a slight knock

[Splorer94]

ok i have a 94 explorer sport with the ohv 4.0. it has 120k miles on it and i bought it not to long ago. 3k miles rolled around and i changed the oil. i used 10/30 valvoline oil because it did have a good bit of miles and i used a motorcraft filter. i had no probems right... well a couple days later i crank the truck up and it has a slight knock only when you crank it up. when it sits at idle it doesn't knock. also it only knocks when the motor was cold or it sat for about 6 hours, and only when you crank it. well i looked in the owners manual and it said used 5/30 oil so i changed the oil again with 5/30 vavoline and motor craft filter. it still does it slightly..... so is that normal for this many miles?? (120k) its not a hard knock just a light knock when you crank it up...

 

[anthonytony]

A bit normal for a ford to start knocking on the lower end and in some cases the oil pump may be getting weak .....

 

[cfkane]

Could the noise be from collapsed/worn lifters? The early 4.0 ltr engine has a tendency for failure in the lifters and the sound is a light tapping or knocking.

 

[Splorer94]

i have been told it could be the oil pump, but i never heard about the lifters. doesn't a little atf in the oil help that out or are they just completely gone do you think..

 

[cfkane]

ATF in the oil is a deposit-cleaning trick. A better choice would be BG Products MOA. It does a great job of cleaning engine oil deposits.

In the case of the lifters however many times it is a wear related issue that cannot be remedied by additives. R&R is the only real option and in this case that means the removal of the heads to get to the lifters.

 

[elkhunter]

If you pull the heads doing this it would be a good time to check for any cracks beginning to form between the valves or valve to spark plug.

 

[F14CRAZY]

It's said that the gasket material used in these engines (RTG?) can begin flying around. It can get stuck in the oil pump sucking screen. You can figure out the rest. Changing the oil often keeps this stuff from getting severe (logically, right?) so it may show what previous care was like before you owned it.

Pulling the pan (screw what the manuals say, because it can be done without pulling the engine) and cleaning/replacing the screen would be a start. Might as well replace the oil pump too.

10/30 oil is fine in your engine (I use 10/30 too) unless you get the valve tick for a few seconds after the engine starts. 5/30 will get there quicker.

Before this, try putting half a can of Sea Foam in the engine oil, drive around for a few hours, and drain the oil. You'll notice that the oil will be a lot darker and may be able to free up oil passages.