F150 4.2 1997
 

Ok so when I drive my truck for about 10 mins or less I turn it off and I hear like a knocking nosie I never hear a knocking nosie when my truck is on only when I turn off my truck you hear the nosie can someone help me out

Are you saying it continues to run, dieseling? If so, I would put two bottles of Gumout with PEA in the gas for the next several tanks of gas to see if it cleans up the combustion chambers and eliminates the dieseling.

How fast is it idling when you turn it off? If the idle speed is too fast this will contribute to dieseling.

So basically when I turn off my truck it makes like a knocking nosie with it being off don't know what that nosie is and I never hear it when it runs only when it's I turn off my truck I hear that nosie

Check your intake manifold gasket. You could be trying to burn coolant.

Check your coolant levels and do a radiator pressure leak down test.

Might not also hurt to do a compression check on all cylinders and report back your findings.

These tools are readily available for rental at most auto parts stores.

Johnathan - welcome to the forum. I've moved your thread to a more appropriate subforum.

I think Roadie has given you good advice. What you are describing sounds like "dieseling" to me too. You likely have a buildup of carbon in the engine that stays hot after you turn the ignition off. This carbon ignites gasoline that continues to be delivered to the engine as long as it is turning over. But, the burning doesn't occur at the right time, so you will hear, and possibly feel, an uneven knocking sound for a few seconds after shutting things down.

Getting rid of the carbon and/or lowering the idle speed will help prevent this.

- Jack

Is this an engine knock? Or like placing the tranny in park and turning off the truck knock? Is it possible it is hitting something?

Basically when I park and turn off the truck the knocking sounds starts it only happens when it's off I don't hear the knocking sound when the truck in running

​​​​​​Thanks I this helps me out alot would you happen to know anyone that I could get a motor from like shipping for cheap around 400 $ a used motor

Yeah I just changed my intake Manifold cuz it was allowing water to get in my spark plugs and that worked . So when I was changing the intake manifold you can see alot of build up and my mechanic seen it and didn't want to clean the build up and then he out it together and it ran good but has the knocking noise only when I turn off my truck

Does the knocking start before the engine stops turning, or after? How long does it keep knocking?

When you replaced the intake manifold, did you replace both the upper and lower plenum gaskets and the front cover gaskets?

Yes yes I replace the intake manifold the upper and lower and it's after turning off the engine when it stops and
knock for like a minute or two

Did you replace the front cover gaskets? Confirm the knocking does not start until the engine completely stops rotating? If so, it could be an air lock in the cooling system, possibly a bad thermostat.

One thing that is worth checking is the harmonic balancer. The keyway has been known to wear and allow the balancer to rotate on the crankshaft. This changes the timing and could cause your symptoms.

Give me a call so I can send you the video it don't matter anyone can text this number cuz I need to know what is happening

Post the video to YouTube or upload it here as an attachment so everyone can see it. I strongly suggest you edit your post and remove your phone number.