The Mercury News Weekend

Oil pressure issue might be easily resolved

- Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, California. Readers may send him email at under-the-hood@earthlink.net; he cannot make personal replies. By Brad Bergholdt

My 2003 BMW 325Ci has 97,000 miles on it and generally drives perfectly. I have always taken good care of it. However, after about 10 minutes of stop-andgo traffic, the oil pressure light starts flickering. I know the problem isn’t the oil level because I always check it after 500 miles and do timely filter changes. The warning light goes away the moment rpms are above 600. I Googled the issue and found four possible root causes: bad sensor, engine pressure leak, bad oil pump or dirty idle control valve. What would you advise? By the way, I always use 10w30 synthetic Mobil 1 oil, not the Castrol oil BMW recommends. — Gary

Your oil pressure warning light likely illuminate­s when pressure drops to a reading of 8 pounds or less. I wasn’t able to find the exact figure. Under normal or hot conditions, idle oil pressure should be in the 10-15 pound range and should increase with engine speed.

Among the possible reasons your warning light might be illuminati­ng during hot idle conditions are: thin or contaminat­ed oil, low idle speed, an off-calibratio­n oil pressure switch, and low oil pressure due to excessive bearing clearance or a worn oil pump.

Let’s start with recently changed, contaminan­t-free oil and correct idle speed. BMW specs call for 650-750 rpm, so you seem to be idling a bit slow, possibly due to a dirty throttle or faulty idle control device. I’m thinking this is your only concern.

Actual oil pressure can be verified by removing the oil pressure sending unit and temporaril­y attaching a mechanical gauge. Removing the idle control device and cleaning it, along with the throttle bore, may just do the trick! There are several YouTube videos illustrati­ng the procedure.

My 2015 Ford Edge SEL is quite noisy. The noise comes from the cargo area and becomes softer or louder depending on the road surface. It’s particular­ly bad on interstate highways. After a frustratin­g and noisy year of cruising, I beg you for advice on reducing this annoying sound. Do you know of a noise-reducing under coating? How about a sound-deadening material to put on the inside of the car? — Hans Wolff

Try cleaning the front and rear wheel wells and applying several coats of Rust-Oleum rubberized undercoati­ng or a similar product. Be sure to wear eye protection.

Further coating of the Edge underside would also be helpful but this would be tough to do at home. Perhaps a quick-lube place could apply it for you for a modest fee. Another angle is to apply some Dynamat or similar material to the inside wheel wells and load floor area. This is a thin rubberized sheet material that really knocks down sound. Removing and reinstalli­ng interior trim and carpeting would be needed. Both products are available at auto parts stores and on Amazon.

Also, some all-season tires are noisier than others. Try researchin­g noise levels at TireRack.com when it’s time for replacemen­ts.

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