Cold start engine noise

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I have a 2007 4Runner w/8000mi. On cold mornings, e.g., < 25 degF, when I start the engine, wait a few seconds, put my foot on the brake and go to back up, the engine has a slight thumping/knocking noise. At the same time, the engine is slightly bouncing, as though it wants to jump out of the hood. Of note, it takes a minute for the start-up high speed idle to settle down a bit.

This noise is not evident if I wait a minute or two, or if the temperature is warmer, or if the car has been used and the engine is warm. It only happens on very cold (by NE standards) mornings at first start.

Anyone else have this sort of noise? The car is almost new (to me) and I would not expect anything major to be wrong.

Thanks!
 
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I have noticed a generally rough[er than most other vehicles] idle on my 4runner... roughly the same miles as yours, although no noise.
Anyone else?
 
I read in a "Truckin" magazine where someone had the same problem but it was with his Tundra with the 4.7. They said something about the noise being a piston slap due to the cold. Toyota knows about and said it won't hurt the engine. Funny thing was right after I read it my 4runner did the same thing in the 30 degree morning.
 
I'm sure I can hear the pistons in my 4.7 V8 until they expand. Especially in colder weather. I never throw it in gear within seconds of starting in cold weather though. I can't see that making the noises you're describing. Noisy pistons sound like a deep valve train noise and it's usually a consistant noise until warm.
 
I have an 04 v8 sport and on cold mornings like 20 to 30 it turns over till the end of start cycle before it kicks then when it does it let's off a little sick rumble noise and then a little shake. But after that she is fine... I have kinda been worried about it but it seems to me that all toyotas start hard in the cold including all the 4.7 and 5.7s I have been in.
 
The 4.7 is known for having piston slap on cold mornings. Mine does it too. It goes away after 30 seconds or so.
 
All the newer motors have piston slap. It's in the design. keeps them light for mileage and power reasons, but the downside is the slapping. I hear it's due to the short skirts on the pistons.

Notice how short the piston is:
2uz_piston_0005.jpg
 
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I just bought a 2006 V8 with 30,000 miles and mine is pretty loud. Im actually a Lexus tech and we use the same 4.7 in the GX and LX. The first week of having my 4Runner I noticed the noise and was pretty upset about it. My first thought was rod knock, but threw me off because it goes away when warm. I was talking to another tech at my dealer about it and apparently its common on the GX470 as well. Ive been here for 7 years and never heard of it. He told me he had a few customers complain about it and we were told by Lexus that it is piston slap and it is normal.

I didnt like that answer and gave my FTS a call. We talked about it for 30 minutes or so and he explained the stuff Toyota has done. He stated the noise started when they started putting the 4.7 in the Tundras. Toyota recovered a few engines for testing and determined it was piston slap, and that it was not a safety or long term durability concern so they declared it normal. I even went as far as to capture a video and send it to him to verify the same noise.

I dont know, we have had a lot of 'piston slap' noises with RX and ES engines that is deemed normal because of smaller skirts and materials used to manufacture them. Ive heard some bad ones that I have unfortunately had to tell customers were 'normal', and my 4Runner sounds nothing like it. You can hear what appears to be all six pistons making noise on the RX and ES. In my 4Runner it sounds like one object is making noise, and to me it sounds like rod knock.

Either way, Toyota is aware and they have gone as far as to recover engines and spend time and resources locating it. Sad truth is that its normal and there more than likely will never be a fix for it. As a tech and an employee for Toyota, I am not happy about it, but thats just my opinion.

Ill post that youtube video of my 4Runner making the noise later today. Sorry for the long winded first post. :cheers:
 
Hello onepointone,

Just doing a search on my engine knock noise and read your post. I just bought a 2008 4runner Limited V8 with 34k on the odometer and I have this cold start "knock" type noise that goes away roughly in about 30 seconds or so and then it does not do it again until a cold soak the next morning. I had another V8 Limited that never made any such noise.

BTW, I am also a Lexus Tech (California, Mission Viejo area) and I have never heard this noise on any GX or LX470. It doesn't sound like piston slap to me however, it is more of a lower deeper sound and it will manifest itself when I put the vehicle in drive and pull out of my garage in the morning.

Anyway, like you I was pretty upset over it and it still bugs me. I have had my wife start the truck and I have my stethescope out trying to pinpoint the noise to no avail so far. Any update as far as your noise is concerned? Any help or insight would be appreciated. Next time my FTS comes in I will ask him and see if he has any other info on it.

Let me know and I will do the same if I hear something on my end.

Thanks for your time,

Guillermo
 
lucas1928 said:
Hello onepointone,

Just doing a search on my engine knock noise and read your post. I just bought a 2008 4runner Limited V8 with 34k on the odometer and I have this cold start "knock" type noise that goes away roughly in about 30 seconds or so and then it does not do it again until a cold soak the next morning. I had another V8 Limited that never made any such noise.

BTW, I am also a Lexus Tech (California, Mission Viejo area) and I have never heard this noise on any GX or LX470. It doesn't sound like piston slap to me however, it is more of a lower deeper sound and it will manifest itself when I put the vehicle in drive and pull out of my garage in the morning.

Anyway, like you I was pretty upset over it and it still bugs me. I have had my wife start the truck and I have my stethescope out trying to pinpoint the noise to no avail so far. Any update as far as your noise is concerned? Any help or insight would be appreciated. Next time my FTS comes in I will ask him and see if he has any other info on it.

Let me know and I will do the same if I hear something on my end.

Thanks for your time,

Guillermo
Click to expand...

I have heard exactly that noise on my truck and it is not a piston slap...
It was discussed in this post: http://www.toyota-4runner.org/4th-gen-t4rs/90662-toyota-techs-please-try-diagnose-4.html
And according to that post it is possibly fuel lines\fuel pump\fuel regulator (dampener) issue.
I my case I hear it on very rear occasions and goes away very quickly so I have not gone to the point of trying to find out the source of that noise… if I do I will share it here.
 
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I brought the 4Runner into two Toyota dealers multiple times and never received a diagnosis that made sense. The last I heard, they said it was the ABS pump pressurizing.

With 5 years and over 60K miles, it still makes the noise. If you learn anything, please share.

Allan
 
I bought my 07 v8 with 56k miles on it back in July 2011. Shortly after I started hearing noises like the OP is describing, only on cold mornings, once it warms up, the noise tends to go away. It was driving my nuts. I took it into the dealer thinking it was a cracked exhaust manifold which seems pretty common. They came back and said it was my Fuel Pulsation Dampener. They also mentioned my fuel pump was not keeping pressure after the vehicle was shut off. So they replaced the fuel pump and that dampener and ever since my engine is quiet as can be starting up every morning. Here is a link to my posting in another thread...http://www.toyota-4runner.org/4th-gen-t4rs/93178-exhaust-manifold-leak-tick-4.html#post842174
 
I have had this problem for 2 years now, and I could not get Toyota to fix, they said this was a normal sound for the v8 start up. It did not do it when new, so I thought I was going to have to live with it. I bought the fuel damper assembly, Toyota part number 2370-50011 (105.00 from my dealer), spent the 10 minutes to replace, and no more cold engine knock. I have no idea how or why this fixes the issue, but it was worth it to me to try it and see if it works. FYI, it takes a 22 mm wrench and literally 10 minutes start to finish to replace. It has not had the knock since I replaced it last week.:bluejump:
 
Glad that fixed it. Someone over on toyota120 just replaced his pressure regulator and fixed his noise as well.

I guess a cracked manifold would be loud even when accelerating until everything warms up whereas we would just here the noise right after starting up the engine and usually when it's idling. Then it goes away usually. Like I said before I had toyota change mine cause I wasn't sure if it was a plausible fix but luckily it was.
 
Sounds like the OP has the famous V8 piston slap or possibly the cracked exhaust manifold. For piston slap there isn't a fix other than a new/rebuilt engine. The manifolds are about 2k if I remember right.


@Marcus that's good to hear that it could be something else and worth trying...
 
if it makes the v8'ers feel better the v6 roars like its about to lift off or taking off on a runway ESP in cold. my neighbor asked me if there was something wrong with my 4R as it wakes him every morning (sorry). can't help it.
 
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