Ask A Mechanic: January 19, 2007

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More mechanical wisdom from Bob Weber

Dodge sludge

Q–I own a 2001 Dodge Intrepid with the 2.7-liter engine. A friend just alerted me about serious problems with this engine regarding sludge build-up. A quick Internet search showed that Chrysler is ignoring consumer complaints, unlike Toyota . I have no problems yet with 80,000 miles, but was wondering if there is any preventive maintenance that can be done. I religiously change the oil myself at 3000-mile intervals. Two mechanics I spoke to strongly recommended against an oil flush.

A–There have been reports of sludging, especially in the early versions of the engine from 1998-02. Frequent oil changes are the best way to prevent sludging problems and that is what other carmakers are telling their customers to do. The fact that you change your oil every 3000 may well have prevented problems. I agree that engine flushing is not recommended.

Pinch protection

Q–I recently bought a 2005 Highlander. When I pushed the window-up switch the window went up quickly, non-stop! There was no warning labels or tags by the switch. I think this is an extremely dangerous situation for the unsuspecting driver. I have learned how to avoid that situation and how to stop and or reverse the window’s movement. The service department also told me that if my hand or fingers got in the way, the window would not stop. I didn’t try it to find out. Is this a normal feature in recent model cars? Is there a way to disable the quick non-stop up movement of the driver-side window?

A–Auto-up windows are becoming more popular, but no car company in its right mind would sell something so potentially dangerous that it would open itself to lawsuits. The folks at your dealer’s service department may be misinformed.

All Toyota products equipped with auto-up windows have pinch protection. The window will immediately reverse if it encounters an obstruction. If you look in your owner’s manual you will see several yellow warning boxes describing the window operation. Go ahead; you can try this at home. You need not disable the system.

Nitro tires

Q–When I went for my last oil change, the mechanic recommended putting nitrogen in the tires. He said it stabilized the air pressure, and the tires would not have to be filled so often. It cost $5 per tire. Did I throw out twenty bucks, or was it money well spent?

A–In my opinion money spent on nitrogen is not well spent. Air has worked well for lo these many years and will continue to be the inflation gas (or should be say mixture of gases) for years to come. After all, air is already roughly 78 percent nitrogen and 21 percent oxygen.

I am seeing more and more tire shops offering nitrogen and extolling its virtues, but I am not convinced. Besides, what if you check your tires tomorrow and they are a couple pounds low? Are you going to drive across town just to get a puff or two of nitrogen?

Shuddering Honda

Q–My 2000 Honda CR-V has 60,000 miles with the original brakes and recently I have noticed that when I make a hard right or left turn at slow speeds there appears a shuddering noise and a vibration felt throughout the frame. It only seems to happen during these sharp turns. I can’t tell if it’s from the front or rear, but it sounds as though the tires are rubbing up against the fenders, though that is not the case. Any ideas on where this noise might be coming from?

A–I seriously doubt that the noise could be caused by the brakes, even if they are worn down to the metal. At most, you would hear and feel a grinding sound, but usually only when applying the brakes. Since the noise occurs while turning, I would examine those things that move and turn at the same time such as the constant velocity joints on the axles. They can make the type of vibration or shudder you describe when they wear out. But it could be something else — so I suggest you see your mechanic about this one.

Switching oil

Q–I have some 10W-30 and 10W-40 oil that I had purchased for an older car. I sold the older car and now have two Camrys that call for 5W-20 oil. Also, my son just purchased a 2006 Accord that calls for 5W-20 oil. Would any damage be done if I use the high weight oil or even if I mix a quart with the proper weight at every oil change? I change the oil every 3000 miles in each car.

A-I would stick with the 5W-20 oil during these colder months since you want it flowing to critical parts as quickly as possible when starting the engine. During the summer, I see no problem using your old oil — provided it has the proper API and ILSAC designation. Consult your owner’s manual for these specs.

Quitter Caravan

Q–I have a 1997 Dodge Grand Caravan with a 3.3-liter engine. Recently, the heater fan in the front console quit working on all settings except high and off. I thought that would be related to either the switch malfunctioning or a resistor located on the fan housing. The relevant copy of Chilton’s did not mention? or? show a related resistor.? A major parts distributor? confirmed that those would be probable causes; however,? they could not find such a resistor in their online system. Another sales rep in the store said he fixed a similar problem, but the switch and resistor were now integrated within the console. I have not bought any parts and want to confirm what I should be looking for and whether the second rep is correct. Switch, resistor, or knuten valve?

A–First of all, Knuten valve is spelled with a capital K and I have yet to see one fail in all my years of auto service. They are as durable as muffler bearings. Now, back to your blower speeds??¦. There is no resistor in the circuit. All blower functions are handled by the body control computer which is part of the HVAC (heating/ventilation/air conditioning) control head. They are not cheap and if you decide to source one from a recycling yard, make sure it is identical to the one you have and that you find someone who knows how to program it.

Due to the large volume, Bob Weber is unable to answer most questions sent to The Car Connection each month. Some may be answered directly, where possible, and others will be included in future columns if the topic is deemed interesting. Be sure to include your real name and full address (city, state, province, country, etc.) when sending your questions.

Weber, a self-proclaimed swell guy, is an ASE-Certified Master Automobile Technician, freelance writer, and former editor of Super Automotive Service magazine. His column, “Motormouth,” appears weekly in the Chicago Tribune. He enjoys good tequila, good cigars, and good times. A chemistry school dropout, he still concocts compounds in the kitchen and makes a mean pot of chili. He and his wife live near the Blue Ridge Mountains of Virginia.

E-mail Bob your questions at

Posted by admin   @   11 February 2007 0 comments
Tags: al, Auto, Automobile, Camry, cars, Chrysler, cr-v, cts, Engine, Highlander, Honda, Identical, KERS, Motor, push, sales,

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