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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