I searched with several criteria and found that people were who were having similar noises were told to check valve clearances. The only weird thing about my situation is that the noise comes in (at least noticably so... it's somewhat more faint otherwise) when I'm accelerating the car. So here's a summary of the condition of the car and also the problem/symptoms:

1. 1996 Integra LS (b18b engine), stock @ ~148,000 miles. Oil level, coolant levels are fine. Engine temp is fine. No CELs. Idle is slightly lumpier than it used to be. I rev the **** out of it once a day Timing belt was changed about 30,000 miles ago, and valve clearances were adjusted at that time. Crankshaft pulley also was changed at that time (since it broke).

2. There is a rattling/chattery noise out of the engine bay when the car is accelerating. The noise is audible from outside of the car and also from the inside. The noise is less prominent when the car is not in gear and the engine is revved in neutral. The noise seems to come on as soon as the throttle pedal is depressed, and stays until I let off. I popped the hood and it sounds like the noise is coming from the intake side of the engine, under the valve cover. EDIT: Also, the noise is directly proportional to RPM (more revs = higher frequency rattle).

3. Car drives just fine. No loss of power or other weirdness to speak of.

TIA


Modified by mdpalmer at 2:11 AM 3/19/2005

 

valve adjustment might help

 

how's your distributor??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JH4DC4-2GSR &raquo;</TD></TR><TR><TD CLASS="quote">how's your distributor??</TD></TR></TABLE>

I don't know. I haven't done anything with it since I've had the car, but it appears OK. The spark plug wires are in decent shape, and I changed spark plugs about 30,000 miles ago as well.... I'll have a look at it. Do you think there may be issues with spark that could be causing this?

 

I took off the valve cover and had a look at the valvetrain; everything looked OK. I didn't have an opportunity to check the valve lash, since I couldn't find a 19 mm socket in my toolset (to turn the crank pulley).

However, I was alarmed to see that the cam gears were pressed up against a plastic cover (in the Helms it's called the "back cover"... see page 6-7). It would seem that when the engine is running that there is constant rubbing of the cam gears on this cover. THere were some obvious signs of wear on the cover... due to the gears grinding against it.

Has anyone ever seen this kind of thing before? Why would it happen at all? I didn't have time to try removing the cover, since it started raining... I'll look into this more and report back. In the meantime, any thoughts on this?

 

bump for some knowledge

 

TTT

 

bump for assistance

 

I have worked on 2 cars recently (one is my own and makes a chattering noise under acceleration dependent on speed, and the other is my girlfriend's brother's, and it doesn't make that noise). Both of them (g2 integras with over 130k) have the same issue you mentioned - having the cam gears pressing against the back cover. As far as I can tell, it's fairly normal, and it doesn't cause that noise. A good way to check would be to pull off the VC and run it around w/o the front timing belt cover for a little while - it should allow that back cover to flex a little bit and get away from the cam gears.

I have been troubleshooting that noise as well, and although I haven't figured out yet, I have tried changing the spark plugs, ignitor coil, and valve adjustment. I have a new dist cap and rotor, as well as new spark plug wires sitting in my living room ready to go in. If that doesn't work, I am thinking it could be several things:

1) spark plug gap issue - next time I will be really **** about checking the gap when I change them
2) bent valves causing clacking (this is my nightmare)
3) a clutch/transmission bearing (I think the sound goes away when the clutch pedal is depressed, although I haven't been paying attention in awhile)
4) some other part of the distributor (pick-up?)
5) a bushing in the front suspension that is put under more pressure when under load, and may be vibrating.

Like you, I really think it is coming from the area near the distributor, so I will be changing everything soon. I should mention that my ignitor coil completely went out on me before I changed it, so I thought that could have been related.

As far as my car, oil consumption is minimal (about 1/2 qt of Mobil1 10w30 every 5,000 miles), and my coolant levels, tranny fluid, timing belt, etc were recently changed. The only things that probably need changing are p/s, a/c, alt belt - I think the previous owner skimped on those, although the clutch was changed 30k miles ago.

PM me if you want to brainstorm a little more, I would be interested in what you tried so far.


Modified by purplegsr (Exospeed) at 10:36 PM 3/20/2005

 

OK, here's a little update: (EDIT-- I noted the rocker arm wiggling BEFORE adjusting the valve clearances )

1. Checked valve clearances. They were slightly out of spec, and I adjusted all of them.

2. Dropped oil pan. There was no metal shavings in the bottom of it, or in my oil (that I could tell).

3. Did a compression check. Results (cyl. 4-3-2-1): 170 180 175 180

4. Had a closer look at the head... noticed that the rocker arms (the fixtures that hold the adjusting screw/locknut) were loose on several of the valves!!! The had some play in them, and I was jiggling several of them around. Is this normal? Not all of them were loose like this... perhaps 7 or eight of them (some on intake side others on exhaust side). What can I do about this?

5. The noise has not gone away, and is not getting better. Help! I'm going to a dealer tomorrow to get further diagnosis. What do you guys think I can do?


Modified by mdpalmer at 9:30 PM 3/26/2005

 

TTT

 

It's normal for the rocker arms to be a little loose when their corresponding cylinder is not at TDC. You should be able to move them back and forth a little bit with your finger.

As you know, I have a similar sound when the engine is under load. Today I finally got a chance to change the dist. cap and rotor, plug wires, and fuel filter. The car performs better, but that chattering is still going on and it seems really loud with the hood up until the car warms up. From inside the car it is imperceptible though. I have already done a valve adjustment, as well as a new ignition coil.

I am still thinking it's a transmission bearing issue, but who knows. I don't want to tear apart my tranny, my clutch is only about a year old.

Good luck with the detective work.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by purplegsr (Exospeed) &raquo;</TD></TR><TR><TD CLASS="quote">It's normal for the rocker arms to be a little loose when their corresponding cylinder is not at TDC. You should be able to move them back and forth a little bit with your finger.

As you know, I have a similar sound when the engine is under load. Today I finally got a chance to change the dist. cap and rotor, plug wires, and fuel filter. The car performs better, but that chattering is still going on and it seems really loud with the hood up until the car warms up. From inside the car it is imperceptible though. I have already done a valve adjustment, as well as a new ignition coil.

I am still thinking it's a transmission bearing issue, but who knows. I don't want to tear apart my tranny, my clutch is only about a year old.

Good luck with the detective work.</TD></TR></TABLE>

Thanks for confirming that there's nothing wrong with my valvetrain I'm starting to wonder if, as you sugggested previously, there may be some vibrating suspension components (or transmission, or who knows) that are contributing to the noise... One other thing that I forgot to note in my last post is that I borrowed a friend's steathescope (spelling?) that was built to help diagnose sources of noise on automobiles, and determined that the knocking/vibrating is definitely coming from the timing belt side of the engine... it's not clear if it's in the head or bottom end, based on my poking around. I don't know. Boy, this is frustrating. Let us know how your car turns out--if you solve your problem

 

Update:

I had the dealer take a look at it (diagnostic fee = $80 (!)). They determined that the noise is definitely coming from the head, and that there is no way to tell what the problem is unless the head is removed (****!). Then they can check the rest of the valvetrain for any damage or problems. So remachining of the head, plus replacement valvetrain components (assuming that only some of the parts took a ****) was quoted at $1200. God dammit! I'm probably going to just pick up another engine and drop it in. I can get away with that for about $2000 I think. What do you guys think about this? Do you think I should have the head removed and checked out, or just get another engine (assuming I can get one in decent shape)? TIA



Modified by mdpalmer at 6:01 AM 3/29/2005

 

Well, we took apart the engine last night to see what the hell happened. In case you haven't read the rest of the thread, I've had a horrible sound coming from my engine a while back... and it got worse and worse to the point that my oil pressure light came on. I shut the car off and had another engine installed.

So we took the head off, and everything seemed fine. checked out the bottom end, wiggled some of the rod caps around and noticed that the #3 cap was very loose. Took off the cap and here's what we saw:





That ****** was ground down to pretty much nothing. I'll put up some pics of my oil pan too, since there was some remanant of the bearing there. So it WAS a rod bearning. if you guessed correctly I'm still trying to figure out why this happened at all, especially since the engine didn't have that many miles on it. What do you guys think? Thanks for everyone's input.

BTW, the block and other miscellaneous parts will be up for sale shortly

 

Either it wasnt torqued or the rod cap just came loose over time, was there any type of anti seize on the bolts? cuz they throw torque specs way out...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sooo_slow &raquo;</TD></TR><TR><TD CLASS="quote">Either it wasnt torqued or the rod cap just came loose over time, was there any type of anti seize on the bolts? cuz they throw torque specs way out...</TD></TR></TABLE>

Anti-seize? You mean like loctite? I have to say that when we removed the rod caps, a really bad smell came out of the grooves where the bolts used to be. My buddy was saying that the smell may be due to some kind of loctite type of substance that stinks like hell when you break stuff back out.... is that what you're talking about?

 

i was gonna say, my car made the same noise when i spun a rod bearing. but you already found the prob

 

Hey I have this same problem with my olds 1989 and it just started having that same loud chatter. At first I thought it was the pistons or a rod yet the car drives just fine. the same no loss of power, yet mine does just the opposite, the chatter is louder when its idling and real loud when put in gear or reverse, but when I step on the gas it almost goes completely away. Could your head be warped a little?