Thread: 2008 GP intermittent problems

Re 2008 GP. I use full synthetic oil, flushed the cooling system and replaced with dexcool. I also replaced the spark plugs. There have been a couple of glitches, but nothing unexpected. Heater motor (during recent cold snap) sometimes stops, but a good knock on the dashboard starts it up again, I suspect that I will have to replace the heater motor and resistor when the weather warms up. All my previous GM 3800 V6 cars have had heater motor failure at about 150,000 Km, without exception. I can also say the same thing about the water pumps. Maybe the 2008 Grand Prix water pump will fail while there is still some warranty left (still covered to 160,000 KM or August 2012). Temperatures here in Calgary during the last two weeks have been hovering around 0 degrees F. It is now warming up for a few days. One other intermittent glitch is that engine power is lost momentarily. This has happened twice in 40,000 Km. I hope this does not indicate a future issue. There are no Trouble Codes.

First time this happened was last February 2010 (about 70,000 miles) at cruising speed of about 60 mph, Temperature of 20 degrees F. light snow, about 2 pm. Momentary loss of power for less than 3 seconds, Warning light came on for about 2 seconds "COMPLETE ELECTRICAL FAILURE" Engine lost power, dash lights went off, then everything returned to normal. When I got home I load tested the battery (pass), cleaned both battery connections (no corrosion found), Checked for high trsistance in both battery cables (OK), checked no load battery voltage (14.2 VDC), loaded battery voltage at 13.48 VDC, checked alternator output at 1800 RPM (14.42 VDC) at idle (13.82 VDC), Checked serpentine belt, tensioner, alternator pulley (all OK). Checked for trouble codes using latest SnapOn equipment (found nothing).

Second time almost the same, within the last week. Cruising, 65 MPH. Outside temp 5 degrees F. 8pm, Momentary loss of power for less than a second. Engine lost power, dash lights went off, then everything returned to normal. No warning lights came on this time.(about 92,000 miles).

I use fully synthetic engine oil, tire pressures at 28 PSI, air filter just replaced.