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Spark plugs Iridium 20000km 15 months old

3K views 22 replies 7 participants last post by  fabbrisd1 
#1 ·
Hi

I was wondering if someone could comment on or confirm the following;

Car

E320 1996 W210 straight six petrol full service history in great condition approaching 300,000 km
I’d buy another one without hesitation

Car symptoms

Misfire under load
High fuel consumption usually I get 800 km out of a tank lately I’m getting 550 km from 80 litres
Lack of acceleration
Fuel starving pulsation

The issue

The car gradually developed the above symptoms

These are iridium spark plugs supposedly good for anywhere between 50,000 km to 100,000 km
I usually do all my car maintenance including plugs, but I wasn’t well and got a mechanic to do it
I admit I haven’t personally changed the plugs on this car before as I haven’t had it long enough
I've never come across anything like these except at a wrecking yard

I thought there was something wrong with the fuel pressure regulator fuel pump coil packs or leads
It didn’t occur to me to pull a spark plug until now

Changed all the plugs problem solved

Some notes

These plugs are 15 months old the car has travelled 20,000 km 50% at 100km/h the other 50% urban driving

The plugs are NGK

2 plugs have H73V stamped on them
4 plugs have M41K stamped on them
The plugs are probably from different batches (No big deal)
They all have significant rust staining on the ceramic
At least 2 of them are showing signs of rust on the metal body 1 worse than the other (rear plug)

Another mechanic said they were far more than 15 months old and look like they had done over 100,000 km

So what I really wanted was an opinion on is:
Do you think they were changed 20,000 km ago by the mechanic or not?
Do they look like 20,000km 15 month old plugs?
Is this normal?

I would be really grateful if someone can comment on this, thank you
 

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#2 ·
Yes, definitely.

Either that, or the coil boot was not making full contact, so the electricity had to arc over.

Would explain the burn marks on the boot section of the spark plug.

Also, I use Bosch F8DC4 on my M104. It's OEM and copper. Iridium? I don't know.

Dialectic grease the boot connectors!

Actually, while you're replacing the spark plugs, its a good time to change the boots on the coils anyway, they wear out fast. Cheap too.
 
#3 · (Edited)
My first guess, based on the not so sharp photos of the iridium tip, and the extent of the rusty flair on the base of the white ceramic insulator, IMO, those plugs have many miles on them, far more than what you said they are supposed to be.

If you could, post sharp close-ups of the iridium tip (side view). That would provide the important clue. When I blow up the photos, the iridium tip should still look sharp.
 
#4 ·
Thankyou for comment


Exactly what I have been working on

The areas with the red line

I'm trying edit some more to post

Here is 1 and the centre ceramic insulator is cracked

I think some how that they have quite a few km's on them. The reason I didn't suspect them as a problem is that they were changed maybe and they NGK Iridium) should be good for at least 50,000 km's
trying to get high res images and they keep getting reduced during upload

most appreciated
 

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#8 · (Edited)
Thanks for the closeups. They are certain close enough. However, unfortunately, they are still not sharp. I think you may need to use a tripod. As is, I am not able to see as much details as I would like: ie. the sharp edges of the iridium tip.

Regardless, I can see some plugs have deposits on them, and some have more miles on them than other. Some of them, although based on not sharp enough images, looked worn. The iridium tip of NGK iridium plugs can take a lot mileage. It is increasingly looking like the second mechanic is onto something.

50,000 km's is nothing for the iridium tips with stock ignition systems. However, iridium sparkplugs which have a platinum pad or tip on the ground electrode last the longest, hands down.
 
#9 ·
When the rust color can come just in weeks when you drive with water in plugs holes, it is the electrodes gap that indicate the actual wear.
You should measure the gap to get firm answer.
Something is wrong with the combustion in this engine.
The plugs ends should be tan/brown, or lightly white - while those do have some bad deposits.
How was mpg on them?
 
#10 · (Edited)
...
t is the electrodes gap that indicate the actual wear.
...
How was mpg on them?
If this was the case, then those with clean plugs will never have to buy new plugs. Just regap.

The firing-end of my plugs in my vehicles are clean. Unfortunately, I still have to replace them even though the gaps are correct.

In any case, back to the O.P.'s question, the O.P. said that he didn't install those spark plugs himself. So there is no way he could be sure what the gaps were to start with.
 
#11 · (Edited)
Its the gap that tells you a lot about the millage. Please see photo, the one on the left, the gap is larger and can not be re-gaped for obvious reason, because of the electrode. You normally consider the gap size with factory specifications for comparison and visually for signs of worn electrodes. The color of the plug its a general indication of how well the combustion is in the engine and used for troubleshooting.
 

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#12 ·
Closeups NGK BKR6EIX 20000 km 15 months

Fuel consumption

was 23.52 MPG

recently 16.22 MPG

Admitedly slightly more urban than freeway 65% urban 35% freeway


The plugs in the photo are marked NGK BKR6EIX not sure why these where used and not all that happy about it

They have been replaced with NGK BKR5EIX gap 0.8 mm or 0.0315 inches recommended please correct me if I'm wrong


Please tell me what you think of the new pictures
Post is a bit messy long days and late nights
Gaps are on the pictures not sure what they started at they are the average of 3 careful measurements each
 

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#14 · (Edited)
Thanks for posting the new photos. I can definitely see more details, especially the third one down with the 0.032" (0.81mm) gap. When the image is sharp, I can see that the plug still looks fine, usage-wise. But note that you do have a fouling problem. The range of gap measured is between 0.0315" to 0.0325", so nothing to draw that from that from the "wearing" point of view, if you factor in human error and manufacturing tolerance.

Those are NGK IX's single-sided iridium spark plugs that were introduced some years ago, and the iridium have gone through two or more generations. First of all, the design of the iridium tip doesn't look that old, IMO (ie. not first generation). Secondly, the ground electrode is just nickel plated, no platinum. But yet, I see no erosion. Thirdly, at least on the sharpest photo (third one down), the edge of the iridium tip still looks good.

The rust on the metal body is due to water sitting there. The rusty buildup on the ceramic insulator is not enough by itself to draw conclusion from.

So, IMHO, there is no evidence to support crucifying the first mechanic.

Incidentally, the colder plugs that were used can at least explain the fouling. The "6" is a step colder than a "5".

The 0.032" gap on the new plugs sounds reasonable.

Here is what NGK says about plug fouling:

WHAT IS A FOULED SPARK PLUG?
A: A spark plug is considered fouled when the insulator nose at the firing tip becomes coated with a foreign substance such as fuel, oil or carbon. This coating makes it easier for the voltage to follow along the insulator nose, leach back down into the metal shell and ground out rather than bridging the gap and firing normally.

Many factors can contribute to spark plug fouling. The air-fuel ratio may be too rich as a result of incorrect carburetor adjustment or a poorly performing fuel injection system. Worn piston rings or valve seals may allow too much oil to leak into the combustion chamber, leading to oil fouling. The ignition system may not be performing properly. Prolonged idling or continuous low-speed driving may keep the spark plug from reaching its optimum operating temperature. Using too cold a spark plug can lead to the same problem. Finally, a dirty air cleaner can create a too-rich condition which can lead to fouling.

Fuel, oil and carbon fouling can all be the result of different causes but, once a spark plug is fouled, it will not provide adequate voltage to the firing tip and that cylinder will not fire properly. Therefore, it is recommended that a plug be replaced once it is fouled.
- See more at: NGK Spark Plugs
 
#15 · (Edited)
Yes, these plugs been changed 20k ago! This is my opinion as I may have changed 1000's sets of plugs and many tune-ups in my life time. Use Bosch plugs next time and exactly what you should use for your engine, not so called "high performance" and do not fall into that trap. I am so glad that Mr. Techyiam and I both agree about this :)

Good luck brother and have fun in beautiful Australia!
 
#16 · (Edited)
Yes, these plugs been change 20k ago! This is my opinion as I may have changed 1000's of plugs and done equal tune-ups in my life time. Use Bosch plugs next time and exactly what you should use for your engine and not so called "high performance" and do not fall into that trap. I am so glad that Mr. Techyiam and I both agree about this :)

Good luck brother and have fun in beautiful Australia!
You do know in your previous post, the so called "worn spark plug" is more like "abused" spark plug.

That plug probably didn't have an iridium tip (more like platinum). Yet, the new plug on the right is an iridium plug. Iridium tip doesn't wear down like that, at least on what I have seen on NGK's and Denso's. Moreover, the erosion on the ground electrode is not "normal" wear with stock ignition, even if it is single-sided. The plug should have been changed many moons before reaching that condition. I have worn out ground electrodes like that on single-side spark plugs in only a few months, the vehicle didn't have a stock ignition though. And that is why I recommend double-sides ones (mind you, there is also the benefit of less initial voltage required as it wears). No erosion. Once the gap becomes too large, a stock ignition would not have the voltage nor the electrical energy to create a strong spark.

With iridium plugs, performance can drop significantly, yet the gap remains the same, or within spec, especially the double-sided ones.

There is no spark plug that will last forever, at least none that I can afford or know about. But boy, do the double-sided iridium's last.

Cheers.
 
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#19 ·
respondents should direct their points and counterpoints to car related issues and leave out the personal attacks or inflammatory adjectives.

if you have a disagreement, word your verbiage in clinical fashion and state why (as factually as possible) you disagree. also, direct your language to the item, not the person. leave the emotion out of it. go to PM if you wish to duel. personal attacks will be surgically removed.

that said, I'm sure we'd have some spirited discussion if we were all together at the Thanksgiving table, eh? :)
 
#21 ·
Well.... technology is amazing.
I have dilemma on wife W211 with 3.2l engine.
I got copy of master inquiry and misread that the car had plugs replaced at 108,000 miles.
The code turned out something else, not the plugs.
So now at 157,000 I still wonder if the engine is on factory plugs.
Passed smog with no trouble last week.
 
#22 ·
Firstly thanks all for contributing your "Opinions" they are valued particularly techyiam Eagleone

I really had no intensions of having a go of the mechanic. I have always changed my own spark plugs and always check the burn patterns, burn colour and other combustion artefacts, It does tell you a lot about your engine. I wasn't shown the old plugs with this first mechanic.

I guess I thought that these iridium plugs were set and forget for at least a considerable period of time or kms
and I was so surprised that the car was driving like such a wounded pig, I thought it had too be something more serious.

I will definitely check them at shorter intervals in the future! and consider the advice given and perhaps choose a different spark plug in future.

I can say that I have learnt a thing or 2 about Iridium plugs and If someone else finds this discussion interesting or helpful then that's a bonus

Until the next post be kind

cheers

It really is beautiful, sometimes I wish I had a swimming pool then, nahhh what for! LOL
 

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#23 ·
Well... my "input" frankly Iridium is the wrong plug choice for your '96 E320 - if my fogged memory serves me correctly your engine is setup for non-resistor COPPER plugs - and yes, all Iridium will be bad match - and frankly you "burnt" the the Iridium's out to misfire..

Correct non-resistor copper for your engine - and you can plan for 25K mile regular replacement - saving grace especially for a Aussie - copper plugs are cheap mate..
 
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