Quick knock sound at WOT

[explr1]

If I'm sitting still at a redlight and I gun it, WOT instantly, the engine makes a quick metal knock sound. Just once thats it. It doesn't make it anytime other that that. What is it and is this bad for the engine?

 

[Jason_25]

I'm sorry I don't have a technical explanation for the knock noise, but I do know that it's just not that good of a idea to rev your engine alot while it's not under load.

 

[explr1]

I need to clarify that this happens when taking off from a standstill with WOT. Theres no lag in power or hesitation, just a very quick knock sound.

 

[MrShorty]

How are the engine and tranny mounts? u-joints?

 

[Rhett]

Do you have the SOHC?

 

[explr1]

I have the 4.0 OHV engine. I don't think it's the engine/trans mounts. Had the truck in to the dealer for 84,000 mile service three weeks ago and they didn't tell me anything. It wouldn't be the TB plate making that noise would it?

 

[Majisto]

The Taurus makes a clunking noise from the passenger side area if you try to accelerate it from anything more than 1/2 throttle. I have traced the problem to a bad motor mount. This is probably what you have too.

 

[Abraxsis]

Maybe?

The slip yoke can also make a clunking noise from under the vehicle. Does the noise also happen occasionally when you stop as well as when you "gun" it? Search for slip yoke there is plenty on it.

 

[explr1]

No, but I did notice that it did it when I started it this morning. Didn't touch the gas pedal, just turned the key.

 

[Rhett]

What weight and type of oil are you running?

 

[explr1]

Originally posted by Rhett Browning
What weight and type of oil are you running?

I've been using Mobil1 10W30 since I bought the truck in July of last year. Someone I work with said it was the oil, but it's Mobil1 full synthetic, it can't be! Can it? I never floored it at a redlight previous to last week.