Constant metallic tapping sound 1ZZ

[Dev]

Well, it just so happens that I have a spare Cat! I'll swap it over to see if that cures the problem.

If it is your cat, replacement is not enough. You also need to replace the front and rear motor mounts due to age as they are usually the cause that leads to accelerated flex section damage.

[Optimus prime]

UPDATE,
I have replaced the cat and it has quieted the noise but it's clear something is not right. Obviously the previous Cat has a an air leak so that problem is fixed.

My next step is to flush the oil out, see if there are any metal flakes in it.
---If there are metal flakes i'll drop the sump and check the bearings.
---If not, i will change oil filter, refill with oil and see if the flush had magically cured it (i'm doubtful).

If the problem is still there i'll check and clean the OCV.

if the problem persists I will check valve clearance with the view of replacing valve shims.

If that fails; I think it's time to remove the head for an overhaul/thorough inspection.

....sound like a plan or can you think of anything else worth doing prior to removing the head?

[Call the midlife!]

My money is still on a con rod bearing, although valve lash is possibly easier to check first.


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[Optimus prime]

I can't wait to get this fixed!

If I find Metal in the oil from the oil change, surely this will be the tell tail sign of con rod bearing failure...?

[Call the midlife!]

I can't wait to get this fixed!

If I find Metal in the oil from the oil change, surely this will be the tell tail sign of con rod bearing failure...?

Definitely a sign of something of that nature as tappety valves wouldn't normally fire off shrapnel.
I think you've answered your own question really, drop the oil, possibly through a coffee filter or similar to make it easier to check for bits.
If you find white metal then off with the sump and check the bearings, having seen a spun bearing on video before it should be fairly evident if one has gone.
You could always pull the plug leads in turn prior to that and see if one is noisier than the rest?


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[Dev]

Do you guys have used oil analysis services in the UK?

If so I would send them a sample of the oil and have it analyzed. You will quickly determine where the wear is without having to open the motor. 

This noise could also be VVT actuator related.  What generally happens is the VVT actuator builds up deposits and is not probably lubricated, the lock pin sheers enough to create a dieseling knocking sound. Some have flushed their engine and the sound lessened.

[Gaz mr-s]

Miller Oils did about 4 years ago. Make of oil irrelevant. You send a litre.  £20 was the cost.

[Optimus prime]

Hi all,

Sorry for the late reply, I have been busy moving house and weekend car repairs took a back seat.

...that said, I've done a couple of things this weekend.

-Flushed the oil system using hydraulic lifter cleaner.
-Got excited and put new oil in (I was on auto pilot)
-Checked old oil and saw brown, crumbly bits of rusty metal (pic below). i'm not 100% sure this came out of the sump or if it flaked off the underneath of the car (I wish I was more careful). I was expecting to see shiny flecks of metal if it came from inside the sump?
-I've checked the OCV and filter, both seem fine and very clean

I previously replaced the Cat and that quietened the sound but it certainly didn't cure the problem. I think the car sounds generally louder (kind of like a blown exhaust) than it did before the problem started, that said I've been driving a Toyota Hybrid daily and that's pretty quiet.

I have been looking into replacing the con rod bearings, I never appreciated what they were... they're basically metal shims. They seem fairly inexpensive, i might as well do all 4 while i'm down there. any other suggestion on things to replace while i'm there?   

[Optimus prime]

Hi,

So I finally got round to doing the bearings this weekend. the ones that came out showed little wear but as I was down there I had them replaced. oil clearance for each big end was 0.050 which is well within spec (shows the car's been looked after)
I let the sump gasket set last night and filled it will oil hoping the noise would not be there today. but no luck, the noise is still there!

My next step to to replace the exhaust manifold gasket in case it's leaking. People on here and facebook suggested it a few times although i must admit, i'm not 100% sold on this concept but i'm running out of ideas.

If replacing the gasket doesn't solve it, i'll take of the cam cover and check valve clearances.

Any input gladly welcomed, i'm slowly loosing my love for 2

[Optimus prime]

bearing 2

[Optimus prime]

bearing 3

[Optimus prime]

bearing 4

[shnazzle]

That totally does not sound like valve clearances. As owner of potentially some of the loudest valves in the North East, I'd know.

It almost sounds like a resonance causing a rattle somewhere. Did you say it goes away as you rev it?

Also, sounds a bit like when I had the crack in my manifold

[Optimus prime]

the noise comes when it's rev'ed. the sound doesn't get louder or quieter when the engine is running at operational temperature (scratching head)

[shnazzle]

I'd jiggle the shizzle out of everything in that engine bay and check for a noise of something hitting something else. Under and above.
It's very odd to have an internal engine noise that doesn't change with rpm isn't it?

[Call the midlife!]

After comparing your noise with my own tappety noise I'm more inclined to think yours is just blowing from somewhere.
Possibly something that just "gives" as the engine tilts on initial revs then sorts itself out.
As Shnazzle says possibly a cracked weld or something on the manifold? Are your O2 sensors nice and tight? Clutching at straws perhaps but does sound like air getting out, I once fired mine up forgetting to refit the O2s and they make a rattling kind of sound.


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[Carolyn]

Very small exhaust leaks sound like rattles.  Could be the crush-rings between the cat and manifold or the doughnut between the cat and the silencer.

[Optimus prime]

Thanks for the speedy replies everybody!

1) The noise is absolutely related with engine rev's. i'm certain of this, I had all heat shields off just to make sure i wasn't going nuts as it sounds like an internal noise. the sound comes when the car is under load and it sounds like it is coming from the head. I bought a stethoscope and had a prod around but it's difficult to pin point.

2) I could remove an 02 sensor and see if the (same) noise gets louder. the manifold on there is the original cast iron lump. Other than physically looking on the manifold for cracks, is there any other inventive ways to check?

3) I replaced the crush rings and doughnut when i swapped out the sports CAT for the stock one, i think that section should be fine.

[Optimus prime]

My dad came round this evening and he's mechanically minded. I showed him the car and he is hearing the same as me but used different terminology.

I said to him it sound likes the engine is underwater so perhaps theirs an exhaust leak. he put his hand over the exhaust to see if we could hear anything obvious. We heard nothing strange as the additional back pressure should have made any leaks more obvious.

Moving on, I rev'ed the car and he instantly thought the sound was coming from the head. aside from the metallic tapping sound be described the car as gurgling. his thoughts were to check the timing as this may be out. I quickly replied with "it's unlikely the timing could have slipped"... but he's right, what if the old tensioner got lazy and let the cam slip a tooth, is this or something similar been known on the 1zz?

[Carolyn]

Really not possible to jump a tooth.  Chain could be very stretched, though.  Especially if a tensioner was not installed correctly.

Stretch can be measured just by removing the cam cover.

That's a great opportunity to measure all the clearances.  Tedious but not difficult.

[Optimus prime]

That's very true, there's a bit of work I can do with the cylinder head cover off. I was reading the BGB i see the cover gasket is reusable so it's a free check!

I might do this first before spending £30+ on a new manifold gasket

[Carolyn]

That's very true, there's a bit of work I can do with the cylinder head cover off. I was reading the BGB i see the cover gasket is reusable so it's a free check!

I might do this first before spending £30+ on a new manifold gasket

If the gasket is old and stiff, best to replace.

[Optimus prime]

Hi Guys,

Just to wrap this up. I replaced the manifold gasket along with the manifold as one too many bolts snapped.

Engine was much quieter and the ticking noise under acceleration has gone. Crazy how much sound escapes from a fault gasket. This really threw me!

My advice to anyone else suffering this problem. If it sounds like there's an exhaust leak, chase that down first before anything else!

Thanks for all your help!

[Call the midlife!]

Glad to hear you no longer hear!


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