bordenj66

Hi All - Bought a used RX300 (2003, 159K) from auction, the third I've owned now. Great cars and this is a very supportive forum, so I thought I would see if there is any advice on a noise I can't pin down.

There is a slight popcorn sound from under the hood when the car hit about 2,000 rpm. I first noticed it on acceleration when the car shifted from first to second and then again, even more pronounced, when shifting from 2nd to 3rd. There was no stickyness or loss of performance when it shifts, just a popcorn sound, almost like when you have engine knocking / pre-ignition. It only does it the first few times after cold-start. If I drive again in the afternoon, it doesn't make the noise.

I checked/changed the AT fluid and AT oil filter, figured it likely needed it anyway, and although it was old and dirty (looked like chocolate milk), there was no evidence of metal shavings on any of the magnets, at least that I could tell.

The car also idled a little rough when purchased, and there was a clear oil leak from the front valve cover gasket. So I changed the front valve cover gasket. The car definitely idles much more smoothly now, but still the popcorn sound.

Then I noticed that the noise is definitely independent of shifting - it will make the noise even in neutral when the car hits about 2,000 rpm. It will do it once or twice, then it stops until started again from a cold-start.

I thought, maybe the belts. So I changed the PS and alternator belts today. They were worn, but the sound remains.

I'm stumped, and hopeful someone on the forum has a suggestion or troubleshooting recommendation. Tomorrow morning I will record the noise and upload that as well.

Thanks in advance!

bordenj66

I should have mentioned - no CEL's and otherwise the car runs and drives great.

bordenj66

This morning the car started making the noise almost immediately, as opposed to once the car reached 2-3K rpms.

From inside the car it sounds like popcorn, but listening to it this morning it was more of a rattle. I took a short video but the Club Lexus system won't accept the file size.

I am thinking there's something loose or cracked that is vibrating, possibly exhaust manifold and/or heat shield (?) which then seals-off once it's warmed up.

Thoughts and suggestions appreciated!

hypervish

If possible, try uploading to YouTube as unlisted and post the link to the video here.

bordenj66

Duh, feel like an idiot for not thinking of it myself.
Here is the link to the youtube video:

https://www.youtube.com/watch?v=BD1q...ature=youtu.be

RayN

Check the catalytic converter heat shield.

bordenj66

OK, interesting finish to this story. After checking everything twice without pinning down the source, I decided to take it in to the dealer for a check. The rattle was clearly getting worse.

The dealer took a listen and said there were actually two separate noises.

One of the noises, the original noise I kept hearing that sounded like popcorn was coming from under the timing belt cover. They said not to worry about this noise, that it sometimes happens that the timing belt will make a little noise on first start at between 1,500 - 2,000 rpm. Has anyone else experienced this noise?

The second rattling noise was more serious and coming from under the valve cover (the same I had just changed). They asked to do what I considered a bit odd - they wanted to change the oil filter. I had also just changed the oil, and I typically use FRAM filters. The dealer said that, in their experience, FRAM filters are notorious for causing a variety of problems.

They changed the oil filter and sure enough, the rattling noise went away. The dealer took off the valve cover to check for any damage to the VVT gears and found nothing. What oil filters do you all use, and has anyone had problems with FRAM filters?

aznlapin

Never used Fram, heard enough bad things about them to know I should stay far far away.
I've used K&N and Purolator PureONE Filters, they both work well for me. No problems for all the years I've done oil changes myself.

If you want to get a larger sample of what's good/bad for oil filters, take a look at the BITOG forum. Apparently there was an issue with some of the P1 filters a while back but seems like that's fixed?

bordenj66

Ok, thanks. Now I know. And we all know what knowing is.

6.0PSD

Funny that I just removed the first fram I ever used on this car... Only had it on for just under 600 miles So can't say it wasn't doing its' job unless it was the cause of darkening the oil with so few miles, otherwise it did well and did not create any noises as you describe...

I have 6 or more oem toyota filters on hand and I just decided to go out and buy a supertech this time to stick in todays' oil change... Not expecting to run it longer than 1000 miles...

bordenj66

Whats causing you to change so frequently? Oil darkening only? Is this the first time you've noticed it, ie only after using the fram filter?

6.0PSD

This will be the least mileage for an oil change that I have ever done to it and so I never expected it to be so dark... This time around it only racked up 600 miles in 5 1/2 months, I usually change it between 2-3k miles as it doesn't get driven much but since I added the half dose of mmo I wanted it out to check things out...next 6 months should get about 1k miles so I'll be changing it again in the spring... In my situation of short oci's I wouldn't hesitate to use fram again as I highly doubt it darkens the oil... Oil still needs changing even if it sits around.

bordenj66

Sorry for my ignorance - what is mmo?

What brand/weight of oil do you use?

6.0PSD

Marvel Mystery Oil

I have been using conventional and try to run 10w30 in warmest months but 5w30 mostly... This past oil change I went with 10w30 mostly because I was planning on adding the mom otherwise I would just do 5w30 year round... After I change my valve cover gaskets I'll be switching to synthetic and will try and use 0w30 mostly

6.0PSD

As for brand, well I'm not picky so whatever is on sale between big brands such as Castrol, Mobil, Penzoil, Valvoline, Motorcraft, Chevron, Shell, the occasional Quacker State... This works for me but may not work for others but as long as oil is a big name brand and not a store name brand it works for me and the short oci's I do.