5DP0's.

To be honest the damage to the head is only a small problem as i was intending to strip the engine for a new camshaft anyway and what happened allowed me to notice that the wrong sodding water pump was fitted.

It going to be tough getting the engine ready for the RR day in 3weeks time but hopefully with a few evenings in the garage i should hopefully have it ready, might even have to provide Yoof with some food so he will come over and lend a hand.

[SamG40]

That will tempt him over no problem Robin, its not like Yoof dosent like his food! 

[Andy]

The reason I say the W5 DPO's could be better from VAG is because OEM manufactured parts, even when manufactured along side aftermarket parts, can be to slightly different manufacturing standards. OEM standards are much stricter and there is usually less room for quality issues as this would obviously give them a bad name. Not saying Bosch would make crap plugs for one second, but aftermarket parts normally tend to have a shorter life as the cars may be serviced more etc.

I know you've worked for a Tier 1 in the past, so have seen that side of the fence - but some of the OEMs I've worked with are particularly ruthless with regard to price, and in some cases are willing to accept a reduction in quality for a drop in price. Was just trying to show the other side of the coin - the parts may be different, but the OEM supplied ones aren't necessarily the best.

Either way as I said, if there are any differences in the quality of the plugs, I don't think it'd be anything to loose any sleep over.

[Yoof]

That will tempt him over no problem Robin, its not like Yoof dosent like his food! 

Shouldn't you be playing with Frodo's ring Sam 

My guess is abit of rough handling in transit, possibly an old batch of plugs, and Robin as an owner, all equates to a breakage.

I'll buy a bulk of the NGK plugs I use and sell them on, I've spent far too much on plugs finding what's right for me not to make a profit out of it!

[lance]

what ngk's do you 2 run then?

[Yoof]

what ngk's do you 2 run then?

I'll buy a bulk of the NGK plugs I use and sell them on, I've spent far too much on plugs finding what's right for me not to make a profit out of it!

[Fred]

Will that be NGK BP7EVX then ?

[Yoof]

Nope 

 

[Robin]

After speaking to a few guys at work today (other than ian - yoof) they have come up with the suggestion that it was the valve which burnt out first, there could have been some wear or damage on the valve seat which allowed gases to pass and caused a heat spot on the valve which then let go.

When i remove the valve i'll get it under the microscope at work and see what it failed from.

[Andy]

When this engine melted a piston was it number 1 that melted?