UZ214

For last couple of days the car is making a Thump sound when the engine turns over. then it gone- single thump sound....It only happens in the morning if the car is sitting in the garage overnight. I do not hear it if i park the car at work after 8 hours does not make the same sound.

I also feel it takes a bit tad longer to start the car(again only in the morning)- i thought it was the battery but the battery has been replaced 2 years ago.

i will try to record the sound tomorrow and post it. the car is fine once started no funny sounds or anything. Its a 2011 with 71k miles on it.

droclex

Curious, does your thump coincide with shifting into gear on an incline or the brake pedal?

UZ214

dont think so, its coming right from the front of the car-the car is not on a incline at all.

i had the camera on today but no sound. Does not sound like brake but who knows, i need brakes soon that job i will tackle on the weekend.

I did read about similar noises in different forums (acura)(ford) which they are talking about the ac making that noise. Today when i started car i had the air off yesterday. Today i will leave it on just to see.

whitewater

mine does a similar noise however I would not call it a thump. mine is the auto parking brake/electronic brakes.

interested if you get a video of this happening.

UZ214

that's good point might be the auto brakes but i didn't hear any sound today also...its like when i am my camera ready the sound is not coming- its like you know trying to reproduce the problem at the dealership.
The temperature is also higher from last few days might be factor

superdenso

I would inspect the motor mounts; the motor rocks the car on start-up...is it consistent with the rocking motion?

UZ214

The sound is not consistent- infant i haven't heard it last 3 days i have started the car with my camera rolling

Rhambler

Can you feel the thump or is it just audible?

UZ214

its a mixture of both, almost seems like the engine or belts have a hard time to turn over. I also recently had 70k service done at the dealer
it might be the serpentine belt?

Rhambler

Personally, I think it's just your battery.

Batteries don't last long in this day and age of modern cars and frankly they cause a lot of issues while people search for less obvious problems when the real one one is discounted because they assume it's not bad.

Now of course, I'm just guessing, but I've never seen issues with the starter (at least I can't recall seeing anyone report anything here) and a bad belt wouldn't necessarily cause the slow turnover, but a slowly dying battery will.

I think we all hear that "thump," but a good battery and starter causes the cranking to happen with normal speed. Slow it down and everything, the noise and feel, becomes more pronounced.

If you're willing to gamble on a haunch, replace the battery and see if it goes away, but again, I'm guessing.

whitewater

x2 - had not thought of this but very likely.

UZ214

Very well be- I will change battery and update you guys

whitewater

should have it checked - cold cranking amps and voltage etc...

UZ214

Lexus did check it when they had the car @70k service- they checked the tires brakes fluids battery etc
It has some after market battery though not the OEM lexus one