M104 Engine What to Look For
 

Dear Folks -

I'm looking to get a '95 E320 to replace my 189K '91 2.6...and have seen some of the posts regading the "peculiarities" -- wiring harness, etc. There is a pretty constant supply here in the Metro DC area......

Were these ever replaced under warranty, so that there may be records within the M-B system under the VIN?

Is there a way to tell if it's ever been replaced? I've also heard of a weakness in the "actuator" - is this the M104 version of the old fuel distributor??

Also, looked at a '95 that had obviously had a light respray on the bumper and clearcoat "freshening". Don't believe it was really hit, but rather cosmetically gone over. However, the outside air temp sensor (behind the front license plate, right??) was tucked inside the bumper cover which I believe led to a steady reading of 107-108 degrees. All of the other electrical seemed to be in good order, other than needing an A/C recharge.

Any comments or further "look for's" wowuld be appreciated.

Marc G.

Many head gaskets were replaced under warranty. I believe very few were replaced under the original 3-year factory warranty, but a lot were changed out under either the Starmark Warranty or as a "goodwill" warranty if the gasket failed outside of either of the two warranties.

Without the records or a VMI, Vehicle Master Inquiry, I have no idea how you could tell.

The throttle actuator is a part that replaces three separate parts in M103 and other engines. It functions as the: EA (electronic accelerator), CC (cruise control), and ISC (idle speed control). Actuators go bad eventually in all engines that have them: M104, M119, even the newer engines (M112, M113) have them. They haven't generally failed yet on the newer engines because not enough time has gone by yet. It is heat that generally kills them. Throttle actuators also fail on '93-'95 cars because the wiring harness on the actuator goes bad.

Sooooooooo, in addition to looking for head gaset leaks (at the right rear corner of the head, passenger side), look and see if it has had the engine wiring harness replaced. They are defective on all 1993-1995 Mercedes vehicles.

suginami,

Question for you.
I know you know alot about this motor.
Does the M104 in the 96 W210 have the same problems with the wiring harness? I always get mixed answers on this question. If so about how many miles do you start to see the problem.

Thanks

No, the engine wiring harnesses were fixed in mid-year 1995, according to Stevebfl (Steve Brotherton).

I know a bit about these cars as my 1993 300E (3.2) "E320" suffered from all of the weak points during my ownership: engine wiring harness (replaced under goodwill warranty), head gasket, throttle actuator, etc.

If you really want to read replies from an expert on these cars, do a search of Arthur Dalton's posts.

"AC recharge"

Look out...if the evaporator is leaking its $$$$ to replace - the whole dash has to be pulled....labor intensive and not a DIY for the mortal man.

Thank you.

Wiring Harness M104
 

This must be a H O T running engine. I took apart my harness last weekend for a problem of hesitation under heavy acceleration and finally at idle. 92.000miles.

The heat of the engine seems to "bake" the insulation on the harness, and the vacumn tubing, for that matter. When a mechanic replaces the spark plugs, it's easier to "flip" the harness out of the way with the resistors in place. Therby putting rotational forces on the wires & insulation.

Each time this happens, the now baked non flexible insulation cracks and exposes the underlying wires. Eventually, arcing and finally grouding out the firing of the sparkplugs.

I was able to buy the new plugs with wires attached and solder them into the harness, connecting to the "good" wire (flexible) about an inch away from the engine. (This was done against advice, from those wiser than me in this forum)

However, what a difference! running smo o o o thly

However, I do have a harness on it's way from Germany ( gray market vehicle) that I will replace upon it's arrival.

Cheers, Bill in Boston