fuel rail pressure question OM642 CD4
Thread Starter
Member
Joined: Sep 2017
Posts: 173
Likes: 25
From: UK
Mercedes R320L CDI 4MATIC 2007
Clamps which can be unscrewed can get undone in time cause of vibrations. To me not too reliable. Had that not once.
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Joined: Jun 2021
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From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
I can think of two reasons for those spring clamps: ease and speed of (factory) assembly and uniform clamping pressure. Quality fuel injection clamps won't loosen up from vibration. Just don't use worm clamps; they dig into the hose too much.
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Joined: Jun 2022
Posts: 739
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From: WA State, USA
2014 Cummins, 2014 E250 Bluetec
They can if over tightened. I like the tbolt style myself but not really for small hose applications. The spring tension ones I like also, regular pliers will work just fine on them which makes it easy to pop off and on.
Senior Member
Joined: Mar 2017
Posts: 258
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R320, Astro, JSW, ST4
Thanks for your posts/follow up, stars-gatherer - Mine started behaving badly again, and I'll check the hoses leaving and returning to the engine area.
I'd replaced the ones near the filter, and the one for the injector returns.
The diagram helps to see how those 2 hoses would have plenty of movement with engine rocking.
I know well how tight the clearances are in the R-Class engine bay!
Another good example is changing the upstream O2 sensor - helps to have a 3' extension!
(You still have to remove righthand air cleaner)
I'd replaced the ones near the filter, and the one for the injector returns.
The diagram helps to see how those 2 hoses would have plenty of movement with engine rocking.
I know well how tight the clearances are in the R-Class engine bay!
Another good example is changing the upstream O2 sensor - helps to have a 3' extension!
(You still have to remove righthand air cleaner)
Junior Member
Joined: Dec 2022
Posts: 29
Likes: 5
R 320 CDI D6 BRABUS
Hi,
As of now I have changed all of the hoses that could have been responsible for the longer cranking during start up, yet the problem is still there. I think that in the next step I'll be replacing the camshafts position sensor as I red that the longer cranking could be caused by a faulty one, especially if it is intermittent. Then if also that doesn't work I'll follow the glow plugs path.
Regards,
Francis
As of now I have changed all of the hoses that could have been responsible for the longer cranking during start up, yet the problem is still there. I think that in the next step I'll be replacing the camshafts position sensor as I red that the longer cranking could be caused by a faulty one, especially if it is intermittent. Then if also that doesn't work I'll follow the glow plugs path.
Regards,
Francis
Newbie
Joined: Jul 2024
Posts: 1
Likes: 0
2014 SPRINTER V6 LWB
HI ALL, this thread has been a very interesting read, i also are having starting issues,
i have a 2014 sprinter 4X4 OM642 ENGINE LWB hi roof
what i,ve found is this is, I live up in the tropics of Australia, where it is 30 deg c all day 365 days of the year
hard cranking started about 2 weeks ago while i was remote in the outback
since then i have changed fuel filter
DPF burn
added to 4 tanks of fuel system cleaner
plugged in my ICARSOFT MB11
results are pretty consistant at the moment, I carried out the same test 10 times under different temprature conditions
my electric tank pump, pumps to fuel rail pressure of 12.13 bar +\- .2
the pressure control valve is between 8.58 - 11.01 % open
the Quantity control valve is also open 33% this should be closed for cranking
the quantity control valve closes to 0% after 30 seconds KOEO
i crank the engine and it starts normally at 2 seconds
if i try and crank before the 30 second switch over it is a prolonged crank and rough start
my injection volumes are between 9 and 10.3 mm3
engine starts and fuel rail pressure consistant at 257 bar every time
i,m yet to find what circuit is the Quantity control valve powered by, but i also have found a very small whisper leak in the return line on the injector of 1 or 3 depending how you look at it,
i,m finding a very small spray of oily substance on the turbo pipe,
will try and remove the return line and inspect o ring
i have a 2014 sprinter 4X4 OM642 ENGINE LWB hi roof
what i,ve found is this is, I live up in the tropics of Australia, where it is 30 deg c all day 365 days of the year
hard cranking started about 2 weeks ago while i was remote in the outback
since then i have changed fuel filter
DPF burn
added to 4 tanks of fuel system cleaner
plugged in my ICARSOFT MB11
results are pretty consistant at the moment, I carried out the same test 10 times under different temprature conditions
my electric tank pump, pumps to fuel rail pressure of 12.13 bar +\- .2
the pressure control valve is between 8.58 - 11.01 % open
the Quantity control valve is also open 33% this should be closed for cranking
the quantity control valve closes to 0% after 30 seconds KOEO
i crank the engine and it starts normally at 2 seconds
if i try and crank before the 30 second switch over it is a prolonged crank and rough start
my injection volumes are between 9 and 10.3 mm3
engine starts and fuel rail pressure consistant at 257 bar every time
i,m yet to find what circuit is the Quantity control valve powered by, but i also have found a very small whisper leak in the return line on the injector of 1 or 3 depending how you look at it,
i,m finding a very small spray of oily substance on the turbo pipe,
will try and remove the return line and inspect o ring
Last edited by blfmtriv; Jul 3, 2024 at 03:53 AM.
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