Changing spark plugs

[rallen]

Hi

E320 W210 2001 model

I had a look and it appears a challenge to change the plugs, especially the ones at the back of the engine. I am not sure I can even reach the back ones, the gaps are too tight, let alone pull out the seemingly welded on boots and insert a tool to remove them.

Has anyone here done it to describe the process?

Thanks

 

[paulcallender]

Use slim nosed pliers to pull off the ignition leads.

Use the correct size spark plug socket, without the rubber boot, and with a 10" or more extension bar, to loosen the spark plug then use slim nosed pliers to lift it, should it fall.

During removal, note carefully the angle of the extension bar. It may not be vertical.

When refitting, match this angle and rotate the bar the wrong way a turn or so, then once absolutely happy that you aren't going to cross-thread the plug, turn the bar on its own by hand, the first 5-6 turns.

 

[nicky]

What you need is small hands to get into the space so you can locate the plug socket onto the plug....Not a hard job,just a bit of persaverance is required.......

 

[rallen]

I think it will be a hell of a job. First I need to use pliers and the block as a fulkrum to yank out the boots. Experimentally I took out one boot (LHS and easy) and it seemed as if it was welded on. I cannot imagine how I will be able to exert force on the rear ones, with all the bits around, A/C, ABS, bulkhead etc.

About placing them back in (and any screws in general) is that I turn the screw the opposite way until it clicks down. At that point it is safe to screw it in as it has just meshed correctly. The problem is that I can tell from now that there will not be enough "feel" when doing the awkward ones to tell that it has meshed and is ready to be screwed in.

 

[jberks]

Hi Rallen,
I have put a comment on this on your other post but for the benefit of anyone else that's interested.
Yes I have done it and yes its a female dog. I think its £100 well spent on labour at your friendly specialist or dealer but if you're still determined ....
1) Bonnet up to vertical. - cover the wing with a rug or something so you don't scratch it and spoil your whole day.
2) O/S - remove the air filter housing (top) and MAS - then this side isn't too bad - though I did manage to crack the plastic cover by leaning on it a little hard.
3) I didn't need any tools to get the leads off though I agree they are virtually welded on. - They are equally hard to refit - lots of wiggling and 15 stone applied seem to do the trick....eventually. If they don't click home, you haven't finished! (look inside and you will see a spring bar - this needs to click over the head of the plug).
4) Do them one at a time - obvious but in desparation at not being able to get to them people do daft things! Also proceed methodically and carefully - I found I had a plug left over at the end! Fortunately I quickly realised which one I had missed but as you can't see them you can easily miss one and if you don't know which, you'll have to pull them all out again.
5) You need a thin plug socket (10 mill from memory), a good quality ratchet as at times you won't be able to move move it more than 20 degrees or so, various extention bars and a universal joint. I found the rubber insert on the plug socket made the socket stay in place when I removed the bar and I had to retrieve it with pliers a few times, bt it did help remove the plug so Pros/cons. I didn't use one, but a mirror may be helpful as I don't think there is a single plug you can actually see.
6) The plugs will be stiff to remove.- they've been there for a while.
7) They drop in a fair way and seat and I found that you can start them off quite easily. Read the tighten instructions carefully for the new ones - they vary according to the washer fitted - officially it says use a torque wrench but I challenge anyone to get one anywhere near! However its a fragile alloy head so be careful - 1/2 turn to tighten etc - I just did it as best I could and it seems fine.
8) The near side is harder to do than the off-side as you can remove the pipes to make the O/S easier - The ABS and aircon are in the way on the N/S - which you do first is up to you.
9) I'm now on my third set of plug leads (5 1/2 years 60k) so if its a misfire - especially lumpy idle - you are chasing - the plugs may be ok and the leads may be playing up.

It took me over 2 hours to complete and I was scratched to hell and couldn't close my fingers by the end of it.- not a fun job.

Finally - do not fit copper plugs as some places will try to sell you - or you'll be back under the bonnet within 10k for another go - they need to 60k rated plugs -so they need to be a harder metal such as Platinum, irridium etc. Pricier but worth it - be wary of plugs that are too cheap - If they are less than £5-6 each be suspicious.
Good luck,
JB

 

[rallen]

Hi

I am getting the Bosch Platimum ones, as specified in the manual. The car has 25K miles and I think is on the originals.

The sample plug I removed was extremely tight on. It had no oil deposits and was not corroded. Could do with a good clean. Of course if it takes 2 hours to remove them might as well renew them.

In the other cars I have had I usually smear a bit of engine oil on the washers so they come our easier next time. But I do not make them tight anyway.

I do not want to wriggle them in case I either loosen the spring inside or snap the cables.

I do not want to give them to the garage to do because it is a hard job and do not trust them not to damage the cables And as eash cylinder has 2 of them, I may not notice the damage immediately.

Got the various extension bars, at the driver's side the rear ones there is about a what, 5 cm gap? You will have to have the exact length bar + socket.

Why do you change leads so often? Do you also have the E320 W210 ?

 

[jberks]

Hi,
The Bosch ones sound fine. Not sure that at 25k you really need to bother though. Assuming the MAS, o2 sensor and ECU are working ok, there is no reason to clean them up. Admittedly MB recon 5 years / 60k and they need doing - but I've also heard of them going 80k quite happily.

I agree that 'wiggling' the leads could lead to problems but they are very tight and some gentle rocking is required together with substantial downward force to get them to fix on correctly - I tried just pushing but to no avail.
I also agree that being the twin spark, its hard to detect one dodgy lead or plug, but to be fair, there is probably more chance of you or I damaging the lead than a specialist or dealer who changes these plugs daily (poor buggers!). Its almost impossible to be gentle with so much effort required and so little space, no matter how well intentioned. I wouldn't dream of giving this job (or anything on my treasured Merc) to 'Kerbside Repairers' but there are some excellent specialists out there that are very reasonable and know their stuff.
As far as the back ones go, I used the UJ directly between the socket and the ratchet. This gave just enough reach whilst allowing me to angle the ratchet enough to get at least a small degree of movement on the bar.

On the plug leads, either I have been unlucky or there are a hell of a lot of W210 V6's out there not running as well as they could. Having had the car from it being a demo and admittedly being very fussy (apparently I am the only customer at my dealer to have detected an out of spec o2 sensor without test equipment!), I can't abide a lumpy idle - if I wanted that I'd buy a 4 pot ford. To me the V6 should idle so as you can't tell its running, and just purr when you accelerate. It did when I bought it. After just over 3 years, it started to rock and knock a little (occasionally a lot!). Pulling up, it felt like the discs were warped. I took it to the dealer who told me that they all do that. To cut a long story short, after much chasing around and arguing with everyone that however poor everyone elses was, mine had been perfect and had only done 25k so wear/age were not adequate excuses for a sudden deterioration, a local specialist agreed that there was a problem and went through it. After 3 days of testing throttle bodies, sensors etc he found the supressor caps had corroded. New leads and all was perfect again. A few months ago, the knock came back. Having done 60k I changed the plugs which helped slightly but didn't solve it. I sent it back to the specialist for another check and although they looked ok (I'd checked them myself when I did the plugs),with everything else checking out fine, he replaced the leads. It seems to have done the trick yet again.

Mine is the E240 W210, so basically the identical engine - just lower cc - V6 twin spark etc, can't tell them apart to look at.

Why are you looking to change the plugs? do you have a problem or is it pre-emptive. - If the latter then my advice would be if it aint broke leave well alone - it could run trouble free for another 5 years yet - if you disturb it, you could create more problems than you solve.

 

[rallen]

You are saying you had problems in the leads and the capacitors? The leads come from those things mounted on the engine block and I had assumed were coils? You replaced the coils and leads at 25K?

There are no symptoms and it idles and revs smoothly. But the service book calls for a spark plug change at 20K and the car is already on 26K. So I thought to do the decent thing and replace them.

But now you have got me worried about the coils and leads, I thought as they are so short and there is no movement at all (noone touches there) would last forever...

 

[woodturner-fran]

One warning:

Don't pull the leads off by the lead itself! Only pull from the holder - its easy enough to pull the lead out of the holder (don't ask me how I know this)


Second, my brother recently changed the plugs on his renault scenic. Within a week one for the coil packs had gone. He replaced it. A few days later, another one went. Anyway it turns out that there are problems created with one or two brands of plugs in this car - ngk and bera I think. So its well worth while getting the OEM plugs!

Fran

 

[rallen]

OK point taken I am getting the Bosch anyway, and that's what's on the car right now.

 

[jberks]

Hi,
not had any problem with the coil packs and I am using NGK Iridium plugs. I doubt there is any real difference between them and the Bosch and I would have bought Bosch ones had I been able to source them anywhere conveniently, just because they are original fitment. The online boys only had NGK and posted them to me so it was just easier.
The first lead problem was down to corrosion inside the metal caps that fit over the plug - Dont ask how this corroded, in a hot sealed engine bay - but 4 of the 12 were bad with visible brown rust inside. The second lot looked fine, but replacing them solved the misfire and I can't argue with that.
I am bit surprised by the 20k schedule bit - Do double check it, as mine is definately 60k and the engines (inc the plug part numbers) are identical apart from the CC. I know there is a 5 year rule too hence why my dealer wanted to do them last November despite only having 45k on the clock, but I refused and only changed them when I got a slight misfire which magically corresponded with 59,750!!. They looked fine when I removed them - perhaps a slightly large gap but nothing to worry about and the miss turned out to be the leads anyway. For the first 4 years of ownership I was doing stop-start 8k per year so they didn't have an easy time, followed by a year of 100 mile per day motorway work and they were still working fine when I pulled them out.

If she's running well, check the 20/60k bit and if I'm right, I would recommend leaving well alone, you could easily get another 5 years out of them yet!

 

[rallen]

My theory about corrosion inside the plugs is you have had the engine steam cleaned?

My service book says (a bit contradictory I know):

Change spark plugs

1580 When more than 18,000-27,000 miles have been covered since last change. If the next interval is expected to be greater than 9,000 miles have the change carried out before the lower limit stated.

1580 When more than 30,000-45,000 miles or 4 years since last change

1580 When more than 55,000-65,000 miles / 4 years since last change

 

[thomasbeeton]

OK point taken I am getting the Bosch anyway, and that's what's on the car right now.

Hi,

I've just changed the plugs in my '98 C240 and everything seemed OK on idle however is reving upto 4K RMP it starts to misfire badly. Can anybody tell me if this is a lead problem. I've double checked all the connections they are secure. The plugs have a preset gap (Champions KC11PYP)
Is there an easy way to work out which lead or coil set is the problem?


Thanks


Thomas

 

[jberks]

Thomas, I believe your question has been answered on another post but if not let us know.

 

[jberks]

My theory about corrosion inside the plugs is you have had the engine steam cleaned?

Its possible the did it when I bought it, though at 11 months old I wouldn't have thought it was needed. Certainly I've never had it done - good theory though!

My service book says (a bit contradictory I know):

Change spark plugs

1580 When more than 18,000-27,000 miles have been covered since last change. If the next interval is expected to be greater than 9,000 miles have the change carried out before the lower limit stated.

1580 When more than 30,000-45,000 miles or 4 years since last change

1580 When more than 55,000-65,000 miles / 4 years since last change

err - very confusing - come on you dealer boys - explain that lot!
All I can say is the the dealer only suggested a change last November when the car was 4 1/2 years old and had covered 45k. I mentioned the 60k to him and he said it was time rather than mileage - so maybe as perthe last 2 lines. - certainly it was never suggested at 18,27 or 38k.
When I discussed it with the specialist he said that whilst they occasionally have to change them earlier than 60k, many have been running fine for 80k+. Its all a bit silly really. I'm sure the construction of the plugs is little different from the ones used the the US V8 Hemmy engines, and they have a 100k service interval.
In your position, I'd still leave it for now. As the engine is smooth, you'll notice a deterioration in the smoothness when a plug starts to give up.

 

[rallen]

The sample one I pulled out is darkened, but not oil and not soot. It just shows its age I suppose. Perhaps it could do with a good brush and clean, but once you have it removed you may as well fit a new one. Certainly I would never leave plugs unchanged for 4 years and the car is 4 years old now.

 

[rallen]

Ok job done. It took 4 hours including breakfast.

I devised a fantastic technique for pulling out the boots. I tied a tie clip around them, as shown in photo but a larger size, and then pulled the strip with a pair of pliers. It is a bit fliddly trying to make a noose and tie it around the rear ones, but there is no force involved, I had them all out in 15 minutes.

The most difficult part was to re-insert the boots. I wiggled them and some would snap into place. Others did not make a re-assuring click sound so am a bit worried they are not in properly. Assuming a few are not in properly, what behaviour ought to observe?

I attach photos of the old spark plugs, I think I was right to change them, they are rusty and look dirty.

 

[Bolide]

Four year old plugs

If that's what the plugs look like after 4 years then there's much wrong with that car, is there?

What do Bosch make them of? I guess all the closed-loop lambda stuff, engine management, fuel injection, electronic ignition, mapping & etc is to thank for this

The plugs in my 1975 BMW 2002 look worse than that after 3000 miles!


Nick Froome
www.w124.co.uk

 

[paulcallender]

Yep, I was going to say they look about right. I guess the limiting factor now, is that the rust which has developed on the exterior of the plug, could have gotten worse and combined with being in the engine so long, could have snapped upon removal, if they'd been left in longer (eg 5 years).

Nick, I'm guessing your fuelling system on the 75 BMW is 100 times less clever than the current electronic setup on modern cars, thus the engine would find itself running lean (extra heat) or rich (carbon deposits) on many occasions. It has 200 times the character, though, so its a big thumbs up for older cars from me!

 

[rallen]

Well the spark plug in my hayter lawn mower also gets filthy oily and covered in soot just after a couple of cuts I take it out, give it a good clean, stick it back in and the mower is like new again purring away at 3000 revs