Engine Knock Issues

[Viro]

'04 Sport Trac XLT 4WD
108 000kms

About a month or so ago I started noticing a knock like noise after starting up the truck. It'll last for maybe 5 min or so and is rather intermittent. I've left the truck idling and it'll do it and does it while driving regardless of speed etc.

To me, it reminds me of the knocking sound you get in the winter while the engine is cooling down in the cold air. In this case it might be a tad louder and 'sometimes' when it does knock I can feel it through the gas pedal.

I've owned the truck for 4 years. I ocassionally tossed in some high octance gas when I first got it but then gas prices got stupid so I stopped doing that (haven't put high octane in it in 3 years). I haven't had any issues with gas mileage etc.

I change the oil every 5000kms and all the fluids still look good. While driving nothing seems out of the ordinary except for the noise. Truck drives fine but the knock is starting to bug me.

I first thought the knock had something to do with the exhaust but I had the hood open and it definitely seemed to be within the engine compartment.

I'm at a point at bringing it in but I'm not really sure what I should be expecting the mechanic to look for seeing as I will most likely have to leave the truck with them as it is a cold start issue.

 

[05dakotatrac]

we need to know if the sound is more forward back left right etc. try to narrow it to a certain location and very discriptively tell us the sound. is it a click noise similar to a pen or is it more a clunk like hammer on metal. if you can video it and upload it that would be best. honestly these motors are notorious for timing chains which click, clunk, bang.

 

[Viro]

Definitely not a pen click.

I sort of noticed when coming home from work today it kind of sounded hollow but it's more like a hammer tap/knock. I have felt it faintly through the gas pedal.

For whatever reason it wasn't as profound tonight. I let the truck idle for a bit and heard a very faint noise but I didn't notice it on the way home (which is like 10 min from work). When idling it takes awhile to get something but if I just kind of get in it and go I'll notice it by time I get down the street.

Normally, once the engine gets up to temp on the temp guage (almost halfway from cold to hot, closer to cold) I don't notice it.

I've also pretty much been getting the gas from the same station for the past few years, and if I don't top up there I still get the same gas brand elsewhere (shell).

I will try to get a video if possible considering the noise is finicky and see how to upload it if I can.

 

[Viro]

If I take off the fan belt and run the engine, and the knock is there what's that gonna tell me? and if it's not?

 

[craigeo]

My truck just had this rattle/knock. I took it in... They replaced the front and bottom timing chain tensioners. Was about $950 repair. No more rattle

 

[ptf18]

TIMING CHAIN TENSIONING SYSTEM!!!!

Watch for this plastic system coming apart. Very bad news. Parts of it came thru the plastic valve cover on the wife's '02 with 134k on the engine which if you search the 'net you will read of simalar accounts.

We ended up replacing the engine for $5300.

I'll be installing new tensioners around 75k SOP.

 

[Viro]

I haven't had a good chance to try and grab a video/audio yet....

Oddly, after posting this thread the noise has not been as loud....

I can hear it but its faint now.....not sure why....

The only thing I could think of is that I put new front wheel well skirts in shortly before I started hearing this issue. Maybe it is condensation in the exhaust? Doesn't really explain why it's more quiet right now because they're still on right now....

 

[MyTrac]

I would not play around with this and just get it checked out. don't let them tell you they cant replicate the issue either. CLEARLY, you are there bc there is an issue. no harm in being safe...

 

[05dakotatrac]

honestly i put money on it being the cam chain tensioners very common issue on these tanks.

 

[ptf18]

You've been warned! Danger Will Robinson!