Any of you bright sparks know about spark plugs ?

[Paulus]

What plugs does the manual recommend?

 

[pubrunner]

*** HELP ***

I've just purchased 3 new spark plugs online - done by entering my car's registration.

The new spark plugs have a thread reach of 26.5mm - in fact, this appears to be the same for any spark plugs specified for a 2008 1.0L Sirion with a
1KR FE engine.

What I can't understand, is why the existing spark plugs only have a thread reach of about 19mm ?

I've checked and double-checked this - what I can't understand, is how the car has been able to run with spark plugs which (apparently) are 7.5mm shorter than specified ? I've checked the spark plugs that have come out and all references tell me that they are not specified for my car - but some garage has fitted them and I'e done nearly 30,000 miles with them ?.

So what do I do now ? Do I get another set of 'short' spark plugs. or do I fit the ones that 'should' be fitted - 26mm ?

I'm a very 'sedate' driver, so it is quite possible (likely) that this is why I've not noticed any possible loss of acceleration/speed.

 

[fossyant]

Double check the correct size. Any forums for your car ? Thats a significant difference. My car apparently doesn't like the Bosch Super 4 plugs so I stick with oem NGK.

 

[pubrunner]

Double check the correct size. Any forums for your car ? Thats a significant difference. My car apparently doesn't like the Bosch Super 4 plugs so I stick with oem NGK.

Cheers for the speedy reply, fossy !

The existing plugs happen to be Bosch Super 4. When I purchased them, I had to buy a set of four, even though the car only has 3 cylinders, so I've one pristine spare. If I enter the details for that plug on any website, it tells me that it does not fit my car.

I'm just worried, that if I fit the 'correct' length plugs, they'll catch the top of the piston. All that I can think of, is to remove the existing 3 plugs, insert just 1 of the new ones and hand crank the engine. If there's no obstruction, it should be alright . . . shouldn't it ?

 

[Profpointy]

Cheers for the speedy reply, fossy !

The existing plugs happen to be Bosch Super 4. When I purchased them, I had to buy a set of four, even though the car only has 3 cylinders, so I've one pristine spare. If I enter the details for that plug on any website, it tells me that it does not fit my car.

I'm just worried, that if I fit the 'correct' length plugs, they'll catch the top of the piston. All that I can think of, is to remove the existing 3 plugs, insert just 1 of the new ones and hand crank the engine. If there's no obstruction, it should be alright . . . shouldn't it ?

Was just going to suggest that - seems a prudent thing to try.
There's still the nagging worry they're wrong, and that the spec changed mid-model, but at least they won't go crunch

 

[screenman]

There is more going on with a spark plug than just the length, just go by the manual is the best advice I can give.

 

[pubrunner]

Was just going to suggest that - seems a prudent thing to try.
There's still the nagging worry they're wrong, and that the spec changed mid-model, but at least they won't go crunch

It's the only solution that I can think of at the moment.

The Halfords website offers 3 different spark plugs for my car,all of which are 26.5mm. Presumably, if the existing ones were too short (by 7.5mm), the compression would have been lowered ? What that might mean in reality, I've no idea - fractionally less power ? Would it affect the economy or emissions ?

 

[Smokin Joe]

Cheers for the speedy reply, fossy !

The existing plugs happen to be Bosch Super 4. When I purchased them, I had to buy a set of four, even though the car only has 3 cylinders, so I've one pristine spare. If I enter the details for that plug on any website, it tells me that it does not fit my car.

I'm just worried, that if I fit the 'correct' length plugs, they'll catch the top of the piston. All that I can think of, is to remove the existing 3 plugs, insert just 1 of the new ones and hand crank the engine. If there's no obstruction, it should be alright . . . shouldn't it ?

Try a few more online sites and see what they recommend. Eurocarparts and Halfords are two that give the correct parts for your car.

 

[pubrunner]

Try a few more online sites and see what they recommend. Eurocarparts and Halfords are two that give the correct parts for your car.

Checked them both . . . both say that the appropriate spark plugs have a thread length of 26.5mm.

Currently fitted Bosch Super 4 have a thread length of 19mm.

 

[byegad]

My Toyota Auris has Iridium plugs. At service I have to tell the garage not to change them as Toyota say they're good for 60k miles.

 

[pubrunner]

There is more going on with a spark plug than just the length, just go by the manual is the best advice I can give.

True, my concern is that if I try to reverse this mistake of having used a plug reach too short for the hole, it will have let deposits fill the plug hole's exposed threads and may cause difficulties when I try to install a plug which has the correct reach.

What to do, what to do ?

 

[Chromatic]

I'd just stick the correct new ones in, it'll be fine.

 

[fossyant]

I always blob some coppa slip on the plug threads. I would fit the correct ones. Assuming they are NGK or such well known make.

 

[keithmac]

You can count the threads on the new plugs and count the turns in to ensure they're fully seated (1 thread is 1 rotation).

I personally would remove the plugs, fit 1 new plug then spin the engine gently by hand (socket on the crank) 2 full crank rotations. Feel for any odd resistance and then pull the plug and check the electrode.

If you could only buy the old plugs in batches of 4 it sounds like they were the wrong ones all along!.

Hopefully the threads aren't damaged as you say, a thin smear of coppa-slip is a good idea as said above.

 

[Grant Fondo]

Hi All,

I've a Diahatsu Sirion with the 1KR-FE engine (1 litre), which is also fitted used in the Aygo, Yaris, Citroen C1 and Peugeot 107.

I thought I'd give the car a service before winter and in view of this, decided to get some new spark plugs - but which ?

There seems to be quite a range from which to choose;

do I go for copper, platinum or iridium ?

Some have one electrode, some have three, the Bosch Super 4 has . . . four .

The prices vary quite a bit - some are £7 or £8 for a set of three, others are £7 each. Are the ones for £7 each worth it ? Would I notice any difference, or is it just another case of snake oil salesmanship ?

Which spark plugs would you recommend and why ?

With the Sirion i would go with some bell wire wrapped in parma ham, you may even see a slight increase in performance ;-)