Bad sound

[ColonelOdem]

A little background.
Just dropped a rebuilt engine into the car this last year and have been driving it fine for the duration. Now the engine has ~4k miles on it (babying it the whole time for break in, actually have another 1k miles to go) Well, I just noticed a new noise coming home from work the other day. It is very loud, people were all staring at me.
it comes in at idle up to around 3k rpm when it disappears. it sounds like it is coming mainly from my timing belt area, like a jackhammer but in a rotational manner like something is rubbing something else (but in a metal on metal sense). When the car is cold and I start it up, it doesn't happen until the engine is warmer. My oil pressure is normal (mechanical gauge) and honestly I can actually hear it coming through the gauge like a stethoscope (faint but it's there). There is another guy in my local club with the same problem.
What I have done since:
I removed the upper timing cover today and checked timing marks, engine is in perfect time. I did however notice that my builder made that one big mistake: put the pan bolts in the wrong spots. My timing belt has the infamous groove etched into it. The timing belt is very tight, but there is a brand new tensioner on it as well. all new timing pulleys were put on as well. I do have the BSE (done when a big name DSM builder originally built the engine 6 years ago so I don't know what elimination type it is)
I also poked around with a mechanic's stethoscope and can't pinpoint location. I don't know the age of the front case, (shouldn't be older than 24k miles) but I know my water pump was reused and that only has 24K miles on it.

Any help on the matter is greatly appreciated!

 

[gprix1]

The one key word I am picking out of your description there is "jackhammer". Whenever I hear anything that sounds something like that, I look at rod bearings. Of course, your descripton of the sound is entirely subjective and since I cannot hear it for myself, please don't just asssume that this in fact your problem. Is this a deep solid kind of knock or more of a tapping sound?

Ohh... also, take a good look at your main pully. Sometimes those can come apart and make a sound like you describe.

 

[Absit]

So you've been babying a fresh engine for 5k miles? You may have broken it right there.. Check the harmonic damper first, but then it's time to go to the bearings.

 

[ColonelOdem]

Actually it's a deep solid knocking. I broke in my last engine by babying it for 5k miles, and it ran great! I do also give it ~10psi and let off to give it vacuum as well. I will try to get a decent video of this tomorrow when I get off of work.
I have a solid crank pulley, OE style. It's also new with this build. I have my fingers and toes crossed that it's not a bearing issue, or anything terrible like that. I don't have a garage to do this stuff in, i'm really dreading the words 'tear into' or 'rod bearings' In fact just 2 weeks ago I replaced my entire power steering assembly. I also have a spankin new timing cover, so I doubt anything is rubbing there. some other posts I searched and read...all the ones I could...suggested the front cover.

 

[XTurbodTalonX]

If it do happen to have to tear into the motor, the rod bearings are all easily accessible by dropping the transfer case and pulling the oil pan. If there's a problem down there making that sort of noise, you're going to see it right off the bat. All you've got to do is drop the cap on each rod. You might be able to drop the oil pan without dropping the transfer case, too. I just wasn't that creative. My prayers are with you that it's something easy though.

 

[gprix1]

For some reason with our cars, the #1 cylinder is the most common to have a problem with rod bearings first (that is where mine did as well) which is of course is right next to the timing belt.
I hate that my car is down but now I'm doing a 4G64 2.4L block which almost makes it all worth it

 

[Absit]

I have a solid crank pulley, OE style.

OE isn't solid.

 

[ColonelOdem]

Oh wow, I just realized that it is two piece. just seemed solid. I don't think I can pull the oil pan though, there is a cross member in the way of it. I will try to get a video.