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Problem removing spark plugs

5K views 7 replies 2 participants last post by  OldDawg 
#1 ·
Hey guys,

I got a set of Bosch plugs, a cap and rotor and set to work and noticed that the plugs that were in there were the correct Bosch plugs, but they used an 11/16 (18mm) socket. The new ones I got use a 5/8. This is the first time I've been in there and so I was shocked to find how deep the plugs were in the head. I can't get the 11/16 socket in there for fear of it dropping off the extension. The hole is very tight in the valve cover, I think I could force it, but I don't want to.

Do I have to remove the valve cover to get the plugs out?

Anybody have experience with this?

thanks,

Dave
91 3.6
Glanschwarz
 
#2 · (Edited)
Hi,


I suspect you may have had Bosch X5DC in there before, which are 18mm plugs.

The correct spark plugs are most definately still 16mm socket.

You have the correct Bosch Y6DC now?

If bought from BMW, they're in a white box with the part number 12.12.9.061.867 for the S38B36.

No other plug than the Y6DC will do, the heat range of this engine specifies these plugs only.

Champion used to make a similar unit, the A6DC, which was sold as compatible, but when compared side by side, they were obviously wrong. They are *not* recommended for the S36B38/S36B36 engine.





There is a BMW spark plug removal tool in the toolkit in the boot. It will do, but I bought a thin T shaped one from an auto store which I find easier. You have to undo and remove the plastic cover, obviously, but after that, nothing else comes off, you just pull out the distributor cables and their long stalks that go down to the spark plugs and then you're ready.

The plugs are very deep, it is really one of those cases where it takes ten seconds with the right tool and a hours of cursing without. With a thick socket set instead of a spark plug spanner, you are most definately without!

Looking on the net, if the tool in the trunk goes missing, BMW make a "BMW Rubber Insert Socket", part number 88.88.6.121.171 but I have no idea, never seen one.





A story:
When I first got my M5, the BMW tool and both sizes of spark plug spanner I bought, 16mm and 18mm, (M5 is 16mm, M30 535i is 18m) would not remove the spark plugs. Confused, new to the car, unable to see into the dark depths of the wells, I had to give up and went cap in hand to the local BMW independant mechanics. They started grinning at my metric tools, then pulled out a roll-up bag of surgeons sockets, all greasy and used, but thinner by far than a normal socket set. After peering down the wells, their trained eyes pulled out one imperial size tool and undid the spark plug. Lo and behold, a imperial sized "split-fire" sparkplug completely unsuitable for the engine!


Regards

Ivan
 
#3 ·
Ivan,

Thanks so much for the reply.

I didn't even think to look at the toolkit. Lo and behold there's a socket in there that matches the new plugs I got. They are so I'm guessing the PO's mechanic used some Bosch plugs that were 11/16 and had a socket that would fit down the hole. I can't get my socket down there and I even went to the parts store to see what other tools they have. They don't have any "thin wall" 11/16 sockets. I guess I'll have to look online to find that tool. I think I'll put it all back together till I do.

The new plugs I got are definately Y6DC's. They have a number on them R0 285 and the old ones say R0 291. Not sure what the diff is other than the wrench size. Any ideas?

Again, thanks for the quick reply.

OldDawg
(Dave)
 
#4 · (Edited)
I tighten mine by hand, but if you have a suitable torque wrench, the correct torque range should be 15-25 Nm (11-19 ft-lbs).

If using a socket rather than the BMW toolkit tool to fit your new ones, I understand that you'll need a 16mm socket with under 23mm outer diameter, preferably 22mm.




You say the new ones are Y6DC for sure, but you don't say whether the old ones are or not. It should be marked below the ceramic collar, below the bolt, above the thread. There's a metal collar with the model number engraved in it. Should say Y6DC Germany.

On the ceramic collar, the brand new set of Y6DC I have here to go in the car soom have R0 291 printed on them.

I suspect this is a batch code or manufacturing quality control mark. No results come up on Google at all, so Bosch and spark plug vendors are not using it.



Regards.

Ivan
 
#5 ·
OldDawg said:
...I can't get my socket down there... don't have any "thin wall" 11/16 (18mm)... the old ones say R0 291


I'm confused.

You can't get the incorrect 18mm plugs out of the engine as you don't have an 18mm (11/16) socket that will reach them, but you know the old plugs hav R0 291 on them? How, if you can't get them out?

If you do have the wrong plugs installed, then your best bet is to do as I did and find a local grease-monkey with a slim set of tools. Any old-skool garage will have seen this situation before.
Alternatively, you'll need to get a metal workshop to lathe off an 18mm (11/16) socket until the external diameter is 22/23mm or so. A pain unless you know somewhere!





Just to clarify, on the E34 M5 3.6, the correct spark plug is a 16mm (5/8) Bosch Y6DC. Anything else on the 3.6 is incorrect.

The new Y6DC plugs I have here from the BMW dealer for the 3.6 car also have R0 291 printed around them but this appears irrelevant.



Hope this helps!


Regards

Ivan.
 
#6 ·
Ivan,

Yeah, I apologize, I got #1 out no problem. My 11/16 sparkplug socket fit in the #1 hole, it does not fit in any of the others, I don't know why. It seems like if I force it, I could get it in, it's that close, but I don't want to do that. I think I'll do as you say and look for a thinwall 11/16 socket somewhere.

I didn't see the stamped # on the sleeve before, and it's wrong. It says X5 DC Germany. The new ones do say Y6 DC. Interesting.

So I'll put it back together and wait till I have the correct tool then.

thanks again,

Dave
 
#7 · (Edited)
IvanDias said:
I suspect you may have had Bosch X5DC in there before, which are 18mm plugs.
OldDawg said:
it's wrong. It says X5 DC Germany
I rock! :bullseye: :haha:




Thought so, someone has used the 18mm X5DC plugs from the E28 M5 and E24 M635CI instead!

The 5 is one heat rating below the 6 of the correct unit, so I doubt that any harm was done. I suspect it would take a lot of very hard driving over time to cause any real damage.





To remove the X5DC you'll need a very slim 18mm or 11/16in socket with 22/23mm or less outer diameter (most are 24-25mm OD)

I reckon you will win if you can try an 18mm version of the BMW trunk tool.

The M30 6 cylinder car uses 18mm spark plugs, (certainly my 535i does), so as that engine was used in so many BMWs, shouldn't it follow that the thin BMW sparkplug tool from the toolkit in the back of another car be ok for you?

Even if it isn't quite long enough, it won't be hard to make or improvise a way to attach it to your existing tools in order to remove the incorrect plugs in this one off scenario.

That means you can go beg/borrow/steal one from another M30 engined car, be it a friends, your local independant BMW mechanics or a scrapyard! That also means you can get one from an older 730/735 series if you can't find a 530/535.

Shouldn't be too hard to get in your area of the world.





Alternatively, a very old post on unofficialbmw.com from ages ago lists the following information and contact details for a suitable third party tool to remove the X5DC sparkplugs.

The telephone numbers date from 1997, so may well be invalid.

Quote:
"18mm or 11/16in socket with 23mm or less outer diameter (most are 24-25mm OD)
Trunk tool kit plug wrench
BMW Rubber Insert Socket 88 88 6 121 160 $36.97
USAG Magnetic Insert Socket $44.50, Europroducts 800.850-0325
Hazet Magnetic Insert Socket $40, Steve D'Gerolamo, 201.262-0412"


I think you need to trawl the scrapyards or go asking for a suitable donors owner in Walmarts car park!

Regards

Ivan
 
#8 ·
Ivan,

You DO rock, thanks.

I will look for that tool at some local junkyards, I'm sure I can find one.

Thanks so much for your help and quick replies. As I sit here in my overalls running back and forth from the car to the computer, I anxiously awaited your replies ;) I've got it all put back together now and hopefully next weekend, I can finish the job.

I've had a lot of cars in my day, and I just love this thing, it truly is handcrafted. I love looking around and learning something new about it everyday.

I hope I can help you someday,

till then,

Dave
 
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