4.9 valve clatter
 

Hey all, '94 e150 with a 4.9l 6, 190k. Doesn't use any oil and mostly runs ok. The valves don't make any noise at idle, while accelerating or decelerating. But when going down a hill (especially at highway speed), and the van "catches up with the engine" so there's no load, there's a godawful clattering until I either let off a bit or give it enough gas to put a load on the engine again. Any idea what would cause that? Thanks!

sounds like it may need new lifters. or you could try a can of seafoam or whatever to hope it'll loosen up your existing lifters - but new would be best. they're not too bad to install.

Normally I'd think weak springs from too much heat like some days of a bad radiator or bad gas which all ethanol is in my book or too low of an octane.

It's not me doing the job so I won't suggest looking under the vavle covers to see whats up :)

if he looks into changing the lifters, he'll have the valve cover off in the process, and at least take a look around. i've put 300s through hell and never had a valve spring problem, nor have i heard of it being a common problem with 300s. but i have had lifter problems on them