Oil ingress in BMW VVT sensor

[Kantaro]

The variable valve timing sensor (or what BMW calls the eccentric shaft sensor) on some BMW engines are prone to failure due to oil ingress in the sensor. The oil eventually fouls the connector, and there is even a TSB from BMW about the oil migrating through the wiring and damaging the ECU: https://static.nhtsa.gov/odi/tsbs/2016/MC-10151300-9999.pdf

Replacing this sensor requires removal of the valve cover, which is a bear of a job and can take up to 6 hours. Dorman sells a revised sensor under their "OE Fix" line, where they claim to address the original issue with ultrasonic welds, but the reviews are mixed: https://www.dormanproducts.com/p-77342-917-030.aspx

My stupid question is can't we just seal the sensor up with some kind of sealant to prevent oil from contaminating the internals?

Part number is 11377524879 if you are interested: https://www.fcpeuro.com/products/bmw-eccentric-shaft-sensor-valvetronic-11377524879

 

[Oliveoil2]

The structure is plastic with a metal plate. The Problem is, can the 4mm bolts hold proper tension….with plastic threads? How many miles on the engine?

 

[barryh]

The oil eventually fouls the connector, and there is even a TSB from BMW about the oil migrating through the wiring and damaging the ECU:

A similar sort of problem occurs with Mercedes M271 engine and some other Mercedes engines. To prevent the oil migrating via the cable from the cam shaft adjuster to the ECU, an oil stop cable is available to insert into the cable harness.

 

[SC Maintenance]

I believe these are Hall affect sensors, and I believe that metal plate is the hall element itself - so there measuring the voltage in that plate, as created by the magnet on the end of the camshaft.

So your issue is you need to seal on the back side of that plate in order to keep it out of the connector. I doubt you can get the plate out without damaging it or the leads associated with it. Guessing only.

Possibly you could get a very thin layer of epoxy to seal the bottom of the connector housing? I doubt oil on the hall affect sensor would affect it - unless the amplifier is built into the sensor itself?

Does the new Siemens version not address the ingression problem? I personally would avoid a Dorman sensor on a job that takes 6 hours - but thats me.

 

[dumkid]

The eccentric shaft sensor isn't a camshaft position sensor. It senses the position of the variable valve lift actuator shaft (which is just a camshaft but not one ran off the engine)

 

[camrydriver111]

If its something you replace every 10 or 15 years. I would just install oem sensor as is and not worry about it.

 

[BMWTurboDzl]

The variable valve timing sensor (or what BMW calls the eccentric shaft sensor) on some BMW engines are prone to failure due to oil ingress in the sensor. The oil eventually fouls the connector, and there is even a TSB from BMW about the oil migrating through the wiring and damaging the ECU: https://static.nhtsa.gov/odi/tsbs/2016/MC-10151300-9999.pdf

View attachment 210834

Replacing this sensor requires removal of the valve cover, which is a bear of a job and can take up to 6 hours. Dorman sells a revised sensor under their "OE Fix" line, where they claim to address the original issue with ultrasonic welds, but the reviews are mixed: https://www.dormanproducts.com/p-77342-917-030.aspx

My stupid question is can't we just seal the sensor up with some kind of sealant to prevent oil from contaminating the internals?

Part number is 11377524879 if you are interested: https://www.fcpeuro.com/products/bmw-eccentric-shaft-sensor-valvetronic-11377524879

View attachment 210835

Have you confirmed whether BMW revised this part?

 

[Kantaro]

A similar sort of problem occurs with Mercedes M271 engine and some other Mercedes engines. To prevent the oil migrating via the cable from the cam shaft adjuster to the ECU, an oil stop cable is available to insert into the cable harness.

Fascinating. It looks like it's some kind of pigtail? Any idea how it works? Does it actually stop the oil from migrating further?

 

[Kantaro]

Have you confirmed whether BMW revised this part?

Seems to be the same part with no revisions since it was first introduced in 2004:

RealOEM.com - Part Search

 

[Kantaro]

The eccentric shaft sensor isn't a camshaft position sensor. It senses the position of the variable valve lift actuator shaft (which is just a camshaft but not one ran off the engine)

Thanks for clarifying. It's referred to as a VVT sensor in BMW TIS for whatever reason

 

[BMW Dom]

It's not really an issue with the sensor, more of the gasket

 

[SC Maintenance]

Fascinating. It looks like it's some kind of pigtail? Any idea how it works? Does it actually stop the oil from migrating further?

Whicking up the cable is common in the industrial world, especially when we put sensors directly into high pressure hydraulic areas, like pressure or position transducers. The solution is typically to pot completely the back side of the cable, and sometimes a flow out epoxy on the front inside bottom of the connector itself.

Of course no automotive OEM would pay for this type of connector.

I assume the oil stop cable is some sort of intermediate cable that employs some of these features?