Knock When Cold

[Roker]

2005 1.8 petrol Avensis, 60,000 mile

On a morning when cold I have a knock which sounds a bit like a diesel when accelerating, It sounds like one cylinder only. it goes when the engine warms up, but is getting progressively worse. It does not use any oil.

Could this be piston slap or an injector? If it was a tappet I would expect it to be there all the time not just when accelerating. Has anyone else got this, is it a normal characteristic of the engine?

[cmia]

If it was a sticky injector - rare on the 1.8 petrol, it would be hard to start.

If it was tappets, then it would be tappetey" all the time.

to check for a knock, get a wooden broom stick, and remove the brush from the other end.

Start the car and put it over the injectors and then on the engine side and listen.

you will find one cylinder / injector making the noise.

PS, when I reffer to listen, put the stick on the spot and make a fist and put it over the stick and put your ear on the fist!

whilst listening, you can open your fist to increase the noise.

Piston slap is where the rings on the piston or the bore has worn down and the piston is hitting the side of the bore.

The only fix really is to remove the rod and piston and replace rings and hone the block. but before this is done you need to check the bore for excessive wear.

maybe easier and cheaper to replace the engine...

BUT

Removing your current oil and putting in thicker oil will make a thicker seal around the rings. This may lenghten the engines life but putting in thicker oil makes the engine heavier, it wont accelerate the same.

What oil are you using now?

[Roker]

It's only 60,000 mile up. I can hear it without a stick. It's Toyota oil, it was serviced by Toyota. if it had a faulty injector it would still start on the other 3, but I am getting great mpg, not using any oil. It does not make sense to put thicker oil in because it is OK when hot.

I am assuming no one else has this problem.

[cmia]

It's only 60,000 mile up. I can hear it without a stick. It's Toyota oil, it was serviced by Toyota. if it had a faulty injector it would still start on the other 3, but I am getting great mpg, not using any oil. It does not make sense to put thicker oil in because it is OK when hot.

I am assuming no one else has this problem.

fine.

Why post if you were going to ignore advice?

Reason why you put thicker oil in, so on cold a thicker film is present around the pisto rings.

Do as you please..

[Roker]

Sorry cmia, But the oil is thin when hot and there is no knock then. Please give good advice, I was asking if anyone else experienced this.

[cmia]

Sorry cmia, But the oil is thin when hot and there is no knock then. Please give good advice, I was asking if anyone else experienced this.

The problem like I have said before is due to

1- Bore wear on one cylinder

2- Piston damage/Rings worn/damage.

When the engine is cold the car is knocking becuase the piston is slapping the bore, Once the car has warmed up parts like piston rings and pistons expand alittle. Once they have expanded the fill the bore and the piston stops slapping the bore.

(hence why you dont hear it on warm) The more it knocks when cold the more damage and eventually it will knock when its warm.

go and speak to any mechanic and they will probably advise you to use a thicker grade of oil.

http://www.carkb.com/Uwe/Forum.aspx/subaru/6557/How-serious-is-piston-noise

I quote

"Theoretically, a thicker oil helps reduce piston slap at start-up

as it drains off of cylinder walls/piston rings much slower, so

that next time you start the car there is more oil left on these

parts to act as a cushion."

and if you google so many people have done this and have had good results..

I would never give wrong advice on the forums, anything I say to you is free of any underlying motives.

Thats all I have to say.

[Roker]

Thanks cmia that makes sense. We do know that there is a design fault with these engines

[cmia]

Thanks cmia that makes sense. We do know that there is a design fault with these engines

Not with the engine.

Its a Piston design fault where the oil holes gum up.

[Roker]

I am told by a mechanic that if I have piston slap, I should be burning oil. Any comment?

[catzilla]

i had this on my 2004 avensis 1,8 it was just the same but at last oil change i put prolong additive and it stopped but now 2000 miles later it is coming back so im just going to put some more :) mine has ca 120.000 miles on it (199.970km)

[cmia]

I am told by a mechanic that if I have piston slap, I should be burning oil. Any comment?

It will only burn oil when the damage becomes more extensive.

Untill then a slapping noise

[Roker]

Took to the Toyota dealer and they said they could not hear anything, (even my son could hear it) so I will have to just wait until it gets worse.

[cmia]

why do i even bother...

[Roker]

Don't Know what you mean cmia. Should I not go to the Toyota dealer?

I quote from another manufacturer:

Some customers may comment on a ticking noise (similar, but not related to valve lifter noise) that occurs 10-15 seconds after a cold engine start. The noise will last for 1 to 2 minutes and will fade as the engine reaches operating temperature.

Note that this is a customer annoyance issue, and does not affect the durability or life of the engine.