I've got a ticking/soft knocking noise on my 83 320i. It's only present when the engine is at operating temperature, between about 2500 rpm and about 4500 rpm and only under acceleration. It does not feel like a rod knock as I've felt this condition, but I'm having a tough time diagnosing the problem. I've checked my bosch super WR9DC plugs and they looked pretty good but a bit burnt on the electrode, possibly indicating a lean conditions under load. I have an a/f meter and my car always runs on the richer side of it. I was thinking maybe my car is pinging because of the coil I'm using which is a mallory high output style which I bought as a replacement to an original Bosch red top. I tried pulling plug wires to see if that would get rid of the noise, but it didn't really eliminate it at all. I also adjusted my timing a bit and that did change the noise a bit. My dad mentioned that it could be a leaky exhaust manifold gasket as he doesn't thinking it's a bottom end problem either. I was thinking about swapping out coils and maybe gapping my plugs a bit larger. I have regular autolite plugs in it right now gapped at the manufacturer's spec of 0.025 inch. Any quick checks I can do beyond what I have done so far? I would really like to figure this out so I can relax about it and fix it.

did you check the essentrics?
they have been known to have a "normal" tick to them....what am i saying they all make noise.
timing could be out, check your vac lines to the timing advance diaphram. also set timing after you take off the vac line:)

I had the common valve tick and I set them almost perfect now. There is no valve tick whatsoever or noise of eny kind outside of 2500 to 4500 rpm. It' just smooth engine sound. I'm gonna check for vac lines and timing, cuz I think it's preignition.

I bet its your exhaust leak. Crab some hose and stuff and feel around the ports, you will pick it up. Mine did it exactly like you described. It will get louder and louder, but really quite at idle. Gets louder under load, and less noticeable when you decelerate at high RPM or keep it steady.

Try to down shift it really hard so you go to high RPM and noise should deminish or go away completely. If not its timing advance problem or internals. Usually if the motor runs smoothly no timing isues should be there. Hard to say without hearing the motor.

A hose or electronic stetoscop is your friend

I am leaning toward the exhaust side as I reused the gaskets when I put on my rebuilt cylinder head. The bearings only have 30k km on them and the cylinders/pistons were in spec with new rings. I've always had oil in the motor and i made sure no coolant spilled into the cylinders when I did the head. I guess I should get some exhaust gaskets and put them on anyway, it'll help quiet down my motor a bit. It's super quiet otherwise, other than the weird ticking sound under load. Thanks so far, I don't really know how to eliminate the exhaust gasket as a cause other than to replace it. I would imagine my O2 sensor wouldn't be reading right if the manifold is leaking. I do have this juddering problem when I'm crusing then apply lower throttle. It kind of hesitates when cruising at preety much any speed. I have retarded timing and it gets rid of the juddering, but the ticking noise is still present under load.

He he those damn gaskets. Check your header/manifold for warping cause mine was almost imposible to seal. Coper gaskets will do nicelly. And dont for get to re-torque once more. Also you may use some high temp sealant of the same brand on there.

The o2 sensor should be off. I had that and the car was leaning our a bit to almost 0% CO.

Before you do anything check with a small hose. I could pin point mine to almost an inch. Mine leaked at the stud and actually smelled a bit, but than started to sound like a race car with all the leaks. You may also get head aches from CO poisoning in some severe cases.

How do I use this hose?

Any soft rubber hose. Maybe about 1/4-1/2 inch thick. 2 foot long. You should make sure it fits flush to the surface and the other end fits nicely in your ear. I used one from an overflow tank.

Practice on the valve cover. You should hear every single roker tapping. It sorta isolates the sound. It takes some time to pin point the possible leak/knock.

For ex. if you had a bearing knock you would have to tell me which cylinder it is, if you cant, go back until you find the exact spot.

Exhaust leak will sound like a tapping valve, but somewhat different.


You can also get creative and find the leak differently. Say, if you add some oil to the intake and rev it before the engine burns all the oil ,you may actually see the blue smoke from the header. ( In the sun light) But it is usually for bigger leaks thoug.

Try to re-torque the studs once more, they might have come loose with the gaskets burning. I had a leak on 350 with bad valve seals case and saw the blue smoke coming out from the leak as weel as the exhaust. Tightened them and its all good. Didnt even have any gaskets whatsoever.

I'll give that a try tomorrow with the hose. I may buy a stethoscope to use as I like to have tools like that. I know what a bearing knock is like, it can be felt through the car. This does sound like a ticking valve that is right out in the open. Whatever it may be, I would just like to find what it is. Thanks for the tips. I'll update when I figure it out.

When a leak begins it does sound like a rocker, Even experienced techs are fooled. Maybe you have a good ear.

Well I have to reduce the causes to the most likely ones. The gaskets were mediocre and the bottom end was rebuilt by me, so I know what went on down there. I've always had oil in the car and the head was rebuilt so I can rely on that as well. All I really care about overall is the durability of my engine. If it's something fixable, I will do it. Especially exhaust gaskets, they are cheap as it gets for this car.

I think I may have found the source, but until I fix it I won't know for sure. Well I checked my exhast bolts just for kicks and found all the nuts were loose, some studs were coming out with the nut attached and the stud underneath in the middle of the manifold didn't even have a nut on it and the stud was loose. I'll get the studs loctited in and the nuts tightened up good and see what happens.

Very well, just might be the cause of it all

I'll find out tomorrow. I tightened the bolts a bit and the sound did get less intense, more of a light rapping than a knock. If this is the cure, I'll be relieved, albeit a bit miffed at the the lack of preventative meaures I took to keep the exhaust tight. I figured tight bolts are good enough, not in this case.

Well I bolted up the exhaust manifold nice and tight but I still have the sound. I did some listening and the sound seems to be coming from the valvetrain. Now I set my valves a couple weeks ago and now the ticking sound from the valves is coming back. I figure that this must be the source of the noise. I can feel the vibration from the sound best on top of the engine. I might take it to a mechanic to see what it is, but I have a plan to do a performance cylinder head with all new valvetrain parts. I would just like to know what it is so I can either worry about it some more, or just leave it be if it is not serious.

Are the rokers new? If not this is it. Other than that of them locking nuts might be stripped? Did you tight them hard enough? Mine used to reset themselves? Also make sure the chain is not slacking. Sometimes a noise like this can come from the camshaft being worn in the head.

How is the manifold looking, no small cracks? If that was a rocker than you should hear it with the stethoscope.

I'm gonna talk with my mechanic cousins and use the stethoscope to see what it is. The head was supposed to be rebuilt, but I figure that a rebuilt head should have had the valve clearances set and stuff like that. I bought it from a guy in calgary and he sent me a machining bill. But I'm still unsure. I'm sure of my bottom end cuz I did it myself and I've never had a rebuilt block fail on me.

If its rebuilt than it should have all the right clearences for the cam, + new guides and clearences, + all new valve seats. If the guy took off all the rocker shafts and rockers, then they might be all. Its too bad, cause you have to take off the head to fix this stuff. Actually, if the rocker is bad you can feel it if you loose that little valve cam and just play with it a little. There should be virtually no play in it.

I did check all the rockers when I set my valves a couple weeks ago. It might be that the cam is loose or something along the lines. It does sound half speed as compared to the engine. For now I'm just gonna drive it sensibly until I can figure out exactly what it is and then decide if I'm gonna fix just that or just go for a full performance build. If it's something trivial, then I'll fix it, but I didn't really notice anything when I had the valve cover off.

If you have a spare valve cover you can drill a big hole in it and put it on the engine to avoid oil flying everywhere. Then run it. Just like adjusting valve lash on regular motors.

I was thinking this also. Can it be some sorta loose peice of carbon or a small chunk of a valve? Or maybe the c-clip from the piston pin? That probablly would make some loud sound thoug.