Spark Plug Life

[weeleyboy]

My 2009 Avensis TR 2.0 petrol auto is due for it's annual/60000 service where it advises spark plug replacement. As the car has only done 37,000 is it worth spending £50 on a new set of plugs which are theoretically only about halfway through their life or shall I wait until the car reaches that mileage before changing them. My annual mileage is only 10,000s or so which would mean another 2 years before changing them.

One piece of advice I've had is to have them changed on the grounds of age but surely they don't deteriorate much when not in use?

[FROSTYBALLS]

Usually the service requirements are six years or 60,000 miles, whichever occurs first.

[avensisd4d786]

£50 seems steep. I got genuine Iridium plugs for an auris from a toyota dealer through eBay.

http://pages.ebay.com/link/?nav=item.view&id=261313555323&alt=web

I would email them with your reg. They will probably be the same.

[Konrad C]

£50 seems steep. I got genuine iridium plugs for an auris from a toyota dealer through ebay.

http://pages.ebay.com/link/?nav=item.view&id=261313555323&alt=web

I would email them with your reg. They will probably be the same.

That's what my car uses (Denso SC20HR11), and it is for all Avensis Mk3 petrol engines 1.6, 1.8 and 2.0 litres.

I will check my car and see what state the plugs are in and that they are the correct plugs. I don't use substitutes. The car had a recent service and the plugs should have been changed on this service. If they look old I will be changing them.

[weeleyboy]

Thanks for the advice guys. When I checked the quote I had from the main agent the schedule showed the plugs at £42.24 + vat fitted - they claim to match other quotes so I'll see what they say. If they won't match the price I'll supply my own plugs.

I'm still not clear how plugs can need replacing 23.000 miles before they have done the mileage at which the change is recommended. I'm told age is a factor but how do they deteriorate when not in use?

[Konrad C]

The price seems fair because, I now need a new spark plug socket as none in my tools fits! 14mm socket. Also the cowling has to be removed, which means removing the wipers - another tool needed for that job.

With all that, just let the garage do the work. Oh yes tell them to give you the old ones for piece of mind. They should be Denso SC20HR11.

[TomdeGuerre]

Thanks for the advice guys. When I checked the quote I had from the main agent the schedule showed the plugs at £42.24 + vat fitted - they claim to match other quotes so I'll see what they say. If they won't match the price I'll supply my own plugs.

I'm still not clear how plugs can need replacing 23.000 miles before they have done the mileage at which the change is recommended. I'm told age is a factor but how do they deteriorate when not in use?

I would quite happily continue to use the plugs for another 10,000 miles provided you’re not having any trouble starting the car or having any misfire when it’s running. I’ve kept plugs in many times when they were due for change time-wise if the mileage was low.

If you were using the car very little, say 3,000 miles a year then there would be the chance of soot or other residue collecting on them due to engine not reaching temperature, unburnt fuel deposits left etc. If you drove the car very hard like harsh acceleration and flat out motorway driving then the plugs could well be burnt out by now. But at 10,000 a year with normal operation I say you’ve got plenty of life left in them.

Personally I’d still take them out and take a look at them. Check the condition of the electrodes and insulators plugs (plenty of pictures on the web to show you what plugs should look like eg http://www.ngksparkplugs.com/about-ngk/spark-plug-101 ) Assuming they’re showing the right combustion conditions, check the gaps and give them a wipe clean on the outside ceramic insulators and re-install them.

Are there naysayers who would tell you otherwise? Absolutely, they’ll tell you all kinds of stuff quoting “proof” of diagnostic equipment readout and the improvement with new plugs. But you could replace plugs that were only a year old and diagnostic equipment would show an improvement however you don’t replace your plugs every year, do you?

[weeleyboy]

I took up the price differential with the main dealer and asked if I could supply my own parts (labour was shown separately in the quote) and the answer was yes, you can supply your own parts so I think I will replace them at a lower cost.

Thanks Konrad for the link to cheap plugs.

Derek

[avensisd4d786]

It was me derek who linked you them

[Konrad C]

I took up the price differential with the main dealer and asked if I could supply my own parts (labour was shown separately in the quote) and the answer was yes, you can supply your own parts so I think I will replace them at a lower cost.

Thanks Konrad for the link to cheap plugs.

Derek

It was me derek who linked you them

Derek, I can't take credit for "I"s link. It has helped me too! So thanks "I".

[weeleyboy]

Apologies to "1" for not crediting you with sourcing the cheap plugs - it's a good link which I've made a note of. Again thanks to all who took an interest in the topic and contributed advice.

Derek

[Konrad C]

For those who may want do their own servicing and wish to change the spark plug, here is what you need.

If the wiper arms are seized on to the spindle, a puller/removal tool will be needed. I got mine from Machine Mart: https://www.machinemart.co.uk/shop/product/details/cht436-battery-terminal-bearing-puller

The price was about the same as online and it can do varied jobs.

Then you need a suitable socket of the correct size. Thank to "I", I got the correct socket which is a Laser 8mm 3/8 14mm bi-hex spark plug socket: https://www.machinemart.co.uk/shop/product/details/laser-4376-8mm-38-drive-thin-wall-spark-plug

Other option is the following: http://www.halfords.com/workshop-tools/tools/sockets-accessories/laser-magnetic-spark-plug-socket-14mm

The first tool (puller) may be needed, as the cowling has to be removed to access the spark plugs, as the engine leans back towards the windscreen. The spark plugs have a smaller spanner size of 14mm, than the usual 16mm in most kits.

There is a size confusion as some vendors say the socket is size 8mm whilst others use the proper hex spanner size 14mm. To be sure, take a nut or bolt that fits 14mm spanner.

To really confuse everyone size 10mm socket = 16mm hex, 12mm = 18mm and I think 14mm = 21mm.

The coils are secured with 10mm bolts. Don't loose the seals!

So a simple job made longer taking extra bits off.

[avensisd4d786]

good stuff now you can relax for another 60,000 miles, did you the ones off eBay? if so they came quick!

[Konrad C]

I have not ordered the plugs yet. I did some of the dismantling of the to engine cover, half the cowling to get at one of the spark plugs, only to find out that I needed the smaller socket!

Now I have the correct tools, I will check the plugs to see if they have been changed at the last service. The car was serviced over a month before I bought the car. The car is 6 years old and now at 51,000 miles.

[Konrad C]

Update. I checked the spark plugs and they look original. Here are pictures of two I checked:

As you can see they are well used.

What I did was remove the left hand wiper, the rubber weather strip and half the cowling covering

This gives enough room to unbolt, disconnect the coils and remove the coils.

The access is fine if the tools used are the correct size.

Now to order the new spark plugs.

[weeleyboy]

I ordered my plugs on Friday 6th and they arrived this morning although estimated delivery was for 11/12th November. Very pleased with the service and they will be fitted on Wednesday when it goes in for the annual service. Quite happy to delegate this job from what you have shown me.

[Konrad C]

I received my plugs today and fitted them.

New and old plugs.

The car drives better with a better throttle response. The test will be the fuel economy.