Strange Rattle Sound At Start

[Paul202]

Dear all,

Two months ago I purchased a 2nd hand RX400h (year 2005, 132.000km).

The car makes a strange rattling sound when the combustion engine starts.

I've checked a German Lexus forum (see: http://euro.lexusown...showtopic=32401) and have the car also checked by the garage/workshop. The workshop's mechanic's statement is: "All RX's show the same behavior, more or less". This mechanic claims he has 7 years of Lexus experience.

Now some background information.

I live in the Netherlands and we've had our summer holiday in France. Which is 2.400km back and forth (approx 1.500 miles) without any issues .

But the next day after returning home, the car starts with a rather loud "rattling" noise.

After opening the hood, I thought the combustion engine was running on 5 out of 6 cilinders: you could see the engine shaking.

Current status is that this sound is not always present. Guess is once out of three starts I hear the same sound. Funny is that, if the car has moved a few feet, the sound is gone.

Explanation of the garage is (sorry, my technical english is not that good):

- The car has no "real" starting motor. So when the combustion engine needs to be started, it uses the electro motor in the gear box to fire it up.

- And (according the mechanic) there is some physical play (mm's) between electro motor, gear box and V6. It is this play that is causing this "rattling".

- And also: it is also depending on the exact position (rotation-wise) of the electro motor. If the electro motor is in a "unlucky" position, it might take some time to start the V6.

- Final statement is that also the new 450 has this issue. It has been improved, but it is still present. According the mechanic.

From both this forum and the German forum I came to the conclusion, that apparantly I am the only one having and RX with this issue .....

Which is obviously not in sync with the garage's statement "all RX's have this issue".

I am planning for making an audio file and upload it here.

But still I am curious about your experience!!

Warranty will expire in 3 months from now ......

Regards, Paul.

PS: the feedback I got from the German forum about this issue was not conclusive.

I got tips like:

- check the condition of the spark pugs

- check the condition of the oil; it might influence the hydraulic dampers between camshaft and valves

[RX400h]

I agree that this issue is rare among RX400h owners. A good mechanic will keep your vehicle while getting it to duplicate the rattling sound. A mechanic's stethoscope should be used to isolate the source. Are ther any other dealerships in your area? If so, by all means,get a second opinion. You need a better troubleshooter.

And by the way,your English is better than that of many native Americans.

[Paul202]

Hi Dave,

Thanks for the quick reply. Yes, there is another dealership in my area.

It is a good idea to get a 2nd opinion.

Thanks, Paul.

PS: I tried a few times to reproduce the "error" and make a video of it. No "luck" so far .....

[RX400h]

Paul, a bad or intermittant spark plug wire will produce similar symptoms. You might want to have the other dealership check them.

Dave

[katzjamr]

I have every once and a while heard the engine rattle when it starts up from idle, always from a parked position, it is random and so infrequent i dont worry about it. Do you think you got a bad batch of fuel with your last fill up?

[lemon]

Also make sure the ISC reset has been done. One of the symptoms of the ISC reset not being complete is a 'rattling from the transmission at idle'. The mechanic at the garage sounds like a Numpty, so print off a copy of the ISC reset TSB and take it to the Lexus dealer and ask them to perform the ISC reset. Alternatively, you can attempt the ISC rset yourself following the directions I've posted in the ISC reset thread that has been stickied to the top of the hybrid forum.

[Paul202]

Hi, an update and some answers.

The worst "rattling" we've heard after our holiday to France, has not happened anymore. In itself is that OK ..... But with an "engineering background" I don't believe in indicents and I keep worrying until I understand the root cause ...

@Katzjamr: Your description fits my situation. Always from parked position, and not always present.

@Lemon: Does the ISC reset also apply for European 2005 model? I will check this with the dealer anyway.

Thanks, regards, Paul.

[lemon]

2006 model year was the first year for the 400h, was it not? Yours may have been built and went on the road in 2005, but it's a 2006 model. Anyway, yes, the ISC reset applies to ALL years of the 400h.

Your dealer may be clueless about the ISC reset, so be sure you print off a copy of the .pdf and show it to them.

[Paul202]

I have an appointment with the dealer tomorrow (to repair something else in the car). I will print the ISC reset procedure.

By the way: fact is that I drained the battery (not the main "hybrid" one) because I kept the doors open too long (leaving the interior lights on). So the ISC reset might be a smart to do anyway.

But also: this "draining" took place after our holiday to France. So this is not the cause of the first "rattle" I heard ......

I'll keep you posted.

UPDATE 29-Aug: No news yet. The car is in the garage to fix the above mentioned "something else" (a squeek in the body work). This is not finished yet; they need to remove interiorparts/lining to check one of the beams on the left side of the car.

UPDATE 1-Sept: In the garage (a non-Lexus dealer) works one guy with (apparantly) 7 years experience in a "true" Lexus-garage. He was familiar with ISC-learning (he read the hardcopies I gave). He contacted (a couple of years ago) Lexus about this way-of-working and their comment was "the learning procedure for US differs from European Lexus's". He explained that in the US the ISC learning procedure sort of "stores" the settings and European cars don't. In European cars the "learning" is triggered every so many times and executes the learning-cycle automatically. He claims that by reading the car's memory/loggings, you can trace back the learning cycle and that the results are OK. So they repeated their statement: "All Lexus RX's have this issue more or less".

So, my conclusion: I leave it at this for now. My main concern was that (since it is a used car) I get unexpected failures-costs lateron. Appart from this being a strange `noise` my objective was the garage to have focus on this issue, so that in the future (after warranty expires) I can remember them on their statement.

Thanks again for all comments/tips.

Regards, Paul