D.I.Y. Info for Changing Fuel Filter on 300E
 

I've tried searching but haven't found D.I.Y. Info for changing the fuel filter on my '91 300E. If anyone has a link to this type of Info, I'd appreciate it.

I suppose my primary question is if and how the lines to the filter are handled to prevent fuel from escaping while the filter is being changed. Also, if I buy the filter from a dealer will I get all the parts that I need to change the filter?

TIA,
Bud

Last time I did this on my 190E, I only disconnected the battery. Loosening the lines lost about 100ml of fuel, most of which ran out of the fuel filter. There will be some pressure in the system but if you are prepared for the fuel leak, it's no big deal. Just be careful whenever you are dealing with fuel to avoid sparks and heat.

depressurizing the fuel system
 

i always pull the fuel pump relay or fuse and crank the engine for a few seconds to release the built up pressure in the accumulator and fuel lines. lessens the amount of fuel spilled or worse, sprayed. wear glasses when you crack a fuel line!

You can clamp the fule hoses to the fuel pump/filter assembly with some small size carpenter clamps, it can save you a big mess.

Don't know about 300E, but for my 400E, i need more copper gaskets besides the fuel filter kit I got, those gaskets can only be used once, fuel pump/filter use almost a dozen of them.

I did a fuel filter change on my C -class for the first time last week, and learned some stuff.

When you buy the filter, if you do it at a dealer, take your vehicle vin number so they can see what type of connections are used to connect the hose to the filter.

My car used clamps, so I purchsed new clamps ( screw connnction ), however the old OEM clamps on the car needed to be cut off, they didn't screw tight but used some kind of interlocking snap. I used a utiliy scissors to snap the old clamp apart.

Some models use union nut and bolts with copper washers, copper washers for this type of filter have to be replaced.

I did disconnect the negative terminal from the battery, I also removed the fuel filter cap to relieve pressure.

The filter under the car is protected by a plastic shield, I needed a twleve inch extension to poke throught the access holes in the shield to reach the plastic nuts attaching the shield to the car.

Some filters use an insulation cover which can either be replaced or reused, and notice the direction arrow on the filter, so new filter arrow points in same direction.

The filter itself may be attached with it's own bracket, easy to loosen with a screw driver. The rubber fuel lines if attached by clamps need a little prying and twisting to get off. A catch bucket for spilled fuel and two hose clamps - small vise grips utilizing some kind of soft surface that touches the hoses - can be used to squeeze the hoses. actually not all that much force is needed to squeeze the hoses closed.

Need to be careful that any fuel spill is minimal and that tools are not banging about which can produce sparks. I doubt a fuel filter change can produce enough fumes to ignite - but be careful.

Everything goes back together easily, reconnect the battery, and when you start the car - expect a little extra crank as the fuel pressure builds up again.

Actually there is a little test you can do with the old filter, blow through the old filter in the opposite direction the filter arrow points ( don't put your mouth on the filter, maybe a little tap that won't ignite a spark ) and collect fuel and debris on a white surface. Check for any rust colored particles or anything to TRY to tell how much dirt was collected.

Thanks to everyone for the great Info. The car has 63K miles on it so I assume it's time for a filter change.

My setup looks like this, but you may have 2 pumps.
The filter is #55 in the image.
Pretty straightforward, but messy.

I did the one on my 190 last weekend.
It was quite a messy job.
I disconected one of the fuel pump teminals (as I cant seem to access to fuse) and ran the engine until it died (a few seconds).
This releases a bit of pressure in the fuel system.

Make sure you disconnect the battery to avoid sparks.

Some fuel will be lost but not as much as I was expecting.

Its an awkward job and this is what takes the time not the complexity.

I found I had to take all the clamping nuts and bolts out before I could take the old filter out.

I found very little difference to the car once I had done it. But it is a service part that needs doing.