E46 Fanatics Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter · #1 ·
Hi Guys,

Whilst installing an electric radiator fan in my E46 330i Auto, I discovered that I had to undo the exhaust cam sensor electrical connector to clear the electric fan assembly as it was locked into the radiator bracket that supports it. When I did so, I noticed that the electrical connector had a significant quantity of oil on the end of the connector. Looking into the female socket on the cam sensor revealed even more oil. I blew as much out with compressed air as I could, and ordered a new sensor. I replaced it today with an OEM part, and then had a good look under a mag lamp and using a magnifying glass to see if there were any cracks in the end of the sensor that is inside the cylinder head. Yep...a very tiny void on the step up from the circa 13mm round end to the 17mm part that the O ring sits on. The new part is the same 17mm or so for the full length and does not have the step.

I understand the earlier M52TU engines and some M54's used the sensor with the step in it, but at some stage, they changed the part to the larger diameter, minus the step and where there is obviously a sealing lip that has the void in my sensor.

The car was not throwing any codes, but I imagine it was only a matter of time till it did, as oil is not supposed to be inside the Hall Effect sensor, or on the electrical parts.

The easy check to see if yours is leaking...unplug the cable to it and use a light to look at both the plug and the fixed socket...it is obvious if there is oil in there.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #3 ·
Post a pic of the said step with crack or void.
It took a very bright LED headlight and a magnifying glass to see the void...it is only about 3mm long and is almost invisible to the naked eye, but I knew the oil was getting in there someway. I think the thicker, single diameter replacement will negate it happening again, as the step down and the sealed area don't exist on the new part.

I'll try to take a photo, but it may not work...standby.
 

·
Registered
Joined
·
7,618 Posts
The non-contact sensor is not under any kind of external forces, so why it was cracked by stress. I'm thinking the oil collected in the socket was from VC leak, got in the connector as it was at the lower side of the VC.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #5 ·
The non-contact sensor is not under any kind of external forces, so why it was cracked by stress. I'm thinking the oil collected in the socket was from VC leak, got in the connector as it was at the lower side of the VC.
Nope...I checked all around the area, the leak is internal. The sensor is 18 years old ! I can see the crack in the seal as
I explained before. There was no indication of oil on the outside of the sensor body, and had I not removed the plug, I would never have known there was an internal leak. Make of it what you will, but the sensor lives in a very hot environment , bathed in hot engine oil.

I'll break it open tomorrow and have a look inside.
 

·
Premium Member
E30M3 Race F10 535 R1150Rt M Coupe
Joined
·
9,417 Posts
Hi Guys,

Whilst installing an electric radiator fan in my E46 330i Auto, I discovered that I had to undo the exhaust cam sensor electrical connector to clear the electric fan assembly as it was locked into the radiator bracket that supports it. When I did so, I noticed that the electrical connector had a significant quantity of oil on the end of the connector. Looking into the female socket on the cam sensor revealed even more oil. I blew as much out with compressed air as I could, and ordered a new sensor. I replaced it today with an OEM part, and then had a good look under a mag lamp and using a magnifying glass to see if there were any cracks in the end of the sensor that is inside the cylinder head. Yep...a very tiny void on the step up from the circa 13mm round end to the 17mm part that the O ring sits on. The new part is the same 17mm or so for the full length and does not have the step.

I understand the earlier M52TU engines and some M54's used the sensor with the step in it, but at some stage, they changed the part to the larger diameter, minus the step and where there is obviously a sealing lip that has the void in my sensor.

The car was not throwing any codes, but I imagine it was only a matter of time till it did, as oil is not supposed to be inside the Hall Effect sensor, or on the electrical parts.

The easy check to see if yours is leaking...unplug the cable to it and use a light to look at both the plug and the fixed socket...it is obvious if there is oil in there.
Good catch. Have seen it before. The plastic ages out and starts to micro-crack. Can also become a pressurized pathway to the DME in time. If it gets inside the lead and around the pins.
 

·
Registered
Joined
·
8 Posts
Discussion Starter · #8 ·
I opened up the old sensor last night, and it was well made, with the electronics part well potted in some sort of epoxy. But, the small crack has allowed engine oil to migrate through the innards into the electrical connector, and into the plug on the end of the wiring harness. The only negative I could see was that oil was in contact with the three pins in the sensor connector. As I previously said, the Car was not throwing any fault codes, but it appears that the sensor, being dated 2003, was the original one the engine was built with, and had come to the end of its useful life ( oil is not supposed to get to where it got to, regardless of the sensor still apparently working ).

I am glad I found it, and for the cost and effort involved, it was worth replacing with what appears to be an upgraded part that has had the area that developed the crack, removed. My grand plan is to slowly replace any sensor/pipe/hose etc that looks to be original fitment...at 18 years old, it is simply logical and preventative maintenance. When we move into cooler weather here, I'm going to remove the intake manifold, and get stuck into the CCV, heater coolant pipes, oil housing gasket...all the usual suspects that can create problems or an oily mess.
 

·
Registered
2005 325i Auto
Joined
·
1,244 Posts
Better than oil in your DME.

Might pay to pull the plug off the Vanos solenoid on that side too, and check if there's any oil in that plug as well.
 
1 - 9 of 9 Posts
Top