1999 ML320 Spark Plugs

[Mikesmerc]

Hello all, going to do a general service on the above car this week end. Have ordered brake pads, oil filter and oil. Went to purchase Bosch spark plugs and the gave me 12 platinum plugs. Is this correct, two per cylinder? and what type of Bosch plug should be installed?
Thanks
Mike

 

[Bob.R]

Did one of these a couple of weeks ago there are two for each cylinder. Platinum plugs are supposed to last 60k miles, just as well - Fiddly job as there is not much room - you need several small extension lenghts for different plugs, and it is time consuming - took me about an hour. Just follow each lead down and work from there.........
I bought plugs from a Merc dealer to be safe - didn't want to change them again..... Cost just short of £100 for the set inc. VAT.

 

[jberks]

Platinum or Irridium are fine, just not copper. If they cost much less than £100 for the set of 12 (twin spark), be suspicious. As above 60k lifespan and given how tricky they are to install, just as well.
I did my E240 (same block) some time ago. All I can say is take your time and ideally have someone with good dexterity and strong fingers around. Also, a good range of socket set bars and UJ's are essential. One of the plugs is at the back of the engine and the rest aren't exactly accessible. I removed the MAS and pipework and I should have removed the engine cover too.

Not only are the plugs a nightmare to access, the plug leads are a b.tch too. They are a VERY tight fit and 'click' onto the plugs. Took me a fair amount of pushing and twisting to get each one back on properly. Pushed on gently, they appear ok, but until they've clicked, they aren't and you will get a weaker spark.

 

[Mikesmerc]

Thanks for the help guys, could I just ask, the plugs(BOSCH) I got have only got a single contact not twin like my old CLK, is this correct? Hve to make sure as it sounds like a bit of a pain.
Thanks again
Mike

 

[Uncle Benz]

Plug leads are indeed very difficult to pull off. Try a little bit of to and fro twisting ( not excessive ) before pulling them off. Be aware that if you detach them from the coil pack end it is very easy to misalign the connector with the pin in the coil pack terminal and end up with a bad connection. From memory these are a single electrode plug, but I am sure someone will confirm this.

 

[jberks]

They can be single electrode. The important factor is the material they are made from. Copper wears out too quickly, hence plantinum or irridium. One pin, multi pin, forked anode etc are all down to personal preference. I paid a bit more for irridium fine pin plugs with a funny anode as they are supposed to be better. I can't say I noticed any difference though and sold the car 9 months later so basically wasted money.

 

[Mikesmerc]

Thanks for the info guys.
Rgds
Mike

 

[artois]

Hello all, going to do a general service on the above car this week end. Have ordered brake pads, oil filter and oil. Went to purchase Bosch spark plugs and the gave me 12 platinum plugs. Is this correct, two per cylinder? and what type of Bosch plug should be installed?
Thanks
Mike

hi mike,
i too am about to do a service on my 320 & was wondering if you done yours ok.
any major problems or things to look out for.
were the brakes easy enough to do i have do them on my other cars but this is my first merc
thanks

 

[basharv]

I used a 17mm spanner to gently ease the caps off on my ML350. It worked a treat.