Got a dilema here, and was hoping someone here could help me out.
The motor is a b18c1 that just recieved a fresh rebuild. Weisco pistons, Eagle Rods, brand new honda bearings, new oil pump, t-belt, waterpump, etc.

Motor is still in breakin period, so it hasnt seen RPMs past 3500k yet, but the motor makes a slight knock sound at idle to about 1200rpms, then goes away all the way up to 3500rpms. The noise exists even with the engine warmed up, which pretty much rules out piston slap.

So what do you guys think it is? Any experiences with this? all advice and suggestions appreciated. Thanks

 

could be a number of things. Did you check your oil? make sure your oil is full. Also kind
of a pain to do but take all your drive belts off and see if the knock is still there or if it
goes away. If it goes away it coming from one of your accessories. If it is still there
you have an engine problem. If it is still there you should do a oil pressure test if you
have the tools. To do that you remove the oil pressure switch and hook up a pressure gauge where the pressure switch was. read your pressures at idle and at 3000 rpm.
That will tell you if you are getting proper oil flow. If that is good I would take it back to
who ever rebuild it.

 

Take some timing out.

 

The knocking sound is very faint, most people probably wouldnt even notice it, but its definitely there. It does sound like its coming from the upper part of the block, between the block and head.

The motor has oil in it, already did a 2nd oilchange on it and its got 300 miles on it now. The motor had a new oil pump at the same time, so I think the oil pressures should be good. The motor ran and sounded fine before the build, but the oil rings were gone, started burning oil. I rebuilt the motor myself, but I do know what I was doing. It has factor sized/color main bearings as the orginials, and the rod bearings were all brown. The oil clearances for the rods were .015 according to my micrometer and plastigage readings.

Im just stumped on what it could be. The Wisecos do have higher compression than factory, at 11.2:1. I put 104 octane in the motor and also retarded the timing via the distributor, but still no change.

 

Up...really need the help guys...I would make a video with sound, but I doubt my camcorder would pick up the noise.

 

Sounds like low oil pressure resulting in rod knock...
When you start it, does the oil light seem to take longer than normal to go off?
I would not run it anymore until you are sure your oil pressure is good...
Have you tried running a thicker oil to see if the sound changes?


Modified by PyroProblem at 11:21 PM 8/18/2008

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PyroProblem &raquo;</TD></TR><TR><TD CLASS="quote">Sounds like low oil pressure resulting in rod knock...
When you start it, does the oil light seem to take longer than normal to go off?
I would not run it anymore until you are sure your oil pressure is good...
Have you tried running a thicker oil to see if the sound changes?
Modified by PyroProblem at 11:21 PM 8/18/2008</TD></TR></TABLE>

Thanks for the reply!

The oil pump was replaced during the build, so it should good ok?!?!? and I dont see a difference in the oil light, goes off immediately after the engine starts just like normal.

I havent tried a different viscousity oil yet due to the breakin period, its got 5w30 in there now, and about 300 miles on the motor since the breakin. I'll go ahead and do a oil change tomorrow and see what happens. But shouldnt a thicker oil lower my oil pressure?

Hoping to hit that 1000 mile mark soon so I could switch to synthetic.

 

are the valves adjusted properly? they can cause real faint tapping/knocking...have you tried killing one cylinder at time to locate where it is? I doubt its rod knock because its pretty unmistakable and it gets LOUDER when you rev

 

Drain your oil and look at it in the sun light. If it looks like gold glitter in there then you have a spun bearing. I had the same thing happen to me after one of my builds. I say check the oil first cause its easy and your only out the $$$ that it cost to do an oil change.

I suspect rod knock but hopefully its something simple like a needed valve adjustment.

You could also be pinging from lack of fuel. What compression pistions and what kind of injectors are you running?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WhiteNess &raquo;</TD></TR><TR><TD CLASS="quote">Drain your oil and look at it in the sun light. If it looks like gold glitter in there then you have a spun bearing. I had the same thing happen to me after one of my builds. I say check the oil first cause its easy and your only out the $$$ that it cost to do an oil change.

I suspect rod knock but hopefully its something simple like a needed valve adjustment.

You could also be pinging from lack of fuel. What compression pistions and what kind of injectors are you running?</TD></TR></TABLE>

UPDATE:

Went ahead and did an oil change today after work, 3rd oil change in 400 miles. Nothing unusual in the oil, crystal clear, no metal particles.

I figured I had a good enough breakin period to at least hit vtec to see whats going on, or if it even gets into vtec. With my fingers crossed, I hit the crossover up to 5500rpms, came back down to idle and noticed the noise got quieter. Dont ask my how or why, cause I have no clue, hahaha...but it did.

I also noticed another thing, when I push in the clutch at idle, the knock/ tap goes away. First thing that popped into my head was "inputshaft bearing" but it sounds perfectly fine while crusing...Ehhh, I dunno, I personally think this car is possessed, lol.

 

ohhh damn dude ur lucky haha

Go to walmart and get some high temp grease....pop off ur tranny and grease the throwout bearing and input shaft where the bearing slides...grease the fork where it touches the bearing as well

Problem solved haha

 

wiseco pistons? what comp are you running?.. sounds like you are detonating.. i was and i thought it was piston slap or a slight rod knock.. but it was detonating..

and i don't think you should 'break it in being easy"...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WhiteNess &raquo;</TD></TR><TR><TD CLASS="quote">
Go to walmart and get some high temp grease....pop off ur tranny and grease the throwout bearing and input shaft where the bearing slides...grease the fork where it touches the bearing as well

Problem solved haha </TD></TR></TABLE>
you dont really want to put too much grease where the throwout bearing is because it will collect all the worn off friction material from the clutch and then start binding/sticking if it collects enough

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by srmofo &raquo;</TD></TR><TR><TD CLASS="quote">
you dont really want to put too much grease where the throwout bearing is because it will collect all the worn off friction material from the clutch and then start binding/sticking if it collects enough</TD></TR></TABLE>

^^^ absolutely correct...I was assuming that since he did a build he would know the correct way to do it...also don't put grease on the part of the throwout bearing that actually makes contact with the pressure plate....good luck

 

You need to remember that Wiseco pistons are a 2618 forging meaning they will expand in the chamber as they get warmer. When the engine is cold it will produce a piston slap which is what I believe you're describing. To go into more detail, honda B series pistons have something like a .0004" piston-wall gap where as wiseco will have something more like a .035" which is obviously a HUUUUGE difference when we're talking engine internals. The reason for that large of a difference is because stock honda pistons are loaded with silicon to keep the engine quiet and put a lot less stress on the top rings when the engine is cold. The adverse effect to this however is that the piston will not take to detonation very well. The 2618 is a softer material and will absorb the shock of detonation, but under heat they expand on contract a lot more hense why you would be getting piston slap with a colder engine vs a warm engine.


Modified by KooK at 3:22 PM 8/21/2008