liquid_helix136

TLDR Version: New engine is knocking, see video below for noise. In depth story is laid out below!

Quick background:
My old engine was in working condition, just had low oil pressure due to running it about 3 quarts low one summer. I decided to replace the short block entirely and get a fresh start. I picked up a short block from a local and member here on this forum.

The block originally had 60k miles on it, cylinder 3 had issues, the guy just replaced the short block entirely, and that had this one rebuilt. They rebalanced the crank (welding marks on the crank near one of the cylinders, my guess was this is how the shop "balanced it") the cylinder walls were rehoned, new rings were put in, ACL race bearings were used over OEM and the stock rods / pistons were reused.
Everything looked like it had checked out, the install went smooth, except that the block was missing the rear main seal and a couple of the bolt holes were stripped (one was the allen bolt hole for the oil pump chain guide and the other was for the idler pulley bracket inside the timing cover)


I broke the engine in relatively hard, some half / 3/4 throttle pulls up to 5k (where vtec is set on my tune) and then let it decel down on its own. Plus some light throttle high rpm spurts as well (no vtec until the first 100 miles). I put 1100 miles on the new engine in total including a 500 mile round trip road trip to Houston and back to Dallas, everything was running 100% perfectly, I used valvoline conventional to break it in, swapped it out at 300 miles, then swapped it out again at 1100 miles to put in Amsoil 5w-40 Full SAPS that I had bought and planned on using on this engine indefinitely. I went out for the night the same day, drove it pretty hard on the way home (took it through a couple gears on an empty freeway, got to about 110) and when I pulled into the garage I heard a noise that I wasn't hearing just seconds before. It sounded distinctively like rod knock, I shut the car off and went to bed pretty upset and decided to deal with it in the morning.

This is what the car sounded like on a cold start the next morning.

https://www.youtube.com/watch?v=umfkGCDhjPQ

Matt (the guy who put it together) wants to hear it before we dig into it, so I'm just letting it sit for now. We're gonna do a compression test and check the vtec solenoid filter etc. to check for simple things before we start tearing it apart. I also have the old dino oil in a fresh oil pan in the garage so I will be sending that off for an oil analysis too possibly.

It sounds like rod knock to me, like I spun a bearing, but the typical reasons why bearings spin seems to be covered, so unless something was already inherently wrong with the engine and it was just a ticking time bomb, I'm hoping this isn't the case.

The engine didn't burn any oil whatsoever when I was using the dino oil for the first 1100 miles, but after this happened, I checked the oil level and its about 1/4 quart lower than it was when I changed the oil earlier that day. Oil starvation doesn't seem likely unless there was something wrong with the block initially, and the oil change and this problem happened coincidentally.

Anyone have any ideas?

davidc1

Hmm...I don't agree with how you broke it in. Break in's should not be at high rpm in my opinion.

You mentioned you honed the cyl walls, but reused the pistons? Isn't that a no no with our FRM linings?

Car Analogy

Even if any of that is a real concern (which it may be, I admit I don't know), it wouldn't show up with this few miles, and certainly wouldn't cause a knock.

So I don't expect honing or old pistons is part of the issue in any way.

AP1Driver

I agree somewhat, but if he "honed" it improperly and removed more liner than necessary, and used the old piston rings, it will not have a seal to the cylinder wall and will create piston slap/burn a ton of oil, and should be smoking blue constantly. Any smoke?

chris_barry

Pull the rocker cover off and check you haven't left any rocker adjusters or bolts on the rocker assembly loose.

liquid_helix136

New piston rings, the car didn't burn any oil at all for the first 1100 miles. The oil level appeared to drop about 1/4 of a quart the day I had issues. No smoke though

liquid_helix136

So my car guy came by and pulled the valve cover to give the head a once over, I've uploaded a couple more videos of the car while it's warm. The sound appears to becoming from the top of the motor, but the head looks good, turned it over, no scoring anywhere on the cams, the timing is where its supposed to be, and we even checked the belt pulleys to make sure the bearings weren't going out and everything checks out.

Matt said it doesn't sound like rod knock to him, and he's kind of stumped, our best guess is maybe piston slap. We let the car warm up to see if it would go away or get fainter with the engine warm, but it didn't, however it did change sort of.

The first video is the car idling while warm

http://youtu.be/qXxrSHFw7vU

The second video includes some light revving, you'll notice it gets a big more pronounced RIGHT as I increase the load on the engine and gets fainter when the engine decelerates.

http://youtu.be/CMMsoa6UFxY

davidc1

okay, so instead of making jokes I'll actually try to be helpful. A lost art these days is using a mechanics stethoscope to listen to things. Since it sounds like you can't tell exactly where the sound is coming from using a stethoscope should be able to have you pinpoint it easily

03suzuka...s2000

Sound similar when I forgot to torque down a rocker arm. I beleive a rod knock would be more consistent but that's what it sounds like to me.

03suzuka...s2000

Definitely wouldn't start it again till I found out what was wrong.