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To select your genuine parts, look at the mercedes parts catalog with engine diagrams.
This will ensure you get the correct parts numbers for your engine.
Last edited by CaliBenzDriver; Mar 26, 2026 at 05:35 PM.
A 270 050 01 22 I think this is the part, based on my VIN. Just wanted to confirm that roller tapet is what I am looking for
Originally Posted by CaliBenzDriver
To select your genuine parts, look at the mercedes parts catalog with engine diagrams.
This will ensure you get the correct parts numbers for your engine.
yes exactly item No40 is the roller bearing pump + seal + roller
now you have trusted P/N you know match your engine.
Just that it can be the pump itself too.
The pump piston returns by a spring force and the spring can get weak over time. This means there may be a gap between the roller and the cam shaft lobes that the make more than usual noice.
I had this and the rattle was quite bad on my S550 and to make sure I fix it I changed both fuel pumps with rollers.
Problem was fixed with all new parts but I don’t know which part it was that needed fixing. Would have possibly taken even four tries to change just one part at a time on the two pumps so I just did them all on one try.
But the tapping noise is normal for these motors with the cam driven HPFP so replacing the pump and the roller follower may not fix the noise issue, but as previous posts say it may just be a good preventive maintenance move to replace them anyway.
I experienced something similar on my C43 after new spark plugs, but turned out to be a dying belt tensioner making a similar whining noise. Made me wonder if the plug change was the culprit but it was just a cheap tensioner giving up.
Well, I changed the hpfp and the roller. The sound can still be heard. When I had the new pump installed, before placing the metal shield back on top, I listened with the stethoscope and the sound was the loudest on the pump, anywhere else it was started to fade the more I would go further away from the pump. You could also hear the sound on the fuel pipes (or whatever pipes go in and out of the pump).
I am running out of ideas from what this could be. The lobes on the camshaft that triggers the pump?
Last edited by Darkecudoua; May 8, 2026 at 08:40 AM.
Well, I changed the hpfp and the roller. The sound can still be heard. When I had the new pump installed, before placing the metal shield back on top, I listened with the stethoscope and the sound was the loudest on the pump, anywhere else it was started to fade the more I would go further away from the pump. You could also hear the sound on the fuel pipes (or whatever pipes go in and out of the pump).
I am running out of ideas from what this could be. The lobes on the camshaft that triggers the pump?
The sound you're tracking is still the loudest on the New HPFP + New Roller...
Then Perhaps...
- 1- it's the normal GDI signature sound, muffled with a foam insert under the metal protection cover.
- 2- Or your camshaft lobes have been damaged by contaminated roller-follower. Inspect old roller bearing for flats spots.
Piezo injectors can make rather loud cricket sound under legacy GDI timings. This sound can transform to become quieter at operating temperatures... 100% "normal" as well.
If anything now you know your new HPFP/Roller won't have any chance to kill your GDI engine. Keep your favorite oil service on 5kMi schedule.
Last edited by CaliBenzDriver; May 8, 2026 at 04:52 PM.
Well, I changed the hpfp and the roller. The sound can still be heard. When I had the new pump installed, before placing the metal shield back on top, I listened with the stethoscope and the sound was the loudest on the pump, anywhere else it was started to fade the more I would go further away from the pump. You could also hear the sound on the fuel pipes (or whatever pipes go in and out of the pump).
I am running out of ideas from what this could be. The lobes on the camshaft that triggers the pump?
Are you running correct engine oil that MB recommend?
Are you running correct engine oil that MB recommend?
If the pump makes noise it comes from too much gap between the roller and cam shaft lobes. There really should be no gap. If you have too much gap with new pump and roller lifter it kind of points to a worn lobes on the shaft, right?
I can’t now remember if the lifter was like a hydraulic lifter that should eliminate the gap between roller and cam shaft lobes.
I think so. I am trying to assess how “dangerous” this is for the engine, as a mechanic told me to wait until 150k km (currently the car has 110k) as around 150k is when the timing system is due for replacement, and perhaps replace the intake camshaft as well.
i cannot seem to find new camshafts tho, only refurbished.
Originally Posted by Arrie
If the pump makes noise it comes from too much gap between the roller and cam shaft lobes. There really should be no gap. If you have too much gap with new pump and roller lifter it kind of points to a worn lobes on the shaft, right?
I think so. I am trying to assess how “dangerous” this is for the engine, as a mechanic told me to wait until 150k km (currently the car has 110k) as around 150k is when the timing system is due for replacement, and perhaps replace the intake camshaft as well.
i cannot seem to find new camshafts tho, only refurbished.
If you are willing to work on this a little bit you could shim between the pump and the Tappet (roller lifter) as if there is wear on the lobes the roller lifter may not reach and leaves a gap that is not supposed to be there. You could use just 0.001” shim and see if noise improves. It really should and you can keep adding shim until you are happy with the noise , but I think there should be some noise to know that you have the smallest gap and are not shimming over the pump limit. I don’t know what the limit would be but for sure you do not want to bottom out the pump.
I asked about the oil as if it indeed is a hydraulic type of a lifter it might not get proper fill if oil is too high viscosity. I always use 0W-40 and do my own oil changes every 5000 miles.
I know some dealers use even 10W-40 oil, which in my opinion is too thick. Ask your dealer what oil they use and request 0W-40 oil as they very often use 5W-40 that could make a difference to how well hydraulic lifters work.
The last time the car was serviced the dealership used 5w40, i just checked the invoice.
should I drain and switch to 0w40?
i will record the sound that’s coming from the pump and leave a post here later.
Originally Posted by Arrie
If you are willing to work on this a little bit you could shim between the pump and the Tappet (roller lifter) as if there is wear on the lobes the roller lifter may not reach and leaves a gap that is not supposed to be there. You could use just 0.001” shim and see if noise improves. It really should and you can keep adding shim until you are happy with the noise , but I think there should be some noise to know that you have the smallest gap and are not shimming over the pump limit. I don’t know what the limit would be but for sure you do not want to bottom out the pump.
I asked about the oil as if it indeed is a hydraulic type of a lifter it might not get proper fill if oil is too high viscosity. I always use 0W-40 and do my own oil changes every 5000 miles.
I know some dealers use even 10W-40 oil, which in my opinion is too thick. Ask your dealer what oil they use and request 0W-40 oil as they very often use 5W-40 that could make a difference to how well hydraulic lifters work.
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