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#16
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By design the pressure relief bypass built into the pump should protect the system. I was curious how much protection was built into the correct pump so I did a little reading. This is from the MB service manual page 405/1
In addition, the pump has a pressure relief device in the shape of a bypass which disconnects the suction and delivery line at approx. 5 bar overpressure. 5 bar is ~72 psi. For comparison a walbro electric I'm using for another megasquirt project hits max pressure at ~140 psi. which is quite a bit more. |
#17
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I couldn't find page 405/1 in my M116/7 engine manual. Which section is it in? Does it refer to the original Djet pumps or the later K-jet pumps?
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Graham 85 300D,72 350SL, 98 E320, Outback 2.5 |
#18
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Boy that's a mouthful. |
#19
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It would be real interesting to see what the MB replacement pump relief valve rating is and what systems the pump is used on. I'm thinking that the pump is sold by Bosch for a multitude of other branded cars. The Airtex universal pump site only shoes a pressure range / flow rates not relief valve pressure. |
#20
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Regarding the Bosch Djet replacement pump 0580464999 (which is most likely the pump that MB is now selling), I found several references saying that this was a turbine pump. Not confirmed! A turbine pump is not a positive displacement pump like the original roller vane pumps. Most modern pumps are turbine pumps. They provide a much smoother flow with minimal pressure fluctuation. The maximum pressure if discharge is blocked would be limited, so perhaps these pumps don't have or need an internal relief? But, some turbine pumps do have internal pressure relief. This is just conjecture on my part. I have asked Bosch, but no answer yet.
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Graham 85 300D,72 350SL, 98 E320, Outback 2.5 |
#21
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The original D jet pumps used by VW in 1969 were roller vane ( 5 or 6 rollers ) and were very noisy, the looked more or less like the 999 pump except all hose fittings were on the head end ( early had 3 , later had 2 , the switch occurred when they went to an internal bypass rather than a hose loop ) I'd expect the 999 pump to be roller since the pump head is retained by 4 screws. ( see "old" pic )
The other brands turbine pumps I've taken apart use 2 turbines stacked together, I don't think there is enough room in the 999 head for that. Newer crimped pumps ( 1997 C280 and E320 ) look like the "new" pic. I've taken two of these pumps apart and found them to be twin rotary screw. ( Look up a twin rotary screw air compressor on the basic layout ) These are virtually pulse free. It would be good practice for a turbine to have a relief valve to protect the motor when the filter is clogged, I can't say if all have or not. |
#22
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Found these threads, didn't read them all
Lots of apart pics http://www.peachparts.com/shopforum/vintage-mercedes/298814-help-i-need-fuel-pump-300sel-109-056-3-5-bosch-0580-970-002-a.html http://www.peachparts.com/shopforum/sl-forum/327148-djet-fuel-pump.html |
#23
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Bosch provided information regarding the 0580464999 pump. They say this is the same pump sold by Classic Center. The pump is a roller cell pump (as was the original). The pump number ending in 999 is actually a kit number. The pump itself is an 0580464042. The kit includes the clamping sleeve and the 90deg discharge required for easier installation.
These are the pump figures (new and old) 0 580 464 005 (original pump) · fuel pressure: 2.0 bar · relief pressure: 3.7 … 6.3 bar · fuel amount (at 2.0 bar): >90 l/h 0 580 464 042 · fuel pressure: 4.0 bar · relief pressure: 4.8 … 8.5 bar · fuel amount (at 4.0 bar): >98 l/h I asked, but did not get an explanation of why there was such a large range in relief pressure except that perhaps that it just wasn't that important??? They said the Djet fuel system including components and clamped connections was capable of handling 8.5bar (125psig) (maybe when new??) Our clamped hoses can leak even at 30 psig, so if the number really is 8.5bar, I doubt the relief valve provides much in way of safety on old cars. The flow numbers are low and not explained, but the original pump was capable of more like 120L/hr. the 90L/hr quoted is likely just a minimum and dependent of fluid used for testing and the motor voltage. Based on what I have learned, I personally will stay with my original 005 pump or the Nissan equivalent referred to above (which I have as spare and can still be obtained). But Bosch did assure me that both they and the MB Classic center have checked the new pump out and approved it. According to their site for Djet (and even Kjet) use. Original 005 (3 is relief valve) and new 999 (2 is relief valve) pump schematics
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Graham 85 300D,72 350SL, 98 E320, Outback 2.5 |
#24
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Hi Graham,
I recently tested a pump that I can recommend in full. It's very low-priced, but it's a well known producer. And it fulfills the needs better then the pump recommended by Bosch: · fuel pressure: 3.0 bar · relief pressure: (measured by me): about 5.0 bar · fuel amount (at 2.0 bar): >155 l/h Log in to see my recommendation... https://oldtimer.tips/de/forum2/jetronic/433-test-und-empfehlung-einer-kraftstoffpumpe-recommending-a-fuel-pump#3953 Regards Norbert |
#25
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I will have a look at the Pierburg pump when I get some time. I have never seen that pump sold in North America, but perhaps it is available somewhere. I posted an expanded version of the above post about the current Djet pump sold by MB and Bosch on Benzworld. I am puzzled by the wide range of relief pressure but could not get an explanation from Bosch. Also not convinced hose claped tubing on our old car should be assumed to be able to handle 8.5bar (relief pressure of the new MB pump). Do you know if anyone has tested the relief pressure for the original Bosch Djet pump 0580464005? New Djet pump now available from MB - Mercedes-Benz Forum The specified pump pressure of 3.0bar for your pump (or 4.0bar for the MB pump) doesn't really mean anything other than pump has been flow tested at that pressure. We would only want either pump to operate at about 2bar. The flow of 155l/hr for your pump at 2bar is on high side - Hopefully fuel pressure regulator can be adjusted sufficiently to compensate. Personally, I still have a good original pump as well as a new in box spare, so my interest is just academic
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Graham 85 300D,72 350SL, 98 E320, Outback 2.5 Last edited by Graham; 07-12-2016 at 10:41 AM. |
#26
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Hi Graham,
the D-Jet-pumps were limited to a maximum pressure of 3.0 Bar. But they are NLA... (I own such a pump 'three-port-model' in NOS-condition and would sell it a t a price similar to that of the new Bosch pumps, because I need the 'two-port-model'...) The pump I recommend in the linked posting is meant for a system pressure of 3.0 bar (L-Jetronic). This is better then a pump developed for the K-Jetronic (4.0 bar) or even higher pressure. The 'specialists' at Bosch don't know much about what they are selling - didn't even know anything about the pressure limiter. Seems they just took a pump they had in the program and sell it with some adapters. You can read almost all about the pumps in English translation here: https://oldtimer.tips/en/d-jetronic/fuel-pump (and some postings about defects and repairs in the forum, but in German) There is a Pierburg-pump that is better for using it in the D-Jet-system than the Bosch ...999 (you see it scrolling down in the link I posted and in Volkers recommendations), but it is much more expensive than the pump I recommend. It is available in the USA, too - price about $50.00, shipment included (checked at ebay USA). The pump is build by the Italian leader in electrical car equipment (I believe...) and seems to be same quality as the other recommended pumps- why don't give this a try? Sorry I don't post the producer or part # here - we keep some 'secrets' in the D-Jetronic-forum visible only to registered users as you are, Graham. Regards Norbert One more tip out of our experience of the last months: There is a hose between the pressure regulator and the damper which bends easily and thus closes the return line. The pressure then rises as high as it comes from the fuel pump - engine runs totally rich or even dies. Here you see the problem, scroll down for the solution: https://oldtimer.tips/en/forum2/jetronic/57-d-jetronic-workshop-an-pfingsten?start=20#1076 |
#27
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You can see the problem hose between the FPR and the damper in this picture by Fonzi on the Benzworld 107 forum:
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Graham 85 300D,72 350SL, 98 E320, Outback 2.5 Last edited by Graham; 07-12-2016 at 10:31 PM. |
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