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1991 420 SEL
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172 Posts
Discussion Starter #21
Ach that's the thing - the socket's a really nice vintage Proto. Needs must though. Or I could get an offset striking wrench - a 5 pound wrench!

Pete
 

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Premium Member
1999 500SL, 1988 SEC
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1,159 Posts
That socket would work fine. Nice in the. Collection too and a great brand. I would go for it
 

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1991 420 SEL
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172 Posts
Discussion Starter #23
MOSTLY done - that 'nice' socket I bought came in, and the bottom had been beat on so badly the male 3/4 drive won't fit, even after some filing.

It might have been OK, I have an old 5/8" drive adapter I probably could've made work, BUT - the sidewall of the socket is too thick and was hitting on the lip that holds the big rubber grommet on.

I could've maybe ground it down (or tapped it onto the strainer!) but it would've been a lot of grinding (or possible damage) and I said heck with it. I bought a 46mm crowfoot (Sunex 97446) off Amazon for $18 and will report back.

Everything else to that point is done and ready to go. A couple comments:

You need FOUR electrical connection grommets 123-997-1681 not the 2 I bought :rolleyes: Fortunately mine are fine and are being reused, as are the rubber mounts the whole shebang bolts to.

I have hose clampoff tools, that work like pliers, not the screw pinchoffs shown on the posted diagram. The main fuel line from the tank ('Fuel tank to Damper cage' 126-470-16-75) is so stiff they wouldn't close it all the way, and even with the pinch type I wonder if it would've worked.

So my idea of clamping off the line, cutting it below the clamp, and filling drain pans on rotation while dumping the full one into my big gas can didn't work, as I couldn't close the hole off completely. FORTUNATELY, I had a larger storage tote with no cracks handy and enough room under the car to get it under there. Otherwise I might've ended up with a few gallons of gas on my garage floor, not ideal! - I'd plan on not being able to control this flow if I ever do this again.

Otherwise removing the whole unit and working on it on the bench is nice. The fat copper washer that comes with the new check valves goes between the valve and fuel pump.

The fuel filter was already missing the insulating spacer a0000910182 so must have been changed at one point. I wrapped good quality duct tape twice around the new filter at the contact area and feel fine with it. The fuel pump insulating spacers were in good condition and so were reused.

Everything else went pretty well, I can't think of anything that stood out.

Hopefully completed tonight!

Pete
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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4,085 Posts
MOSTLY done - that 'nice' socket I bought came in, and the bottom had been beat on so badly the male 3/4 drive won't fit, even after some filing.

It might have been OK, I have an old 5/8" drive adapter I probably could've made work, BUT - the sidewall of the socket is too thick and was hitting on the lip that holds the big rubber grommet on.

I could've maybe ground it down (or tapped it onto the strainer!) but it would've been a lot of grinding (or possible damage) and I said heck with it. I bought a 46mm crowfoot (Sunex 97446) off Amazon for $18 and will report back.

Everything else to that point is done and ready to go. A couple comments:

You need FOUR electrical connection grommets 123-997-1681 not the 2 I bought :rolleyes: Fortunately mine are fine and are being reused, as are the rubber mounts the whole shebang bolts to.

I have hose clampoff tools, that work like pliers, not the screw pinchoffs shown on the posted diagram. The main fuel line from the tank ('Fuel tank to Damper cage' 126-470-16-75) is so stiff they wouldn't close it all the way, and even with the pinch type I wonder if it would've worked.

So my idea of clamping off the line, cutting it below the clamp, and filling drain pans on rotation while dumping the full one into my big gas can didn't work, as I couldn't close the hole off completely. FORTUNATELY, I had a larger storage tote with no cracks handy and enough room under the car to get it under there. Otherwise I might've ended up with a few gallons of gas on my garage floor, not ideal! - I'd plan on not being able to control this flow if I ever do this again.

Otherwise removing the whole unit and working on it on the bench is nice. The fat copper washer that comes with the new check valves goes between the valve and fuel pump.

The fuel filter was already missing the insulating spacer a0000910182 so must have been changed at one point. I wrapped good quality duct tape twice around the new filter at the contact area and feel fine with it. The fuel pump insulating spacers were in good condition and so were reused.

Everything else went pretty well, I can't think of anything that stood out.

Hopefully completed tonight!

Pete
Good job, Pete. I use Vicegrips with a section of rubber tubing on each jaw to clamp fuel hoses. Gives you plenty of leverage for a stiff hose.
 

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Registered
1991 420 SEL
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172 Posts
Discussion Starter #25
Thanks Lucky, I'll remember that.

Had to work late so I didn't get it finished, but the strainer is changed so it's all downhill from here!

The old strainer was in nice shape, just a little brown, happy. This whole car is so nice.

Anyway, I got the big crowfoot and had to grind down one 'leg' to fit it. Even then it only turned a little bit (man that sucker was TIGHT, old rubber seal), but it was enough for 12" channellocks to finish the job. I also used the channellocks to tighten down the new one. No issue.

I suspect a pair of 16" channellocks may have worked to remove it from the start. Regardless, if I do this again I will get a non-striking offset 1-13/16 wrench off ebay. Although there's none for sale at the moment, a completed listings search shows 2 used ones sold recently at a very reasonable price, so if you planned for this job you might land one. This would almost certainly turn the filter into just another 'bolt'.

A 3/4" crowfoot wrench tightened the 19mm return line to the tank nicely (my metric set only goes to 18mm). To remove the old one I just cut the line near the fitting and stuck a socket on it.

Per someone's rec here, I seated the main feed line into the tank filter then removed it, before installing the filter. This seems like a good idea.

I do have things to do this afternoon after work (periodontist for the first time) but still hope to get it buttoned up tonight. My wife would like 'her' car back!

Pete
 

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1991 420 SEL
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172 Posts
Discussion Starter #26
Giant idiot alert!

Finally got it all back together, 99% certain all is good.

Go to fire it up and - gas spraying everywhere. It looks like it's coming out of the front electrical connection of the forward pump - spraying hard.

I suspect (know?) I over tightened the check valve/hose banjo bolt. So the question. How likely is it that I actually damaged the pump? Can you crack the housing? It sure looks like it's spraying near the electrical connection, not the fuel line connection.

Yikes.

Pete
 

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1991 420 SEL
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172 Posts
Discussion Starter #27
I looked again a few times - I'm pretty sure it's leaking from around the electrical connection stud.

I'm guessing I over tightened the electrical connection. Maybe it was ready to go lol

Darn it.

Pete
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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4,085 Posts
Unless you really overdid it, I doubt the electrical connection is leaking. Hopefully it's a bad copper washer.

I suggest drying everything then having an assistant turn the ignition key to run (not start) while you observe the pumps. This gives you a two-second burst on the pumps to get the pressure up, and hopefully you can see the origin of the leak. I suggest using a very bright light and maybe even blowing some flour or something on the dry pumps to highlight where the leak is when it starts.

I've fought with the copper washers not sealing. I accidentally barely scratched one of the banjo surfaces of the metal tube that connects the two pumps and the filter and ultimately had to file the surface to get it smooth again. Just pointing out that the surfaces can easily cause a leak.
 

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1991 420 SEL
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172 Posts
Discussion Starter #29
Thanks Lucky. I'm settled down now. I want the job done!

I've heard about the copper washers not sealing and it surprised me somewhat as I've been installing them occasionally for years on domestic brake pigtails with no issues. So I tightened the heck out of them on this job.

It's spraying out pretty heavy. So if it's a washer it almost has to be a crack on the thick washer on the check valve and I can't figure out how it would spray the direction it's spraying, basically straight out from the electrical stud. But it could be bouncing off? I got a face full trying to track it down :eek:

So heck I went ahead and ordered the Bosch pumps, $180 for both on Amazon. I'll try heating the new copper washers for the banjo bolts.

Pete
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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4,085 Posts
Pete, sounds like you're well on top of things so we'll wait to hear the good news. That's a great price on pumps.
 

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Moderator
1991 500SEC sub 50K mi. 1987 560SEC Now 150K mi. 2018
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4,283 Posts
Hey Pete,

I the MBCDs there is a reference torque on the check valve of 22nm or a scrunch over 16ft/lbs.

When I did mine, I used new ones from MB. They are made like little copper wave washers.
I have never seen any like that before.

M.

IMG_3948.JPG
 

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I " wave" my copper washers also prior mounting. The wave slightly reduces the inner diameter with the positive effect that the washer doesn't fall off so easily when you are in a tight spot and are bending backwards to try to fiddle in the bolt plus washers.
The other thing on bending the washer is to feel if they are still soft enough to be compressed and actually seal off. If not then heat em up until the are cherry red, dump em in a cup of water and they are ready for re-use again.
 

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1991 420 SEL
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172 Posts
Discussion Starter #33
Super interesting, thanks guys! I'll heat and wave them :)

Probably tonight.

A note on safety. As I get older I've become must more likely to use safety gear. I had attempted to use my full face shield while looking for the source of the gas spray but it was too dirty from grinding work so I set it aside instead of stopping and cleaning it. If I didn't wear glasses I would've been gassed in the eyes. Just FYI.

Pete
 

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I " wave" my copper washers also prior mounting. The wave slightly reduces the inner diameter with the positive effect that the washer doesn't fall off so easily when you are in a tight spot and are bending backwards to try to fiddle in the bolt plus washers.
The other thing on bending the washer is to feel if they are still soft enough to be compressed and actually seal off. If not then heat em up until the are cherry red, dump em in a cup of water and they are ready for re-use again.
Super interesting, thanks guys! I'll heat and wave them :)

Probably tonight.

A note on safety. As I get older I've become must more likely to use safety gear. I had attempted to use my full face shield while looking for the source of the gas spray but it was too dirty from grinding work so I set it aside instead of stopping and cleaning it. If I didn't wear glasses I would've been gassed in the eyes. Just FYI.

Pete
[/QUOTE

Probably the only safety gizmo I would use is to avoid smoking while searching for a fuel leak:eek:
 

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1991 420 SEL
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172 Posts
Discussion Starter #36
Heated, waved, installed!

And leak free. Thank goodness. My little hose replacement project turned into a complete rear fuel rebuild costing more than tires.

Still have a hard cold start, darn it, and still have an occasional whiff of gas.

But one big thing done. Next!

Pete
 

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Regarding the whiff of gas, are all hose connections on the tank connected and are the hoses in good shape? Have you tried removing the back rest of the rear seat to check around the level sensor?
 

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1991 420 SEL
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172 Posts
Discussion Starter #39
well now I'm sick, a pretty bad cold, glad she's running.

As of now, all hoses in the back are new. There are no leaks. I do have the sending unit oring to change as well as the fuel filler neck grommet.

The gas smell seems a little stronger now, maybe the system pressure's up a bit with the new components. I did have some small seepage around the ETA and will look at it again once I feel better. All I have to do is goose the gas petal a bit on a cold start and it's fine, but no! No I say! :-D

In the meantime, I'll bask in the warm glow of new rear hoses lol

Pete
 
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