General Rattling noise from carburetor?

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General Rattling noise from carburetor?

Bolinhas899sx

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Hi good people.

Don't know if anyone can tell me why is the carburetor on my fiat cinquecento 899 98 doing this noise? (i made a video on YouTube with the noise)

https://youtu.be/YxXfCwBhouE

If anyone could give a clue what's wrong?

I've posted also some images of the carburetor inside..

Thank you very much everyone.
 

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Not a carburettor, it is fuel injection.

But I don't think the noise is from there.
It could be a stuck tappet on a rocker arm.
Does the frequency change with RPM?
Is it different when started from cold?
Is it better (or worse) after driving?
 
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Bolinhas899sx

Bolinhas899sx

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Not a carburettor, it is fuel injection.

But I don't think the noise is from there.
It could be a stuck tappet on a rocker arm.
Does the frequency change with RPM?
Is it different when started from cold?
Is it better (or worse) after driving?

Thank you very much for your reply.

Sorry for that.. Still bit of a nub here?

I thought it was from there cause it really seamed it came from that part as on the video.. But i don't know..

I've uploaded an audio with RPM acelaration ( https://www.4shared.com/s/fB2G9NXaZea )

To be honest while driving you can't hear it, believe the Bonnet and the engime running and me inside the car isuflates it.

This is the noise ( video and audio) with the car starting from cold (not started for a Couple of days)

But I will have to drive it and then check it again to see if it goes.. If it goes away after driving what could it be?
 
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Xylaquin

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Sounds kinda normal, the 899 is a tappy engine, especially when cold and the oil hasn't circulated back to the rocker train yet. Sometimes when I start mine it's really noisy for the first few seconds, then the oil hits and it muffles it down a bit. After a minute or two the revs (or RPM) should settle and the speed of the noise will decrease too.

The cause of the noise is wear on the hydraulic valve tappets. After all these years of constantly pushing the valves they just get louder. To fully eradicate the noise you'd have to replace them. I usually just chuck in some hydraulic valve lifter cleaner potion every once in a while... it helps a little for a while.

Before you turn the engine on though, check your oil is topped up. Then just drive on.
 
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Bolinhas899sx

Bolinhas899sx

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Sounds kinda normal, the 899 is a tappy engine, especially when cold and the oil hasn't circulated back to the rocker train yet. Sometimes when I start mine it's really noisy for the first few seconds, then the oil hits and it muffles it down a bit. After a minute or two the revs (or RPM) should settle and the speed of the noise will decrease too.

The cause of the noise is wear on the hydraulic valve tappets. After all these years of constantly pushing the valves they just get louder. To fully eradicate the noise you'd have to replace them. I usually just chuck in some hydraulic valve lifter cleaner potion every once in a while... it helps a little for a while.

Before you turn the engine on though, check your oil is topped up. Then just drive on.

Thank you very much for your reply, it really enlightenment me and helped alot!!

Yes did a oil and oil filter change one week ago, but the noise was there before and after the oil change..


Guess the replacement of the hydraulic valve tappets is another high skill league of mechanics! ? Or is it something can be done at home?

And where do i put the hydraulic valve lifter cleaner potion? Do I need to remove the top of the engine?
 
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Yup, David C is absolutely right, this is not a carburettor its a fuel injection unit - to be specific SPI, which means Single Point Injection. It was the system which replaced carburettors and is to some extent like a carb in that it delivers the fuel into the main air intake manifold but does it in a much more controlled way so cuts pollution and gives you better MPG. Later they went to MPI Multi Point Injection where there is an injector poised in the manifold pointing at each inlet valve, which was more efficient still and they've even moved on from that now with Direct Injection, but that's of no interest here.

If you look at your original pictures you will see a yellowish brown "thing" with 2 wires going into it situated above the intake venturi. This is basically a solenoid which is metering how much fuel is being injected into the engine. The noise you can hear is the pulsing of the moving parts inside it. In very simple language, how it works is that the ECU sends a pulse of electricity down those wires into the electromagnet inside the yellowish brown unit. This magnetizes it and it pulls the core "slug" up so opening the petrol delivery jet. If you look down the venturi whilst the engine is running you can see the petrol spraying onto the throttle butterfly. Be very careful though, it's easy to cause a fire! This solenoid unit jiggers up and down at high speed and the longer it stays up compared with when it's down it will admit more fuel. It's complicated. What you are hearing is the solenoid valve jumping up and down metering the fuel being delivered to the engine. If you look carefully you can see it's not a smooth stream but a rapidly pulsed delivery. It's normal.

I'm not all that familiar with the cinquecento but I do work on Pandas a lot and that set up looks exactly like the one on my old 1992 Panda. Cam followers would not make such a rapid ticking at idle and anyway that noise doesn't sound right to be tappets (valve lifters) to my ear. The Panda doesn't have hydraulic tappets by the way and I'd be surprised if the cinquecento did? Anyone who knows cinqs on here just now? A valve lifter treatment in an engine that doesn't have hydraulic tappets would just be a waste of money? Our tappets (valve lifters) are solid with clearances being adjusted with shims. It's a bit of a fiddly job and probably not for the complete novice but is very seldom necessary so don't worry about them too much. Your video didn't sound like cam followers/tappets/valve lifters (all names for the same thing). By the way it's not unusual to hear your tappets "rattle" from a cold start first thing in the morning or after the car has stood without being started for a couple of days or more. It's a tapping noise which only lasts seconds, until the oil reaches them, and is at a lower frequency to the metering unit you can hear here. After standing overnight, or perhaps longer on some engines, the oil drains down into the sump and it takes just a few seconds for the oil pump to send oil back up to the top of the engine to lube the valve components. One very good reason never to rev an engine hard immediately after it fires!
 
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I'm not all that familiar with the cinquecento but I do work on Pandas a lot and that set up looks exactly like the one on my old 1992 Panda. Cam followers would not make such a rapid ticking at idle and anyway that noise doesn't sound right to be tappets (valve lifters) to my ear. The Panda doesn't have hydraulic tappets by the way and I'd be surprised if the cinquecento did?
The 899 Cinq (& Sei) do have hydraulic tappets.
Early 899 Cinqs had hydraulic tappets on the valve end of the rocker and a mechanical screw adjuster on the pushrod end of the rocker.

Later 899 Cinqs & Sei had larger hydraulic tappets on the valve end of the arm but no mechanical adjustment.

I think a 1998 car should have the later type.


I converted my 1994 Cinq 899 to use the purely mechanical rockers from a 903 Panda. It was considerably quieter with the old Panda rockers than the Cinq hydraulic rockers..!

I expected the Panda setup to need frequent adjustment, but after fitting and initial adjustment I didn't touch them again. That was done back in 2008, 13-years ago and they are still fine. :cool:



As for his noise, it's really difficult to tell via the Internet, but that sounds very loud to just be the injector, but it could be a very sensitive microphone!!
 
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Bolinhas899sx

Bolinhas899sx

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Yup, David C is absolutely right, this is not a carburettor its a fuel injection unit - to be specific SPI, which means Single Point Injection. It was the system which replaced carburettors and is to some extent like a carb in that it delivers the fuel into the main air intake manifold but does it in a much more controlled way so cuts pollution and gives you better MPG. Later they went to MPI Multi Point Injection where there is an injector poised in the manifold pointing at each inlet valve, which was more efficient still and they've even moved on from that now with Direct Injection, but that's of no interest here.

If you look at your original pictures you will see a yellowish brown "thing" with 2 wires going into it situated above the intake venturi. This is basically a solenoid which is metering how much fuel is being injected into the engine. The noise you can hear is the pulsing of the moving parts inside it. In very simple language, how it works is that the ECU sends a pulse of electricity down those wires into the electromagnet inside the yellowish brown unit. This magnetizes it and it pulls the core "slug" up so opening the petrol delivery jet. If you look down the venturi whilst the engine is running you can see the petrol spraying onto the throttle butterfly. Be very careful though, it's easy to cause a fire! This solenoid unit jiggers up and down at high speed and the longer it stays up compared with when it's down it will admit more fuel. It's complicated. What you are hearing is the solenoid valve jumping up and down metering the fuel being delivered to the engine. If you look carefully you can see it's not a smooth stream but a rapidly pulsed delivery. It's normal.

I'm not all that familiar with the cinquecento but I do work on Pandas a lot and that set up looks exactly like the one on my old 1992 Panda. Cam followers would not make such a rapid ticking at idle and anyway that noise doesn't sound right to be tappets (valve lifters) to my ear. The Panda doesn't have hydraulic tappets by the way and I'd be surprised if the cinquecento did? Anyone who knows cinqs on here just now? A valve lifter treatment in an engine that doesn't have hydraulic tappets would just be a waste of money? Our tappets (valve lifters) are solid with clearances being adjusted with shims. It's a bit of a fiddly job and probably not for the complete novice but is very seldom necessary so don't worry about them too much. Your video didn't sound like cam followers/tappets/valve lifters (all names for the same thing). By the way it's not unusual to hear your tappets "rattle" from a cold start first thing in the morning or after the car has stood without being started for a couple of days or more. It's a tapping noise which only lasts seconds, until the oil reaches them, and is at a lower frequency to the metering unit you can hear here. After standing overnight, or perhaps longer on some engines, the oil drains down into the sump and it takes just a few seconds for the oil pump to send oil back up to the top of the engine to lube the valve components. One very good reason never to rev an engine hard immediately after it fires!

Man, first of all a huge thank you for the lesson! Amazing.. I'm really loving this community in the forum!
You tough me aloot! I really appreciate it! I really want to learn as much as I can on this car, I want to keep it and preserve it! ?

Regarding to your feedback, i will trust your opinion, cause from what I could ear on YouTube about bad valve lifters, it wasn't quite the noise.. And went as well to ear SPI on fiats and it looked like the normal noise..

I'm not saying it might not have as well bad lifters (the car has 20y on his back and arround 150.000 km / 94.000 miles), but probably can be on my list of to-dos for this year, maybe on summer to look into this.

Just one thing as I can see you're an expert on this SPI, on the endless hours of thecnical research on this car.. I saw this guy on YouTube doing this to his seic SPI unit.. First question being: what is he doing and would you recommend it?

https://youtu.be/AR2oRRPOkmc

Once again a huge thank you for the explanation, expertise and patient!! Really! ?
 
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Bolinhas899sx

Bolinhas899sx

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The 899 Cinq (& Sei) do have hydraulic tappets.
Early 899 Cinqs had hydraulic tappets on the valve end of the rocker and a mechanical screw adjuster on the pushrod end of the rocker.

Later 899 Cinqs & Sei had larger hydraulic tappets on the valve end of the arm but no mechanical adjustment.

I think a 1998 car should have the later type.


I converted my 1994 Cinq 899 to use the purely mechanical rockers from a 903 Panda. It was considerably quieter with the old Panda rockers than the Cinq hydraulic rockers..!

I expected the Panda setup to need frequent adjustment, but after fitting and initial adjustment I didn't touch them again. That was done back in 2008, 13-years ago and they are still fine. :cool:



As for his noise, it's really difficult to tell via the Internet, but that sounds very loud to just be the injector, but it could be a very sensitive microphone!!

David you're amazing as well! I really appreciate and thank all your help! ?

And yes my phone mic can be quite sensitive and there is a chance its intensifying the noise, i use my phone mic to record my bass sometimes ?

Tomorrow i will record a video and sound with the bonnet closed and in a bit of distance, i might have leaned the phone to close, cause i really wanted you guys to ear it.. And I might as well use a stethoscope to try and see where the sound is really coming from.. ?
 
Last edited:

Xylaquin

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Messages
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Location
Orkney, Scotland
In any case, whether it be the tappets or the solenoid inside the throttle body, it's pretty normal to hear. I'd only be concerned if it doesn't settle down when the engine has been running for a while, has warmed up and you can hear it clearly inside the car with the bonnet and doors shut.
 
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The 899 Cinq (& Sei) do have hydraulic tappets.
Early 899 Cinqs had hydraulic tappets on the valve end of the rocker and a mechanical screw adjuster on the pushrod end of the rocker.

Later 899 Cinqs & Sei had larger hydraulic tappets on the valve end of the arm but no mechanical adjustment.

I think a 1998 car should have the later type.


I converted my 1994 Cinq 899 to use the purely mechanical rockers from a 903 Panda. It was considerably quieter with the old Panda rockers than the Cinq hydraulic rockers..!

I expected the Panda setup to need frequent adjustment, but after fitting and initial adjustment I didn't touch them again. That was done back in 2008, 13-years ago and they are still fine. :cool:



As for his noise, it's really difficult to tell via the Internet, but that sounds very loud to just be the injector, but it could be a very sensitive microphone!!

Thanks for all the info on these earlier engines. I'm fairly familiar with the F.I.R.E. engines - certainly no "expert" though (is anyone really an expert?) - So can I ask if these Cinq engines we are discussing are FIRE engines or the earlier OHV engine?

Regarding the solid tappets/cam followers on the Panda/Punto 8 valve engines. I've found you can pretty much forget them. Yes they do wear slightly at high mileages but even then they seem very happy to just soldier on. Of course if you get a blocked oil delivery jet so the follower or it's associated cam lobe gets damaged or are doing a head overhaul and grinding in the valves then you will be spending a few enjoyable/frustrating hours fiddling about with shims!

I agree it's very difficult to diagnose things from a distance let alone trying to watch and listen to noises/symptoms posted in a video clip. I was just making a best guess. However the noise does sound "wrong" to be valve/cam related don't you think? If it were me I'd be getting a length of tubing, sticking one end in my ear and moving the open end around the top end of the engine. Usually you can quickly pin point where a noise is originating this way. Now a days I guess you can probably do this with the microphone on a mobile phone? bit too high tech for me though, I'd rather stick a bit of grubby tube in my ear!

Thanks again for the info David - Once again I find my knowledge base expanded by the great wealth of knowledge available here on "our" forum.
 
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Just one thing as I can see you're an expert on this SPI, on the endless hours of thecnical research on this car.. I saw this guy on YouTube doing this to his seic SPI unit.. First question being: what is he doing and would you recommend it?

https://youtu.be/AR2oRRPOkmc

Ok, looking at the video, The fuel is coming in from the tank via the bottom black fuel hose and travels through the passages in the injector unit to the metering unit directly above the air intake/venturi. This fuel is under high pressure so, when the Metering Unit triggers, fuel is squirted violently down the air intake to the engine. Any fuel not needed at that time continues on past the Metering Unit into the pressure regulator (which is what that thing is that he's adjusting with the Allen Key.) Inside this is a diaphragm with a spring behind it. The diaphragm is trying to hold the fuel flow back to give a constant pressure of fuel at the spray nozzle in the metering unit. But when the pressure gets great enough the diaphragm will lift against the spring pressure and allow excess fuel to return to the fuel tank. So what it's doing is maintaining a certain constant pressure of fuel at the metering unit and the whole system will be calibrated with this in mind.

By screwing the adjusting screw in - as the video shows - he's increasing the fuel pressure and the ECU won't "know" this so one of the parameters the ECU relies on to correctly calibrate fuel delivery will no longer be within specification. I suppose increased pressure may make for better atomisation of the sprayed fuel? but will probably have other implications too? Personally I'd not be fiddling with this unless I knew what the pressure should be and could connect a pressure gauge to the supply side so I could monitor it and achieve the pressure specified.

Anyone else got any thoughts on this - Is there some "tweek" going on here I don't know about? - Wish I understood what the video poster is saying!
 
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Thanks for all the info on these earlier engines. I'm fairly familiar with the F.I.R.E. engines - certainly no "expert" though (is anyone really an expert?) - So can I ask if these Cinq engines we are discussing are FIRE engines or the earlier OHV engine?

The OHV Pushrod engine.

In the Panda & Uno they had pure mechanical rockers with screw adjusters on the pushrod side of the rocker.
Early Cinq added hydraulic on the valve side of the rocker.
Later Cinq removed the mechanical screw adjuster and used bigger hydraulic bits.

The Cinq with the hydraulic+screw rockers were very noisy. The Hydraulic bits were rubbish!
The later Cinq & Sei with the bigger hydraulic bits were much better.
 
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