paperthin

Hello all;
I have tried to search this forum but really haven't come across anything for the current generations of lexus or for RX specifically. On my wife's RX450h twice now from cold start there is a grinding noise. The grinding sounds like it starts when the button is pressed and last for a second or two after the engine has come on, then disappears. There is no engine light at all and it drives like normal. Anyone else experience this? My first thought is the starter, after all it is a hybrid with 230k kms on the clock. COuld this be related to bad spark plugs? If i was related I would expect to see and engine light.

Droid13

I've had this happen to me a couple times last year. I attributed it personally to some gunk that initially slowed the oil flow to the VVT-i (variable valve timing system). Reason I think it's this, it happened immediately after an oil change. It threw a code basically stating such. The first time it happened (when code was registered) it grinded for about 7 or 8 seconds, then ran fine. I can't remember if I cleared the code, or it cleared itself. It did it again twice for a couple of seconds, but no code. Since then, no issues.

Here's a thread where this, among a bunch of other possible causes and related issues are discussed: https://www.clublexus.com/forums/hyb...up-rx450h.html

paperthin

Thanks Droid; This sounds reassuring. The linked thread was also interesting. I plan to do an oil change shortly so maybe it will help the situation, I am overdue. Nice to see someone local.

tempestv8

Hope its not a rough idle at cold start - https://www.clublexus.com/forums/hyb...anty-work.html

paperthin

The engine is fine, no CEL or rough idle. If had to guess it is the starter but it has only done it twice to date. I am thinking it is not the injectors.

Droid13

It definitely is not the "starter", since the motor that actually spins the engine for startup is a major integrated part of the drive system, not some noisy bolt on little motor as found on non-hybrids. For correct terminology, the RXh does not actually have a starter motor. It uses the MG1 hybrid motor to spin up the engine. If that motor ever made that kind of noise even once, that would be an extremely serious event and unlikely the vehicle would even function afterward.

ukrkoz

Just in case, check on inverter coolant level in expansion canister. That coolant also cools down both MGs, motor generators.
I am very well familiar with low oil pressure noise from engine during cold start ups, as related to hybrid engine. But it's nowhere to be called a grinding noise. Rattle, thumping, shaking - but not grinding.
Now, brake actuator priming at start up can go for grinding... somewhat.
Besides, if you really think about it. In hybrids, engine does not even start right away during system start up, unless traction battery is very low on charge or it very cold. That said, I backed out of my garage on both hybrids I owned, without ICE turned on, prolly 98% of time. Or, moved forward from parking stall at work. Usually, takes anywhere from several seconds to quite a few, depends on various factors.
That in mind, does it happen immediately after you start the system? Or some time later? Does ICE start right away AND the noise? as if the ICE is not ON, but noise IS, then it's outside of ICE components and then you have only MGs and other electronics, like brake actuator, to consider.

paperthin

ukrkoz,
Grinding as an adjective is subjective....it is not the typical grinding noise from a malfunctioning starter of a typical vehicle, perhaps i could have chose a better description. I have learned since that the hybrid does not have a starter. That being said it might be that rattle thumping shaking as you have suggested it has only happened twice. Once last Saturday morning, and one once on Tuesday morning of this week. Like you, we have it in the garage, push the button and begin to back the vehicle out in battery mode, sometimes without the engine on or sometimes it is on depending on how long either of us take to put the vehicle into reverse (sunglasses, check phone etc). It appears to me it is a function of time before the ICE turns on, let's says approximately 4s from the time the button is pressed. The noise starts when the engine is starting to turn over (as the car is already moving in reverse) and lasts for about 2 seconds after the engine is evidently on and running. The first time it was me backing out the vehicle which I noticed from inside the closed cabin of the car, the second time I was standing beside the car as my wife reversed the vehicle to go to work. We haven't heard it since and I cannot tell yet if it from the engine bay or form underneath the car. Tomorrow evening I will go and check some of the vitals.

paperthin

Update: It happened again yesterday morning. I would re-describe the noise now as a extra vibration that I feel is coming from underneath the car (not 1005 sure on that though). This time also the vibration continued after the engine was on only for about 2s instead of the 4s mentioned earlier. So far what is consistent is that it does it after resting overnight as the first use in the morning. Also I checked all vital fluids and all of there levels are exactly where they are supposed to be. I am beginning to think it is a Oil pressure thing now. I will change it as soon as I get time.

paperthin

Update:Once more.....I went back and checked the coolant reservoirs after reading an informal replacement procedure as posted online here in this forum. It appears that the engine coolant reservoir was low, almost invisible in the white container (first thing in the morning). Shocked, I put in just enough coolant to reach the low level line (half cup maybe), and sent my wife off to work. At the end of the day after checking again it was all sucked in again (immediately after a hot car ride) so I put in another half cup to get it to the low level line. Next morning I checked and it was still there, so no concerns and sent the wife off to work. When she got home I checked again and it was sucked into the system yet again, so I put in another half cup. After a total of approximately a cup and half, and a week of driving, the coolant seems stable in the reservoir.

After this story, I am beginning to think that there was air in the system due to low coolant that just evaporated over time. Historically in the past coolant is not something check (by choice), I have not ever needed to and I drive all of my vehicles well over 300k+kms, but now I will check a bit more often. I am attributing this rattling noise to low level coolant in the engine block, the noise has not come back, and quite possibly the vehicle just might be running smoother again. I will update if there is any change in the future. I am not looking for further comment from other just providing an update for anyone that reads this.

ukrkoz

OK, that was not the coolant I suggested to check on. I referred to inverter coolant canister, which is a small rectangular canister above the HSD section of the power train. Canister is at 90 deg to radiator. If it ran low, you have overheating motor generators.

Anyhow.
I had, by now, Camry Hybrid, Highlander Hybrid, RX300 and RX350. After water pump on TCH was replaced, ALL of those vehicles NEVER had a drop in coolant level anywhere. As in - for years, it will sit at the mark.
Hence, yours does have coolant leak somewhere and you SHOULD be worried. That you added this or that and next day it .... means nothing. It takes coolant, so get it diagnosed and fixed. ASAP.

As of the shake at cold start up. You have low oil pressure at the start up, resulting in poor engine lubrication resulting in shake. It can, actually be very scary. I had this about 6-7 times on my TCH. Never on Highlander. But, TCH ended failing oil consumption test and had it fixed under recall, then it never happened again.
So far, the ONLY way to prevent it that I know of is do this: Press Start button>allow system to start> WAIT until engine starts> THEN pull out of garage.
Otherwise, lubrication system is not tight anymore, oil pressure takes longer to build up pressure= shake.
Been discauused down to the bare bone at toyotanation. The only real fix is to restore oil pressure. Which is crankshaft bearings and upgraded pistons/rings.

paperthin

ukrokz;

1. For two weeks i have no change in engine coolant level. Therefore am I losing coolant?
2. I checked a more than month ago, and I checked again two weeks ago inverter coolant is where it is supposed to be. I just didn't mention it in the last post.
3. Whenever I am around when the wife leaves the garage, we purposely wait for the ICE to come on for the purposes of me trying to identify the location of the sound (which is damn difficult). The sound is still there. To date i estimate there have been less than ten instances of this sound over the past three months, varying in length after ICE starts.

Thanks for you input. I do find your last paragraph interesting. Our plan is to drive this vehicle to 300k km like we do all of or vehicle...so less than 70k km to go,

ukrkoz

Sure thing.
If you went that low on coolant, you are loosing it. Sorry. Coolant does not just disappear "normally". I literally had fat sharpie mark - and still have - on coolant canisters on our Lexi and my Toyotas - and level simply sits there unchanged. So if it was empty, refilled, "sucked it in", refilled again - you had major coolant loss with partially empty cooling system. Sorry.
I had hybrids for seven years and was daily in toyotanation hybrid forum. Which is a much more active forum than here. We had quite a few posts on that cold start shake. Various theories. I have mine, you saw it.

ukrkoz

2010 RX? Has what - 50-60 000 miles on it? No, coolant should not be vanishing. I'll repeat myself - it does not disappear that low without a problem causing it. You need to do dye test or run pressure test on cooling system. which out of two, I'd rather do dye test.

tempestv8

I concur - coolant simply doesn't "evaporate" or go low. If you find the level dropping, then there is a leak somewhere.

Check the underside of your engine oil filler cap. Is there evidence of a "chocolate milkshake" under the cap? This could be a sign of a head gasket leak. But this would be rather rare because the V6 engine isn't known for failing head gaskets.