tspllc

I've been looking for a GX470 for about a year. I am particular and these vehicles have some very common issues unfortunately. I was about ready to buy one after a test drive today until I kept hearing a ticking sound.

The ticking sound only occurs when the vehicle is in gear. It does not need to be moving/driving, but RPM's do need to get to about 1000 till you can start to hear it. At 1500 is very clear. It doesn't matter if it's in Drive or Reverse.

The sound is coming from the front passenger side and sounds like it is near the belts, pulley's, tensioners, etc.

The A/C was not on when it made the noise. The A/C did work, but it wasn't on when I was checking the noise.

I might be wrong, but I don't think its engine or trans related...even though it only happens when in gear.

I had texted a mechanic after I left and he first asked if it had a timing belt or chain. I told him it was a belt. He then said to check the drive belt tensioner by loading or turning on the A/C. Unfortunately, I had left the dealership by that time. The vehicle has about 120K on it and no record of the timing belt being done.

Any ideas?

Thanks for any help.

Chris

chiph9

It's not uncommon for the exhaust manifold to develop a crack.

Chip H.

tspllc

Thanks. So, by simply putting the vehicle into gear will effect the exhaust manifold or the sound coming from it? That somehow doesn’t seem right. But, I’ll look into it.

IanB2

Putting it into gear will lower the RPM's at idle, which could be the condition required for the leak to be symptomatic.

tspllc

OK. So, putting it into gear can cause the exhaust system to react differently? I'm not doubting and I'm not a mechanic, just trying to understand why the exhaust system would respond differently once the car is in gear. And, to be clear, I don't hear it until RPM's are above 1000 and is very clear at 1500. I can have the car in Park or Neutral and rev it way up and you hear nothing at all. Just seems really odd that the exhaust manifold would react differently...but again, I'm not a mechanic or engineer.

chiph9

If you're in gear and on the brake (like you would be in your driveway) it will shift the engine on the mounts and change the position of the manifold relative to the rest of the exhaust system. And this could open up an otherwise unseen crack.

Chip H.

IanB2

This is a great explanation of WHY in gear vs. in park/neutral could make a difference.

It's going to be a tricky one to confirm, as it's kind of dangerous to have your head where you can see the exhaust manifold while the vehicle is in gear and being revved, so be careful. You should be able to get a straight shot at the manifold to hear for yourself if that's where the noise is coming from if you remove the fender liners on that side, while still being out of the way and safe in case the vehicle lurched forward suddenly or something.

tspllc

Well that I can understand. So, if that is it, then the solution is to replace the exhaust manifold? If so, anyone knows what that might cost?

IanB2

I've never had to do the job myself, I believe one side is harder than the other but I'm not sure which. Get a quote from a Toyota dealer as well as a Lexus dealer if you're going that route, Toyota is sometimes cheaper.