Pugs

Hi, a few weeks ago I bought my first Lexus, an '07 GX 470. It has roughly 75,000 miles on it, 2 previous owners before me. Anyway, I hear a noise sometimes which either sounds like a slight belt slip or fuel being pumped into the injectors when I give it a good amount of gas and the engine downshifts to accelerate. I had the dealer replace the drive belt(serpentine belt) because of 2 reasons, it needed to be replaced and I thought that could be the problem(I did not have to pay for it since I have had some problems with the Lexus dealership I bought it from, they did it as a "goodwill" gesture, that's a story for another thread) and inspect the tensioner and pulleys, they said the pulleys and tensioner were in good working order.

I drove the GX home tonight after said replacement, and I still noticed the same noise. The best I can describe it is like I said above, a slight belt slipping noise or it could also be described I guess as fuel being injected under acceleration as soon as the trans downshifts to accelerate. I am just curious if this is normal for this engine or do I have a possible problem? It's covered under the Lexus used car warranty for another 5 months so if there is something wrong, obviously I would like it fixed under warranty if something is wrong. Can you guys please advise me on what could be wrong, or if it's normal, thanks. Oh, one thing I should probably mention is, the noise is semi quiet and I guess the average person might not even notice it. It's definitely there though, you know how when you buy a new car you listen to the sounds of the engine/trans to see if it sounds healthy(well us car lovers do anyway ), well that's how I came across this noise. Thanks again. Glad to be here!

mann777

Sorry to hear about your truck, Firstly welcome to CL and GX is a fine truck. Looking at the symptom you could post a sound clip, and then we could conclude. Hope this helps.

Pugs

Ya I was thinking I should make a video maybe after work tomorrow. I hope it picks it up because like I said, it's a slight noise under acceleration. I hope I can capture it, I'll give it a try tomorrow. By the way everything is stock(as far as I'm aware), stock intake etc. Years ago I had a 96 civic that I installed an intake on and the sound is similar, so I am hoping it's a normal noise of fuel being injected, even though this is a stock intake. The noise only lasts for maybe a quarter-half of a second right after it downshifts under acceleration or as it's down shifting.(Oh and happy 1,000th post.)

Pugs

Oh, one more concern I have is when I put the GX into N, and shift from H to N to L on the transfer case, I can feel the transfer case spinning/slightly hitting the shift lever as I switch between H N and L on the transfer case. Is this normal also? I never had a dual range transfer case before so...I'm not sure. It goes into gear but a little resistance is felt and the spinning action can be felt through the shift ****.

mann777

For shift, you could have the Diff fluids replaced, that could smoothen that out. I had the same groan noise which you have been mentioning, And it took me one year to get to the root cause of the problem, and replacing the front and back diff fluids, and had the Front axle Greased and replaced the front CV boot kit for $55 from the local toyo dealer. All this completed and the noise disappeared. Here is the attached diagnostic, if you are grease monkey with tools, you could do it at home garage ramp. with some basis tools.)

Mparent

Pugs, congrats on your purchase. Perhaps, a quick and inexpensive way to compare the noise and symptoms you are experiencing is to test drive another GX470. Swing by a different dealer and ask to drive one. I don't recall any significant differences between 2007-2009 engines but others on the forum can confirm. Just a thought. Mike

Pugs

I took your advice and stoped by the same lexus dealer I bought it from. I told my salesman I wanted to test drive another '07 GX to compare and see if something was wrong with my car. He and I both went and after I let the engine warm up a few minutes, floored it multiple times and almost every single time I heard the same noise. After I asked him "Do you hear what I'm talking about?" he said yes and said it's normal and he just figured it was something on the fuel injection side of things making that noise but never really thought about it before. He said they all make that. I also tried the 4 Low, and just like mine, this one made a grinding noise while shifting into L from N.

So it appears this is "normal" for this car. I took a video earlier today to try and capture the noise, I think I got it on video but I will have to post it in a couple of hours after I upload it from my phone. I am glad at this point everything appears to be mechanically in good condition(brakes could be changed to stop the pulsating, I gotta see if that is covered under warranty).

Pugs

Here is a video I shot today, I floor it 3 times, the 2nd time is where the noise is the clearest at 32 seconds into the video(more of an audio clip rather than video). You might have to replay that portion a few times if you don't know what I'm talking about. I guess every single GX 470 makes this same noise? Anyone know technically what that noise is?

http://www.youtube.com/watch?v=vihBA...ature=youtu.be

mann777

I cant hear much from the video, as lot of air gush seems to be heard, and acceleration.

What I used to hear was when you stomp on the accelerator, there was a 30 sec whining noise, and then dissapears.That was pretty irritating to me as could be heard within the cabin.

Ttkelly

I am not the only one who is hearing this noise!!! Phew...I am not loosing my mind
So from what I can gather this slight "screech" is normal? Fuel injection as the culprit? I was about to run out and change my Serp belt.

Ttkelly

I just had an oil change and my mechanic found that the belt tensioner was going! It was not the injectors.

burny

yes that will make an irritable noise

sheikhmax

I am never able to shift L to N to H while I put it in N because of that grinding noise and its not only the noise you can feel it when trying to shift the 4WD lever... But once i put it in P and then shift from H to L or L to H it goes smoothly. So probably try that.