Engine Knocking

Sound like valvetrain chatter. During cold starts the oil hasn't warmed up and circulated to lubricate all the bits and pieces so there is some metal on metal chatter. This is normal for all cars. Things that would help include:

- Using a lower viscosity synthetic oil e.g. 0W20. This flows better at lower temps so it gets flowing quicker on cold starts.
- Using a factory oil filter. I don't know if this applies to your engine, but some OEM filters have a check valve that keeps some oil in the engine after shut off. So when the engine is started there is already oil in it, instead of all in the sump. Some aftermarket oil filters don't have a check valve.
- If it's really cold outdoors (Alaska, Minnesota), keeping the car in the garage or using an engine block heater can help.
- Once the engine has started, get the car warm quickly by driving it immediately. Sitting there idling doesn't really warm up the engine much.

It doesn't sound like pre-ignition or detonation, but if it was, using a higher octane gas would alleviate that.

I put a similar comment in the old forum and will repeat it here in case someone gets a more definitive answer from Toyota.

I purchased my 07 w/30K miles, and the morning after taking it home I noticed the knock as soon as I started a light acceleration from 10-20 mph. Bummer! Screwed up engine. It sounded like piston skirt or rod bearing knock because it was only under load with the engine cold and cleared up as it warmed up. After about 5 minutes or 5 miles, it was not noticeable.... again matching piston slap or rod knock. While it could be something related to an exhaust leak, the sound did not match what would be expected.

It definitely was not ping or knock caused by fuel detonation,(that's hard to accomplish with a cold engine and light load anyway) and would not be fixable via a recall that modified mixture or timing changes. It also had nothing to do with the lifters as this would not be load dependent and lifter noise is a "lighter" sound. (engine talk)

So before going to the dealer service folks, I got the salesman to let me start a bunch of other vans and Camry's in the used lot with the same engine and mileage between 10 and 30K. I went through about 5 or 6 vehicles, starting each one, letting it idle for about a minute, then while holding the brake, put it in drive, and applied some gas. Sure enough, every one had the same crappy noise, and based on the repetition rate, it sounded like a single cylinder issue. Of course the salesman acted like he didn't hear anything abnormal, and honestly may not have, since he did not seem too mechanically knowledgeable. (I had to explain how a timing chain was different than a timing belt)

So it was good that my vehicle was not necessarily abused causing the noise, but I found it strange that all the engines did it. I did not test any brand new vehicles, and would be interested in how they compared. It would seem like an easy problem for Toyota to verify and at least give us some blah, blah, blah language stating it is considered "normal" and would be covered should it ever necessitate being repaired. I doubt it would ever have to be repaired as I have been around vehicles with this type of problem over the years, and while it might get worse over time, it is unlikely to cause a catastrophic engine failure. It just sounds like crap. It does keep your foot off the gas while the engine is warming though, which is a good thing.

Besides taking it easy while it warms up I also use synthetic oils to minimize wear. (Maybe not provable, but psychology comes into play too.) I have had the van for about a year now, and the noise has not become any worse at a given outside temperature. It did get worse as the temperature dropped during the winter, necessitating a longer period of easy driving. Also, as the temperature dropped, the noise could also be heard with the engine idling, not just under load. Assuming it is a dimensional clearance problem, this also makes sense since the slop would be greater at 25 deg vs 70 deg overnight temperature.


Bottom line: I'm pretty sure it is a mechanical clearance issue which I will have to endure for the life of the vehicle. However, it would be nice to find out that there is some external component known to make noise during the warm up cycle until it is no longer needed. It would be easier to accept the "clunker" sound knowing it was a peripheral device and not part of the engine structure. (psychology again)

One thing for sure, if I purchase another Toyota, I'll be sure to test drive it cold.

Cheers.....

Hydraulic valve lifters. The valves require a certain amount of oil pressure and flow to work properly. Whenever you start the engine there is less oil and pressure available and you get some tappet noise. It is completely normal. It should go away in a few seconds to a minute, depending on how long the engine has been off, temperature, oil grade and condition, backflow valve function in the oil filter, etc.
The 3.5l engine has a timing chain. That will be noisier until it is properly lubricated as well.

If you are truly getting engine "pinging", that is much different than a bit of valvetrain noise (sounds like sewing machine). In that case you need to get your knock sensors checked (there was a TSB about this on the old site, not sure of the #. Anyone?) or the cam adjuster that controls the valve timing (VVT-i unit). something isn't adjusting properly for the grade of fuel you are using...this will show up more especially when the engine is cold.

Sounds like good advice! I just recently purchased a 2008 LE (47,000 miles)and have been worried about the engine knocking. I noticed the noise on cold start up and usually only under load( in drive accelerating from 1500-2000 rpms). It is a unnerving sound, sounds like a performance diesel. After the engine warms the sound subsides and everything sounds good. Judging by the other post this must be normal. I guess I just expected more from a Toyota. The dealer states that his is "normal" hydraulic lifter noise for a vehicle with that mileage.(humm, I thought 47,000 miles was fairly low for Toyota) They claim it is unrelated to the TSB concerning VVT. Dealer states if it was VVT I would experience a ticking noise consistently even after warm up.

I'm new to the forum and was very appreciative of the posting about day time running lights. Placing a jumper in the unmarked slot brought my DRL's to life. The local Toyota dealer did not even now this trick. Thank guy/gals.

Revisiting this thread after a year.....

Anyone figure out what the noise is all about??? Morbidly curious....

Kicking this thread farther down the road.....

As far as letting the engine warm for a few minutes.... I've come to another conclusion. Unless you need heat to clear the windows of snow, ice or humidity letting the car sit and warm up is really old school.

When starting the van after sitting overnight in the cold garage, the revs hit about 1800 rpm in about two seconds. It will whine away for several minutes and then s-l-o-w-l-y start to creep down to a normal idle as it warms up. Now if you crank it up there's the normal jump to 1800; putting it in gear drops the rpm to about 1100rpm. If you drive away, without waiting for it to 'warm up' the highest rpms are ... (drum roll!!!) 1800 to 2200, depending on the ambient temp and the transmissions shift points.

If there's no difference in rpm, why wouldn't you just light'r up and drive off and drive gently till the temp needle offs the peg????

Cheers! (and ducking under the table!!!)

Old Crows said:

diesels are notorious for not warming up due their large and efficient cooling systems.

Click to expand...

Good try, but I don't buy that explanation at all. There's nothing about a diesel which leads it to have a larger or more efficient cooling system than a gasoline engine, although of course a big truck's engine will have more cooling than a small car; heavy-duty applications requiring sustained operation at high power mean higher cooling capacity, regardless of the fuel. Until the coolant is hot, the thermostat just recirculates the coolant, so the radiator is irrelevant and the cooling system is just the coolant (water) pump and the passages through the block and head (the "water jacket").

The more likely explanation is that a diesel does less work at idle than a conventional gasoline engine, because the diesel has no throttle while the gas (actually, spark-ignition) engine is pulling its air past a nearly closed throttle plate (that's pumping loss). Even while driving at low power levels (not accelerating full-blast) the same logic applies. Less work means less fuel burned which means less heat produced.

I'm not doubting that typical diesels warm up slowly... only why.