1988 straight 6 300ci sat for 3-4 years got fuel problem fixed ran fine next day only 5 cyl. were hitting took cover off and found bent pushrod on intake valve new lifter and used rod then hitting all six ran smooth next day same thing but found 3 bent pushrods and all other intake pushrods off lifters on intake only any ideal what may be happening and why where should i go from here

 

The easiest way to bend a pushrod is by over-revving the motor and floating the valves.


The reason it's happening on the intakes is those valves are bigger and heavier, and more likely to float.

The I6 does not like to rev.

Keep the revs low and shift early, and see if the problem goes away. If you have bent pushrods, replace with the best quality ones you can find.


The valve springs could be sacked out, contributing to the problem. But if there is ever a motor that could live its whole life below 3,000 rpm, it's the I6.

 

i have not even drove the truck to over rev

 

Pull the valve cover and check everything out in there. After sitting that long I bet the rocker arms are running dry.

 

have had covers off didnt see anything there and why only intake valves or lifters

 

So you are not even driving it, but it's bent four intake push rods in two days? And three other intake push rods are jumping out of the lifters?

Just from firing it up and letting the motor run a little in neutral or park?

Maybe explain it a little better with some more details about how long you let the motor run, what work you did before you started it, etc...

 

Pull the lifters and inspect them. Sitting for a few years they could have frozen and then collapsed.