AngelEyes

I recently bought an LS430 with 120,000 miles on the clock. The timing belt was changed at 100,000 (or at least I've been told). During cold starts the engine makes a kind of squeak/tappet noise which goes away after the engine warms up about 3-4 minutes later. Even if I start the car 8 hours later it doesn't make the sound, so I'd need to leave it with a mechanic over night to get an understanding of what it could be. If anyone here with experience would care to listen to the audio file I've attached in a zip file of the engine running while cold, I'd appreciate that very much. I've also attached a picture and circled the area where the sound appears to be coming from.

My best guess so far is hydraulic lifters, or a squeaking belt or worse an engine bearing of some sort.

As you can tell I'm not overly savy when it comes to engines, especially one as complicated as this, but I'm a keen learner I guess.

Thanks.

rkw77080

The location you identified points to a bad belt tensioner (see arrow in picture).



However, your description suggests that you may have a temperature-related lubrication problem. The metallic sound is troublesome. Another thing you can try is to remove the drive belt (do this in the morning), and manually turn the various equipment the belt drives to look for loose parts and check for rotational smoothness.

AngelEyes

Thanks so much, your reply is a great help. I'll take a look at that tensioner first and post a reply.

gemineye

I would temporarily remove that air ducting so you can see what the tensioner is doing with the engine running.

From the audio clip, it sounds like something is "wobbly" and there is also an intermittent high pitch squeaking......these are not sounds typically associated with noisy hydraulic lifters. If I had to guess as to what's going on (which is tough to do just from audio clip), I would say the tensioner is failing or a maybe a idler pulley is failing. But like I said, I would remove that air ducting and run the engine so you can get a better look at what the belt is doing with the engine running (and you may be able to pin-point exactly where the noise is coming from).

If you see the tensioner acting very "bouncy" against the belt, it needs replaced.....that's typical of a failed tensioner and it's not a huge deal, but I would still replace fairly soon.

Regards,
Randy G.

gebo

Just replaced the tensioner pulley on my LS400. You can buy it a Advance Auto, Napa, O'Reilly, etc. I just bought the pulley itself. You can remove the belt by turning the nut on the pulley counter clockwise and the tension will go away. Slide the belt off, remove the pulley, replace the pulley, turn the nut clockwise to get you some slack and slide the belt back on. Not as easy as that, but I did it so I know you can. Mine would do it periodically which would mess up my diagnosis.

AngelEyes

Hi Everyone,

Thanks for all your valuable input, I appreciate it very much. As a followup to the advice I received, I removed the serpentine belt and checked all the pulleys for wear. They all seemed in good shape to me, no unusual movement or anything so I went to and replaced the belt with a Dayco brand. Fixed the squeaking problem straight away. The guy from the parts stored explained how the belt is stretching while cold, hence the noise. Cheap $30 fix, so I'm happy. Engine sounds beautiful now! Interesting how the Dayco belt felt like much better quality compared with the belt I took off which btw had mitsubishi written on it.

Thanks again for the advice I hope this thread would be of use to others who come across simple problems like this.