My lexus makes knocking noise when I
put in gear and accelerate but when it's in park and I accelerate there's no knocking sound
anyone have any ideas on what it could be???

 

Hello,

What's the mileage on the car?
Where the sound is coming from?
Does the sound get worse as the load increases, like on the highway ramp?

The video of the sound you hear will be helpful.

I have a 2000 ES300 with a similar issue, it was a tricky one to find, since the sound would vanish and come back seemingly at random, the culprit turned out being one of the valves on the charcoal canister. I am not exactly sure why it makes that sound, from what I know, it is normal for those cars, and since I have a post-facelift model with the canister near the tank, I need to take the whole rear subframe off to access the canister, which went a bit beyond my plans for an easy fix..

In your case, the canister is located under the hood, which may be what is making the sound. To find out, get a stethoscope like this one and go around the car to get a general idea of where the sound is coming from, and go from there. In the process, make sure that the car won't have even a slightest chance of driving off on its own, chock the wheels with proper wheel chocks, not just wood laying around, and pull the parking brake as far as it will go, it's really not worth the risk.

Hope this helps and best of luck!

 

Hello it's at 295000 miles sounds like its coming from the lower engine and the sounds does get a little louder as im acceleratimg but its not too loud makes me think it's some kind of exhaust leak it doesn't go away only when I'm in parking and accelerate but once I put it in drive or reverse it makes the knocking sound
I will try to get a video up
Thanks for your help!

 

This is the sounds I hear when I accelerate but it doesn't happen when I'm in parking and accelerate

 

Well, there is a whole plethora of weird sounds that shouldn't be there.. First of all, that whining sound present in all gears, it sounds a lot like a transmission fluid pump, below is the video as an example of what I mean, though it can be a Power Steering pump. Check the fluids in both, if it is just dark, do a drain and fill, but if it smells burnt or has metal particles, it is probably better to leave it be for now.


It also sounded like you shifted out of Park on the hill, without using the parking brake. Transmission can handle that, but it is really not the best practice if you want it to last. Use Parking Brake before shifting into Park, which can potentially save the transmission.

As for the noise that changes when you switch gears, it is definitely not the sound I was referring to above. It sounds a lot like a hole in the exhaust, but then I am not sure why would it disappear when the gear is engaged, could it be because of greater load on the engine..? One way to test the load theory is to turn on every electronic component, all the lights, radio, phone charger, etc., and turn the A/C on, which will considerably increase the load even while in Park, see if the noise would return.

Check the exhaust system, especially all the joints around the engine up to the resonator, see if any are shot. Also, check the engine mounts, if the engine shifts too much, it can cause a leak over time, especially with such a mileage. A sound like that can also be caused by a faulty EGR system, if it is clogged or leaking, which could explain the sound is only present when you are in gear, here is a diagram for that system.

Hope this helps and best of luck!