What is this engine noise

I finally fired up the rebuilt 225 today. What is this tapping noise? Here are some youtube links:

http://youtu.be/8se_D-LULjw
http://youtu.be/pF-igszVbWQ
http://youtu.be/vonl0uEj1pQ

The motor was rebuilt by reputable shop. I primed it with oil with a drill shortly before starting. Never had less than 40 psi during the cam run in period. I am guessing its a rod so somehow I loss one of my rod bearings but that is just a guess. If anyone is wondering about the garden hose, that was my backup cooling system. I had to stop my first run-in when my electric fans did not kick on. One standard room fan doesnt do it. Ran the garden hose into the heater connection and ported it back out the other heater connection. Hose pressure will lift a radiator cap btw.
Thanks,
Jon

 

Sometimes a rod knock can be diagnosed by removing a spark-plug wire (one at a time) while engine is running. Remove plug wire and if noise continues then put it back on and go to the next one.

 

It sounds like something in the valve train because it sounds really fast. Does it increase when you rev it up? Use a long screwdriver as a stethoscope and listen at various points around the engine. If it is loudest down low, then it is something in the lower end. If it is louder up high, then something with the valves. My rebuilt v6 had a noise similar to that and it turned to be one of the end bolts to the rocker arms loosened up, so that was noisy.

 

it sounds louder at the bottom end than the top. put your hand on the oil pan and see if you can feel the noise. was the pan dented in anywhere? reason i say that is because it looks like someone did some weding to the bottom of the pan. sounds more like hitting metal than a rod knock

 

I agree drop the pan . if its a rod bearing shouldn't be hard to locate . now if its a wrist pin . that's another tear down . bummer . did the engine shop have a warranty with the engine . sounds too loud for valve noise

 

"The motor was rebuilt by reputable shop. "

Yes, but I've had reputable shops build two engines and both had MAJOR issues.

 

Sounds to "solid" to be valvetrain noise and def. louder underneath. I'm with the "pull the pan" crowd. Good luck.

 

Thanks everyone, it does seem louder down below. I welded the pat on to bottom of the oil pan, there was no damage to the pan. I used a screw driver to listen to valve covers, it did not seem to emanate from there but easy to pull those. Guess I go drop the pan to verify. It does change w/ rpm, gets faster.

 

Very unlikely you'd have the same problem as I found today but your noise is almost identical to mine and was also louder in the pan than it was up top. Noise has a strange way of traveling within an engine. I had a retainer clip either let go or wasn't all the way in the groove when I installed the lifters. Even with the valve cover off it was still hard to locate.

 

Oddfire jeeper got it. I pulled the pan, the rods felt fine, took the pan outside to clean it and notices a scallop where a rod was hitting the pan where it had gotten bumped up. Like problems I can fix with a hammer.
Jon

 

Wish mine had been that simple .

 

That must have been one heck of a relief!

 

Good call by Oddfire.

 

the reason i suggested that was because i had a pan that i dented up on the rocks and sounded exactly like that. beat it out with a hammer and all is fine now.

 

Interesting videos and thread! After reading all the posts, the source of the noise sounds logical. But with no experience or input, a noise like that would certainly be perplexing! Gotta file this little bit of knowledge away.