I've been having a problem with a bad metal-metal pounding coming from my engine. This started back in January, and after rebuilding and checking the engine over (with a few addons) I fired it up again this past weekend, to hear it have the same problem. Its not the heat shield or "normal honda ticking". It sounds like a hydraulic lifter thats gone bad, but obviously, they don't have lifters. Its not the LMA's either... already checked. It happens throughout the entire usable rpm range (up to the 4500rpm wall for engine break-in). Something else I've noticed, probably related to the problem, is a surge in vacuum. I didn't pay much attention to it at first, because I noticed I was getting boost into the engine (and partial boost) around 3k, instead of the usual 4k. What I don't like is that the vacuum shoots up to around 10inHG when I'm cruising, where it was at 20inHG before this all started happening. Also, instead of a smooth climb, before building into boost... the gage shoots. The engine then falls flat on its face at 4k rpm, with very little accelleration or pull.
Does anyone have an idea what could cause this? I've heard everything from cracked head (which was NDI'd and found to have no cracks) to a broken valve spring (none, but one was .015" under stock height) to a bad cam (which isn't warped, but I have no real way of checking for flat spots and such). Any help I could get on this would be much appreciated.

 

Rod knock? Piston slap? Piston hitting the head?

 

No. No. No. :thumbup:

Here's what I've done with it:
new rods, pistons, intake manifold, fuel rail
checked the free length of the springs
balanced drivetrain
plastigaged the bearings with the engine rebuild
I took it to a shop who said the problem was definitely in the head (although I'm still suspect of the throttle body and junk below the intake manifold)
Removed the LMA's and Vtec followers
Ran the valve lash to zero (still tapped)
Adjusted the valves with a dial indicator (which I highly recommend over feeler gages)
Removed the alternator and power steering pump

The vacuum problem is perplexing because I don't know if its related or just a leak somewhere. The tapping is intake manifold side of the engine, and it sounds like its below the #1 or #2 runners. :thumbup:

 

hate to say it but I remember talking to you about this 2 months ago and I had the same sound... that motor is dead now and it was from a main bearing and then, a rod bearing. I know you feel like it is something else, I have listened to you mpeg and mine sounded VERRRRRRRY similar... I also had a B18C1

holy crap, I read your post again and my sound was resonating
from the same place under the intake manifold. bro, stop this and pull the motor, tear down the bearings again and start over. It sounds like a crank bearing

 

Yeah I heard your mpeg too, and it sounded like rod knock to me.

 

Sorry to hear about the car.
I would heed your advice, except that the engine was rebuilt with new rods and pistons... the sound didn't go away, and I then plastigaged all of the rod and main bearings, to find them perfect as per the Helms manual's specifications. The surge in vacuum, and the fact that it accellerates like a dog, with hiccups every few seconds has me looking at an air/fuel problem, or something in the valvetrain.
I'm going to call up Carboy in Houston tomarrow I think and schedule an appointment for it to go in to them. Unfortunetly no one around Corpus really knows too much. Thanks a bunch for the advice though. :thumbup: Like I said, if I wasn't absolutely, positively sure that wasn't the problem, I'd take it and tear the engine down.

 

Does the engine shake when it makes that noise?

 

Lets see you have all new rods and so forth as per engine rebuild. Did you get new pistons and wrist pins, you may have a loose wrist pin. Also in referance to your vacuum problem, you may want to check your cam for flat areas and timing. DOHC motors are a pain to time some times Also check you brake booster vacuum hose for leaks. Check it out and let me know.

 

I know you dont want to admit the fact that the motor has an issue, I am telling you that PSHknock PSHknock sound is the crank bearing yelling at you. soon you will have metal in your
oil pan saying, babbit! babbit! hey... babbit! it could be as simple as the TQ spec on the main caps being too tight... dude just drop the pan and the windage tray and look at them for cryin out loud
you have been dealing with this for MONTHS, what will one day under the car hurt you in finding out for sure? Do a bearing inspection, not a rod, a main bearing. Overtightened bearing caps KNOCK ask me how I know. That happened to me with a cam install, I made them 28ft/lbs and the motor sounded like the bottom end was coming out. Once it FROZE from oil starvation, we determined that it stopped 10 deg past BDC where the valves did not hit anything. We took the cams, cleaned them and the head and caps although galled and the car ran for another 8K without too many issues... however we feel the additional play in the cams caused me to wipe a crank bearing eventually.
Have you monitored your oil pressure? Did you replace the CRANK or polish it and reinstall?

oh, by the way, thanks for the sympathy on the dead block... all that went wrong was a main and a rod bearing/rod. we plan on putting a new crank, new rings, mains and thrust washers, putting new sensors and selling the shortblock at a refreshed rate. I bought TOTALLY NEW ITR REPLACEMENT BLOCK :naughty:
and I had to go ahead and get another P72 head due to the galling on the bearing journals... didnt want to take a chance on it. hope you get it worked out man,

MIke:thumbup:

 

qtiger: the engine doesn't shake no. There's no other obvious indications.

Lipscomb: I got new pistons, pins and rods. The pins are held in by circlips and not pressed, but otherwise went in fine. The timing was checked with an inductive gun, and I'm running about -3* from stock spark advance, for the turbo.

Mike: The inspection has already been done once during the rebuild, and again after it was run a little bit. The crank was polished, checked for align bore and reinstalled. Other than watching for a dummy light, I have no way of monitoring oil pressure. My pops said something along the same lines, where maybe a galley was clogged and that was causing a rocker arm to run a little dry.

Thanks for the help guys.