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Discussion Starter #1
Hi!

I have heard this sound a few days ago... Recently I have done a complete rebuild of this engine, has 190000 km on it.
The sound appears around 30 seconds after cold start(first video), and disappears a minute later(second video).

https://youtu.be/L-me4oSHK-Y

https://youtu.be/p-_IG1JiVUI

Do you know what this could be?

The car runs great. Tested vtec yesterday, opens freely, has good power. It has been around 1500 kms(1000 miles) since the rebuild. I'm not sure if it was there before, I just heard it a few days ago. After rebuild I did a break-in procedure, have rechecked valve clearances after 300 kms, changed oil. Running 10W-40 Motul xcess 6100. No fumes, no oil lost(dipstick with no change) after 1200 kms. Gas consumption is fine. Have OBX 4-2-1 exhaust header, 2.5 inch piping. Also K&N intake panel filter. Runs on 100 octane gas.

Is it LMAs? Is it ok to drive it?
Any idea and advice is appreciated...
Thanks in advance...
 

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That sounds pretty loud to me. You say you did a complete rebuild, does that include the bottom end? What were your bearing tolerances and piston to wall clearances? OE pistons?

Stock cams? Which LMAs did you install, the 'hydraulic' ones (older) or newer spring type? What do the rockers look like?

Compression or leak down test?
What's your base ignition timing?
What do the spark plugs look like?
 

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Discussion Starter #3
That sounds pretty loud to me. You say you did a complete rebuild, does that include the bottom end? What were your bearing tolerances and piston to wall clearances? OE pistons?

Stock cams? Which LMAs did you install, the 'hydraulic' ones (older) or newer spring type? What do the rockers look like?

Compression or leak down test?
What's your base ignition timing?
What do the spark plugs look like?
Let me start off by saying we did the rebuild just because the engine is 23 years old and I wanted to renew it. It didn't consume oil, was working steady and had good power. I assumed this car would be a keeper, that's why we did it.
We did the bottom too, also we installed new piston rings on OEM pistons(cylinder walls were as new), bearings by spec.(all were red), cams left stock.
We didn't change the LMAs...so the ones on the head are the old ones, we just washed them thoroughly - old piston-hydraulic type LMAs. Rockers were as new to my amateur eye after a good soak and wash.
Compression is good, even on all cyls, I don't recall the exact numbers, but my mechanic who is a local Honda guru, was really satisfied...
Timing has been checked with strobe gun.
Spark plugs are new, iridium NGK - corresponding to manual.

Now I'm confused a bit, why would the sound last only for a short period of time? After it heats up more, I cannot reproduce it at all...No CEL, no loss of power, no blue or white smoke, no fluid mixing or anything unusual besides the ticking that lasts like 30 seconds.
And maybe it's my phone cam that's picking up sound weirdly... :grin:
 

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I have gone to see my mechanic and he is positive it is the LMAs...so we changed to thinner oil to get better penetration when cold. Before I had Motul xcess 6100 10w-40, and when cold it is almost as thick as honey! Now we put in Mobil 1 5w-30, and the ticking is quieter, ticks less and lasts shorter...
But I'm planning to put new type beehive LMAs the next time I do valve clearances...
 

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If it was running fine before and now it's got all new factory parts of the same spec then I'd be suspicious of the LMAs too. I swapped out my OBD1-style LMAs for the 1998+ variety, but you have to add some 2mm shims to get the rocker to the right installed height in the older head.

Otherwise I'd be suspicious of the tune or fueling. The computer does weird things if the injectors aren't all flowing the same rate. You get detonation on a lean cylinder and potentially fuel wash-down on the rest. That's why I'd ask about the ignition timing and I'd check the plugs for an even burn. The ECU does different thing during warm-up and normal operation too.

I do not know what the specification on the oil is there in Croatia, but in the US Mobil1 Synthetic has removed a lot of the high pressure additive package from 'modern' oils to meet emissions standards and sliding rocker and flat tappet style valve train have suffered greater wear than usual. It's cheap insurance to dose the oil with an aftermarket zinc dithiophosphate (ZDDP) additive if you intend to run Mobil1 for a while.
 

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I know you've already checked the valve clearances but check them again, very carefully.
You could be off just enough on one valve to make noise and when the motor warms the metal expands enough to take up the extra clearance and the noise goes away. Always check the easy stuff first.
 
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