What do my spark plugs tell me about my car (with pic)

[PeterTorbet]

With the exception of the oily spark plug, all plugs had the same appearance as the one on the left. I'm guessing these are original (since 2006). Is this what I'd expect to see? And anyone any ideas on whats happened to the one on the right? 

And the damp seal on the fuel pump, common says says I should change this also?

Thanks in advance (and apologies for all the questions as my quest to service the motor continues)

[Barry14UK]

Picture of plugs could have been better. Replacement plugs seems overdue! Blow by on oily one.  Service history/mileage? What does it look like beneath oil cap - dirty indicating inferior oil/ overlong periods between servicing?

[Herbie]

A Google search on the string "what does condition of spark plugs indicate" (without the quotes) returns over 17m hits, the very first of which is this one:

https://www.championautoparts.com/Parts-Matter/automotive-repair-and-maintenance/how-to-read-spark-plugs.html

[steve2006]

Two different makes of plugs won’t help, “chocolate brown” were always the key words for correct colour of the tips if the mixture was correct so looking OK there. The oily one looks more like blow by than spark plug tube gasket failure probably under torqued.

To refit the spark plugs get a piece of rubber tubing that fits snugly over the electrode nipple ( also make sure these are tight), lower the plug into the engine then twist the rubber hose to get the thread started. This will prevent the possibility of cross threading as you have more feel when turning the plug in. Finally nip them up to the correct torque. A smear of dielectric grease on the top of the plugs will assist plug lead removal in the future but iridium are usually good for up to 100,000 miles.

[PeterTorbet]

Thanks all, here's the complete set of pics. 

[PeterTorbet]

47 minutes ago, steve2006 said:

Two different makes of plugs won’t help, “chocolate brown” were always the key words for correct colour of the tips if the mixture was correct so looking OK there. The oily one looks more like blow by than spark plug tube gasket failure probably under torqued.

To refit the spark plugs get a piece of rubber tubing that fits snugly over the electrode nipple ( also make sure these are tight), lower the plug into the engine then twist the rubber hose to get the thread started. This will prevent the possibility of cross threading as you have more feel when turning the plug in. Finally nip them up to the correct torque. A smear of dielectric grease on the top of the plugs will assist plug lead removal in the future but iridium are usually good for up to 100,000 miles.

No. 3 spark plug - I was able to remove this by hand. It's also the hardest to get at due to the (air) suspension turret. I'm guessing that's affected it's fitment.

[PeterTorbet]

9 hours ago, Barry14UK said:

Picture of plugs could have been better. Replacement plugs seems overdue! Blow by on oily one.  Service history/mileage? What does it look like beneath oil cap - dirty indicating inferior oil/ overlong periods between servicing?

Added better pics. 136,000 miles, Full Lexus service history up until 90,000 miles and then it gets a bit wooly. Had 132,000 miles when I bought last August.

[J88TEO]

Problem with garages etc..... they charge for service ie oil, filters and plugs but how many can be trusted that is the question!

I bought mine at 134k miles and seller showed me the invoice for service done at 132k miles ( oil, filters and plugs ).

However I checked and only the oil and air filter were changed! 

The oil filter cap looked too dirty to have been opened so I did the service myself to confirm it wasn't changed. Plugs were not changed too,.

Same for pollen filter!

Will get my tranmission and axle oil change soon.

[rich1068]

Correctly fitted recommended plugs, an oil change, new oil filter, new air filter and a new pollen filter and your car is going to love you forever 

[Baldguy]

Its like a handbag for your girlfriend/wife... works in the same way

12 minutes ago, rich1068 said:

Correctly fitted recommended plugs, an oil change, new oil filter, new air filter and a new pollen filter and your car is going to love you forever 

 

[BigBoomer]

Looks to me like the rocker cover seal around #3 isn't sealing. There is no significant amount of burnt oil on the electrodes of #3, just the oil on the cap and insulator.
From what I can see on the diagrams, the Spark Plug Tube Gasket on #3 needs replacing which will require the rocker cover to come off.

[PeterTorbet]

17 minutes ago, BigBoomer said:

Looks to me like the rocker cover seal around #3 isn't sealing. There is no significant amount of burnt oil on the electrodes of #3, just the oil on the cap and insulator.
From what I can see on the diagrams, the Spark Plug Tube Gasket on #3 needs replacing which will require the rocker cover to come off.

I've been watching how it's done, but struggling (in general) to find the gaskets anywhere? Is this normal to struggle to get replacement parts for the engine / car, to just symptomatic of lockdown etc? 

 

 

[BigBoomer]

I suspect that many of the Lexus/Toyota dealers will have shut down for the lock-down. Otherwise they should all be able to order in the gaskets/seals for you.

[Barry14UK]

While plugs are out I would suggest you take the opportunity to do a compression test as apart from the oily plug there is evidence of carbon build up around central electrode not consistent with deposits on earthing electrode.  It could be poor sealing valve guides or excess oil getting past piston rings.  I would at least monitor how much oil is being used.  There are two schools of thought about using flushing oil.  It can get rid of a lot of crud but there is a risk that it can block narrow oilways and some manufacturers advise against it. A good idea of what's circulating is seen in the oil filter.

[Malc]

I guess it's unlikely the plugs had ever been changed .....  it's a " hidden " job and no one will ever know until it hits YOU, as it has just now

It is a long tedious job, 8 plugs, at least an hour or more and if a garage can get away with charging for the time and for 8 new plugs then sadly many will do just that

get the right repacement plugs and they will last you maybe 10 years or 120k miles or more .....  I'm not sure of the lifespan of these new modern plugs but I believe it's min 100k miles

but maybe you have one or two other issues alongside, which probably haven't been helped by the prior owner not changing the plugs on time

best wishes with it all whatever

Malc

[steve2006]

Now look what you’ve done, been sitting in my garage for a few months and now I keep seeing them, looks like the next project after the seats now 😀

[MLW]

They look a mess. But that is the past. We need to look to the future.

I changed mine at 60,000 miles as they should be. ONLY buy Denso iridium plugs. Opie Oils do genuine (be careful on Ebay) ones for about £58 for 8. I was so worried about cross threading and torque specs I bought a low torque wrench. Being very thorougher, it took me just under 2 hours to do all 8 plugs. Would have been 15 minutes on a Mercedes W124.

This is a difficult but rewarding job you do every 6 years. DO NOT snap off any of the small soft wires.

[Mihanicos]

From my experience, oil on the thread of the spark plugs occurs when they are under torqued. For my car the recommended torque is 19 Nm but I usually torque to 25 Nm. 

Oil on the plugs may be caused by a long overdue oil change, using the wrong type and viscosity, excessive oil in the sump [ over the maximum level ] worn oil seals on the intake valves and worn piston rings. A weak spark can also cause oil deposits.

Stoichiometric combustion normally gives a light chestnut brown colour but for the electrode insulator to be white is normal. Like another learned member pointed out, iridium plugs are normally replaced every 6 years or 72 000 miles, whichever comes first. As the plugs wear, their gap increases and for iridium plugs the gap should not be adjusted. From the photos, I think they have done quite a few miles over the top. If they are the original and fitted on 2006, the time span has been exceeded by far.

I agree with the recommendations of other members and I always begin repairs and fault identification by doing the easy steps and cheap repairs first.

 

Chris.

 

 

 

 

 

 

 

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[ColinBarber]

4 hours ago, Mihanicos said:

Iridium plugs are normally replaced every 6 years or 72 000 miles,

60k miles in the UK for OEM iridium plugs if you want to conform to manufacturer's schedule.

If you upgrade to high performance plugs, such as Denso iridium Power, then the schedule will be different, for IR it is 30k miles. Or long life iridium TT which is 100k miles.

[Mihanicos]

Thank you very much for the information on spark plugs. 

My knowledge comes from following the manufacturer's recommendations for normal service conditions.

Chris.

[Malc]

3 hours ago, ColinBarber said:

Or long life Iridium TT which is 100k miles

well worth the extra cost ( whatever that may be ) as the labour time less spent over 2 changes of plugs will surely outweigh the capital cost ??

that's assuming you keep the car for 100k miles or more

Malc

[MLW]

Having done this job, I agree. Only fit iridium plugs. It is such a faff to do, once in 6 years is more than enough. Anyway, iridium plugs give such better performance. If they only give a 2-3% improvement in mpg, that is a lot of fuel in 6 years.

[ColinBarber]

24 minutes ago, MLW said:

Having done this job, I agree. Only fit iridium plugs. It is such a faff to do, once in 6 years is more than enough. Anyway, iridium plugs give such better performance. If they only give a 2-3% improvement in mpg, that is a lot of fuel in 6 years.

No question to fit iridium ones, just which ones - long lasting or standard 60k ones. I suspect most people wouldn't think they will have their existing vehicle in another 100k miles and therefore settle on the standard ones.

[MLW]

A spark plug that lasts 60,000 miles or more is amazing to us 'older gentlemen' who changed every 10,000 miles and cleaned and gaped ever 5,000 miles just 30 years ago.

[ColinBarber]

19 hours ago, MLW said:

A spark plug that lasts 60,000 miles or more is amazing to us 'older gentlemen' who changed every 10,000 miles and cleaned and gaped ever 5,000 miles just 30 years ago.

😃 

But they only cost £1 each and you could access them without dismantling half the engine 🙂