odd motor knocking

[1978fiatspider2000]

hi im a fiat noob just wont to get that out, in fact this is the first time i ever really worked on cars before in my life. im 20 and just got my 1978 fiat 124 for my birth day last June. my dad got the car about 14 years ago and it didn't run for over 12 years. well with a bit of coxing my fiat started up, but their is a strange knocking coming from the left side of the motor (if looking from front bumper) i was told to take a long screwdriver and use it as a stethoscope and i think i pinpointed the location of the sound. here is were i become very noobie, as i said before im a complete noob. its a black tank looking thing with a small L pipe on the top of it. please help because this amazing car needs that second chance that it deserves.

ps. give me all the possible coses for this noise just in case im wrong about were its at.

[So Cal Mark]

if the oil pressure is within range it sounds like the auxillary shaft is not timed right

[RoyBatty]

I thought the same thing Mark, but he said on the left side as viewed from the front bumper, after doing the stethoscope thing.
It sounds to me like he has described the air injection pump on a car so equipped.
You and I both know it's not a tank but the author of this thread is not quite with us yet with regards to the finer points of things under the hood.

So 78FS2K,
Take a look at the object you described as a tank with an L pipe. Is it driven at the front by a belt that is only driving that part? And does the L shaped thing connect to four smaller pipes that plug into the head? If so, that is an air injection pump, sometimes called a "smog pump". Depending on where you are and the year of the car, you might have the option of just removing that part and plugging the ports in the head. If you are required to keep it, it may need bearings or need to be replaced. If you have it removed, be aware that one of the mount bolts
We need more details about your car and where you are located.

[So Cal Mark]

I missed the point about turning the car around. The left side is the left side, it doesn't change when you are facing east or looking in a mirror.

[RoyBatty]

Well,
There is left and right as viewed from the front bumper looking at the windshield.
Or there is left and right as viewed from the driver seat looking towards the engine.

As I was trained in aviation maintenance, you should always get the customer to reference things to you from the pilots seat.
That way, when dealing with a guy that comes in with a twin engine plane, complaining of the left mag on the right engine......well I think you might see what I'm saying.

[joelbert2k]

Should be simple to test. Just remove the belt and see if the noise goes away.

[1978fiatspider2000]

ok i will try this, and is the belt you are referring to the timing belt. Once again sorry bout the noobie talk but this car is my baby and i wont to be the one who works on here. this is really the first car i ever worked on before.

[azruss]

now you understand why everyone uses DS (drivers side) or PS (passenger side) for location. If the aux shaft is off, the knock could easily broadcast thru the entire block. if you look at the timing belt, it drives the crank pulley, aux pulley, intake cam pulley and exhaust cam pulley. the last 3 are the same size. rotate the motor so the location holes in the exhaust and intake pulley align with the pointer. the hole in the aux pulley should be between 1 o'clock and 2:30.
This should put the location of the knock on the drivers side of the motor under the intake manifold.

[1978fiatspider2000]

OK and how would i go about rotating the motor

[rlux4]

The easiest way is to remove the spark plugs (you won't be pushing against compression) and use a 1-1/2" socket on the crank pulley nut with a ratchet. If you don't have the socket you can do it by hand, push in on the alternator belt to apply pressure so it doesn't slip and then rotate the engine using the nut on the alternator pulley.
Ron

[joelbert2k]

The belt that I was referring to is the V belt that would be driving the smog pump, not the toothed cam drive/timing belt

[kmead]

I would suspect an exhaust leak which can at times sound like a knock.bAre all if the exhaust manifold nuts in place and tight?

You should really buy a manual and read it through so that you know the names of things, where they are located and what they look like. It will also give you a good guide for how things come apart and go together. Get at least one of the following: Haynes, Motorbooks, Clymer or the Fiat Factory manual. The Haynes manuals are always available, just don't trust the torque values as some are not correct. Trust me this will make your and our life easier so we can help you more effectively.