engine "noise" at 2000 rpm only?

[Vitalie]

Ok. I thought to keep you guys busy and post an other mystery that my car possesses. This time is a strange sound or noise that comes from the engine. It happens only at 2000 rpm sharp. Past that is fine and before that too. Moving or stoped.

some kind of vibration that makes this noise, not sure.

Here is the video. You should probably crank up the speakers to hear it better.

http://youtu.be/KOPK0SgbHPA

I had this crazy thought that it may be a designed feature , a feedback from the engine to let you know it's time to shift. I know some cars have a light in the dash for the same propose.

Dose anybody else have the same "feature"?

[fixkick]

no such feature, the ECU just injects and fires spark, and fiddle idle, and some odd VSV valves, for EGR, EVAP, etc.

use a stethoscope to find it $5 tool.

i hear it, that is very very odd sound,
it sound to me as sympatic vib. loose tins, on exh man. or other parts, exhaust?
id use 2 persons, one doing above, and other putting force (lever) to many things, connected to the engine.
and the stethoscope. listen for source, look in many places.

[gorkyb]

It's just funny how these old cars make the strangest noises. I can hear it too, if someone can try holding it at 2000 rpm and you listen with stethoscope like fixkick says, maybe you'll find it. Just watch those fan blades, they almost caught me the other day. I find it so weird that when you let the gas pedal go and the RPM's just pass by 2000 rmp's you can hear the noise too.

[Vitalie]

Thanks guys.
I ordered the stethoscope form amazon. somebody was selling for $1.95 + $5.49 shipping. Also the harbor freight has it on sale too for 2.99.

I was messing with the engine trying to locate the sound and I decided to take that exhaust manifold metal cover off and see if it makes the same noise. well look what I found

Surprize!
   

This is cylinder #4. Cracked manifold. Not sure if this is the problem for this noise or even for my unresolved slight shiver on idle?
But definitely looks not too promising.


Frankly I don't even feel like fixing it. This is getting pricy.

What do you think about these apples?

Thanks

[gorkyb]

Ouch! Welcome to the cracked manifold club, I asked my great welder friend to weld that crack for me, it lasted about 6 months, then he rewelded it 3 months ago and it's been holding good so far. Unfortunately there is no cheap fix for this other than trying to weld it but as you can see by my experience that doesn't always work. I'm sure more specialized welders can do a better job, cast iron sucks, it needs to be superheated before it can be welded. The new manifold option will cost you around $350 which is an aftermarket manifold, Calmini is the best according many. See fixkick hard to find parts page for guidance. There are rumors of OEM manifold still being sold in some suzuki dealerships but even if true, they are almost as pricey as the aftermarkets and will likely break again. The aftermarket makes them from stainless steel rather than cast iron.

Once that crack opens enough to leak air it will drive your upstream O2 sensor crazy and you'll start having all sort of issues. I'm really sorry for the bad news. It doesn't matter where in the world you go, these manifolds are expensive. I went to Ecuador where they still made these cars brand new until 2013 and tried getting one of these manifolds brand new thinking it would be cheaper, I was wrong! They priced me over $400 in more than 3 places.

[fixkick]

crack fix:
some might just do that (wait) , drive it, until the MPG goes nuts.
yes, the welding of cast iron preheated first is hard to do.

that rattle sounds to be , like:
1: CAT shield. loose or cracked, (pry it)
2: or loose header flange.(donut long header) or flat gasket and bolts short version.
3: main intake manifold bottom mount to top rear exhaust manifold mount loose, use levers to find it, a 2x4 board levered with say 20 lbs force, on many places, exhaust pipe to rear to.
and do be sure to stay away from fan and belts.

i don't think its actual engine, it self. based off video sound track.
good luck @

[Vitalie]

I got the mechanic doctorscope and listened different parts on the engine. It is actually pretty cool.

The noise is coming from the metal pipe that connects the header and the TWC . I think they call it collector. And it seems that the noise is stronger at the header fitting. I wanted to take it out and inspect it as I don't see anything wrong from the outside but those nasty bolts on springs won't budge, not even after soking them in w40. I did not want to snap them or hurt myself as I am limited in tools and was using just the regular 14mm wrench.

What suggestions are there?

Thanks

[fixkick]

take of shield on top of header tubs. is #4 cracked like most are, and if very bad, it can make noise.
the 16v on yours has the donut gasket.
and will sound alike blown rod bearing when bad (banging away) or can make any sound at all like a kids Kazoo toy.
yes, those 2 bolts on mine took my 3/4" drive to come off, after long soaks in pen oil.
they can be very hard to get out. one is easy, no angle but the other took a odd angle and was much harder.

you can get a shop to take them loose but if they break them then its stranded.
at home you can deal with this better.

on mine i bought 2 new bolts first. then used pen oil , then heat. and power full impact gun, on 1 side.

[gorkyb]

I had to cut mine off then drill and tap the two holes at the bottom on the exhaust manifold, bought the springs and washers from amazon, put back together and used spring lock washers and nuts on the other side of the bolt in case my new treads wanted to give up.