The M104 straight 6 ( and the 4 cylinder version as well ) have two types of ignition coils but I've been unable to come up with any specs. I suspect it has something to do with primary resistance but have no proof.
The split interweaves a bit but it looks to be 96 and older ( HFM_SFI injection / ignition control ) has UF137 ( standard motor part brand ) 0 001 500 280, 0 001 587 003, ( Bosch ? ) 88921409, E537A


and 97 up ( ME SFI 2.1 injection / ignition control ) UF527 ( standard motor part brand ) 0 001 587 503 ( Bosch ? )

Any ideas? Thanks

We assume the car is nice and kept up in good shape, why do you want to go with the domestic coils? the car is designed with Bosch specs and should have the right Bosch parts in there. Or if you would like problems down the road go with the domestic garbage.

Meh... . Do you import fuel ( in sealed drums ) so your precious car avoids those awful USA fuel stations?

Standard Motor Products / BWD / Intermotor / 4 Seasons is a known high quality aftermarket brand. ( They have a high line and a lower T line ). Besides, I just used those part numbers as an example and said nothing about what brand I'm going to use.

You are aware that aftermarket Bosch isn't always the same as factory Bosch?

I've been in and around the automotive business since my mid teens, at 18 - 19 got full ASE ( NIASE back then ) Master mechanic cert for car _and_ heavy duty truck. Owned a shop for 10 years and now an engineer at a factory.

And now, in the other corner, introducing . . . . . ..

I didn't know that about bosch,I heard their quality has gone down since they started outsourcing.I use their coils,but haven't had luck with their plugs,they carbon foul.I use Denso 5061 plugs instead.

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

Here is what I've come up with, the coils seem to interchange but the older blue ones frequently fail. I'll have to look at the 2 or 3 bad ones I have sitting around, one side arcs to ground shutting of one plug while the other still works.

rounded with a blue sticker with part# ( frequently go bad ) first used in 93/4
UF137 ( Standard Motor Parts / Intermotor )
0 221 506 444 ( Bosch # )
000 158 70 03 ( MB # )


flat block with a black sticker with part# ( later coils ) introduced in 97 on SL320 and S320, used on all by 98
UF527 ( Standard Motor Parts / Intermotor )
0 221 506 002 ( Bosch # )
A 000 158 75 03 ( MB # )

Interesting, I own two M104 engines (94 and 95) plus a M102 (2000) and know others with both late and early coils.

Personally, I've not noted any higher failure rate on my early cars (94, 95) than what I've observed over my admittedly limited sampling.

Since the coils are interchangable, I'm going to keep this in mind whenever I come across any in the yards for spares.....

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

I'm with Jim, I have a 96 S320 and 95 SL320, and the coils are bullet proof. I know the "coils" are just a transformer coil with no active transistor potted parts like the M119 96-99 coils, so did the 97 - 99 M140 coils come with active transistor potted parts?

97 SL320, post a picture(s) of your coils. I have never bothered to look at the coils of M104 97-99 engines at the wrecking yards as I go a lot . Now you got me thinking?

Martin

Supposedly this is the TSB that talks about failing coils ( I don't have access to the actual info. ) af15.10-p-6700dv

The bad coils I've had were from a 97 E320 with ~ 200 K and 97 C280 with 161K.

I'll see if I can dig up any pics.