Porsche Enthusiasts Club Forum

Hi,

My mate has an S2 Cab that has developed running problems.
He recently renewed the plugs & it seems that they work their way loose (as in not as tight as put in) after a short period of running.
He has renewed the dizzy cap & rotary arm and this made it fire up lovely & had a good smooth run so obviusely thought this was the problem sorted, but after leaving overnight & getting wet it struggled the next day to fire up & tick over smoothly, next thing is to replace the ignition leads I think but anyone know of anything else to check?

thanks

Steve

Hi,
Are you saying the plugs themselves come loose from the engine?
Regards
Paul

Yes, he doesn't want to over tighten them but seems once they've got hot they seem quite loose in there no more than finger tight.

Eh? Does your friend have a torque wrench? S2 head very similar to 928 for which from memory the correct torque for the 14mm thread plugs is 30Nm max.

What is the figure for S2 head (bet it's same), and has he tightened to that spec?

Has he changed plugs before on this car? When removed the previous set were they tight?

I'd like to understand a bit more about this spark plug thing. Is it something I should be worried about? I left a set with my local (non porsche specialists) to fit as its in there having a load of steering, brakes and bearings done (which they are experts on)

Is it easy to overtighten. I really hadn't thought about it to be honest...

Regards
Paul

Hi,

Daft question probably but are the threads in the block ok? Plugs not gone in cross thread or owt 'as it?

Ben

I wondered about stripped threads but then thought unlikely that all 4 (was going to say 8 then remembered I wasn't in 928-land!) had been stripped, and also that if stripped it wouldn't be possible to tighten the new ones.

I suppose if the previous set had been put in too tight, and if not replaced for a very long period, then they could all pull out the aluminium threads when removed but then how would the new ones be installed?

It's fine as long as they know the max torque (30Nm) and use a torque wrench. With aluminium you can't rely on the old "hand tight then 1/4 turn" rule of thumb suited to cast iron heads.

Best to use a little smear of anti-seize on threads (Optimoly TA) to minimise risk of stripping on removal.