nastron

Hi guys,

I recently purchased an L/Certified 2014 GX 460 and I'm loving the truck! I've recently noticed that after turning on the engine (cold start) for about 20 or 30 seconds, I start hearing a clicking noise that's not rhythmic at all, say like with a normal engine that's knocking. Could it just be thermal expansion, with the engine, manifold, and other stuff heating up and whatnot? Here's a link to the video I shot this morning where you can hear the first click or tick happening at second 2. the one after at second 5, then 7.5, 9 and so on and so forth:

Thanks!

GX4602011

The secondary air injection system functions for around that time on startup. So as a guess, perhaps it is the air valve making the noise as it opens/closes (may be normal). Here's a thread about it: https://www.clublexus.com/forums/gx-...50k-miles.html

nastron

My GX doesn't have air suspension (not the luxury trim), it's got the premium package.

Acrad

Actually the air injection system is an "emission" device that all GXs have. The air pump is located in the front area near the power steering reservoir. Air is blown in the exhaust stream via the exhaust manifolds during startup to reportedly improve catalyst efficiency

nastron

Oops, sorry, I misread GX4602011's reply! Thanks for the explanation Acrad35751!

So, it doesn't look like that noise is normal, right?

Acrad

Like GX4602011 said...that air system does run around the first 30 seconds. It could be the switching of air pump and the air valves on the exhaust manifold which would be normal. I've never tried to listen to mine in that area on a cold start. How many miles? I have a feeling more normal than anything.

nastron

The car has 57k miles.

nastron

I forgot to mention that the first time I heard it was from inside the vehicle, radio and A/C were off and I heard that clicking noise, so I went outside and heard it more clearly.

Acrad

Is it reproducible every time you start it cold? You may want to get dealer to look at it if warranty covers it. One can't rule out some rare valve issue/oddity.

Do you have the vehicle service history from Lexus?

nastron

Yes, I've only listened twice but I think the noise will be easily reproducible. And yes, I do have the service records.

Acrad

I wish I had something more definitive to offer up but can't recall anyone reporting this issue either. Hopefully just air pump, normal electric relays or thermal expansion. As long as you have a warranty I'd see if dealer can pinpoint it as normal. Do they charge a diagnostic fee for vehicles that are L/Certified if dealer mechanics don't find anything?

nastron

Appreciate the help Acrad35751, thanks! Yeah, I think all of the Lexus dealerships around here charge a diagnostic fee that's waivable assuming they do find an issue. I'm probably gonna give them a call and try to explain over the phone. This issue shouldn't bother me, but for some reason I haven't stopped thinking about what the culprit could be after hearing it earlier today.

nastron

Also, I'm thinking the computer would've thrown a code had this been an issue, no?

Acrad

Correct... that system in a failed state tends to easily throw codes. If I pay attention I can hear the fan fire up on mine when I start it cold.

nastron

I can always hear the fan when I cold start the car, or if I'm sitting on a traffic light idling for like a min, then I'll hear the fan again when accelerating for about 5 seconds (becomes louder when depressing the gas pedal) then it goes away.