My first post and it has to do with a problem with my truck! Well, I bought the truck about 3 months ago and it has 65,000mi on it. The weather just turned cold here in TN and the thing is knocking when I first crank it up. What can I check for or do to stop this from happening. Any advice is appreciated. Thanks in advance.

 

maybe its a valvetrain noise due to inadequate lubrication at startup... i think that when the engine is cold it would knock less because it will be running richer and will not have hot spots in the cylinders.

if its the oil, try running synthetic or lighter cold-weight oil (eg run multi-visc. oil with a lower first number, such as 5w30 or 0w30 instead of 10w30).

 

normally knocking occurs at low rpm under heavy load... my truck has always pinged a bit when i lug the motor, but never at any other time.... the manual says a small amount of pinging is expected... all the other v6's i've driven (3 incl. mine) did the same thing; it shouldnt knock at no-load idle, though.

 

It may be as simple as the winter blend fuel. Here in Minnesota it's introduced in mid October. If this is your first full tank of winter blend the computer may not have adjusted to it yet. The 4.2L has a relatively high compression ratio at 9.2:1 and the engine probably has a harder time burning it properly at cold start. Over the last month there has suddenly been a number of people complaining about engine knock/ping all around the county. It seems logical to me that it has something to do with the fuel supply.

If it's just minor knocking/pinging do to carbon build-up then a simple fuel system cleaner added to your gas may clear this up.

You should also try cleaning your MAF sensor (Mass Air Flow). If it is dirty or has oil on it then it will not read the incoming air properly. If you do a search on MAF, you'll learn a lot about how it funtions.

 

If you try running synthetic oil in the truck and make sure you have a high quality filter (with an anti-drain valve feature) this really helps reduce the dry starts. A good brand filter like K&N or something of that quality will be the best bet. Hope this helps some.

 

It could be noisy fuel injectors,which is a pretty common problem and most often noticed at start up.

I agree with jrm 1493 that it could be too thick an oil causing valve train noise and that pinging is unlikely in an engine that is not under load.

 

Use a good quality oil filter, one w/ an anti-drain back valve (like motorcraft or mobil one).

 

LIKE DIRTBIKE DAVE SAID, IT COULD BE NOISY FUEL-INJECTORS. I HAVE A 2001 F-150 WITH THE V6 AND IT'S NOISY WHILE IT'S RUNNING, BUT NOT AT START-UP. MAY JUST BE BAD INJECTORS, THEY ALL MAKE A LITTLE NOISE DONT THEY? OR MAYBE IN YOUR CASE IT'S IN THE TIMING.

 

Knocking and pinging are two different things. Knocking is metal to metal contact between parts in a motor. Pinging is the pre-ignition if fuel in a cylinder and the sound of the two flame fronts hitting each other. The knock on start up is due to oil not staying up in the valve train. I have experienced this when i drove from phoenix(running 20/50) to LA(where it got real cool one night). Pinging in a motor running pump gas is NOT NORMAL! Unless the gas has gone bad, the computer systems now a days are made to control the timing and a/f ratio to prevent pinging to occur ever(unless the parameters have been altered by aftermarket products.....). 87 octane, 9:1 comp., and cold weather definately do not spell detonation. The injector noises are a quite ticking and cannot be confused with a knock. My truck does this knocking thing ever once in a while here in Oklahoma and it goes away within seconds(plus the RRockers are noisy too), it's nothing to worry about and a lighter oil may allow it to go away faster(maybe a second..) An anti drainback oil filter is one way to help.

 

Thanks everyone. I am going to change the oil today and get one of the filters with the anti-drain valve. The knocking does go away in about 2-3 seconds it just doesn't sound good . I hope I can reduce it or get rid of it totally. Thanks again.