Access panels for fuel tank - W164

[Mark A]

Any tips for removal of the access panels for the fuel tank on the W164??

I have managed to get one off and it involved lots of swearing and several cuts to hands on sharp edges. I still have 1 panel to go, any tips (other than wear gloves).

Does anyone know the size of the sealing o-ring on the top of the level sensors??

I called MB, and they told me it isn't available separately.

Mark

 

[Cole@MBS]

Last time I did one I used a heat gun to soften the bond!!

 

[Steve@Avantgarde]

As Cole has said, a paint stripper will do the trick, a couple of cups of coffee and a swear box will also be standard tooling.

 

[Mark A]

Many thanks guys, I will try the heat gun on the other one.

Any idea about the o-ring size, presumably it does need to be changed.

 

[Mark A]

Fuel level sensors replaced, but the system still says I have a problem with the left sensor. I guess there could be a problem with the rear SAM, despite the indi telling me that it was fine.

I now have another problem that appeared after changing the sensors. The engine has gone into limp mode. STAR is indicating that there may be a problem with the fuel pressure regulator Y74. Seems a bit suspicious that it happened just after the sensors were changed.

Thoughts??

 

[Mark A]

Does anyone know if the 320 & 420 use the same regulator, might steal the wife's one to see if it clears it.

 

[Mark A]

Just been told that the valve only comes as part of the rail assembly, at a cost of £300.

Even then it's on back order.

Surely these are available separately.

Is it worth changing over the level sensors again, just in case there is something wrong with them that could have sparked this error - although I can't see what could affect the rail pressure from back there. But the car was working fine before I changed the sensors.

Mark

 

[Steve@Avantgarde]

You will need to check the coding in the rear SAM unit after replacing the fuel senders for starters.

The SAM unit is in the OSR corner of the car underneath the light, the seals are known to leak on the light cluster and knacker the SAM.

Secondly, what is the actual fault with your car?

 

[Mark A]

A number of faults unfortunately.

Started when the engine wouldn't shut down, followed by battery symbol and almost every light on the dash.

Replaced both battery's , but afterwards I would get a better symbol and SRS fault every 2 days. I took it to an indie as I suspected the rear SAM was at fault, but was told that everything was OK, and there were no major current drains.

On the way home the fuel gauge went haywire and went to empty in a few miles. I made sure the tank was full and the gauge went to full but doesn't come back down again. STAR indicated a fault with the rear left level gauge - no communication. I picked up a set of level sensors from a breaker, but no change in the outcome with the new units.

Since changing the sensors, I get limp home mode and STAR indicates that there is too high a pressure at the rail and there is a problem with Y74 (pressure control valve).

Looks like one of the original issues with the battery drain has been to do with the alarm as I have had no further issues with battery or SRS after I pulled fuse 110 from under the bonnet.

I have had water in the boot in the past,which is why I suspected the rear SAM to start with.

Thanks for the help Steve.

Mark

 

[Steve@Avantgarde]

I would check the rear SAM for coding firstly, I cant remember off the top of my head whether this needs to be done like on the 203's, ill see if I can find it on WIS.

Secondly I would pull the battery out and check for water ingress at the front SAM. Disconnect it and check the pins and connectors, make sure none are green or corroded. The reed valves underneath the car block and allow water in through the sills causing all sorts of weird and wonderful electrical issues.

Thirdly its possible your pressure control valve fault is unrelated, dont rule that out, but could be connected to the fuel sender fault, are the senders for a 420 the same as a 320CDI??

 

[Steve@Avantgarde]

You should be able to test the senders via STAR diagnosis actuations too.

 

[Mark A]

Thanks Steve.

I have had the battery out recently and the compartment is dry, no sign of issues with corrosion on the front SAM.

I did make enquiries about a replacement rail from a breaker, but as there are 2, unless I know which one has failed I'm on a hiding to nothing.

I will have a look at what tests can be performed tonight.

It's on the 420 and the code was 2020-001, Y74 (Pressure Control Valve).

 

[Steve@Avantgarde]

Actually disconnect the front SAM, the water traces along the wiring and into it, its not always obvious.

 

[Mark A]

Will do Steve.

Sounds like a Saturday job though.

 

[Mark A]

I have been through the testing and it seems to confirm that the pressure control valve Y74 is faulty. It seems to be outside the specified values (20-30) actual value is 16.9. On the pressure sensor offset test I get voltage 1.207V with pressure of 318.6 bar. And "the rail pressure sensor is faulty".

At least I can go ahead and order it from the breaker. £75 + VAT vs £300 from dealer - worth a punt.

I have checked the fuel tank level sensors again, and I get 128 on one and 1 on the other. I didn't see anywhere to manually change the value for the left one.

 

[Mark A]

Does anyone know what the part number is for the Y74 Pressure Control Valve?

Unfortunately eBay isn't very helpful, I get both sides, but it. Lists one as a pressure sensor and the other as a pressure regulator, whereas DAS shows Pressure Control Valve and Quantity control Valve.

 

[Mark A]

Replaced the fuel rail with sensor, reset the adaptations for the sensor and still no joy. I pulled the drivers side level sensor out again (the one with the pump) and replaced it with the original. Still an error, and the car runs in limp home mode.

Thrown the towel in now.

Can anyone recommend an indi in Aberdeenshire??

Mark

 

[Mark A]

Finally sorted.

Fuel filter sorted out the limp home mode and a new rear SAM sorted the fuel level out.

 

[Mark A]

W164 water leaking into boot

After getting the SAM replaced, everything is still working as it should.

I have been keeping an eye on the SAM area to see if moisture was getting in, and up until today, no issues. Today the absorbent cloth I put in is quite damp.

I have had the rear light out and everything looked fine, but to make sure I ran a bead of silicone around the existing seal.

I have read that there are 2 other potential sources, 3rd brake light and the rear quarter panel glass. I'll start with the easier one first. How does the 3rd light come out ??

Any other eareas to consider as a source for the leak.

On the later ML's they moved the SAM to under the rear seat. is there a kit available that would allow me to do this myself ??

Cheers,
Mark

 

[television]

I cannot check on this as my WIS is down