A reader has a question about coolant for his roadster

Car Doctor answers a question from a Porsche Boxster owner.
Car Doctor answers a question from a Porsche Boxster owner. Porsche

Q. I have a 1999 Porsche 986 Boxster with 176,000 miles and have a question about coolant usage. Is there any difference with the pink G40 coolant between different companies – Pentofrost or Zerex – compared to all vehicle coolant/antifreeze like Prestone or Peak?

A. I am a proponent of using the correct coolant for the vehicle. Finally, there are at least eight different types of coolant. All vehicle coolant is suitable for topping up the system, but when it comes to a complete drain and refill, it is best to use G40 pink coolant with hybrid organic acid technology. Mixing different engine coolants or using the wrong coolant can lead to a lack of lubrication and an increased chance of corrosion.

Q. I have a problem with my 1986 Dodge pickup truck powered by a six cylinder engine. I ran it this morning with no problem and was driving through my block when it just shut off. When I tried to restart it, it fired right up, but died again as soon as I turned the key. Knowing this was typical of a faulty ballast resistor, I had a spare, replaced it and it did the same thing. any thoughts?

A. The ballast resistor reduces voltage to the ignition to improve component life, and is also a regular point of failure, which is why many Chrysler owners carry a spare. At this point you should test the wiring (ignition circuit) of the ignition switch. Check that the wiring to the ballast resistor has power when it should. You may find a faulty fuse or fusible link that cuts off power to the ignition coil. The other possible and common problem is a faulty control module.

Q. I have a 2009 Pontiac GT two door with 138,000 miles. I have noticed a slight screech or something like a rubbing sound when I start and turn left. A few years ago I replaced the steering rack and pinion. Could this happen again?

A. The steering rack is unlikely to make noise. It is possible that the drive belt or tensioner is the source of the noise. When the engine is started, the alternator works harder and the belt may slip slightly.

Q. Do you have an app I can download to answer questions when I have a problem with my car?

A. No, just email me, [email protected] or aaa.com/cardoctor. I try to answer every question.

Q. I have a 2017 GMC Yukon with MagneRide struts and shocks. My dealer service department recommends replacing all four modules at a quoted price of $4700. I know these units are more expensive than stock struts, but the amount quoted seems high. Does this price match the expected replacement costs? Would non-OEM struts be an acceptable alternative.

A. Magnetic shock absorbers use a special metal-based liquid. When an electrical charge is applied to the shock body, the fluid changes its viscosity, allowing for a change in ride and handling. The shocks are controlled by various sensors. GM’s MagneRide is quite expensive, and the quoted price of $4,700 is not out of line for factory parts. There are aftermarket parts that can save you some money and are certainly worth looking into. Be a little careful and make sure you get an OEM replacement part. One last thing, if these shocks are being replaced due to fluid leaks, some slight discoloration from oil seepage is normal and does not mean the shocks need replacing.

Q. My car stalls, hard to start and almost every available light comes on. Constantly shows TPMS and works fine for a while after clearing the codes. The FIXD code reader pointed to the sensor in the intake manifold that the Kia dealer told me to replace and I did. I replaced the ignition relay and spark plugs, changed the oil and flushed the transmission myself. I need a car for my work at Uber and Lyft. The codes are P2016, P200A, P0644 and P0365.

A P200A could mean the intake manifold is a problem. P2016 is a wiring problem with the sensor you replaced. The most common repair is to replace the intake manifold. PO365 indicates low voltage to the camshaft position sensor. The PO644 code is a communication problem between the computer and the various modules. If this was my vehicle with these codes I would be looking for a wiring issue.

John Paul is AAA Northeast’s automotive doctor. He has over 40 years of experience in the automotive business and is an ASE Certified Master Technician. Email your Car Doctor question to [email protected]. Listen to the Car Doctor podcast on johnfpaul.podbean.com.


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