engine knocks only sometimes??

[davidgn214]

my engine has about 4000 miles i have .30 trw pistons rjc engine girdle stock crank and rods ported stock heads. i had 40lb red top injectors with a turbo tweak chip. 206/206 comp cam 70mm tb, lt1 mas air, alk, turbo te61c,


i changed injectors the other day for some 60s and tt chip.. car ran fine no knocks
the next day i jumped in it let it warm up i would give it some gas and it would knock but only when i give it gas and the knock is not that loud... but i can hear it inside motor doesn't shake or radel :frown: anybody have any ideas what it could be (i hope not a piston)

 

[GNguy]

what are you using to monitor the knock? scanmaster or a DS?

 

[87natl]

I got a scare yesterday. went for about a 50 mile drive, stopped to idle for a while and heard tapping in the motor. Shut it down for a few hours and fired it back up again for a few minutes in the garage. Sounded fine for about 5 minutes, then after warming up, the tap came back loud and clear. I got my stethescope out, and listened for a bit. Feel sure that the sound was coming from the drivers side ....... new roller lifters tapping from leakdown, I feel certain. Went to bed with a grimace.......

Today I went out and started it up and let it run for a good 20 minutes, bumping the throttle occassionally....and no noise. WTF?? Let it cool off a bit and did it again...nothing.

Soooooo.....I'm kinda wondering when it will show up again. Will it be a one day thing, or something that is going to haunt me?

 

[johnnyttype]

is it a knocking or tapping noise. if its a 206 roller cam u have it could just be the type of cam and lifters setup u have. my car has a weber 206 hyd. roller and it sounds like a little typowriter in my car and engine bay. dont know if it is the profile of the cam causing it or the comp lifters i have. cams got 12,000miles on it and been clickin since day one!

87natl, does ur noise just sound like one lifter goin bad or tappin, if so check for exhaust leaks, cracked header, leaky gasket on drivers side. in my experience, exhaust leaks on these cars sound just like lifters tapping! i actually had the same problem as u before, only leaked when warm and what not, back stud loosened just enough to be annoying and leak

 

[davidgn214]

i have a scan master

 

[davidgn214]

its not exhaust leak and i just changed the lifters about two weeks ago... and it doesn't sound like a tap more like a knock when i give throttle????

 

[87natl]

is it a knocking or tapping noise. if its a 206 roller cam u have it could just be the type of cam and lifters setup u have. my car has a weber 206 hyd. roller and it sounds like a little typowriter in my car and engine bay. dont know if it is the profile of the cam causing it or the comp lifters i have. cams got 12,000miles on it and been clickin since day one!

87natl, does ur noise just sound like one lifter goin bad or tappin, if so check for exhaust leaks, cracked header, leaky gasket on drivers side. in my experience, exhaust leaks on these cars sound just like lifters tapping! i actually had the same problem as u before, only leaked when warm and what not, back stud loosened just enough to be annoying and leak

In my case, as i said today it didn't happen even after a long run period. I would think that if it were exhaust, when it heated upI would hear it. Also, last night when I was checking on it, I considered the exhaust. Turned out all the lights and looked for any kind of fire visible around the header just for the heck of it, and I saw nothing. When I've had header leaks, you could generally see them that way, in the dark. I dunno, didn't sould lkie exhaust to me, and as I said also I listened directly to the enhine with a stethescope with a metal probe. Sounded mechanical to me.

 

[johnnyttype]

do u know around the area where it is coming from, like driver side, passenger side, trans. bellhousing area, turbo/ exhaust area, oil pan. some other things u could check for a knock could be broken/loose engine mount, loose flexplate to converter bolts, intercooler brackets.

 

[XLR8]

What is your oil pressure? Did it drop since the knock started?

 

[davidgn214]

What is your oil pressure? Did it drop since the knock started?

when it gets hot at idal its at 15psi and when im runnig it hard and i stop sometimes i see at at 10 or under...

 

[davinci50]

10 or under?, I think you found your problem.

 

[XLR8]

Idle pressure at 10 may indicate a spun bearing.

 

[davidgn214]

Idle pressure at 10 may indicate a spun bearing.

well i guess i im just gonna have to pull the motor out to find out there goes more money.... it sucks to because this is the last week for the track untill april

 

[XLR8]

I feel your pain, I only made it to the track once this year on my new motor.

 

[SPOOLFOOL2]

Cut open your oil filter and see what's in it.

 

[davidgn214]

Cut open your oil filter and see what's in it.

i will try that..