S-Prihadi

Sharing.........

ISSUE 1 - For M276.8xx ( 3.0 Turbo ) engine only
Do not use/trust the ONLY available WIS for High Pressure Pump Removal.
Attached the :
AR05.10-P-7620-04MM Place engine on cylinder 1 at 40 degrees after top dead center ( version year 2020)
and
AR07.02-P-1020EL Remove/install high-pressure pump 06.03.2020
Yes, I titled them different as PDF, easier to remember.


Mercedes did not include M276 3.0 Turbo for Place engine on cylinder 1 at 40 degrees after top dead center because the writer ( dumb azz ) assumed all M276 is the same.
No it is NOT !!! M276 3.5L has only 3 fuel lobes on the intake camshaft, while M276 3.0 Turbo has 4 lobes.
40 degrees after TDC is not yet the flatest/lowest part of the fuel lobe. 0* TDC is what M276.8xx techy must use.

The point of the document is to allow techinican to remove fuel pump while its spring is at lowest load, or the fuel lobe at camshaft at flat zone and not the highest lobe.
This is important for ease of installation/removal and also to prevent damage of the plunger/piston if the pre-load is too high and techy do not loosen the 2 screws bit by bit equally on both sides.
Yes, spin screw ONLY 180* degrees to loosen, change to the other/2nd screw do 180* loosen and back to 1st screw do 180* loosen and keep repeating/swap .....do this all the way untill spring is no more loaded by fuel lobe.
The WIS and the Bosch HP Pump video installation/removal enforced this important SOP. I marked mine, so I know when I done 180* degrees.



The HP pump spring is crazy heavy tension. 2 screws only for HP pump.






ISSUE 2 ( probably only mine )
My M276 3.0 Turbo, its crankshaft pulley is a TOTAL DISAPPOINTMENT, it has no degree marking whatsoever ? Hello MB Indonesia/Germany ...WTF is happening ?
I have to create my own TDC marker.

This is the P/N of mine and one seller shows it has the degree markings. I do not know if the crankshaft pulley is the same as M276.9 3.5L. DELA means Direct Injection (DE) Turbo (LA)










The silver tape is the true TDC for M276.8 using boroscope to see piston true top position while both intake and exhaust valves are closed.
The L1 and L2 are my ealier marker ( before I change to yellow ) showing fuel lobe highest peaks per one 360* degrees crankshaft revolution, which is only 180* degrees of CAMshaft revolution.







M276 3.5L intake camshaft, 3 fuel lobes.







M276 3.0 Turbo, 4 fuel lobes, the same as M278 V-8










So, below is the fuel lobe highest peak in yellow sticker, in respect to crankshaft degrees reference marker at the water pump housing.
Since there are 4 fuel lobes, it does not matter TDC or BDC is the reference, as far as when you want to find the flat/lowest portion of the fuel lobes.
Between the 2 yellow marker is the flat area of the fuel lobe and that is where you want your camshaft to be when removing the HP fuel pump.
So M276.8 can be at TDC and is good enough, DO NOT follow 40* dgree after TDC bull-shiet.



Remember, 2 crankshaft revolution is equal to 1 CAMshaft revolution.







Crankshaft pulley and fuel lobe view



















Oky doky............... have fun spinning the crankshaft pulley.



PS,
Those who is wondering what is the red marker at the crankshaft pulley is for ?
That is the degree where the intake valve open the biggest/most.

S-Prihadi

Sorry, PDF is here :

Attached the :
AR05.10-P-7620-04MM Place engine on cylinder 1 at 40 degrees after top dead center ( version year 2020)
and
AR07.02-P-1020EL Remove/install high-pressure pump 06.03.2020
Yes, I titled them different as PDF, easier to remember.

DubVBenz

Good info, just curious, why were you removing? Did it fail and require a replacement?

S-Prihadi

Nope, mine is healthy. I have a new one as spare, so I got ithcy handed.... LOL
By mileage, I would never kill this HP fuel pump ( as long as fuel filter kept to 25,000KM no higher and watch LP fuel pressure once in a while ) even at 15th years of car age.
Today 8th year, only 36,000KM.

So I might as well replace it now with a new one and the old one I keep as spare and then I can start to scope its fuel quantity valve, to see any difference there.

S-Prihadi

To add, why I emphasized :

==============
This is important for ease of installation/removal and also to prevent damage of the plunger/piston if the pre-load is too high and techy do not loosen the 2 screws bit by bit equally on both sides.
Yes, spin screw ONLY 180* degrees to loosen, change to the other/2nd screw do 180* loosen and back to 1st screw do 180* loosen and keep repeating/swap .....do this all the way untill spring is no more loaded by fuel lobe.
The WIS and the Bosch HP Pump video installation/removal enforced this important SOP. I marked mine, so I know when I done 180* degrees.
==============

Un-even loosening or tightening can create crow-bar effect as the fit is quite tight but precise, between fuel pump's piston/plunger and the roller lifter bearing.
The piston is the delicate one.







Typical HP fuel pump roller : https://zzperformance.com/products/fuel-pump-roller or
.

DubVBenz

Very cool. I was curious about why you chose to do it because I haven't heard of too many HPFP in MBs as compared to VAG and BMW products. I know of a ~230K miles on a M276TT that required a HPFP, but I haven't heard of any others

S-Prihadi

I also need to remove the HP fuel pump to confirm where are its peak lobes position in respect to crankshaft degree/angle.
For future troubleshooting sake.

There are 2 variation of data on the VVT range, however I would beleive the WIS one instead of the M276 3.0 Intro Booklet.


HP fuel pump tag along the Intake CAMshaft.

The HP fuel pump pressure and volume delivery duty is a very fast and complex one. The VVT will create extra work load on HP fuel pump overall performance as the crankshaft to CAMshaft corellation is dynamically
changing. Oil control VVT is slow and not so accurate and whatever VVT does wrong, HP fuel pump get the shi-et too. I hope the HP fuel pump relies only on the CAMshaft sensor reading as it is fixed in relation to
the fuel lobes. The VVT sprocket is the dynamic one in respect to CRANKshaft degrees.

I am not worried mechanically of the HP fuel pump robustness, as long as fuel kept super clean and never allow fuel starvation to HP fuel pump, I bet 100,000KM* ( *my traffic jam and often WOT ) it would be able to last.
100,000KM is approx 5,000 running hours for my case.

I am worried on the fuel quantity valve accuracy drift over time. Audi as per OPUS tech videos I seen, the fuel quantity valve going bad is often the culprit ( Hitachi brand I believe ) and not the piston/plunger itself.
I also have to prove something I find counter-productive on the HP fuel pump vs load & RPM mapping I am actually seeing now. I do not know if that is the way MB engineers wants it to happen, or my fuel quantity valve has drifted.
This is what I need to verify with the new HP fuel pump : Post #11 https://mbworld.org/forums/e-class-w...ml#post8554915
Xentry information stingy-ness is not helping. If there is a data field of the commanded/desired HP fuel pressure, I do not need to be this curious

Also 99.9% of M276.8xx owners won't pay attention to what seems a normal HP fuel pressure, but I do....for learning sake.

Imagine this :
4,000 RPM CRANKshaft, this speed will produce 2 pumping cycles of HP pump per 1 CRANKshaft RPM at the intake CAMshaft with 4 lobes.
4,000 / 60 seconds = 66.6 pumping events x 2 = 133.2 pumping events
1,000 milliseconds divided by 133.2 = 7.5 milliseconds per pumping event

On a 4 fuel lobes camshaft, 1 suction and pumping complete event is worth 90 degrees of CAMshaft revolution.
45 degrees is for suction and 45 degrees is for compression, total 90 degrees of CAMshaft rev.
That means 3.75 millisecond per 45 degrees. This is very short duration considering springs and solenoid is involved and its lag.
Our GDI injector is piezo, it is super fast reaction time, I don't know if HP fuel pump uses piezo or not ?... most likely not.

S-Prihadi

Ha ha ha...so now I know. M276 3.0 TT Introduction Booklet VVT data is still using M276 3.5 NA data




I got this excellent Direct Injection HP Pump document/study.
Find attached. GDI 101 - Pfister_Christophe.pdf

I think our HP pump plunger/piston is ceramic coating, or something like that.

From Master Tasos










My 36K KM piston's

CaliBenzDriver

Thank you Surya for spoiling our curiosity

150 pg on the complexities and advantages of pumping with HPFP
One big lump of German knowledge to grasp - Thank you

S-Prihadi

My approximation of fuel 4 fuel lobes degree on intake camshaft of M276.8 3.0 Turbo in respect to the tone/signal wheel .
Crank TDC is Cylinder 1.

Intake Camshaft Tone-Signal wheel as seen from front view


Easier view





Sanity check...approx

S-Prihadi

.

I just discovered that my HP Fuel Pump Pressure ( & Temperature ) sensor has drifted its ZERO to read 7.x BAR
I do not know if at higher pressure it will drift positive or negative, or more drift for that matter.
.




I think anyone can test this : simply by purging the fuel out of the small Schrader valve or/and disconnect the fuel line at the Tee and use an MB capable scanner or Xentry to read the fuel pressure at both sensors A at fuel tank filter and B at engine near fuel rail.
Sensor A should be reading approx 1.2 BAR if you purged well. HP fuel pump quantity valve is a normally open valve when no electrical power or signal applied by ECM, so purging the fuel
out of the Schrader valve and later disconnection the fuel line , will purge all pressure well enough to give sensor B ( HP fuel ) a near zero BAR reading.

Below is the fuel line Tee where the Schrader valve is also located.



In 4 days the new HP fuel pressure sensor + temp combo will arrive. Local MB Indonesia price for it is 250% higher than Europe.

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