thatpurplexj

So quick background, bought a 2002 Civic EX with 124k miles for my sister. Soon after she overheated it and had it running at over 260* for 2-3 minutes.. Needless to say she blew the headgasket, had a shop check the head and deck it and they found no problems. Replaced the headgasket and timing belt and a few other things and it ran great. For about another 1000 miles.. Now it has a knock in the motor.

Here's the thing, the sound is intermittent and it has no rhyme or reason to start or stop. I pulled the top end back down to the timing belt and found nothing loose or something that would cause that noise. Pulled the oil pan off and all the bearing caps and found nothing else. All the bearings are in decent condition for the wear and tear you'd expect. Clearances were all tight so this is seriously throwing me for a loop. Torque converter bolts are tight so that doesn't seem likely. I'm about to sell this car for scrap but we've only had it for about 3k miles.

What the hell else could it be? Everything seems fine!

ezone

I don't see anything scary in those pics right off the bat...Internal noises (bottom end bearings) are usually pretty dang consistent once it starts and doesn't go away.

Post up a good recording so we all can hear the noise?
My laptops suck for sound reproduction though.


Use a stethoscope to pinpoint a noise source?

Alternator mounting bolts and the 5 big bracket bolts all tight?
Compressor pulley bearing isn't going bad?

thatpurplexj

Obviously I was a little upset at the time lol. It doesn't even sound like a damn rod knock, sounds like something is bouncing around. I used a screwdriver as a stethoscope and it definitely sounded like it was coming from the bottom end. I was really hoping to find my lost 10mm socket down there but no luck..

ezone

Uhhhh that's a helluva loud rattle!

First comes to mind is something you (or machine shop) had apart:
Cam gear bolt coming loose? (will be a disaster if that is loose and pulley spins free)

Timing belt tensioner spring broke free of the tensioner? (disaster if it jumps time more than a couple teeth)

thatpurplexj

Seriously! Never heard anything like it and it increases with RPM but also will go away for a second or two. Cam bolt was tight and tensioner spring hasn't budged.. I don't believe the belt has jumped but I'd imagine being an interference motor I'd notice. Alternator brackets are all tight. I did another 1.7 headgasket at the same time I did my sisters and sent the head to the same shop at the same time and that Civic has been perfect since.

ezone

What happens as you raise RPM?


Wherever it's loudest RPM is, hold it there and disconnect each coil one at a time (briefly) and see if the noise changes....
That might isolate to a single cylinder, or rule it out


You're gonna facepalm so hard once you figure out what it is.



Cam journal bolts not tight?

thatpurplexj

The knocking becomes quicker with higher RPM. Cam journals were all tight, only play was in the head with the valves but that was minimal. I'll have to put it all back together to run it again which I have absolutely no motivation to do..

ezone

You said it's auto trans......
In gear/out of gear make any difference?

Flex plate is cracked around the center bolt circle?

thatpurplexj

Auto trans, no difference in different gears or driving vs idling. Haven't looked too hard at the flex plate but nothing I noticed, I will look harder tomorrow though.

On a different note, anyone want to buy a low mileage Civic ex? Got a nice throaty sound

ezone

You MIGHT be able to see it without tearing the trans out if you already have the pan off, but a crack around the center bolt circle may not extend far enough outward past the rear main seal and its carrier to see.

You MIGHT be able to figure out if it isn't solidly attached to the crankshaft by holding one still and trying to move (rotate) the other.

I've only dealt with it a few times on other brands but I've read of a couple on Hondas of some sort and the noise pattern kinda matches so I thought I'd toss it out there.

Engine ever been out? Trans ever been out? Dowel pin missing from the bellhousing or misalignment can cause it.

Rando GIS

Wankenstein

Sounds similar to the video posted below except 7th gen Honda's do not use intake runners. Posiible object in inake or exhaust manifold?

thatpurplexj

Bought a new feeler gauge instead of the old one I had and checked the connecting rod clearance. They're measuring between 0.011-0.013. I looked it up and it's supposed to be in the 0.002 range. I think I'm going to throw a set of connecting rod and main crank bearings in and see how that works.
​​​​
​​​​Should I go ahead and order a set of oversized bearings? The difference is 0.01 which are available online. Is there a recommended brand?

ezone

How does a person use feeler gauges to measure rod bearing clearance?
Unless I missed something in your pictures, the bearing shells pictured in the first post look a whole lot better than your numbers seem to indicate...so.....

WAIT WAIT WAIT
Are you mixing up metric and standard measurements?
Because this looks all effed up right now, isn't making sense in my little pea brain yet.


If you used them to check side clearance (also called end play), side clearance won't make the horrible rattle noise.



To measure oil clearance between the crank and bearings, you typically would use Plasti-Gauge

or use inside and outside micrometers to measure the diameter of each part and calculate the difference.


Not until your machine shop grinds the crank/rods/line bore, and at that point you let the machine shop pick and obtain the correct bearings to match whatever work they do.

thatpurplexj

You're correct I was measuring end play, my apologies. Although I definitely want mixing up between standard and metric, those are the measurements between rod cap and crank.

Would you recommend I use a plastigauge? The flex plate does not seem to be cracked for what I can see and I can't think of any other things that could be making this noise but a rod knock.

ezone

It's the accepted standard.
Read up on how to use it before you dive on it.


But if a rod bearing has enough clearance to make a knock that loud, I think you should have been able to see and feel free play when you wiggle the bad one.

FGS that video had a loud knock, something ought to become apparent sooner or later.

Thinking.....

Did you ever get to make this check:


Wherever it's loudest RPM is, hold it there and disconnect each coil one at a time (briefly) and see if the noise changes....
That might isolate to a single cylinder, or rule it out



Did you check crank thrust clearance?
Rods all swing free, no wrist pin binding?
Piston rock, cracked or broken skirt?

Have you pulled pistons out yet? Check pattern on skirts for diagonal wear markings of a bent or twisted rod. (If it warped the head, it might have hydrolocked against the starter)

Also......with all the bottom end assembled.... Did you rotate the crank by hand (wrench, socket-ratchet) to feel if there are any tight spots as the crank is slowly rotated?

Check if there is free play as you change direction at crank90* (rod clearance knock)?
(set crank at 90* so all pistons are middle of bores then rock crank about 1 degree back and forth, many times you can feel one with a whole lot of clearance)

No stray nut (or 10mm socket) embedded in the top of a piston? LOL

thatpurplexj

The only play I felt was side to side on the rod, nothing up or down

I have not because the lower end is still apart and before I put it back together I'd like to check everything I can.



Have not checked thrust, rods all move freely, no broken skirts, only a small amount of side to side play in the wrist pin.

Haven't pulled pistons but when the head was off the walls and pistons seemed to be in very good condition for what the engine had been through. Machine shop said the head was 0.08 out which wasn't good but not horrible.

I'm moving this weekend so I'll have to load it on the trailer and play with later. I'm going to order and read up on the plastigauge and see what I get there but you're right if it was bad enough for that noise you'd think I'd see something more obvious.

mac25

Did you check the exhaust bolts from the header to the down pipe?

If they are loose or misaligned, the carbon seal might not hold and you would hear the exhaust rattle and rpm climb, but with extra heat it could expand and close until cooled again.

thatpurplexj

Watch the video I posted above, this isn't a tick like a header leak it's a hammer slamming the oil pan sound.