Clacking (lifter?) sounds on acceleration

[Delfin]

Hi,
I tried installing a straight pipe and an almost free flow muffler on my 1994 325IS
and i think i noticed the clacking (like lifters on old cars) sound then, but cant b sure it caused it. After returning to my original BMW spec muflr, the clacking sound didnt go away. I usually get it on 2nd or 3rd gears during mid to hard acceleration. I tried changing to thicker oil, from syntetic to organic and vice versa didnt help ghead . My mechanic didnt find anything wrong, it does not make any abnormal noise during idle reving. If any has any clues or suggestions please come forward.
Thank you all in advance!

[thekid]

could you describe the clacking as popcorn in an aluminium can? If so your engine might be pinging, what kinda gas do you put in?

Also is your mechanic experianced with BMWs?

[Bengali86]

My 93 325is is having the same issue... If anyone has anyinfo on this problem, please let me know- Ive had Knock sensors replaced, and Use Cheveron Techron premium gas ghead

Thanks
Ben

[Delfin]

I would describe it as an aluminuim can. The machanic has 20 years working 4 BMW dealership. But he says as long as it doesnt show any deviations from specs on the computer its all good. Also the sound doesnt appear untill there is a strain on the engine. I also noticed it when i was rolling off the hill on 2nd gear it wasnt a clean sound but clacking (aluminium can). I put 91 gaz and sometimes 94 (top in Canada). Also car lags on acceleration from stop, i have to rev the engine 2 at least 2500 and go otherwise if i start with no reving from 1st gear i get a jolt of power, then sudden lag and then slow acceleration.

ps. Thank you for your prompt reply.

[thekid]

I honestly have no idea then. At first I figured that you were pinging from too low quality gas, but with 91 or 94 there is no way you should be pinging. I don't know enough abou the engine of the car to tell you what it could be in there, especially if your mechanic with 20 years experiance with a BMW dealership tells you everything is ok. That being said, has he actually taken at least some of the engine apart to check the clearances? Or is he just looking for codes? I don't think he needs to take it completely apart but at least until he can actually see and measure the cylinder clearance and most of the moving parts that move with the cylinders. That would be kinda expensive to do, several $100 US, maybe less depending on how well you know the guy. Good luck, sorry I can't tell you any thing more/better.

[Bengali86]

I was pretty much told the same thing.. only code that I had was the knocksensors, had both replaced, My Mechanic said, well you cannot hear it in the cab very well, it shouldnt be a problem, just annoying sound



I doubt BMWs should sound like this, it seems to happen when the car temp. gauge is fully upright, my needle goes a little past the 12 oclock positon, I think it may have somthing to do with the heat, also get worse on hot days (like today B) )

it is quite embarassing to always hear

-Ben

[Delfin]

I think it happens 2 me also more on hot days...and my mechanic was just reading the codes since he couldnt hear the sound on idle reving...maybe ill take him 4 a ride...but its freaking ennoying to see old rust bucket civics accelerating with a cleab roar and my bimma like an aluminum can...

[Deloriant]

omfg straight pipes are so insanely loud on e36's...

[Delfin]

I narrowed the clacking noise to only happen between 2 and 3k rpm.
It doesnt appear bellow or over that.
Any1 has any ideas?

[ntenzin04]

i've got the same problems, only on 3 & 4 gears, really sof clanking sounds RPM between 2-4, 1st and 5 gear's fine, haven't checked it up yet, there was a similar post, check it out.

[nycbmw325is]

Guys, I hate to tell ya, your engine doesn't know or care what gear you are in. If you are hearing this noise under load only, I would say it is likely pre igntion(also called detonation or ping) It can happen happen when you get carbon deposits on your valves and in your combustion chamber, which effectively raises your compression ratio. Try some techron gas treatment. Of course it could be rod knock, but you can usually hear that at idle. I am in agreement with the post above that says if your mechanic is only going by codes.. then you need to get a new mechanic. A top end tear down may be required if you still dont find the source, but now you are looking at some pretty serious bucks.

[ntenzin04]

i'll check it out with the gas treatment and hola the results

[007ben]

could just be lifter/cam noise. which is normal.

[enemigo]

Originally posted by 007ben@Aug 16 2004, 02:25 PM
could just be lifter/cam noise. which is normal.

i think lifter noise should be also at idle not only when car accelerates.

[nycbmw325is]

hydrolic (speeling) lifter almost never tick above idle. The get pressurized and fully extend. could be a worn cam chain that has a resonant frequency at the specified RPM.. How many miles you have on that motor man?


let me know