hopzhopz

Hi guys:
2011 RX350, 75k miles, well-maintained. Mid-age oil which is changed regularly, with Mobil One. In other words a great SUV that I have taken care of.

Went on a 250 mile road trip yesterday and after a stop for fuel on the return leg we noticed a rattle noise from the engine at idle. Engine was normal hot, in other words not a cold start. Weather was 60's, we both heard the rattle noise, which seems to dissipate underway. Car ran strong at highway speeds- obviously could not hear a problem while under way.

Car ran great all day. Lots of highway speeds but nothing excessive. The gas may have been a little sketchy. Outside of our normal city. One of those Quick Stop kinds of places, Someone may have pumped one of the lower grades by accident.

When we got home I started the car in the garage and opened the hood. There is a clear chain-like medium high frequency rattle which seems to come from the passenger side of the engine... kind of near-to the rear of where the oil -fill cap is... No funny smells, No excessive heat. Temp gauge was normal all day.

Will go to the shop Early in the week but any experience or thoughts on this strange noise? Timing Chain? Maybe- but Engine was strong all day..???

salimshah

Did you check all fluid levels .. specially oil?

Salim

hopzhopz

Yes, I had even checked the oil prior to the trip... and after too. No leaks. Level was/is good- the same

Hydraulic Tappet...? Possible I guess but I don't know...

Gampa

Had something similar with my 2010 RX450h with 65,00 miles. Since the oil is a thin 0-20w weight and there may be gunk residue on the hydralic lifters which may cause them to stick,,, I decided to use a good engine flush in hopes of breaking up the build up.

There are several good engine flushes out there , Sea foam, Motor Medic, Lubeguard flush but I decided to use Liquid Moly engine flush #2037, at $16 a can. I followed the instructions, idled for twenty minutes, then drained.

I refilled with Mobil 1, 0-20w. and also left room for 1 quart of Lucas Heavy Duty Oil Stabilizer, part 10001.,, $8,77 at Walmart

I know it is an long used product in the trucking industry, so i decided to give it a try,

It has been a month now and have not had any of the metal tapping or stuck hydraulic lifter incidents yet.
The oil checks has been clear and no loss in oil... so the flush worked well in my opinion,

It appears the pressure in the engine has increased also and the car has been noticeably more powerful to a point of when i first bought it.

I did also add Lucas10003 upper cylinder lubrication & injector cleaner to the gasoline tank,,,4 oz per tank. I do not know if this has any affects on the cars but use it in all three of my automobiles as a preventative maintenance.. Lucas claims it is safe for Catalytic converters.

I will keep you posted if there are any negative results but all I have so far are positive results.

ukrkoz

There is wide spread myth that chains are some sort of indestructible lasting forever part.
they do stretch and do so very easily.
Tensioners fail just like on any other car.
Also, far I know, Toyota does not do any hydraulic lifters, it's simple tappets. Nissan does lifter/tappet combo. At least, did.
So if it moves like a duck and quacks like a duck - it's a duck.
If it rattles like chain - it is chain.
I have clear example sitting in my garage. 2005 RAM. "oh, every RAM engine we ever heard makes rockers noise on cold start ups". yep. So did mine, unti head gasket blew and they replaced gaskets and - same time - chain tensioner. That engine now purrs like a pleased kitten. Cold or hot.
Just saying.

hopzhopz

Thank You... to all the respondents...
Went to my local go-to shop and the noise, as it turns out, is coming from a failed bearing in the alternator.

Shop Forman loves Lexus and did the the job himself since he was available. He "thought" it might be something else but he tried it and had to keep looking.

Alternator replacement= 5 hours plus parts... over $1k... oh well. I could probably do it but its cold in the garage and I don't have the time at the moment...

Thanks again.

hopzhopz

UPDATE... the highly skilled/experienced mechanic replaced the Alternator but it turned out not to be the source of the noise.

He discovered a bad bearing in the Water Pump. He put the OEM Alternator back and replaced the Water Pump with an OEM pump, changed all engine fluids and filters and the price came back quite a bit lower than the estimate on the Alternator... plus a 3-year warranty on parts and labor.

Just FYI.

Drove great and quiet back home.

BenRX

Just had the water pump replaced under warranty on my '15 F-Sport at 55,000 miles. The knocking sound gradually become louder to a point that I could hear it from the driver's seat while idling at stop lights. I finally took it to the dealer, which diagnosed that the water pumpbearing was failing and causing the loud noise. I did not experience higher-than-normal engine temps and dealer did not mention any leakage, so maybe I caught the problem early enough.