2004 3.4L Engine Knock

When my truck is at idle, A/C on, brake applied and tranny in Drive. There is a knock, mechanics at my work are saying it sounds like its coming from the behind the timing cover or possibly the flywheel. Anyone expirience this yet on there 04. Please let me know if so. Thanks

 

How many miles are on it? Have you replaced the timing belt and tensioner?

 

i just turned 52000 and no i have not changed it

 

yep... i notice it as soon as i come to a stop and apply the brake, the truck sometimes jumps with a knock..not sure what it is but your not alone.

 

Hey Mitchhilo333 I think you have a different thing going on there. I have heard something about this a while back, if I can remember correctly it had something to do with the universal joints, They need to be greased and you also have to purge all the old grease out of them. check with your local dealer there is a TSB on this. I have been doing this to my 03 Taco and so far so good.

As for Onetrack236 sorry dude have not heard anything about that problem.

 

is that really bad if i dont fix that problem?

 

I don't think so, you will just hear the clunk when you come to a stop and apply the brake. Next time you get an oil and lube tell them to purge those universal joints, all they are doing is puttting grease into the fitting until the old grease comes out. see if it helps.

 

After searching more, my truck is doing exactly what the OP said. Anyone else have this issue? I'm hoping it's something simple and not a rod knock. The thumping is inconsistent, but does match the speed of the revs when it's doing it. Because it's inconsistent, I'm hoping to rule out a rod bearing.

 

Its very common on the automatics. Its your universal joints not being greased well enough. They bind and then release at a stop.. its annoying as all get out.

 

you ppl aren't reading the OP's description.. he said the truck is idle at a stop. Not the clunk associated with slip joint grease of axle warp.

To the OP: Do you get a knock that goes and goes? And once you hear it, does it go away immediately when you turn off the HVAC fan?

 

Just to revive this thread b/c I had the same symptoms that the OP did. I found the answer. My 04 that I've had only a week is at the dealer. Yes, I gave up trying to mess with it myself. It went in for a t-belt b/c it needed one (109k) and we thought the tensioner was making noise under load (noise was why I went in-sounded bad). They got in there and found out I need a water pump....whole deal is about $800 bucks. So yeah, I'm gonna bend over and get raped (the w/p is expensive and added another 300 or so to the bill).

Anyway, the thumping noise is my #1 bearing ticking!!!! Apparently when you put belts on these trucks, do NOT, do NOT, overtighten them. When the belts are on too tight, it causes this bearing to make noise. I don't fully understand how as you should just be loosening the idler pulley nut and not messing with the harmonic balancer/crank bolt. The Toyota master tech stated that once he torques them properly it should quiet down. I hope so! Apparently the tech has seen this happen before, so it's nothing new. On my Taurus SHOs I've had, a ticking bearing meant a scored crank, and a ruined motor. They were confident that it would be ok, but they said they'd see once they got it back together this afternoon. I hope I don't have an $11k paperweight now. I may need to run thicker oil in it.

This sucks--had the truck 1 week, $800 in it (although it's routine maintenance), I hope my motor isn't toast. This is one reason I took it to Toyota b/c of the strange noise. I'm new to these trucks and didn't want to battle with it myself. I wanted someone with a good knowledge of these trucks to look at it.

 

But it only occurred when you had the HVAC fan on?

How loud was your knocking? Mine can be heard if I only pay attention to it..

 

No, it got louder when the a/c was on. If you let the truck idle in park, you could not hear it, if you put it in any other gear, you could hear it a little bit...and it was a more on/off type deal. Kick that a/c compressor on while it was in gear and it was louder and more consistent.

Man, I hope this engine is ok......I really can't deal with this after replacing a $2000 tranny and selling my Acura to only buy this thing and wind up with more issues. I will find out later this afternoon. They're pretty confident that this engine is going to be ok though. I'll update everyone when I get an answer.

 

Shop called back today. They got the truck back together and it's still making a noise!

The tech said that the fan pulley where the clutch mechanism attached is wobbly (which both the service advisor and I noticed). The tech looked further and found the pulley bent! I guess this is from where the last person tightened the belts on so hard. He's thinking that this will solve the noise problem (I hope). The part is $375 and no labor since he's already in there. They will have the part in and have it back together Thursday.

I hope this fixes the problem. I'm now about $1200 into this thing and if the bottom end is making noise after all of this; I'm going to push this truck off a cliff.

Do NOT do NOT overtorque anything on your accessory drive. It WILL cause problems!

 

Have you found out anymore? did that fix your problem? Mine is do the same thing and i have had mine in and had the timing belt changed to. it is driving me up the wall.

 

After mechanic # 3 and # 4 looked at it, both said it was coming from the main bearings. There are thrust washers which can go bad on these engines. When they go bad, the crank begins to wobble around in there bumping against the mains. Could let go in 10 days or 10 years. I just spent 11 grand on the truck and didn't want a headache, so I traded it in on an 07 4 Runner. Lost 3 grand on the truck, which could have probably bought a rebuilt/used engine. I didn't want any part of it. I wanted something newer/more reliable with a warranty. Sucks but I'm out of it now. It can be someone else's headache.

 

Anyone find a solution to the problem yet? Mine started shortly after a water pump and timing belt replacement.

 

Main bearings fixed it on mine. Was told it was from the belts being over tightened and pulling the crank over.

 

Just the front main crankshaft bearing was replaced? Not sure if yours was the same but it only does it when its up to operating temperature with the transmission in drive and the ac compressor engaged. Who did your work, Toyota?

 

Get the flex plate checked out, it could be cracked. At least thats what some people on other forums say.