Western-Star

Wheels: An e-mail from Steve says, "The oil pressure light in my 1997 Ford Taurus, 3.0 liter, V-6 started to flicker when my engine was idling and the engine was completely warmed up. Otherwise, there is no flickering when the engine is cold and idling or when driving. The local mechanic says that he measured my oil pressure as below specifications when the engine idled at 700 RPM. He replaced the oil pressure sensor and changed the oil to 15W-40. He and I agreed that changing the sensor wasn't really necessary, but we replaced it anyway since these sensors seem to go out of range as they age.

What concerns me is using 15W-40 oil to increase oil pressure. Although the oil pressure light no longer flickers at 700 RPM, can there be any harmful effects from this high level of an oil viscosity? If the engine is running too lean when idling, could this cause the oil pressure light to flicker? It seems to me that the dashboard tach shows the RPM actually dropping a bit below 700 RPM from time to time."

Halderman: The problem with using this thicker engine oil is that it could make it hard to start (slow cranking) in cold weather, and this will reduce fuel economy. The air-fuel ratio does not affect oil pressure, but several other more serious items will cause the oil pressure to be low, including:

1. Worn engine bearings — As the bearings wear, the clearance between the crankshaft and the bearing increases, which means that the oil leaks out faster than normal and into the pan, reducing the oil pressure.

2. A worn oil pump and/or a clogged oil pump pickup screen can reduce oil pressure.

What to do? If you plan on keeping the vehicle, I suggest that the oil pan be removed so these items can be checked. If the oil pump screen is clogged, replacing the oil pump and screen may solve your problem. If the oil pump and screen are OK and the engine bearings are worn, then it is time for an engine overhaul or engine replacement.

Wheels: Paul writes, "I have a 1986 Dodge Ram 1500. Last summer I went to raise the door window on the driver's side and it would not go up. I sprayed about a can of silicone lubricant in the glass channels, but it still would not go up — it just stayed there and spun. I then took the inside door panel off and cleaned off the old grease and put on new grease. It still does the same thing. I can pull it up or down by hand, but that is a lot of trouble. Do you know of any cure for this problem?"

Halderman: The window handle operates a gear which is attached to another large gear that in turn is attached to levers and arms that move the door glass. This entire assembly is called the window regulator because it is used to regulate the window height. The most likely problem is that the gears are stripped. The only reasonable repair is to replace the window regulator. Many shops or body shops can handle this repair.

James D. Halderman is an ASE-certified master technician. Submit questions to Halderman via e-mail at jhalderman2@juno.com, or write him in care of: Wheels, Marketing Publications Department, Dayton Daily News, 45 S. Ludlow St., Dayton OH 45402.