Mystery noise

[sproutdreamer]

Our 2004 Yaris 1.3 auto has developed a strange intermittent noise. It mostly happens when pulling away from rest and is a sort of grating or growl and seems to come from the front. It does not increase in frequency as you would expect if to do with the wheels or CV joints. I wonder whether it is a alternator bearing or perhaps an exhaust rattle as it seems to pass off when above a certain speed/revs. I did wonder about the aircon pump as the aircon radiator had a leak last year and lost fluid and whether there was a problem running that partially low on fluid (plan to replace aircon condensor when other stuff sorted).

I realise this is a difficult question but has anyone some inspiration on this. I have checked all the wheels, tyres etc, under engine covers and nothing is loose .                                                     

[stantheman1]

Probably unrelated but i experienced a strange 'pinking' or 'rattling' noise when under load especially when accelerating up hills or 90 degree turns, turned out to be the fuel I was using, I was on my second tank of 'v power' (not used for power but for the detergents) once i ran the fuel to almost empty and refilled with regular  'fuelsaver' the problem soon disappeared. I tried using v power again many months later and the same happened.I was always under the impression that using a lower octane fuel would cause this and not by using a higher octane fuel! 

The reason I mentioned this was because i could see nothing on the car that was causing this (I had checked the obvious such as exhaust heat shields front and back etc) and the only thing that I'd done differently was the fuel. 

[bathtub tom]

Have you tried turning off your heater fan?

[mrpj]

13 hours ago, stantheman1 said:

(not used for power but for the detergents

Which "ordinary" unleaded contains anyway. These "go faster" fuels are just a con and an enormous marketing success.

Yes,some engines are built for and need higher octane fuel. Not the Yaris though.

[Mick F]

56 minutes ago, mrpj said:

Which "ordinary" unleaded contains anyway. These "go faster" fuels are just a con and an enormous marketing success.

Yes,some engines are built for and need higher octane fuel. Not the Yaris though.

Utterly agree.

Mick.

[FROSTYBALLS]

Toyota owners manuals for the majority of their cars, state under 'fuel': "Research octane number - 95 or higher"

So one can use higher octane fuel and comply with the vehicle manufacturer's requirements. Down to personal choice.

[stantheman1]

9 hours ago, mrpj said:

Which "ordinary" unleaded contains anyway. These "go faster" fuels are just a con and an enormous marketing success.

Yes,some engines are built for and need higher octane fuel. Not the Yaris though.

...But the premium fuels contain far more cleaning additives and anti friction additives. Like I said, I don't care much for the performance aspect and not really noticed any difference to be honest. I'll put what I think is best for the vehicles I run, I do the same with engine oil, whilst semi synthetic is recommended by the manufacturer I will use top end synthetic oils and change them more frequently than recommended as I don't like to see 'dirty' oil in my engines. Yes I am different to most folk, no I don't care for the extra expense and yes I gain a great deal of satisfaction doing what I do, Oh, I also keep the bodywork in pristine condition too!

[bathtub tom]

2 hours ago, stantheman1 said:

...But the premium fuels contain far more............................................................. anti friction additives.

Really? Anti friction additives in fuel?

I'll put a couple of tankfuls of premium fuel in once a year, not for any performance boost, as lower octane fuels have the same energy content as higher octanes and I suspect the ECU can't advance the timing enough to benefit from the higher octane. I do it for the cleaning additives as my consumption seems to improve afterwards and the engine seems to run a little smoother. Although this could be entirely due to thinking so to justify the extra expense.

 

[stantheman1]

20 hours ago, bathtub tom said:

Really? Anti friction additives in fuel?

...Yes anti friction additives are what's quoted in their ingredients and I suspect that's why you gain better fuel consumption. I even find the same with Shell's 'basic' fuel that it improves petrol mileage but is negated by the extra expense over supermarket fuel.

EDIT: This thread  seems to have been derailed somewhat and is no help to the OP. (My apologies sproutdreamer)

[Bernard Foy]

Does using or not using the handbrake make any difference?

[Longcock]

Could be a lot of things try transmission fluid level l hope it's something simple