1zz 'chuffing' sound

[m1tch]

Hi all,

After having a drive in the car over the past few days I have noticed a sort of 'chuffing' or bearing sort of noise that seems to be coming from the back left of the engine, happens when the engine is up to temp and usually when on idle (but will also see if its the same at high RPMs). Its not clutch dependent and seems to vary with the revs - I know this engine is know for various ticking noises but the noise seems to be coming from the back left/gearbox side of the engine so there aren't any chains, belts or pulleys on that side of the engine.

I am unsure what it might be, I am going to check that all the spark plugs are tight - as it does sound like compression loss, thinking is that the spark plug washer might seal fine when cold but then doesn't fully seal when warm.

I will also do a compression test on the engine as well, really unsure what it might be, I am hoping that its something simple like a bracket knocking on something, I know the 1zz intakes do crack over time and cause all sorts of noises but this is more of a 'chuff' rather than a 'tick'.

Really hoping that its not 1 of the pistons eating away at the bore! The car doesn't really burn oil, I did put probably about 100ml in as it was sitting just over half full - currently have some sea foam in the oil at the moment so I am guessing it might have dislodged something, although I think I did remember it was making a noise a bit back but I havn't drive the car in a while.

Anyone got any suggestions?

[Carolyn]

Ah ... with seafoam in, your oil is probably very thin.  Might not be getting to the end of the camshaft when warm.  Running with stuff in the oil is pretty risky, I think.
Anyway, I'd drop that oil and put some new stuff in and 'keep me fingers crossed'.

[m1tch]

Ah ... with seafoam in, your oil is probably very thin.  Might not be getting to the end of the camshaft when warm.  Running with stuff in the oil is pretty risky, I think.
Anyway, I'd drop that oil and put some new stuff in and 'keep me fingers crossed'.

Sea foam isn't an engine flush, it's meant to be run in the engine for around 150 miles or so prior to an oil change. It doesn't change the viscosity of the oil so there is no issue with running it in the engine.

[Carolyn]

Fair enough.  We're going to try the vacuum into the inlet method this weekend, on Jon's car, to see if we can get some crap off the valve seats and get the valves to sit higher.
Should be interesting...

[m1tch]

Fair enough.  We're going to try the vacuum into the inlet method this weekend, on Jon's car, to see if we can get some crap off the valve seats and get the valves to sit higher.
Should be interesting...

Think I heard the same noise a while back on the before sea foam, if it was a harsh chemical flush I would be more worried.

Plan is to:

Check on start up to hear if its there - goes onto high idle so might be masking the noise
Get the engine up to temp with it on normal idle
Listen for where its coming from
Check intake manifold, air filter and anything else that might be loose around there (and vibrates against the engine)
Rev the engine and listen for rod knock
Swap out the chain tensioner for a low mileage spare one I have from the project engine

I will also be looking to check the plugs to make sure they are tight as it does sound like its compression escaping, will also run a compression test on the engine as well as change the oil.

It is possible that its simple a case of the tappet clearance and old oil so might sort itself out after I do an oil change.

It might even be a case that I have a bent inlet valve or something which means that a cylinder isn't fully sealing perhaps caused by stretch on the timing chain - compression test should be able to flag this up.

If it were at the cam end of the engine I would think its the tensioner going bad, but because its more the other end of the engine makes me think its not - might be terminal although the engine runs fine, idles perfectly and isn't down on power at all.

[Carolyn]

I really doubt that it's terminal.  Rods usually go on #1 first....

There's plenty of scope for slack chain before anything hits anything.

Good luck with it.  My money is on oil change and tensioner sorting it out.... got to be optimistic eh?

[m1tch]

I really doubt that it's terminal.  Rods usually go on #1 first....

There's plenty of scope for slack chain before anything hits anything.

Good luck with it.  My money is on oil change and tensioner sorting it out.... got to be optimistic eh?

Yeah I figure it is probably something really simple that needs sorting, the oil is due a change which is why I put some of the seafoam in etc although its only been in there for about 40 miles so ideally I would want to run it for a bit longer.

Grabbed some more 5w30 fully synthetic oil as well, weather is really good at the moment but typically looks like showers all weekend - REALLY wanted to drive the car into work this morning and drive it a bit this evening but it looks like that isn't going to be the case.

Will do as many checks as I can before I drop the oil, might take off the rocker cover again to check for wear if needed but as you said, might be something as simple as oil, filters and tensioner.

[jonbill]

I would think a chuffing sound would be a compression leak - so plug or manifold leak would be my guess.
But hard to know if we all mean by the same thing as chuffing [emoji3]

Is the sound in time with the crank or the cams?
Every turn or every two turns?
That might help narrow it down to top or bottom end perhaps.

[m1tch]

I would think a chuffing sound would be a compression leak - so plug or manifold leak would be my guess.
But hard to know if we all mean by the same thing as chuffing [emoji3]

Is the sound in time with the crank or the cams?
Every turn or every two turns?
That might help narrow it down to top or bottom end perhaps.

Yeah it's hard to describe, will try and get a video of it, it's something top end which is why I am thinking plugs etc, was thinking it might be an injector seal but there is no pressure in the manifold so there wouldn't be a pressure difference etc.

[shnazzle]

I really need to stop pressing the wrong button...
I keep editing other people's posts hahaha..

From "Is the sound..." Onwards in jonbill's post is what I meant to post in a reply.

Sorry Jon!

[m1tch]

Good news, engine is sorted, bad news, its really stupid issue.

*Drum roll*

It was the evap solinoid that had been unplugged somewhere in the past - normally this is closed so the engine is sealed etc.

When the engine warms up the evap system then works - its located on the gearbox side of the engine and it pulses - hence the chuffing!

I have now blocked the pipework (as its a large vacuum leak if not), does come up as a code now I have unplugged the solenoid.

This would make sense as I have deleted the canister on the driver side for weight saving and some additional space.

Didn't notice this before as when its cold the pipe doesn't draw a vacuum, only when up to temp.

*feels stupid*

[Carolyn]

Result!  You can plug off the line on the 'out' side of the solenoid and plug it back in.  No leak and no EML?

Hey -we ALL do dumb stuff.

At least nothing was bent or broken.

[shnazzle]

That just reminded me of a thread not long ago.
Even after I saw yours I had a dejavu moment and now I know why. Someone else posted the same thing and I think it was either spit or loadswine that immediately came in with "evap solenoid".

That's years of experience for ya

[Big G]

Hi
I had the chuffing noise on my first MR2 facelift 2005 model, it was a small return pipe that fits onto the throttle body just before the plastic pipe goes round the front of the engine nearside. I dont now what it is called but i re-fit it and the noise went
cheers
George

[shnazzle]

Hi
I had the chuffing noise on my first MR2 facelift 2005 model, it was a small return pipe that fits onto the throttle body just before the plastic pipe goes round the front of the engine nearside. I dont now what it is called but i re-fit it and the noise went
cheers
George

That's the one