Engine Rattling Under Load

[TONEDOG]

Hi,

I could really use some help/advice.

I have a 2007 Toyota 4runner Limited 4.7L V8 2UZ-FE

After sitting overnight, when I startup in the a.m. and put it into any gear while holding the brake i get a knocking.

The knocking is definately engine, sounds like lower engine, a lower frequency knock, not like tap or a rattle.

The severity changes depending on the teperature, worse during colder days.

I always let the the motor run for a few min, at least until the needle passes the "c" on the temp gauge before moving.

It lasts for a block or two, or about 2 stop signs, hearing it at each stop sign.

I use Mobil1 5-30, change every 3k no matter what.

I use premium gas (93) from moble or shell

What could this be?

Thanks for any responses,
TONEDOG

 

[TONEDOG]

Engine Rattle/Pinging

Hi,

4.7L 2UZ-FE

Engine rattles during hard acceleration. Sound like pistons or lifters maybe timing chain rattle (but I think I have belt not chain in the 2UZ-FE)

This has been since the motor was factory new.

I use premium (93) mobile or shell gas

Lately I have noticed, rattling under slow acceleration up small hills while the a/c is on, and alot of rattleing when the engine is hot, a/c is on and hard accelerate.

56k on the motor

plugs changed at 30k

any ideas would be greatly appreciated
TONEDOG

 

[Zuffen]

How old is the vehicle.

I would suspect it has faulty knock sensors and should go back under warranty.

 

[Zuffen]

How long does it take for the oil light to go out, or if it has agauge what sort of oil pressure are you getting on start up?

 

[TONEDOG]

thanks for the reply...

the oil light goes out with all the rest of the lights, quickly. there is no guage.

t

 

[TONEDOG]

thank for the reply...

im the first owner, got it april 2007, 56k on it now.

would a faulty knock sensor throw a code?

if not, is there a way to test it/them?

T

 

[spf_lexus]

You can test a knock sensor by smacking the block/head with a rubber mallet while the engine is off. If you probe the sensor wire with a DMM/DSO you should get a voltage spike if its working properly. If you dont see a voltage change your sensor is bad. Its a cheap and easy test to rule out knock sensors. These sensors generally last a long time and realy go out but anything is possible with electronics.

 

[Zuffen]

So the knock goes away when the engine gets warm and only knocks at idle.

A little left field but the harmonic balancer may have wear in the keyway and is chattering until it warms up. I've seen that many years ago on an old Renault I once owned.

Another option would be the flex plate being loose but i wouldn't expect it to stop chattering.

I'd be inclined to get someone close by to have a listen as it doesn't sound like something we can diagnose effectively over the net.

 

[Zuffen]

If the engine has been doing this since new it could be a dodgy connection in the knock sensor wiring?

 

[cribbj]

Get it back to the dealer; you're past the normal 36 month or 36,000 mile initial warranty, but your 60 month 60,000 mile powertrain warranty should still in effect. Put this monkey on their back.

If it's been rattling since new, why didn't you bring it back to the dealer the first week you bought it?

 

[Zuffen]

John,

You're spot on.

Take it back as soon as it does something odd.

My wife sent her Mercedes CLK500 back some years ago. They ended up selling her a new SLK55 at a give away price and also gave her a new car drive for 6 months whilst her's was built.

Give the dealer a hard time.

 

[samsdad]

1. I came very close to buying one of these new in Manila 4 years ago. Lesson learned "Do Not listen to the wife"

2. Do not run it on any less than 95 octane.

3. Check trans fluid colour

4. Wrap it up in cardboard and send to perth wa

 

[TONEDOG]

the knocking is during warmup when under load, then after warm up the rattle starts when accelerating hard or in between tranny shifting.

at idle, its not really noticeable. running 93

tonedog

 

[TONEDOG]

spf_lexus - i dont have a dmm/dso for testing. good idea though i have to get that checked.

zuffen - good input gonna have to check that.

cribbj - I have but all i get is "its normal" run around. im gonna have to get ugly to get someone over there to pickup a wrench! atleast its all documented, so when it blows up it wont be my fault.

zuffen - I wish i could get rid of this thing... there are other issues drivinf me crazy also and comined, i dont even want to get in the thing at all!

T

 

[stevieg]

the knocking is during warmup when under load, then after warm up the rattle starts when accelerating hard or in between tranny shifting.

at idle, its not really noticeable. running 93

tonedog

what you're describing is actually rod knock i think, usually very quiet when idling but becomes very loud under a "free-wheeling" situation basically when the engine is in between decelerating and accelerating

Steve