i think the tapping is from a spun rod bearing from over revving or oil starvation.
and the low compression is a broken ring land.

 

I think its a spun bearing too.

 

what about a wrist pin ?

 

yeah i put it all back together last night and it ran the same still, lots of blow by so it has to be the rings for sure. i know that, so next is the tapping issuse ... i had one of those stethiscopes for cars, and i put the metal end up aginst the oil pan and sounded like a tap, if its a spun rod im going to throw my dx block on my d15b head, but the guy thats helping me said it could be piston slap or a wrist pin ?

Can someone elaborate on piston slap is or a wrist pin. like how you can tell its them?


Modified by gofastcivic W at 5:20 PM 11/13/2004

 

bump

 

Spun rod bearing/s (the knocking) and cracked ringlands (the blow-by) are signs of detonation. Tear down the bottom end and you should find both.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gofastcivic W &raquo;</TD></TR><TR><TD CLASS="quote">
Can someone elaborate on piston slap is or a wrist pin. like how you can tell its them?</TD></TR></TABLE>


Anyone else ?

 

the greddy blue box caused that

Edit -&gt; Meaning my cracked ringlands


Modified by FredoSP at 5:54 AM 11/14/2004

 

another thought ... can u get a video of the tap?

 

sorry no vids,


Modified by gofastcivic W at 11:54 AM 11/14/2004

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pngfolife &raquo;</TD></TR><TR><TD CLASS="quote">Spun rod bearing/s (the knocking) and cracked ringlands (the blow-by) are signs of detonation. Tear down the bottom end and you should find both.</TD></TR></TABLE>

How can cracked ringlands cause blowby? Ringlands are only there to hold the rings in place, not seal the combustion chamber. It might scratch up the cylinder walls but then he would actually see wear on his cylinder walls.

Point is.. just tear down the block because theres something wrong with it. If you dont... problem is only going to get worse. Youre just spending more time and money dianosing when you couldve just tore down the block and been done with it already.

 

well the thing is if i have a bad wrist pin then i need to get a new piston, if its a spun rod bearing i need to get another block. i just would really like to know what up with it before hand b/c tuesday is the next chance ill have to work on it.

 

i believe the tapping could be knocking. and i think that could be caused by low compression in that one cylinder. ur piston is gone fosho. smoke out ur valve cover definitely sounds like blowby and ur rings.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gofastcivic W &raquo;</TD></TR><TR><TD CLASS="quote">well the thing is if i have a bad wrist pin then i need to get a new piston, if its a spun rod bearing i need to get another block. i just would really like to know what up with it before hand b/c tuesday is the next chance ill have to work on it.</TD></TR></TABLE>

Theres no way to tell for sure before hand. When Tuesday rolls around, tear that block down. Takes an hour max. Whatever the problem is, you'll need to take apart the block. So whats the point in diagnosing it anymore?

 

well i dont see a whole lot of info on wrist pins going bad, is this uncommon ?
and what are tell tale signs of it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ozzyman &raquo;</TD></TR><TR><TD CLASS="quote">

How can cracked ringlands cause blowby? Ringlands are only there to hold the rings in place, not seal the combustion chamber. It might scratch up the cylinder walls but then he would actually see wear on his cylinder walls.

Point is.. just tear down the block because theres something wrong with it. If you dont... problem is only going to get worse. Youre just spending more time and money dianosing when you couldve just tore down the block and been done with it already.</TD></TR></TABLE>

Do you even know how rings seal? Cracked ringlands allow combustion pressure to circumvent the rings.

 

word

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gofastcivic W &raquo;</TD></TR><TR><TD CLASS="quote">
Can someone elaborate on piston slap is or a wrist pin. like how you can tell its them?


Modified by gofastcivic W at 5:20 PM 11/13/2004</TD></TR></TABLE>
piston slap sounds like a rattle usually when the engine is cold due to smaller pistons. and the noise may quite down to nothing when warmed up
wrist pin knock would sound just like a rod knock so u wont ba able to tell till u tear it all down

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 18gsir &raquo;</TD></TR><TR><TD CLASS="quote">
piston slap sounds like a rattle usually when the engine is cold due to smaller pistons. and the noise may quite down to nothing when warmed up
wrist pin knock would sound just like a rod knock so u wont ba able to tell till u tear it all down
</TD></TR></TABLE>

thanks alot everyone !! im tearing it back down tomarrow to find out for sure what it is, but i know its not piston slap. if its a wrist pin then i need a new piston correct ? and if so does anyone know where i can find 1 new piston ? i hope its not rod knock because i really dont feel like using my old dx block

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pngfolife &raquo;</TD></TR><TR><TD CLASS="quote">

Do you even know how rings seal? Cracked ringlands allow combustion pressure to circumvent the rings.</TD></TR></TABLE>

Yes, I do. Combustion pressure creeps behind the rings and pushes it outwards. Sometimes they even put holes on the top of pistons or on the underside to ensure the gases is directed behind the rings to push it outwards against the cylinder walls. This is called 'gas porting'. Ringlands are just the spaces in between the rings. Not on top where the gases would be.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ozzyman &raquo;</TD></TR><TR><TD CLASS="quote">

Yes, I do. Combustion pressure creeps behind the rings and pushes it outwards. Sometimes they even put holes on the top of pistons or on the underside to ensure the gases is directed behind the rings to push it outwards against the cylinder walls. This is called 'gas porting'. Ringlands are just the spaces in between the rings. Not on top where the gases would be.</TD></TR></TABLE>

Right, and if the ringlands crack, they allow combustion pressure to "leak" past the rings into the crankcase causing excessive blow-by and loss of compression.

 

checked out the rod bearings and they look brand new gonna have to be a wrist pin i guess ehhh ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sportinemotions &raquo;</TD></TR><TR><TD CLASS="quote">checked out the rod bearings and they look brand new gonna have to be a wrist pin i guess ehhh ? </TD></TR></TABLE>
My bet is still the ringlands. Did you check the oil pan for any pieces of floating metal?

 

no metal at all man

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pngfolife &raquo;</TD></TR><TR><TD CLASS="quote">Right, and if the ringlands crack, they allow combustion pressure to "leak" past the rings into the crankcase causing excessive blow-by and loss of compression.</TD></TR></TABLE>

So does this mean this pistons is garbage and causes you to lose compression? I've seen pistons where the wrist pin is deeper into the piston. This is used for people who want to run longer rods. (Couldnt find a better pic but this will explain what I'm saying)



<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mattssi &raquo;</TD></TR><TR><TD CLASS="quote">
My bet is still the ringlands. Did you check the oil pan for any pieces of floating metal? </TD></TR></TABLE>

Not the ringlands. Ringlands breaking is not that common at all.