Technical Spark plugs not tightening properly

[tduknet]

Hi all,

My mums 2000 SPI seicento has an issue where one of the spark plugs won't go in properly e.g it goes about half away in and then goes tight I mean really tight but it's not all the way in. Now when the engine is running you can hear hissing from that spark plug.

Any advice please even tried new plugs and same issue.

Martyn

 

[fingers99]

I can only guess that the thread is buggered. You can get spark plug thread chasers

pretty cheaply (eBay). Or even cut knock out the electrode from an old plug, put 4 cuts down it with a hacksaw, coat with grease and use that.

As the head is aluminium alloy and the plug much harder steel, the issue will be with the head, rather than the plug.

If the chaser doesn't do it, it's a head off job for a helicoil insert or a threaded brass plug.

 

[Metalguru3]

Remember years ago when I had a garage in Birmingham. There was an Alfa dealer next door who used to sell his better part chops on the forecourt.
The owner had a bit of a reputation for being tight so nobody wanted to work for him.
One day he knocked on our door around closing time saying he'd got a Mercedes 500 going out the next day and it kept popping a spark plug out, straight into the underside of the bonnet and PLEASE could we helicoil it for him in situ.
Like a pair of nutters me and my mate did this with a bit of grease on the drillbit and threading tool, inserted the helicoil, and hey presto one smooth running Merc.
He dropped the bonnet, said thanks lads and drove off in it!! Net profit zero.
I doubt very much you could get it done for that price these days!!

 

[portland_bill]

I can only guess that the thread is buggered. ..... Or even cut knock out the electrode from an old plug, put 4 cuts down it with a hacksaw, coat with grease and use that.

If the chaser doesn't do it, it's a head off job for a helicoil insert or a threaded brass plug.

:yeahthat:

Old plug, cut as above, the grease will hold any metal filings. Make sure you get it in straight, as not straight could be why you have the issue in the first place.

DO NOT run the engine with a plug not fully seated.
The seat/gasket of the plug is an important part of the heat path. If not in properly, the plug will run hot and you will hole a piston. I've seen this with a plug properly screwed in, but just not tightened properly.