Q: I just had a new engine put into my 2005 Chevy Suburban. When I start my truck after it sits for a few days, I get blue exhaust smoke out of my tailpipe. I’ve been monitoring my oil and the level has been going down. It was down 1 ½ quarts when I brought it in for an oil change. There is no leaking. A mechanic friend said it is either my valves or valve seals. The mechanic at the dealer who did the work said I need to give it 10,000 miles and he said it should seal itself. Does that sound correct? My buddy the ex-mechanic does not buy it. I spent a lot of money to get this fixed and have a three-year warranty with the new engine. I’d be interested in your thoughts on this.
A: Based on consuming 1.5 quarts in 3,000-plus miles, the engine’s oil consumption falls into acceptable limits of 1 quart per 2,000 miles. Normal oil consumption occurs when a very small percentage of the oil film left on cylinder walls as the piston is driven downward on the combustion stroke is burned. More important, this level of oil use would not generate significant smoke on start-up. To put this tiny amount of oil consumption in perspective, if an engine burned one drop of oil in each cylinder each combustion stroke it would consume a quart of oil in less than 5 miles!
It is far more common for that puff of blue oil smoke on start-up to be caused by oil that has collected on the valve stems after the engine is shut off. If there is a problem with the oil seals or valves/guides, this oil can drain past the oil seal and down the valve guide where it collects on top of the valve head. Then, when the engine is first started, this oil is drawn into the combustion chambers and burned, creating blue smoke from the tailpipe. Were the cylinder heads on the replacement engine new? Or were the heads from your original engine reused? If so, this could be the source of oil smoke.
I would not expect oil smoke from valve guides or seals to “seal itself” in 10,000 miles. Since the oil smoke isn’t harmful to the engine and you have a three-year warranty, I would suggest documenting the oil smoke and consumption at this time and mileage, monitoring the oil consumption carefully over the next two oil changes, and if the blue smoke and oil consumption continue, I’d press the dealer for help.
Q: I have a 2000 Chrysler minivan with 65,000 miles. The last time I filled my gas tank the dash gauge went to “Full” and will not move, after being driven 200 to 300 miles. What is wrong? A fuse maybe? Would you suggest using the trip odometer?
A: Does the needle on the fuel gauge move when the ignition is first switched to “on”? If not, the problem could be in the instrument cluster. According to my ALLDATA automotive database, Chrysler built in a simple self-test for the instrument cluster. With the ignition in the “off” position, press and hold the “Trip” and “Reset” buttons simultaneously. Turn the ignition switch to the “on” position and continue to hold the “Trip” and “Reset” buttons until the word “Code” appears in the odometer window. If there’s a problem with the cluster, a three-digit DTC fault code will show. If there are no problems with the cluster, “Code 999” will momentarily appear.
Next, have a scan tool check for any BCM (body control module) fault codes. Also, the function and calibration of both the fuel gauge and sending unit can be checked for accuracy. If a problem is found with the gauge or cluster or sending unit, you’ll have to decide if it’s worth the cost of repair on your 13-year-old vehicle. Like you said, the trip odometer is a good backup plan.