Spark plug replacement

[Willy]

I didn't notice until now that there is a time limit on the replacement of the spark plugs.
The maintenance table calls for replacement after 36Kmiles (60Kkm) or 3 years!
Does anyone replace the spark plugs after 3 years (or any other fixed period of time)?
It seems to me that spark plugs will not deteriorate simply by being installed,
until now I have always replaced them based on distance.
Willy

[billr99]

I didn't notice until now that there is a time limit on the replacement of the spark plugs.
The maintenance table calls for replacement after 36Kmiles (60Kkm) or 3 years!
Does anyone replace the spark plugs after 3 years (or any other fixed period of time)?
It seems to me that spark plugs will not deteriorate simply by being installed,
until now I have always replaced them based on distance.
Willy
Yeah, that doesn't make much sense. I've seen many an old wreck start right up with the plugs that had been sitting in the engine for years. The shells might have been a bit rusty but what is there in a plug that would go away after x number of years?

Cheers,

Bill

[Chilled Man]

for as cheap as they are ?

[jmoser]

If anti-sieze was not used on the threads too much time can lead to corrosion of the threads in the head. My 1st set of plugs [factory] at 30K miles / 3 yrs were pretty bad - I always use never seize and it makes a huge difference, plus you get more accurate torque wrench tightening. I don't think you have to worry too much but as stated its a cheap and easy job so why risk it past 3-4 yrs regardless of mileage?

[Jules]

Provided they are not cracked (causing arcing and subsequent power loss) spark plugs will last a long, long time. That said, spark plug replacement from time to time is probably the cheapest form of preventative maintenance you can perform to ensure a strong running engine and good fuel economy.

I find the '36K mile / 3 year' spark plug replacement schedule to be a bit much (too soon.) That is to say, if you only have 27K miles on the vehicle after 3 years, don't worry about changing the plugs just yet. It can wait another year until you reach 36K mile and 4 years. Conversely, if you have 36K miles after only 2 years, it can easily wait until you get to the 3 year mark (and presumably 48K miles.)

Alway use a little Never-Seize or Copper-Kote on the threads to prevent them from seizing in the heads, and NEVER torque the plugs unless you have a torque wrench and the specific torque value. Just thread them in finger tight and then use the wrench until they come up snug, then another gentle tug to ensure they are snug enough. Trust me on this one... I found out the hard way about 40 years ago. I also learned about Heli-coils at the same time.

Cheers

Jules

[Willy]

As Chilled Man replies, it isn't the cost, neither the work, but replacing things without a good reason is not my way [happy]
I have been worried if possibly a part of the treading could be in the combustion chamber. On the other hand, if that were
the case, it probably wouldn't take 3 years to deteriorate and give problems when the spark plugs need to be removed.

The question of anti-seize and torque is an interesting one. Is the specified torque given on "dry" thread" or not,
I am sure lubrication makes a difference. I forgot to mention that the car hasn't even 25K miles on the clock :o

Seen the (very) low mileage, I was thinking about doing a number of things together, once the car is eight years old,
such as timing and auxilliary belts (with idler pulley and tensioner), PCV cleaning, fluids (brakes, manual transmission, bevel gear).
Perhaps I could spread the job, replacing the spark plugs and brake fluid now, the rest after another two years [happy]
Willy

[sjonnie]

Everything deteriorates with age so I don't see why spark plugs should be any different. I think it makes sense to check the condition of your spark plugs after 3 years because they will also give you information (http://www.spark-plugs.co.uk/pages/technical/diagnosis.htm) about the running of your engine. You could just take them out, check their condition, check the gap, then and reinstall with new anti-seize compound but it seems kind of silly to go to all that effort and not install new plugs. Torque on spark plugs is surprisingly little and yes it is always with anti-seize compound on the threads.