Leaky Beemer
Nigel attempts to make his 323i’s engine oil-tight
Like any new purchase, my 323i is throwing up plenty of little jobs early in ownership as I get the car into shape. I’ve dealt with all its routine maintenance needs but there were still a couple of minor faults to fix.
The first was a persistent oil leak from the valve cover, which was letting oil dribble down the block before coating the anti-roll bar. Not serious but certainly messy. Apparently this is quite a common problem with BMW’S M52 six-pot motors and happily it’s easy to repair. The moulded plastic valve cover relies on a synthetic rubber gasket to seal around its circumference but heat and time cause the rubber to harden. I ordered an OEM specification Victor Reinze gasket set and got to work. First the top cover needed to be removed from the engine, followed by the six individual coil packs. After undoing the valve cover’s fifteen M6 retaining bolts, it proved to be stuck fast… no great surprise after 20 years. I couldn’t afford to be too brutal, given that the cover is made of plastic. Gentle tapping with a rubber mallet didn’t break the seal, I sprayed around the edges with penetrating oil and went to put the kettle on. Following a tea break, I tried the rubber mallet treatment again and this time the cover came free, the penetrant having done its job. The old gasket was rock hard and completely different in appearance from the pliable brand new replacement, so no surprise it was leaking.
Cleaning the valve cover and digging the remains of the old gasket from its retaining groove took a while. I pressed the new gasket into place in the cover, plus the two pieces around the plug holes. The cylinderhead was prepared by cleaning its mounting face with thinners and lightly coating the area with silicone sealant.
Cover star
The cover and gasket were quickly eased onto the still wet silicone and I refitted the retaining bolts, torqueing to the recommended 10 Nm. Such a low torque setting, a mere 7.4lb ft in imperial units, was well below the range of my usual torque wrench so I invested in an 8-60 Nm Draper Professional series wrench, figuring it will see plenty of use on the BMW in future. With the cover torqued down, I soon finished reassembly. After several weeks’ use, the oil leak is gone. The BMW has also shown a tendency to produce a cloud of oil smoke from the exhaust when starting from cold. Online research suggested
likely causes were valve stem oil seals – a pain in the proverbial to fix – or a blocked crankcase breather valve. Applying the logic of going for the easiest option first, I bought a kit containing a new breather valve and its two associated hoses.
Access is somewhat challenging. Out came the air filter box followed by the trunking connecting it to the throttle body. The cooling air duct to the alternator was also removed, making it just possible to wriggle a hand under the inlet manifold and touch the valve. It’s a conical black plastic moulding that uses vacuum from the inlet manifold to draw fumes from the top of the engine. Using the same cyclone principle as a Dyson vacuum cleaner, oil droplets are collected then returned to the sump via a tube on the side of the dipstick. If the valve fails, oil can find its way into the inlet manifold, causing the smoky start-ups.
Hooky hose
Various contortionist tricks successfully manoeuvred the valve and hoses out from under the manifold. The cause of the problem then became obvious. At some point in the past, the oil drain hose back to the dipstick had been replaced by a length of garden hose. Unable to tolerate prolonged exposure to hot oil, the hose had collapsed, blocking the return path to the sump. Another half hour saw the new valve and hoses fitted and I’m delighted to report, the BMW has quit smoking.
The final job this month was a second bite at changing the brake fluid. When servicing, I had attempted to renew the fluid but found the flow from the bleed nipples was very slow. I’ve just fitted a shiny new set of nipples but still the fluid only comes through slowly. Anyway, I bled through plenty more fluid from each corner just to be certain the job had been done thoroughly.
To convince myself the fluid was now free from moisture, I bought a cheap electronic tester online. These little tools cost under £10 and when dipped in mineral hydraulic fluid give a readout via a series of coloured LEDS to show the moisture content. Testing the contents of the BMW’S master cylinder gave a perfect reading of less than one per cent moisture, so I can cross that job off the list.
The BMW’S mechanical to-do list now has a neat line of ticks through every item, and it drives like a dream. It’s time to think about fixing the rust on one wheelarch and smartening up the paintwork.
practicalclassics@bauermedia.co.uk