In another topic we were talking about valve ticking and the Lost motion assembly was brought up. Now i have quite a bit of valve clatter when the car idles and such, but my power is not taken away by it as if there was a bent valve. My compression checked out good with 225ish across the board. The valves have been checked many times to insure that they are correctly tuned. What else would cause this valve clatter? Some one said the lost motion assembly. What is the lost motion assembly? what would it do? Would it be in a 91 JDM h22? All info would be helpful.

 

Get a FSM for the prelude. It has a section on how the VTEC system works, and it covers the lost motion assembly.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Honda Prelude FSM &raquo;</TD></TR><TR><TD CLASS="quote">Lost Motion Mechanism
The mid rocker arm is always driven by the high-speed cam lobe, even at low speeds. At low speeds, the lost motion mechanism keeps the mid rocker arm in contact with the high-speed cam lobe. At high speeds, the lost motion mechanism acts as a part of the valve spring load.</TD></TR></TABLE>

It's on page 5-8, in case you have a FSM.

 

Can you provide more details of under what conditions do you hear the valve noise?

For my 2001 base Prelude, with 56000 miles on it, the valve noise has become noticeable within the past three months, where on a warm engine, at slow rpm only, I hear excessive valve noise.

But this does not occur on a cold start, or at higher rpms (but before the high cams are engaged). It also does not occur if the engine is completely warmed up.

I think it may be correlated to the engine oil's temperature. But I still haven't narrowd down exactly the cause of the noise.

Even worse, once in a while I feel some small amount of high frequency vibration from the engine. Would this be a loose main bearing allowing the crankshaft to vibrate slightly?

 

my engine does this also. someone at honda told me it was the lost motion assembly. so i am simply replacing all of them.

 

sorry it took me forever to post back. The noise isnt AS loud when the engine is cool. However gets a little louder as it warms. I know i can hear it up to 3k rpms. But here is the strange thing. I can hook up a p14 ecu and the clatter is gone, where with my jdm p13 it is very much present.

 

The lost motion assembly is purely a mechanical part of the valve system, much more like a dummy valve, so to assume that it is somehow affected by replacing the lectronic control unit, which can only affect the engine's electronic controls, doesn't make sense. My suggestion is to make sure that the noise is not being made by the fuel injectors. Use a stethoscope to pinpoint the source of the noise.

 

Again...

are you running cams?
What year head?
did you upgrade the LMAs?

 

all stock internals.

 

older LMAs such as early preludes and early b series experienced worn out LMAs. This sounds usually like an inconsistant chatter from the valve train. If they are worn they can be louder than normal. replacement is a good idea to be done if you upgrade to bigger cams. Use ITR LMAs or 98+ Prelude LMAs and a .040" shim under them.

 

would upgrading the LMA's be a big job? and put a hole in my pocket?

 

how can i tell if that is the problem? the chatter continues to atleast 3500rpms that i can hear until the engine and exhaust gets noisy.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AznBlueBoy &raquo;</TD></TR><TR><TD CLASS="quote">would upgrading the LMA's be a big job? and put a hole in my pocket?</TD></TR></TABLE>sure it could, but ruining a cam could cost you even more, right?

 

Has anybody ever replaced LMA's while the engine or head is in the car? I think you have to remove the head while the engine is in the car since the rocker arm shaft will not have enough clearance to be pulled all the way out. Anybody has any experience on this?

 

Would the LMA's even be making noise at that low of an rpm? Don't they only serve a purpose when you enter vtec? or am I completely wrong? Would you hear them at idle if they were bad?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2point3h22lude &raquo;</TD></TR><TR><TD CLASS="quote">Has anybody ever replaced LMA's while the engine or head is in the car? I think you have to remove the head while the engine is in the car since the rocker arm shaft will not have enough clearance to be pulled all the way out. Anybody has any experience on this?</TD></TR></TABLE>They can be swapped in the car. I have done it many times.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by staticrex &raquo;</TD></TR><TR><TD CLASS="quote">Would the LMA's even be making noise at that low of an rpm? Don't they only serve a purpose when you enter vtec? or am I completely wrong? Would you hear them at idle if they were bad?</TD></TR></TABLE>That would be when the sound is most predominant.

 

They serve a purpose when you are not in VTEC also, by pushing on the middle rocker to keep it in contact with the VTEC lobe. The early H22 LMAs had a two stage spring setup, where a light spring would hold the rocker against the base circle and the heavy spring would handle lobe travel/accelerations. As they wore the light spring would not be enough, they would stick a litttle and the middle rocker would click against the cam. When you adjust your valves on a VTEC head, you can push down the middle rocker with your fingers and it should move smoothly and there should be enough force from the lma to return the rocker against the cam. If the rocker sticks down at all, this could be your valvetrain noise. The newer LMAs are a single stiff spring. Good luck.