Godless Commie

iTrader: (2)

I first noticed valve ticking on low RPMs and during slow speed decel a while ago. Took it easy till I tore the engine apart, but the noise became more apparent over time.
Valve lash numbers were pretty excessive upon teardown inspection, especially on the exhaust side, with a couple as high as 0.42 mm. (MSM calls for 0.28 - 0.34 mm)

Off went the head to the machine shop, and all clearances were set to factory specs. The machinist invited me over to check everything, and we both verified the results.
I also checked all clearances on the bench in my garage, AND after I bolted the head on the engine. Everything was torqued carefully in 4 steps.

I have +1 mm nitrided Supertech valves on the intake side, and exhaust valves are +1 mm inconel Supertechs.
Supertech light double springs, titanium hats, Bill Wilner's Manganese-Bronze guides, serious porting and polishing, Japanese spec cams, new timing belt, pulley and tensioner, new seals on the head.

It took a while to assemble everything in the car, and I started it up for the first time last night.
Started great, ran pretty good (no adjustments at all, just wanted to start and do leak checks and stuff) till it started warming up.
A pretty loud ticking reared its head as the engine warmed up. Pretty much the same noise as before all this work, but a little louder.

I have a couple videos of the said noise, and it comes on pretty strong as I gently rev the engine and let it return to idle.
Once it is properly warm, it persists.

As I was watching the videos at home, I believe started hearing a bottom end noise, too. Or, I am getting really paranoid, I don't know.

I measured valve lash while the engine was good and hot, and got the following numbers (in mm):

Intake:
.23
.22
.25
.27
.26
.25
.26
.26

Exhaust:
:33
.38
.35
.35
.35-.36 (between those two, I do not have incremental feeler gauges)
.38
.36
.38

(I will also measure them cold tomorrow, once it cools overnight.)

I could be wrong, but these numbers do not look like they would cause such a ruckus to me. Moreover, the noise I'm hearing sounds like it is coming from ONE valve. A single tick.
None of the numbers above is dramatically larger than the rest to make the noise I am describing.

What do you think is happening here?

Here is the cold start with no apparent ticking.





Here it is, all warmed up and ticking:





And, here is another version, shot with a different camera with an external mono mic, to better capture the said noise.
Ticking is pretty apparent




I spoke to an experienced Mazda mechanic today. He told me he has seen two cases that are similar to mine.
One ticking case was solved once they found out one of the shims was just a tiny amount smaller in diameter than the rest, and it was moving side to side, crashing into the sides of the shim holder.
And, valve stems were shaved/cut too much in the other case, and valve keepers were standing slightly proud above the height of the stem, and were moving up and down as the cam pushed it down, causing a strange behavior and loud ticking noises.

I will know more once I disassemble the head. Machine shop owner told me to hold off till we inspect it in situ.

Please let me know what you think. Any input is greatly appreciated.

gooflophaze

I once had a friends Tercel I swapped a junkyard engine into, ticked. I was sure it was valvetrain - turned out to be water pump (that I had replaced before putting everything in the car). Yank the belt and run it briefly?

Godless Commie

iTrader: (2)

I don't think the water pump would wait for the engine to warm up, it would just tick away as soon as the engine started.

andyfloyd

Well, it definitely sounds like its coming from the head. I dont hear any bottom end noise there so that is one positive. It does seem to be a lot louder on decel than when the engine is revved a bit. Im sure someone like Andrew could tell you likely what the sound is since he has built a ton of engines.

sixshooter

iTrader: (12)

Use a mechanic's stethoscope to isolate the origin of the noise. That will help narrow it down a bit.

Godless Commie

iTrader: (2)

The more I think about it, the more it sounds like a wrist pin to me.
I listened very carefully, and the noise definitely has "duller" harmonics underneath the sharp metallic tone.

On the other hand, I pulled the plug coils one by one (cops) and the noise did not go away.
My understanding is, a wrist pin knock is supposed to go away when the offending cylinder's ignition is disabled.

I also removed the water pump pulley and the belt to remove the pump and the alternator from the equation, and there's no change in the noise.
I have no other belt driven ancillaries attached to the engine.

Next step is removing the plugs and feeling the tops of the pistons with a wooden dowel while I rock the crank back and forth.
Will report back soon.

andyfloyd

Like are you thinking one of the wrist pin retainer clips are not installed correctly?

Godless Commie

iTrader: (2)

Or, the wrist pin and/or the rod is worn, creating a clearance between the rod and the pin.
Just a theory at this point.

andyfloyd

This motor was just built though correct? Wouldnt it be odd for it to wear so quickly? I wish you luck though sounds like youve got some money wrapped up into the engine I hope its something easily fixable.

Godless Commie

iTrader: (2)

Just had an idea..
I'll hook up the timing light to the engine to "see" the frequency of the noise.
Timing light flashes at rpm speed, because wasted spark..
If the noise is half the speed of the timing light, I could conceivably determine it is indeed from the valvetrain.
Synchronized speed of the noise and flashing would more than likely mean it is coming from downstairs.

Godless Commie

iTrader: (2)

The noise definitely matches the timing light, meaning it is NOT half speed, meaning it is NOT coming from the valvetrain, meaning I am pulling the engine right now.
Damn.

andyfloyd

boooo that sucks man.

Godless Commie

iTrader: (2)

I got the engine really hot this time and revved it to 3500 or so...
Aaaand, #4 knocks double time when I pull the plug wire.
That pretty much confirms a sloppy wrist pin on #4.

I might just wrap some electrician's tape on that wrist pin.



I am kidding.
I shall of course repair it properly and use duct tape instead.

andyfloyd

If you cant Duct it **** it.

sixshooter

iTrader: (12)

What pistons and rods are you using?

Godless Commie

iTrader: (2)

I have 84 mm 9:1 JE pistons and M-Tuned rods.

Sourcing a single piston is not difficult.
I'll need a set of bearings, as well.

Godless Commie

iTrader: (2)

Aaand, I guess I found the source of the annoyance...

Presenting the culprit, in broad daylight, red handed and all.
Notice how the bushing is protruding from one side, too.



Good news is, looks like I will not have to buy a piston.
And I contacted a machine shop, where they told me the bronze bushing on the con rod is perfectly replaceable.

This is all pending a thorough measurement of engine internals with precision equipment, of course.
Or, I'll just wrap some duct tape on the wrist pin.

Godless Commie

iTrader: (2)

I remember reading a post by Savington where he said such damage is more than likely the result of foreign material(s) in the engine, which is pretty self evident by the looks of the bearings I pulled so far.
So, a maniacal cleaning of everything everywhere all over the place will ensue.

andyfloyd

Did the machine shop you used clean all oil passages thoroughly?

Godless Commie

iTrader: (2)

I did all that.
I removed the factory installed oil gallery plugs and installed removable, threaded plugs instead.
That way, I am able to clean everything inside and out.