I have a 53 plate Suzuki Ignis Sport that has covered 45k miles and is still running on the original iridium NGK spark plugs. I've owned the car 4 years and it has always run sweet as a nut and been 100% reliable.
I wonder would changing the spark plugs now make any difference or should I leave well alone?
Handbook says they are due a change at the 63k mile service interval (7 years)
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We're a dual-diesel household, so can't help much there - although I was surprised years ago, watching an episode of Fireman Sam with a very small Beestling to hear Sam boast to his boss that he'd changed the plugs on one of their fire engines.
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Not sure if you do but I'd pop them out in between change intervals as plugs have been known to seize in.
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Good point. In my ownership the plugs are checked every annual service and prior to that the car was main dealer serviced. I know the plugs are original because I have every invoice issued.
Last edited by: gramar on Sun 11 May 14 at 09:30
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Iridium plugs in Jazz. every 75k.
Just as well - need to remove part of the trim above them...
Last edited by: madf on Sun 11 May 14 at 10:16
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I've got a set waiting to be fitted to the Astra. I had an hour to spare on Wednesday and took that stupid plastic thingy off thinking they'd be underneath. They're not, there is apparently some other cover that needs to be removed too and I couldn't be 'arrised.
I've penciled it in for next Wednesday - subject to the weather, of course.
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That other cover on your Astra will be the coil pack cassette.Plug change on my Mondeo is 75k miles,so probably no change for another 4 years.
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>> We're a dual-diesel household, so can't help much there - although I was surprised years
>> ago, watching an episode of Fireman Sam with a very small Beestling to hear Sam
>> boast to his boss that he'd changed the plugs on one of their fire engines.
>>
>>
He'd done the glowplugs :-)
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My Vectra is every 8 years/80,000 miles (whichever comes sooner)
They actually didn't get changed until something like 86,000 miles. According to the garage they had minimal wear.
My old Mk1 Astra was something like every 12,000 miles. Every time I took them out to clean and regap them they looked fine. I never got around to changing them until something like 36,000 miles. I only changed them in the end because the electrodes had worn so thin that you could almost regap them with your fingers as the metal was so thin ;)
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>> My Vectra is every 8 years/80,000 miles (whichever comes sooner)
Same here for my Zafira. When the coil pack was changed at 112,000 miles they pulled out the spark plugs to check them but said they were fine
Last edited by: Victorbox on Mon 12 May 14 at 10:56
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On the Harleys, remove and clean every oil change; this has nothing to do with the oil, more to do with the comment above that if you leave 'em in too long, especially on aluminium heads, they can be a pig to remove. Long established habit with all bikes actually as they tend to catch more of the weather than car plugs do.
Never touched the Hyundai's plugs, that's a job for the dealership.
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Modern plugs in modern engines last an amazing length of time and of course can't be gapped like old-style ones, nor do they take on colour or need to be cleaned.
Nevertheless asked the garage man to put new ones in a while back when the car had done nearly 100,000 miles. The running had become very slightly fluffy. The former owner whom I know well doesn't know whether they had ever been changed before!
In any case, the old plugs were visibly foxed and pitted, and the car runs better on the new ones. Indeed last tank it did nearly 35mpg on mainly short but mainly rural journeys, a distinct improvement.
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Slowing down a bit are we ?
;-)
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>> Slowing down a bit are we ?
Just a bit, yes. But nothing silly. I am seldom the first car in a long jostling queue. I am seldom overtaken. But I don't overtake as often as I used to. However there are limits (see my last post in Unusual Sightings :o}).
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A good stress test for plugs is to get up to medium revs, cruise with not much throttle for about 5 seconds, and then press the throttle to the floor and see if the engine miss fires.
What you are doing on full throttle is using full compression in the cylinders and they then need much more plug voltage to spark -- the voltage when you are pootling along is not much more than 1KV, but full throttle will require 12KV or so.
That will test if one or more plugs has insulation break down --- I had a couple of years designing and testing electronic ignition systems, many years ago.
On another tack, I read a garage advert today that offered an oil change service --- "we will give the engine an oil flush which will give the plugs a more powerful spark!! " Not true.
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The jalopy is going even more sweetly today because yesterday I put it through the most expensive car wash option. It was so unspeakably filthy after months of winter country roads that even now there are a couple of places that need a wipe, mainly on the tailgate. But the number plate is legal once again. And the thing does look a bit nicer with its wheels agleam.
There's a squiggle of something hard to remove on the already graunched bonnet snout panel. It isn't bird crap or a pupa thingy. Perhaps some kind soul has treated me to a squirt of Araldite or similar. I'll have to check when I can be bothered. Oh yes, and clean the floor inside which is awash with mud, debris, small stones and nipperish artefacts.
Cleean cars run better, but it takes real discipline to make them run more frugally. The tendency is for euphoria to add a bit of weight to the right foot. That's my theory. Anorakish of course, but that's what one is on this subject.
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Changed the HT leads on the MX5 today as it had a slight misfire - not present now, but the fault was intermittent anyway so I don't really know whether I've cured it.
Without giving it too much thought, I got some new plugs too as the set was less than £8 delivered (NGK), and fitted those at the same time.
Remembered just now that it had new plugs last April, about 3,000 miles ago! No wonder they showed no sign of wear. They were all the right colour which is reassuring.
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"Changed the HT leads on the MX5 today"
These days, I think leads need changing more often than plugs. I'm not too sure what has changed to make the plugs more durable, but I've changed the leads on two high-mileage 1.8 Mazdas, with benefits to both. The first time, the leads were already fairly high-spec replacements and I only changed them after a long chat to a local mechanic whose opinion I value. I argued for some time that the leads were fine and showed no arcing, even in the dark, and he said 'just replace them'. I did and it worked.
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>> These days, I think leads need changing more often than plugs.
Pretty much what my mechanic friend said when he called for a chat just as I finished. The replacements were actually fairly cheap but thicker, which he thinks is really all that distinguishes one set from another - the thicker the insulation, the better.
I think I might have cured it anyway - been out this morning and no hint of a stutter.
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Erm, has anybuddy changed the plugs in a Subaru Forester I wonder, not the easiest of jobs by the looks ovvit.
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>> Erm, has anybuddy changed the plugs in a Subaru Forester
>> I wonder, not the easiest of jobs by the looks ovvit.
>>
My petrol X type is scheduled for a plug change.
7 years/ 70K even though it has done less than 30K.
Apparently extra labour charges as a manifold etc need removing to get at the plugs nearest the bulkhead.
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>>Apparently extra labour charges as a manifold etc need removing to get at the plugs nearest the bulkhead.
b'Jaysus! - I didn't know X types were made in France.
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The weirdest car maintenance access thing I've come across in ages is doing the initial BMW service checks there was no sign of the brake fluid reservoir... not just hard to spot but not anywhere to be seen. Looked in the handbook and the brake fluid level is a dealer check!!
Turns out you have to remove a pollen filter housing and it's underneath virtually sealed away.
Last edited by: Fenlander on Thu 22 May 14 at 09:17
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My recollection is the plugs were easy enough to get to in the non-turbo Foz - there's reasonable free space either side of the engine block to reach down to the plugs.
The Legacy with the same 2 litre block is more crowded under the bonnet...
The trick would be to extract the rear two without dropping them into the bowels of the engine bay!
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Spark plugs are extraordinarily sensitive to being dropped. I've twice accidentally dropped a new plug about a foot onto the workbench when clumsily opening the packet, and despite looking undamaged they caused a small misfire.
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Mine were 'supposedly' replaced 10k miles ago, before I purchased it, I have changed plugs on boxers before of course, even on 911's, but that was a long time ago :)
>>The trick would be to extract the rear two without dropping them into the bowels of the engine bay!
Oh dear :(
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Pre 2001 Foresters have a coil on top of the inlet manifold and good old fashioned HT leads with iridium plugs - still a pita to remove but just takes time and a sore back.
After that the plugs have their own coil packs and seem significantly more annoying to fettle out - takes about 45-60mins for someone who has done it frequently and about 2 hours for a novice going by Interweb advice.
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I thought that would flush you out Doc :)
Back in the day when I was changing the plugs on 5 cars a day 6 days a week, I had all manner of tools to assist in the removal/refitting of spark plugs in difficult to access areas.
My favourite method was to use a short length of pipe attached to said plug and (this is the important bit) if it wont screw in easily by hand then DON'T DO IT Ethel.
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Once managed to break a recalcitrant sparkplug trying to remove it from my old 300ZX - was the 6th plug of course, with the rest coming out fine.
Upshot was I drove the 5-plug V6 half a mile to my friendly mechanic who managed to remove the retained metal threaded part with an 'Easy-out' - reverse threaded thingy that dug into the plug as it was turned anti-clockwise.
Fortunately the threads were ok and no head-work required.
I imagine a similar escapade with a flat engine would have meant engine-out.
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Erm, strictly between thee and me, I once got the firing order mixed up on a P5 V8 Rover, so 2 plug leads were arso about faceo.
I didn't twig until I had to go back on the car due to reports of very poor MPG.
18436572 :)
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I have a nice new set of plugs in the garage for the 1600 Note. I just haven't got the bottle to attempt a change yet. According to interweb.....huge dismantling job..manifold, etc. Then a huge mantling job afterwards ! I can get no. 4 out easy so I just keep an eye on that one.
I've got a fair few home made tools to suit various problems. The Jowett plugs are easy to get out but you can't get a modern plug socket round the hex. I cut down an old box spanner and welded an old half inch drive socket in the top for that one.
For motors like the Renault 1600 and other where the plug is fairly deep in the head, a length of wooden dowel with a small magnet at the end lifts the unscrewed plug out easily.
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>>a length of wooden dowel with a small magnet at the end lifts the unscrewed plug out easily.
I've got various sized rubber hose that fits over the metal cap or heater hose that'll go over the insulator.
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How often do you change your spark plugs - WillDeBeest
