i think i broke something

[1fastredsc]

Gave the car a good beating on the highway the other day, and when i was done, and slowed down, i noticed an audible knocking noise. So i went into limp home mode and drove the car the remaining 6miles in 5th gear at about 40mph (kept the revs as low as possible). Got home, noise didn't get any worse or better, so before shutting it off, i went to the back to localize the noise. It's coming from the right side bank of cylinders toward the back (my guess is #6 or 5). It's definitely in the valvetrain because it sounds like it's right behind the valve cover. So............ worse case is that the oil spray bar got clogged and i damaged the valve guides on my new heads. Best case is that a rocker shaft is moving or one of the rockers backed out of it's adjustment. Thought i'd share this with up coming pics this weekend of what happend.

[mtelliott]

Let's hope for the best case scenario.

[snowman]

Lets get the noise straight. Knocking is usually caused by rods, maybe pistons. Clicking is usually caused by the valve train.

Which is it? Knocking or clicking?

A knock is usually a deeper sound, a definate KNOCK like on a door.

A clicking is usually like a knock but without the deep, door type sound. More like pebbles thrown on the door.

If it feels like a knock, sounds like a knock and you are sure its a knock, and not a click, then hold on to your wallet cause its most likely a rod. and it its a rod, most likely it was a rod bolt failure. IE improperly torqued, bad bolt, or severly over reved.

[mtelliott]

Snowman

When my rocker shaft came loose, I would have sworn it was a rod. I know what a rod sounds like and was just thinking about the cash flowing out of my wallet. When the rocker comes loose, it will sound like a knock.

There is hope.

[1fastredsc]

I didn't open the case in the rebuild, only a top end from the barrells/pistons up. Besides, it's easy to tell because i put my ear right next to the motor and the noise was at it's loudest right at the top of the valve train. I can't comment on the knocking/clicking because i don't know what a bad rod bearing sounds like.

[1fastredsc]

OK, no pics, but i did break something. There was a small piece of a green seal that blocked the entrance of oil to the camshaft oil spray bar. Which means that noise came from the right side bank going dry. I cleaned it all up, and used air pressure to make sure there weren't anymore blockages. I then fired it back up, and while the noise was much quieter, there's a permanent knock coming from cylinder 6. And although i didn't notice this before, only 5 cylinders are firing. My conclusion, i bent a valve when it went dry. Reasoning, well it burnt asbolutely no oil, which tells me that the guides didn't take that much damage if any. But with it running off of 5 cylinders, the loud knocking coming from the valvetrain/head area, and the firm possibility that when it went dry a valve got stuck on it's way back. So, since i'm firmly in college now, i guess it means the car will be sitting for awhile until i'm finished with it. Thanks for all the help, and hopefully i'll be back sooner than later.

[mtelliott]

What green seal would be a part of a top end rebuild?

[KobaltBlau]

anything viton ... might need a picture or more detailed description of the chunk of seal.

[addictionMS]

green paper or rubber, green is the color of a valve cover gasket....

Jim

[snowman]

After you have caused a number of loose rods you learn to know what they sound like. I learned the sound very well in my youth.

Remove the spark plug for the bad cylinder and see what it looks like. The appearence can help determine the source of the problem. Mechanical damage, like the piston would do when contacting the plug, indicates a very loose rod.


If it is a rod certainly do not run it anymore. The crank might still be salvageable. You may also have damaged valves if you have a very loose rod. A compression test will tell if there is a bent valve or hole in the piston or both. A leakdown can tell which is bad and it may be both.

Good luck, hope its just a bad rocker.

[1fastredsc]

Sorry no pics, but it's a light green, not dark green. And my cover gaskets are an orange silicon. The light green i *think* is from one of the seals on the oil return tubes from the cam tower to the case. I remember that they gave me quite a bit of trouble when going in, and one specifically looked as if the seal didn't quite go in all the way even though it doesn't leak. Either way it's my fault, and i'm going to have to pay. So for the time being (i'm sill going to do a leak down) the car is going to sit until i'm done with school or come in to a large sump of money somehow. Of course, i'm not holding my breath for that large sump of money

[snowman]

Don't get to discouraged. I repaired my gia once. we removed the engine one night, took it to my 3rd floor dorm room and rebuilt it before the maids found it.

[1fastredsc]

Well, i haven't touched the car in quite some time. Partly because of school, partly because i'm pissed off at it. But yesterday i decided to mess with it some. Did a leak down, and pitch cold all 6 cylinders came in at 5% or less leak down. Therefore my cylinders are holding tight. Next step it to take it out and strip it apart to get to the source, i'm afraid of opening the case and finding something i don't like . I'll wait till i'm done building my dad's motor than start ripping it apart again. Looks like you might be right about that rod bearing snowman.

[sammyg2]

I would do a valve adjust and replace the spark plugs and see how it runs. If it still makes noise shut it off quickly, no sense making things worse. But.. if it is quiet and runs good there is also no sense taking evertything apart.

It is probably hosed but you can find out for sure.

[asphaltgambler]

See my post; this forum " You won't believe why it blew up"

[1fastredsc]

I did a valve adjust the day after the carnage, all 12 valves were already set to perfect clearance as i had already done, so i'm not getting out of this that cheap .
Thank you for the info asphalt, although my motor is a 3.0 with the much stronger designed rod bolts, so i can't see them stretching unless some shmuck over reved the piss out of the car before i bought it.

[1fastredsc]

I was on my way home today from my calc 3 exam and was thinking about the car. How feasible is it that one of my pressure fed tensioners colapsed, and if so, does the chain slapping the motor a bit make a sound that sounds a lot like knocking on the motor?
If possible, then maybe i shouldn't throw in the towel on the motor just yet, and take the chain covers off this weekend.