Often a knock when cold is caused by piston slap, which is pistons rocking in the cylinders until they expand in size when the engine warms up.
Check for vacuum leaks.
Gm used a short piston skirt on this year. The knock is piston slap that normally goes away when engine warms up. Sounds bad, but should not cause any problems.
Some causes will:A leaky lifter will pressure up and quit, and can sound like a rod knock when the clearance is bad enoughA collapsed piston skirt will quiet down when the engine warms upA rod can knock under load or start up and quite down when oil pressure is applied. Its only going to get worse though.
Does it quit shaking when it warms up? What engine and year of Aerostar?
The preheater warms up the engine so it will start easier and in freezing weather will help to avoid freezing of the coolant.
When an engine is cold, the oil is thicker, and flows slower. When oil doesn't get to valvetrain components quickly, you'll hear knocking, also known as valvetrain clatter. As the engine warms up the knocking should go away.
It is because of how fast the car idles. When you start the car it is idling high and when the engine warms up it slows the idle to about 650 RPMs and the torque converter in your transmission is slipping and not moving you forward at that low an RPM. what causes the torque converter to slip? CAn it be a sensor problem?
If its coming from your engine, you may need a valve adjustment..
A cold engine will often experience trembles due to the inefficiency of engines when not at operating temperatures. This quickly goes away as the engine warms up.
i have a 2000 dodge work van 318 engine when i start in the morning it stalls several times until it warms up then ok
Valves tapping?
is the van getting spark? does the fuel rail have fuel pressure Might want to check your knock sensor if equipped