Engine trouble 320cdi
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Newbie
Joined: Nov 2020
Posts: 4
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R320
Engine trouble 320cdi
Hi! A 2006 R 320 cdi that I have owned for a year. All the time the engine has never run fine. It has allways been hard to start when cold. When warm it starts normally. The revmeter jumps (just a little) all the time at idle. When driving, occactionallt the engine jumps a little, sometimes more. At highway speeds it works normally but also here I see small jumps at the revmeter. I have now changed air filters, air intake with air mass sensors and today egr valve. No change at all. There is no engine light and no error codes. My workshop mech say that the next thing to change is the torque converter. Now this old steel piece really starts to get expensive. Can that be right? When the engine is hard to start when cold? Maybe a small common rail leak? All help is highly appreciated.
Member
Joined: Sep 2017
Posts: 173
Likes: 25
From: UK
Mercedes R320L CDI 4MATIC 2007
Hi! A 2006 R 320 cdi that I have owned for a year. All the time the engine has never run fine. It has allways been hard to start when cold. When warm it starts normally. The revmeter jumps (just a little) all the time at idle. When driving, occactionallt the engine jumps a little, sometimes more. At highway speeds it works normally but also here I see small jumps at the revmeter. I have now changed air filters, air intake with air mass sensors and today egr valve. No change at all. There is no engine light and no error codes. My workshop mech say that the next thing to change is the torque converter. Now this old steel piece really starts to get expensive. Can that be right? When the engine is hard to start when cold? Maybe a small common rail leak? All help is highly appreciated.
Senior Member
Joined: Mar 2017
Posts: 258
Likes: 50
R320, Astro, JSW, ST4
Regarding hard cold start, try turning ignition on and do not start with ignition on for 30 seconds. Let rear pump prime fuel to the front. Then start. If there is a leak in hp system this could help. I have cold start issue, this helps me avoid hard cold start. I am not sure where my problem is, suspecting injectors as replaced other components and stopped at injectors. A couple of them show excessive leak off test result. So i am blaming them. Runs ok so not bothered yet.
I tested injector fuel leak-down and found one way more leaky than the reset. Plus I had one with black death. After changing out these two injectors the car starts and runs very nice.
No more than a full rotation or two before it lights up completely.
We'll see for sure this winter (I'm in Florida but it does get below freezing still).
Have your mechanic do the injector leakdown test.
Hopefully is not the rearward cyls 3&6 - they are harder to access than the front ones, if you have to get a slide hammer on them.
Of course for me, those were the ones needing help.
Newbie
Joined: Jan 2022
Posts: 1
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From: PNW
R320
there is a Glow Plug light on dash (looks like a pigtail) that appears when key turned to second 'notch' /position- wait for it to go out THEN start it. if that doesn't work then you probably need new glow plugs (or at least some of them)
Senior Member
Joined: Apr 2007
Posts: 352
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Get rid of it would be my advice. Terrible engine that only causes grief for those that own them for long enough. The lift pump is a valid option and can eventually spit out a fuel rail pressure fault.
Torque converter would never be a valid option for either concern so find another shop. Possibly a crank sensor by your description (certainly a cheaper shot from the hip)??
Torque converter would never be a valid option for either concern so find another shop. Possibly a crank sensor by your description (certainly a cheaper shot from the hip)??
