Newly built engines, how noisy?

[ATAl]

Massive edit of my original post after a bit more testing.

I've just rebuilt a 4age blacktop, got it running but there is a tapping / knocking sound, it's fairly loud, I'd say about the volume and sound of a sticking hydraulic valve gap adjuster (that's the only comparison I can think of)

The noise seems to be occurring at the same speed as the engine, but I'm not sure about that. Is louder around the cam belt and intake sides of the engine.

The engine has only run for 5 to 10 mins so far so maybe it just needs more running?

Things I've checked:
VVT pulley, sound doesn't change whether this is on or not.
Hydraulic cam belt tensioner /pulley, took the cam covers off and watched this while running, there was no apparent vibration.

Things it could be:
Valve gaps incorrect, I've set them to the specs provided by the cam manufacturer, and double checked them, but it's possible they will always be noisy when cold - does anyone have experience what after market cams sound like in a 20 valve?
Some bearing gap wrong on the bottom end, but I did check these when building it using plasti-gauge and everything was within spec.
Con rod small end - the only gap I didn't measure because I had no way of measuring, but both con rods and gudgeon pins are new.

So any ideas?

[strx7]

when you say it "sounds like a deisel" does it "idle like a tractor" ?
when you say you have turned the vvt on and off, does it actually make any difference to it? it should change the sound of the exhuast note, if the pulley is poked, it will idle like a tractor.

[ATAl]

When I turn the switch the vvt the revs drop or raise by about 500 and the exhaust note changes a lot, so it's definitely working.

[allencr]

The engine has only run for 5 to 10 mins so far so maybe it just needs more running? So any ideas?

Wishful thinking, not a chance in the world that it will get better by itself.
I'm constantly amazed at the engine noises that are mistakenly diagnosed and then finally pinned down as really coming from an exhaust leak!!!!!!!!!!
There are 20 valves and they will ALL sound the same with similar lash/gap.
The valves make noise at 1/2 engine speed, a rod bearing will be twice engine speed & change when that cyl's spark/fuel is disabled, the VVT I got no idea but is by far the most common one for sure. [/b]

[BZG Wagon]

Manifold leak?

[ATAl]

The engine has only run for 5 to 10 mins so far so maybe it just needs more running? So any ideas?

Wishful thinking, not a chance in the world that it will get better by itself.
I'm constantly amazed at the engine noises that are mistakenly diagnosed and then finally pinned down as really coming from an exhaust leak!!!!!!!!!!
There are 20 valves and they will ALL sound the same with similar lash/gap.
The valves make noise at 1/2 engine speed, a rod bearing will be twice engine speed & change when that cyl's spark/fuel is disabled, the VVT I got no idea but is by far the most common one for sure. [/b]

Thanks for that, the knock is definitely not twice engine speed, but I'll try disabling individual cylinders and see what happens, but that makes me hopeful it's not a bottom end thing.

Will also tighten up the exhaust manifold, I'll be stocked if it's that.

[l1ttle_d3vil]

Not the injectors ticking? Some of them can be pretty noisy...

[strx7]

Not the injectors ticking? Some of them can be pretty noisy...

especially with aftermarket ecu firing them all at the same time

[tsoob]

got oil pressure?

[CXGPWR]

What has been done to the engine?
I pulled down a 4AGE 16v that was noisy(i thought it was tappets on first listen, measured & they were all fine.
Turnes out the pistons were hitting the serface of the head just slightly.
Cause = thin head gasket + skimmed head.

[ATAl]

Not injectors ticking - they are fairly noisy but this drowns them out.

Oil pressure - this is good, 60-80psi.

Also, ran a sound pulse generator on my laptop set to half engine speed and it matches the sound coming out at the engine's speed.

Had another go at it this morning, I have a suspicion the whole problem is caused by the engine running on three cylinders, but I didn't notice this straight away because of the upgraded cams, I was expecting it to sound like a subaru anyway...

Will check that all cylinders are firing next.

[rollaholic]

Also, ran a sound pulse generator on my laptop set to half engine speed and it matches the sound coming out of the engine's speed.

cool trick!

[CAMB01]

Check to make sure the shim under the bucket hasnt fallen out when they have been fitted, it happens quite a bit.
Sometimes aggressive cams can cause noisier than normal tappets.

Just a few ideas for you to check.

[ATAl]

Right found at least part of the problem, it's always something simple:


No idea how that happened, maybe I dropped it and didn't notice, or maybe the guys at the exhaust shop decided to have a look inside the engine...

Either way that's fixed most of the noise and vibration, but there's still quite a noticeable amount, I'll check the valve clearance once again, and make sure no shims have fallen out and see if that fixes it.

[allencr]

and make sure no shims have fallen out...

If it had it would be making so much noise that you'd have been afraid or should have been afraid to start it a second time.

[matt dunn]

I would be double checking the shims are in place.


When you lift the cam the buckets stick to it, and the shims stick to the buckets,
then the shims falls down out of place and then the bucket drops back over it and you dont see it and dont notice it,

and this can all happen after you have set the valve clearance.

I have seen it happen and also seen the car drop a valve after an hours runing.

You have to physically lift each bucket and reposition each shim to make sure, a bit of a job but definatly worth it.

[pc]

What has been done to the engine?
I pulled down a 4AGE 16v that was noisy(i thought it was tappets on first listen, measured & they were all fine.
Turnes out the pistons were hitting the serface of the head just slightly.
Cause = thin head gasket + skimmed head.

I've had this exact problem, and the engine was a bit noisy from the rebuild. The engine ran for about 1.5 years, then the piston eventually cracked enough and pressurised the sump too much and I had to pull the engine out and have another go.

[ATAl]

What has been done to the engine?
I pulled down a 4AGE 16v that was noisy(i thought it was tappets on first listen, measured & they were all fine.
Turnes out the pistons were hitting the serface of the head just slightly.
Cause = thin head gasket + skimmed head.

I've had this exact problem, and the engine was a bit noisy from the rebuild. The engine ran for about 1.5 years, then the piston eventually cracked enough and pressurised the sump too much and I had to pull the engine out and have another go.

Hope it's not this, I'm sick of pulling this engine apart
But it shouldn't be, the head has been skimmed but there's a normal head gasket and supercharger pistons in it so the clearances shouldn't be to tight.

[MAGN1T]

Since when did skimming a head change the head to piston clearance?

A thinner gasket does in some motors though because some pistons stick out of the top at TDC but you'd measure it first?

Steve

[Mr Revhead]

when the piston crown sticks out of the block.... into the combustion chamber in the head....