1998 300E TD, fuel shutoff mounting bolt strpped
 

The common o-ring leak on a 1998 E300 fuel shutoff has returned..... I replaced the o-ring less than a year ago and it is leaking again

So, I figured I'd simply just change it again and when removing the fuel shutoff mounting bolts, the most forward one (the recessed one) stripped out on me..... I tried using an impact driver to get it to turn but did not want to get too aggressive for fear of possibly damaging the fuel pump or the shutoff.

I think I'm going to have to drill the head off of the bolt in order to remove the shutoff and then un-thread the bolt with pliers or vice grips.

Any suggestions?

Thanks in advance!!!

also, is there a PERMANENT fix for this leak?....... I'd really rather not have to do this every 6 months.

Why not just use an extractor bit, they aren't that much and I've removed seized glow plugs with them, work like a charm. And it's most likely leaking cause you may have cross threaded the bolt and it never tightened properly. If torqued properly it shouldn't leak for at least another 5-10 years. It could also be the delivery valve seals leaking and the fuel running down the side of the pump.

Great idea but where can I find a T30 metric torx extractor bit?

Left hand drill will usually back out something like this. You can get a cheap kit in various sizes with EZ outs. Use one a little smaller than the screw diameter at first. If the left hand drill doesn't back the screw out, go in a little and switch to a size a little bigger than the screw, it will take the head off it. With the head off, you can remove the valve, grab the remaining stub with vise grips and break the loctite. Should come out with your fingers at that point.

Ok, so....last time that I replace the fuel shutoff o-ring I was able to access the two torx bolts without taking the manifold off...... This time, I have to because (and it's my fault) when I reinstalled the shutoff screws I overtightened them.... I remember turning them both that extra quarter turn.... duh!!

Anyway, looks like I'm going to have to pop the heads on both of them as the other stripped as well...... Does anyone know what size the bolts actually are, as in length and thread mm size?...... I'm going to have to try matching them with replacements that will more than likely not be torx head bolts!

Thanks,

I think they were 5mm. Can check here in a few when I open my shop. Thought I had lost one on my firend's car and grabbed one from work. If you go with a different bolt, they are an odd length. I had to cut a longer bolt down about 4mm to get the exact length. Also you will have to use an allen head bolt if not the torx. There is not room to get a socket on a hex head.

6mmx1 25mm under the head. Only had 20 or 30mm at work, so cut down a 30mm.

Had to order the bolts from the dealer as they did not have the bolts in stock, also ordered new o rings for the plastic lines but the dealer could not find copper crush washers for the lines. How tight should the bolts be? I purchased a new shutoff valve as O do not want to revisit this repair again.

Couldn't actually find a torque spec, so I ran them down firmly with a 1/4" ratchet choked up on the handle (head of ratchet in hand) and used blue loctite last time. When the valve itself turned out bad on my firend's car, I had to remove the loctited bolts again. No problem. Put them back in the same way.

The shutoff valve is plastic. Maybe you can just break it up and remove it, exposing the torx head bolts that hold in onto the injection pump. That would let you remove the bolts with pliers. The shut off valve costs about $150. [This might not work if there are metal sleeves that line where the bolts go through the valve.]

You can get new bolts from the parts desk at a Mercedes dealer. I thing the bolts they now sell have 10 mm heads. I heard from someone [parts guy at Mercedes or Peach parts] that the '99 e300 has 10mm bolt heads as original equipment for the same shut off valve as on the '98.


I've owned a '98 for more than 11 years and have changed that O ring twice. Neither of the ones I took off was leaking and the one most recently installed does not leak. I've used the original bolts the times I changed to O rings and just tightened them so they were pretty firm but not enough to strip the aluminum threads.

There are brass bushings about 1/2" in diameter set in the plastic. Trying to destroy the plastic to get the bolt out would be futile. I may be wrong, but I really don't think a 10mm hex head will allow a socket to fit, that's why the torx or Allen head.

Thanks for all of the great info, I got the bolts from the dealer and installed the new fuel shutoff with minimum torque as suggested by using a 1/4" ratchet.... seems reasonable.... I also changed all of the o-rings on the 3 fuel lines that go into the fuel shutoff valve.

Now, I'm reinstalling the intake manifold and decided to get the allen bolt started first (the one that you have to get from underneath using lots of extensions) and was able to do so with a bit of wiggling of the intake manifold.

But now, I am having amazing difficulty reinstalling the clamp that joins the pipe on the rear bottom side of the intake manifold to a fixed pipe that I believe goes to the EGR valve. It is IMPOSSIBLE to install that clamp with the bolt in, so after removing the bolt I have the clamp on but because the pipes don't line up perfectly and the EGR pipe is pretty stiff the gap inch the clamp is too wide and this approximately one in long bolt is not long enough for me to make the clamp.

Any suggestions????...... I guess that the obvious would be figuring out how to unloosen the EGR pipe so that the two pipes can mate perfectly.... I was hoping not to do that because there just aint a whole lot of room with the manifold in place...... I even took a block of wood and put it between the manifold and the head to get the pipes closer to lining up, but no cigar!!!

Any advice?

thank you guys as always

Fit the intercooler to manifold last, get the manifold egr together first then put manifold bolts in and tighten them up and then do egr bolt and then go under car and do intercooler pipe /manifold join.
The bolt under car can be awkward so get a bolt the correct thread size say 4 inches long , measure threads on original bolt and then put two nuts together and weld to bolt at that length setting and then weld a handle to make a T the other end.
Then its easy to fit and push up at the same time as you get it started.
I find you also need the egr pipe in place before the manifold is in position

The EGR pipe in inflexible, it doesn't budge and I have to seat the intercooler pipe into the manifold just to get close enough to get the clamp on the EGR. I have r by e champ on but because it doesn't line up perfectly, the clamp is spreading wider than the original bolt is able to reach the threads

Loosen and remove the lower bolt that holds intercooler pipe, then you can fit the intercooler to manifold connection last.
So manifold almost touching head and get egr connected ( no need to clamp it yet) and then when egr is joined to manifold drop manifold down that last inch or so and start putting bolts in.
Fit the clamp around egr and tighten and then just go under car and push the intercooler pipe in and tighten bolts up.
I have often wondered why its always described as a nightmare to fit manifold and I have never found mine hard to do at all !!! , because I have just realised the bracket is broken on mine at the lower intercooler connection so I am able to just push the pipe into manifold because it is flapping around . Once top bolt is tightened then the broken bracket holds the pipe in place.