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Inside the WUR

Started by Feather535, 18 December 2022, 08:27 PM

Feather535

IMG_4284.jpegIMG_4284.jpeg 

Thanks.  Let's see if this works.
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1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

revilla

Your setup looks correct.
This is what I'll do, if you decide to do this test please be very very careful. If you're not confortable with it please don't try.
Engine off, key in position 1, disconnect blue connector on FD. Pump is now running. Look at your gage. Very slowly unscrew the return line at FD head. Very very slowly with a rag underneath to capture fuel. When the first drops start leaking, does the pressure go down? Let more fuel out, pressure goes lower? If yes, you have a blocked return line. Go closer to the tank you should hear fuel flowing into it. Repeat the same exercise after reconnecting the return line but this time unscrew the fuel pressure regulator (16mm wrench) on top/front of your FD. Very slowly again until first drops leak. Lower pressure? Unscrew more but never completely. Pressure goes down? Same exercise but this time with the 12mm line on the side of the pressure regulator. With pump running you should see fuel flowing out. If not, either the orings inside the regulator are damaged (there are a total of 3: tip, middle body, small inner chamber), or the guts of your FD need to be rebuilt. The WUR is the other option, but I have never seen this extreme CP >5bars situation before related to WUR adjustment.
In your other post you asked about how to set this up. You don't need to reopen the WUR as you're dealing with a high pressure issue. You need to tap that insert that connects the bimetallic strip and the "valve". Basically tap it inward so the gap between the WUR top surface and the insert increases. Essentially you are "opening the valve" to let more fuel pass through decreasing therefore the CP. Before tapping, observe and measure the gap between surface and insert. For a CP >5bars so should have zero mm gap. Tap very carefully but firmly. The insert is solid but sensitive at the same time. If you overdo CP will then be too low. Then you'll need to tap it outward from the inside of the WUR. This can be painful with multiple iterations, but this how we learn the mechanics of how things work. This is a trial, measure, error type approach. Measure that gap with a digital caliper if possible. You're looking at 1-2mm no more. This is assuming the guts of your WUR were correctly assembled. I'm a bit worried with the part where you blew compressed air through those ports. The metal plate is so delicate, hope it's not damaged. Worse case send it out for repair/calibration. Plenty of sources for that in the US.
Please keep us posted.
R
Robert
W116 1977 280SEL & 1979 280SE
[img width=150 height=100][url="http://revillagodfroy.com/MB%201977%20280%20SEL/album/thumbs/IMG_0371.JPG"]http://revillagodfroy.com/MB%201977%20280%20SEL/album/thumbs/IMG_0371.JPG[/url][/img]

daantjie

I feel for you guys with the 280 engine, the WUR is in such a crap location!  On the V8 it could not be easier to access.
Daniel
1977 450 SEL 6.9 - Astralsilber

Feather535

Un grand merci Robert.  I will do these tests, but I have one question.  Where you say

Quote from: revilla on 30 January 2023, 12:36 PMSame exercise but this time with the 12mm line on the side of the pressure regulator.

do you mean the smaller fuel line just to the rear of the 16mm fitting on the pressure regulator?

No need to worry about the thin steel diaphragm in the WUR, by the way.  It was removed when I blew air through the ports, and I replaced it with a new one anyway.

I'll do the tests and report back.  Wish me luck!
--------
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

Feather535

Quote from: daantjie on 30 January 2023, 01:25 PMI feel for you guys with the 280 engine, the WUR is in such a crap location! 

Yes, it's awful!  One of the worst locations for a critical component on any car I've worked on: difficult to see, let alone reach with tools.  And filthy, at least on this particular car.

In one of his videos, Kent from mercedessource.com shows how he relocated the WUR on an M110 to a place behind the fuel distributor.  That would be a huge improvement.  I could probably fabricate a bracket and reroute the wiring and vacuum lines, but I don't know what I'd do with the hard fuel lines. 
--------
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

revilla

Quote from: Feather535 on 31 January 2023, 10:02 PMUn grand merci Robert.  I will do these tests, but I have one question.  Where you say

Quote from: revilla on 30 January 2023, 12:36 PMSame exercise but this time with the 12mm line on the side of the pressure regulator.

do you mean the smaller fuel line just to the rear of the 16mm fitting on the pressure regulator?


Yes, exactly that line.
Robert
W116 1977 280SEL & 1979 280SE
[img width=150 height=100][url="http://revillagodfroy.com/MB%201977%20280%20SEL/album/thumbs/IMG_0371.JPG"]http://revillagodfroy.com/MB%201977%20280%20SEL/album/thumbs/IMG_0371.JPG[/url][/img]

revilla

Quote from: Feather535 on 31 January 2023, 10:08 PMIn one of his videos, Kent from mercedessource.com shows how he relocated the WUR on an M110 to a place behind the fuel distributor.  That would be a huge improvement.  I could probably fabricate a bracket and reroute the wiring and vacuum lines, but I don't know what I'd do with the hard fuel lines. 

Haven't seen the video, but that's what I've done years ago.
Vacuum line = no problem
Wire harness blue connector = no problem
Plastic FOT vacuum = no problem
In/Out fuel lines I replaced them with fuel hoses.
Fuel pulse damper was also relocated next to FD (1977 model) MB already relocated that damper after Model/Year 1978 so my 79 has it next to FD already.
Robert
W116 1977 280SEL & 1979 280SE
[img width=150 height=100][url="http://revillagodfroy.com/MB%201977%20280%20SEL/album/thumbs/IMG_0371.JPG"]http://revillagodfroy.com/MB%201977%20280%20SEL/album/thumbs/IMG_0371.JPG[/url][/img]

Feather535

OK, I did the 3 tests Robert suggested.  CP stays above 5 bar when the main return line and the smaller return line to the WUR are loosened and fuel starts to flow out.  Loosening the 16mm fitting on the FD does cause the pressure to drop, on the other hand.  The more it's loosened, the lower the pressure goes. This also causes the pump to run faster, probably trying to maintain pressure. 

So what does this mean?  I already replaced the 3 o-rings on the assembly attached to that 16mm hex head.
--------
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

revilla

Hi,

You have isolated your issue (pressure regulator PG).

Please take pictures and post them here.

Probable causes:
- Wrong O-Rings used.
- Wrong re-assembly.
- Too many shims. How many you have in there? Are all of them 0,1mm type?
- Wrong large spring, unlikely I know.

Robert
W116 1977 280SEL & 1979 280SE
[img width=150 height=100][url="http://revillagodfroy.com/MB%201977%20280%20SEL/album/thumbs/IMG_0371.JPG"]http://revillagodfroy.com/MB%201977%20280%20SEL/album/thumbs/IMG_0371.JPG[/url][/img]

Feather535

Quote from: revilla on 02 February 2023, 04:35 PMYou have isolated your issue (pressure regulator PG).

Probable causes:
- Wrong O-Rings used.
- Wrong re-assembly.
- Too many shims. How many you have in there? Are all of them 0,1mm type?
- Wrong large spring, unlikely I know.

Looks like progress at last! 

Before taking it apart, I'll guess that wrong o-rings and wrong reassembly are not the problem, since the CP was the same before I replaced the o-rings.  But I'll post pictures and we'll see!
--------
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)

Feather535

There are 2 threads going on this topic, so to avoid further confusion, I'm starting a new one combining this one and "WUR fuel cell height and control pressure".  Stay tuned.
--------
1977 280SE
1983 300D (sold)
1988 BMW 535is
1999 E320T (sold)
2009 E350T (wife's)