All right guys well i wanted to know what are the signs of a dropped valve on a motor???

This is what my car did last night and than this morning.
Last while driving home I was on 5th gear at 45mph at 2700rpm when I would go more than 30percent throttle i started to hear as knocking/rattling noise coming from the engine and it sound more from the head....after I get past maybe 3200rpm the sound went away.

This morning when going to work when i tried starting the car it took forever to get it to fire up alot more than the normal....once fired up the rpms were all jumpy and when I would flick the gas pedal to rev it up the rpm would drop to the point where the motor almost died...so i shut it off and resort to my second source of transport...


Is this a sign of a dropped valve?

 

Sure sounds like a bent/dropped valve to me. my k20 sounded just like this....

 

I'm sure there was no piston to valve contact so i'm going to tear it down starting today what are some things i should plan on replacing?

 

Always start with the basics. Pull the spark plugs and have a look, they'll give you a pretty good idea as to what's going on in their respective cylinders. If any of them are physically damaged, it's a good indication that a valve has dropped (snapped off into the cylinder). Your timing belt could have jumped a couple teeth causing you to bend a valve(s), so if the plugs look ok, I'd perform a leak down test to see which cylinder(s) might be affected. Then I'd pull the head off and repair whatever damage I had to.

 

Well i pulled the plugs out already they look really clean the only thing is that the insulator is kinda a reddish of color so i'm not sure if it fuel related or timing related or maybe just a bit of both...and i checked the timing and it's still right on the money...crank pulley lines up with the mark and so does my cam gears...

 

Have a leak down test or at the very least, a compression test done to see how the cylinder sealing is.

 

Should i crank it over I mean i don't want to mess anything up beyond repair you know what i mean? I just wan't to make sure i'm not going to scare my block or bust a whole through a piston...what are some other methods?

 

rod knock.

 

You've already cranked over the engine and driven it so I doubt cranking it over to do a test will affect much at this point. It does sound like it could be rod knock.

 

This is NOT the sign of a dropped valve. Dropped valves will make HORRIBLE HORRIBLE sounds and usually lock up the engine... This is the sound of audible detonation aka knock...
Did you recently fill up on gas by chance?

 

you can't mistake rod knock.. specially at a certain rpm
if you dropped a valve your car wouldn't run.. and if it did, it wouldn't last long i promise.. trust me.

 

It's not rod knock that is one sound i can recognize right away it sounds more like a clanking/rattling like when you have a rocker thats completely loose....did a compression check i had:

1- 233psi
2- 235psi
3- 235psi
4- 225psi

There was no pressure drop at all everything stayed with no leakage....

 

Dude - if you drop a valve, you're done. You're on the side of the road with a car not running. Simple as that.

 

Yeah i'm starting to wonder what else it could be i'm going to unbolt the valve train and recheck it see if something is loose and see what it does again.....cuz the noise is coming from the head no the block and usually if i had rod knock u can really hear it on a cold start up

 

with compression like that i doubt you've dropped a valve

 

rod knock.
drain your oil or pull your valvecover.. tell me if theirs metal shavings everywhere.

This isn't my first rodeo bro.. i'm just trying to help you..

A dropped valve would have destoried your motor.. you might have a stuck lms, but that wouldn't cause a "clacking noise"

 

what type of fuel management are you using?

 

Chipped p28/ Hondata S200 and 440cc injector, 255lph fuel pump, B&M Fuel pressure regulator and fuel pressure gauge. I made sure not to skimp out on the fuel system when i first starting building this motor....


Well I drained the oil last night i only had 250miles on that oil and it didn't have any metal shaving came out clean even my magnetic drain plug had no shavings. The oil did look a bit darker for only 250 miles of driving. Checked around the motor for any no leaks, i also decided to drain my radiator and check the antifreeze it's clean so i'm honestly stumped right now... When i built the motor I had the crank balanced and micropolished, block was honed,decked, hot tanked. I measured everything before the machining than after the machining and before the assembly and I was well within the factory spec not even close to the service limits.It's not the first motor ive built but i've never had this problem this is completely a first for me...

 

I was searching around and there was a thread somewhere mentioning similar symptoms. The head is off a 99 Si and the dude I got it from said that the valve stem seals were only a few hundred miles old but he was full of sh*t. I did get the head inspected when i first bought but fail to change the valve stem seals running off the seller info...anyways the thread i read had some guy on start up have the similar noise come from the head and he said when he pulled the head apart the when he pushed down on the LMS it would stay stuck down and he would have to actually pull it up. And like i mentioned it really sound like a rocker is loose and flapping around i mean this head is 10yrs i'm just going to see what some updating will do...

 

Does it sound like pebbles being shaken in an empty coffee can?
Can you make the sound happen with the car not moving (no load)?

 

in for the answer.

 

me2

 

double checked everything and took the car for a retune first guy that tuned it had to much timing and the car was pinging really really bad... been driving it for a week already and it running really strong going to be pulling the head off pretty soon to install new style LMA and upgrade the valve train to get it ready to retune with BC Spec 3+ cams...