knocking on start up

[canine6]

During morning startups after the x has been sitting over nite it tends to knock for about a minute. it has good oil pressure and just changed oil last week

It only seems to do it on cold starts. the rest of the day its fine.

any comments?

 

[Alec]

I'd try cleaning your MAS and also run some fuel injector cleaner through the fuel system.

 

[Rhett]

It's probably oil not getting to the top end of the engine quickly enough after a cold night. 4.0 OHV's are known for doing this, as they have an oil passage design where pressurized oil won't get to the pushrods adequately. That's why 4.0 pushrods tend to wear prematurely, and get noisier with time.

Mine does it too, if the truck has been sitting out a day or two without being driven in cold weather. 93,000 miles on the original pushrods.

Don't worry though, that's why most good motor oils have zinc in them--protects, as much as is possible, against excessive wear in those short-duratin no-lube situations.

 

[canine6]

thanks for the reply guys