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N52 Engine Oil Leaks
Posted to Technical Tips Forum on 2/2/2014 22 Replies

I arrived for work on Monday morning to find this 2006 325i waiting for me. Over the weekend our apprentice technician had diagnosed an oil leak to be the oil pan and oil filter housing gaskets. The oil pan gasket leak was obvious and the filter housing was too, except the front of the engine had a little more oil than you'd expect from just the oil filter housing leaking. N52 oil filter housing leak N52 timing cover leak

I figured I'd do the obvious first then wash the engine down and recheck for leaks. I had to support the engine so the subframe could be lowered to facilitate oil pan removal. 2006 BMW 325i, Engine/Propulsion Photo a little trick using the tow hook I picked up from an instructor at a BMW class in Ft Lauderdale over the weekend engine support brace to tow hook. Once I had the oil pan down I noticed something in the oil pick up: 2006 BMW 325i, Engine/Propulsion Photo there was also a bolt head in the bottom of the oil pan. Two broken timing cover bolts and one external head bolt near the oil filter housing had been mentioned in the class as being notorious for breaking and causing oil leaks that the oil filter housing gasket was being blamed for. Talk about relevant 24 hours hadn't even passed since the class.

I had our service advisor contact the customer and explain about the broken bolts the leaks and the possibility for bad things to happen in the area of the timing chain. The customer approved the removal of the valve cover to verify the timing cover bolts were broken and then to remove and replace them.

Be advised if your going to work on these all the bolts are aluminum and must be replaced when released and you'll also need a good torque wrench that can measure angle at low torque and tight spaces. The broken aluminum bolts will usually spin right out with a sharp pic although not the case with the timing cover bolts.

Time for valve cover removal(the valve cover is probably the most common leak on these engines and usually will have a broken bolt or two), after removing the cabin filter cowling, cross brace and plastic cover you'll need to remove the valvetronic motor: valvetronic motor release there's a 4mm hex at the back of the motor for unwinding from the eccentric shaft. Do not attempt to unbolt and pull the motor out! Remove the single valvetronic motor brace bolt to valve cover first, then loosen the two bolts at the motor flange just enough that the motor is starting to pop out then turn the 4mm hex clockwise to draw the motor towards the valve cover and remove the bolts then turn the 4mm hex counterclockwise to draw the motor out. To reinstall the valvetronic motor turn the 4mm hex clockwise so the motor pulls in flush to valve cover.

Another thing you should pay attention to when replacing a valve cover gasket is the eccentric shaft position sensor. It's the connector that goes through the front of the valve cover. If there's oil in the connector you need to replace the sensor it can cause strange driveability errors and catastrophic failures if ignored too long. No special tools are needed to replace it as the cam timing is not disturbed.

Valve cover removed and broken timing cover bolts confirmed: broken bolt I tried to spin the broken bolt out with a pic but it really didn't help. I could've tried a long left hand drill bit if I had one but I didn't. What I did have was a 16" long snap on slotted screwdriver with a 5/16" tip that I pounded an impression of a slot into that broken aluminum bolt: broken bolt timing cover to cylinder head I was then able to spin the bolt out easily and came to the next block in the road. The camshaft sensor reluctors were in the way of getting the bolts in or out.

I had to remove the camshaft reluctors and in order to do so I needed to lock the cams. I needed the camshaft locking tools so I ordered the AST 3028 tool set from Amazon and two days later it worked flawlessly: N52 camshaft locking tool N52 camshaft locking tools N52 camshaft timing jig With the camshafts and gears locked I removed the center bolts then the aluminum jig that locked the gears. Good thing the tool was at hand because the reluctors are not keyed! Now I could remove the broken bolts easily but it was too tight to put the new bolts in. exhaust camshaft reluctor removed The vanos gears had to be removed to clear the bolt heads. At this point I decided to cheat a little and used my wizzer to sand a flat spot on one side of the bolt head: N52 new timing cover bolt Reinstalled the reluctors and gear jig then new bolts, tightened everything to spec removed jig and: N52 ready for reassembly As a note the valvetronic motor will reset when the key is turned on and a scanner is not necessary to relearn the end limits.

James from Rhode Island

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car Vehicle Data

2006 BMW 325i 3.0L

Engine3.0 L
Trans6-speed Automatic (Electronic)