I know this sounds bad, and I am prepared for the worst once I take it to the dealer, but the truck is running fine except when cold....

1999 F150 5.4 4X4 SC, 80K.... about 2K ago I started to hear a faint knocking noise when the engine was cold... at first it was just during warm up. Maybe the noise was still there but couldn't be heard once I was moving.... anyhow it got a bit worse now and although stable for the last 1K or so it is pretty noisy when cold, even for the first couple miles, or until I turn up the radio.

Once warm, I hear nothing... The performance is unaffected whether warm or cold, just the noise. I know this is a joke to ask 'what is that clanging in my engine' but I figure it's worth a try.... the sound is a pretty distict knock... almost sounds like a diesel for a couple minutes. The colder the outside temp, the louder the noise.

Again, I know you can't diagnose a sound on a chat board but any ideas or advice is greatly appreciated..

 

mtofell: First be sure you are using the right oil for this time of year, 5/20 also use only a 820-S oil filter. Second have you heard of Piston slap if not do a search here and get informed before you head to the dealer. Piston slap sound like the problem you MAY have and it hurts nothing just sounds like Sh$t until it warms up.

 

Piston Slap Search Results

Sounds like a classic case of piston slap. Read some of the psots from the link above. I've got nearly 300k miles and it's slapped since around 70k

 

My wifes 97 5.4 Expy started the cold knock at 95k miles... It now has 144k and still running strong.. Dont guess there is anything to worry about.. If you do a search on this subject there are lots of other 5.4s doing it.

 

mtofell

Have you checked your oil level to see if it is low?. I have read on the forums and experienced for my self the same knocking you describe at cold startup for quite some time(current mileage 68K).
When my truck gets between 1/2 to 1 quart low on oil it will make a very pronounced knock at cold startup and until warm. I'm using Mobil 1 5W30 and I always lose some oil between changes. On my last oil change I added an extra 1/2 quart and thus far haven't noticed the knocking (I had read here that you can overfill by up to 1 quart and not cause any harm).

HiO

 

My 4.2L is doing the same thing - it doesn't do it at idle (or at least not that I can hear), but it does it as I'm releasing the clutch to start from a stop. It only knocks about 6 times and then stops once the truck gets moving. It stops altogether after the truck warms up.

Oops - On further reading, I see that the 4.2L was not one of the problem engines. I wonder what my problem is? It sounds like a woodpecker under the hood.

 

girlwithtruck:

it sounds like you might want to take it back to the dealer or a trusted mechanic.

Your problem (as far as I know) does not sound like piston slap. First, I think it is mainly a 5.4l engine problem (?), and also, the PS occurs immediately from starting, at idle, on cold mornings.

 

The oil is full... I have never over filled it but that may be worth a try. On one particular cold morning when I really noticed the noise I realized I was over my 3K since the last oil change... I had it done that day and the next morning heard the exact same sound. I have always run 10-30 oil through it.... not sure why, that is just what the guy at the quckie lube recommended I guess. Maybe I will try another weight and see if it changes. I am just glad to see I am not alone. Thanks for the help

 

I think if you listen to the tapping long enough you will hear it is morse code.

believe it taps out FOMOCO


tk