Tight Spark Plugs

[almyland]

Time for a first service under my ownership of my Ital based Roadster. I can undo one spark plug with ease. The other three however, won't budge with resonable force applied. As they are only supposed to be done-up tp 9 Ft lb I am reluctant to use a bigger leaver as the head is Alloy! Has enyone had this experience and how did you resolve the problem?

Thanks.

Alan

[amalgamated users from prior forum]

Re: Tight Spark Plugs

Message originally posted by: Don
What engine is it? If it's a 1.3 with a cast iron head, then there is no problem, use brute force. The problem comes with the alloy head on the 1.7 (or 2.0). The plugs corrode in. If the threads strip taking the plugs out then the head is not scrap as the holes can be "helicoiled" and I have even heard of this being done with the head in situ. Helicoils usually have to be put in by an engineer.

[h_m_cumming]

Re: Tight Spark Plugs

Try getting the engine hot and pouring "PlusGas" round the plugs. That should free them although a couple of sessions may be needed. Also tighten them before trying to undo them. Best of luck.

[almyland]

Re: Tight Spark Plugs

Thanks guys, the engine is a 1.7 so I will have to try and free them some way. Unfortunately there isn't a nice well for the plugs to sit in and fill with penitrating oil so I will have to make a cup and stick it onto the side of the head - over the plug. Hmmm, could prove interesting. I'll let you know how I get on.

Cheers

[Dane_Rescueman]

Re: Tight Spark Plugs

Hi,

When the dust settles after removing the plugs and repairing the threads if required, before replacing the new plugs try a thin coating of iodine on the threads. I was taught this many years ago when working on old BMW six cylinder engines. The iodine somehow stops the steel plug threads and the ally head reacting/corroding. I guess that copper grease may work just as well.

Ah yes, don't get the iodine in any cuts. You will notice that!

Good Luck

[h_m_cumming]

Re: Tight Spark Plugs

Don't put copper and alloy together, they dont like each other and will corrode very quickly.
Try making a plasticine dam to keep the penetrating oil round the plug.

[almyland]

Re: Tight Spark Plugs

Thanks for the copper advise Hugh, I was intending using copper grease if and when I get to putting new plugs in; I won't now! I am going to try and build dams with silicone sealent.

[artrider50]

Re: Tight Spark Plugs

Loctite 'Freeze and Release' might do the trick - if you can find some. I had to order online after much searching.

http://www.manufacturingtalk.com/news/hen/hen120.html

[h_m_cumming]

Re: Tight Spark Plugs

From working on 'bike engines, the majority of which have alloy heads, I've noticed that the ones that usually give trouble with tight plugs are those where the last thread of the plug sticks through into the cylinder i.e. too long, and gets coked up. When you try to take them out the coked up thread then tends to strip out the threads. Might be something to take into account when you manage to resolve your problem.

[almyland]

Re: Tight Spark Plugs

Thanks again Hugh, that's really cheered me up. Still, better warned than not!

Cheers

[Dane_Rescueman]

Re: Tight Spark Plugs

I have used copper greased plugs in the past on Peugeot, BMW and Rover SD1 6cyl engines and never noticed any corrosion, but, as I was always tinkering I guess that the vicious ions had little time to get working. Do they not alloy Al(~95%) with Cu(~4%) to make Dural from which aircraft used to be made? (thinks " my old Sea King was made from that metal and, yes, the b******y thing did tend to rot. Ah well....!". Back to the drawing board. I'll stick to iodine on the plug threads in my 35 tonne granite and any old iron Pinto cylinder head.

[amalgamated users from prior forum]

Re: Tight Spark Plugs

Message originally posted by: Jim Mountain
I would like to put the copperslip/alloy corrosion idea to rest. I have been using copperslip on plug threads every day for 17 years, (I'm a mechanic), and never had a problem with corrosion of any form. These include Rover V8's, Fiat twin cams, thousands of Peugeots and Fords.

[almyland]

Re: Tight Spark Plugs

The silicone sealent dam approach is working well with the plugs sitting in a nice bath of wd40. With this cold weather, will the penitating factor be effected by the low temperature?

[amalgamated users from prior forum]

Re: Tight Spark Plugs

Message originally posted by: Sue Roedel (Editor, MOC)
Dane, what does this sentence mean?

Do they not alloy Al(~95%) with Cu(~4%) to make Dural from which aircraft used to be made?

[b_caswell]

Re: Tight Spark Plugs

Halfords do a special anti seize in a little tube just for plugs.
Sue my emails are very iffy The word alloy means mix ie mix 95% aluminium with 4% copper to make an alloy called Dural.