How do I remove the rear seat on 300SDL - PeachParts Mercedes-Benz Forum

MercFan · #1 11-13-2009, 01:22 PM

This is for the 1987 SDL - need to remove the rear bench seat - the thing is mechanized - ie. you can slide it in and out - what's the trick of removing it so I can access the Fuel Sending unit - which needs to be serviced.

Thanks,
james

Ian White · #2 11-13-2009, 01:26 PM

You will have to remove the seat back. The lower seat has two 10 mm bolts which attach it to the sliders. The upper seat will pose more of a challenge. You have to remove the hinge pins where the seat hinges to recline. They are a bear to get out.

ah-kay · #3 11-13-2009, 01:27 PM

Wow, you have the reclining back seat option. It is nice. I hope it works as mine did not work and I spent a lot of time fixing it.

Remove the 2 bolts at the front of the bench seat to lift the seat. It is similar to others except they use 2 clips.

I think the fuel sender unit is under the First Aid cover. Access it from the top. Other members can help.

Ian White · #4 11-13-2009, 01:30 PM

Quote:

Originally Posted by ah-kay

Wow, you have the reclining back seat option. It is nice. I hope it works as mine did not work and I spent a lot of time fixing it.

Remove the 2 bolts at the front of the bench seat to lift the seat. It is similar to others except they use 2 clips.

I think the fuel sender unit is under the First Aid cover. Access it from the top. Other members can help.

Correct, Mercfan, you may find that it isn't required to remove the entire seat, The fuel sender can be accessed underneath the rear parcel shelf. If it is the same as a 560sel, which I'm sure they are...

MercFan · #5 11-13-2009, 02:13 PM

Quote:

Originally Posted by Ian White

Correct, Mercfan, you may find that it isn't required to remove the entire seat...

That would be awesome if I didn't have to remove the seat - I've looked into the first aid kit compartment but it looked like it was not possible to pop it out without removing the entire parcel shelf first... Is this the best way?

Looks like the first aid box is sandwiched in-between the parcel shelf on top and the trunk cover)... how do I remove it?

MercFan · #6 11-13-2009, 10:48 PM

Bump - anybody ever removed the parcel shelf in the 300SEL or SDL?! Everything is pretty brittle back there from years of Texas sun...

TheDon · #7 11-13-2009, 10:58 PM

Quote:

Originally Posted by Ian White

Correct, Mercfan, you may find that it isn't required to remove the entire seat, The fuel sender can be accessed underneath the rear parcel shelf. If it is the same as a 560sel, which I'm sure they are...

I'm not sure sir.. I had my rear seat out on the SDL and it appeared that the sender is accesed from the bulkhead behind the seat.

quaid · #8 11-14-2009, 01:26 PM

The first aid compartments should lift out from the front edge once the screws are removed. On my car they are pretty tight.

You should then have access to the fuel tank sender through the openings left by the compartments.

The rear seat doesn't need removing for what you are trying to achieve.

MercFan · #9 11-14-2009, 08:47 PM

I spent few hours today removing the back seat to access the Fuel Sender unit. I went for it since it seemed easier than removing the parcel shelf after looking at it for a while.

First I removed the two 10mm bolts in the foot wells, which allowed me to slide out the bench and remove it from the car. The back rest looked like it was going to be tricky - I've started by removing three 10mm bolts that holds the back rest in place. This allowed me to pull on the bottom and swing it out with only the hinges supporting it on top. I dove under there to see what I can do next and it looked it was going to be a fight... retreated a bit and took another look. Turned out that I could remove a 10mm bolt on either side down by the motor sprocket on each side. This made the whole thing swing up and allowed the seat to just lift right out of there -voila!

Found a small treasure trove under there of old pens, some change, a playing card, Clinique mirror, one puzzle piece, gum wrappers, hair pins and a couple of pencils...

Most importantly, it allowed me a clear access to the Fuel Sender unit - which was the primary goal. I can now conclude that (see the photo below) that it would not be possible to access the fuel sending unit on my car through the first aid box... It's in such location that you have to remove the seat to get to it. My luck continued - I was able to source a large (I think 2 1/2 inch) socket from my neighbor to remove the 45 or 46mm nut around the fuel sender, which came out quite easily and it was filthy - see the rest of the photos.

The last photo shows a little tool I make out of aluminum strip to remove the little nut from the end of the sender unit - it was the only way I could get it off - I didn't have minature pliers.

I cleaned it all off with Brake Cleaner, I cleaned all the contacts and wires gently with fine sand paper and I measure resistance on the wires.

For those interested there were three prongs on the Fuel Sender Unit marked W, T and G. Here is the resistance measurement between them (after thorough cleaning). I performed measurements with the float either all the way up or all the way down as follows:

G to T with float up = 2.8Ohms
G to T with float down = 81.4Ohms - (variable resistance depending on location of the float)
G to W with float up = Open circuit
G to W with float down = 81.5Ohms

Judging from these readings, the G and T plugs control the fuel level indicator. The G and W terminals control the fuel reserve light. The circuit between them is open, until the float is all the way down and then the resistance goes up to 81.5 Ohms.

That concludes this task (at least for now) - time will tell if this fuel sender unit is performing properly.

Thx to all for your help.