Questions and Answers
Cold Engine Knock
Q. I own a used 1995 ford windstar with a 3.8 V6 engine, Air, Automatic transmission, 110000 miles. When I start this motor it knocks very heavily until it warms up. Once it reaches a warm temperature it runs as smooth as silk. What I want to know is does it do any damage to move this auto while the knocking is going on or should I wait until it warms up enough for the knocking to disappear?
I thank you very much for any help you may be able to give me.
A. Knocking, cold or hot is not good. The kind of noise you describe usually indicates a large amount of wear in the lower end of the engine, usually the connecting rod bearings.
The first thing I would check is that you have the proper grade of oil (Ford recommends SAE 5W-30) and that it is up to the full level on the dipstick. If the oil is correct and full, I would take it to a shop and have a Technician listen to it to determine the exact cause of the noise. At this point if it is the connecting rod bearings, there is a good chance that they can be replaced before they damage the crankshaft.
I would get this looked at as quickly as possible.