Technical Ticking noise when hot

[Kosen500]

G'day guys,

New member here so obligatory intro. I recently purchased a 1970 500F (Rocky) with a later 650cc engine installed. I have followed the forum for a while in anonymity and have already found some great advice from you guys (Rocky now starts happily when warm due to correct valve clearances!). I haven't been able to find a solution to my current issue.

I am currently bombing Rocky around the French countryside and he runs like a dream apart from one thing, after a while (30-40mins), he develops a ticking noise which matches engine revs when I lift-off the throttle to change gear, so when engine braking. As mentioned above I have done the valve clearances and he runs well when cold. One of the clips holding the distributor cap was a bit loose so I fixed that last night but don't hold high hopes of that fixing the problem. Given that the problem is only appears when nice and warm (thermostat working correctly) and goes away after a 15 minute rest, I suspect that it may be an oil pressure/viscosity or bearing issue. I haven't seen the oil light come on but I don't know if it works (how do you test that?). I changed the oil for some standard stuff but was thinking about putting some 10-60W in there until I get home and am able to have a better look. I have some basic mechanical knowledge.

The engine was recently rebuilt so I'm hoping this isn't a major bottom end issue. Just wondering if this sounds familiar to anybody?

Thanks for having me!

 

[Kosen500]

Just checked, my olio sender and circuit work as normal so à priori, no oil pressure issue. Here's a photo of the beast.

 

[the hobbler]

Neatly made, but very unusual, heat shield---have you tried running without that in case it is touching something when the engine is hot? Also, please remove that fuel filter--(a) not required (you have 3 in the system from factory ---pick-up in the tank, top of fuel pump and top of carb) and (b) it is plastic; if it should break it will spray fuel over the alternator--not a good thing.

 

[Kosen500]

Hi Hobbler, thanks for the advice re the fuel filter. I'll take care of that. I left my car parked at my wife's uncle's place saying I would buy the missing heat shield and fit it. I came back two days later and he'd made and installed that. It is a good fit/firmly attached and engine bay is noticeably cooler with it but unfortunately the mystery noise was there before this was installed.

 

[lazylobster]

Exhaust studs / bolts are they tight? Can you take a video when the car is hot and post it?
R

 

[Kosen500]

Thanks for the lead. I just checked and all is well in exhaust studs/bolts land. I just took him for a 40km drive to try to explain it a little better. Noise appears after about 20km of reasonably spirited driving. After a warm up like this, a typical scenario is driving out of a Village accelerating up from 50km/h in third up a small hill. Slowly revving it out up the hill, approaching a rev range that will allow me to grab 4th, the ticking begins quietly and becomes gradually louder. Lift off throttle to grab 4th and tapping becomes noticeably louder and "winds out" as revs drop back down during change. Can't get a video unfortunately as it doesn't seem to make the sound at rest. In my limited experience it sounds "tappety", like a car that's low on oil.

 

[Bleeding Knuckles]

Thanks for the lead. I just checked and all is well in exhaust studs/bolts land. I just took him for a 40km drive to try to explain it a little better. Noise appears after about 20km of reasonably spirited driving. After a warm up like this, a typical scenario is driving out of a Village accelerating up from 50km/h in third up a small hill. Slowly revving it out up the hill, approaching a rev range that will allow me to grab 4th, the ticking begins quietly and becomes gradually louder. Lift off throttle to grab 4th and tapping becomes noticeably louder and "winds out" as revs drop back down during change. Can't get a video unfortunately as it doesn't seem to make the sound at rest. In my limited experience it sounds "tappety", like a car that's low on oil.

Hi K, Does this noise only manifest itself when you drive the car and not when you simply rev it in neutral gear ????? If only when driving I would check to see of the driveshaft rubbers are ok and not fouling the rear suspension arms at speed !!!
Otherwise suspect a possible out-of-balance fan, if you can remove the lower end of the air intake hose and use a mirror to look for any rubbing debris inside the housing!!!!
Ian.

 

[Kosen500]

Thanks, Ian. Definitely only when driving and definitely only when well and truly warmed up. Something is definitely touching something and one of the somethings seems to be directly proportional to engine revs. I'll have a look at the fan.

 

[Kosen500]

For further info, if pertinent, when I did the valve clearances the other day, there was no play (cold) in any rocker except exhaust on cylinder 2. Set intake to 0.2 mm and exhaust to 0.25mm as per a previous thread. Noise was present then as it is now (perhaps a bit quieter now?) but at least the car starts when hot. Not sure if relevant but you guys seem to know your stuff!!

 

[Kosen500]

G'day guys,

So this noise has existed since I bought Rocky about this same time last year. The original post was about 500 km into a 2000 km road trip and I couldn't work out what the issue was. The Italian Stallion didn't get much attention over winter, with just a couple of short weekend drives around Paris to keep him turning over. My wife has decided that 2000 km in a noisy tin can was so much fun that we should do it again this summer - she's a good'n. I was tinkering in prep for this trip the other day and I noticed that one of the contacts in the distributor has a groove in it from where the rotor has worn it down. The tapping sound and the fact that the sound matches engine revs suggests that this is the culprit (I'm sure you guys probably would have noticed rubbing of the contact but my inexperienced eye needed to see a bloody groove!).

For info, the dizzy has a Hall Effect ignition fitted. I replaced the "more accessible" dizzy clip before leaving on the trip but the other one still has plenty of spring in it.

So now I think I have found the source of the noise, does anybody have any ideas as to what the issue is? I thought maybe the dizzy shaft is bent but as described above, the noise only happens when the engine is hot, under load and then when I lift-off the throttle. I would have thought if the shaft was bent then the problem would be constant. As madame has insisted on another road trip this year, I was considering "upgrading" to a 123-ignition system but I'd like to understand this problem before I invest in more kit.

Any ideas are greatly appreciated.

Andy.

 

[fiat500]

As madame has insisted on another road trip this year, I was considering "upgrading" to a 123-ignition system but I'd like to understand this problem before I invest in more kit.

Any ideas are greatly appreciated.

Hi Andy, I'm not sure that the 123 will be a good long-term solution to this. I had the same distributor cap/rotor arm issues using one of those. The problem comes partly from badly dimensioned, pattern parts; 123 uses Beru. There is also potential for trouble if you mix (as often you must) older original with newer parts.

I think that it is the weakening with age of the spring-steel or brass leaf housed within the socket of the rotor arm which loosens the friction-fit of the arm on the shaft. This sets up a wiggle which will be accentated by the centrifugal force cause when it spins.

I searched for a genuine new set of Marelli components and then fitted them on a genuine Marelli distributor. My 123 distributor had either been improperly assembled at the factory or a shim washer had worn. So in addition to the same problem you describe, I had a ticking which came from a spinning, aluminium plate being caught by the heads of three tiny screws. The manufacturers were not even interested enough to reply to an email with images; I wasn't asking for replacement or repair.

https://www.fiatforum.com/500-classic/484980-damaged-distributor-cap.html

https://www.fiatforum.com/500-classic/485254-worn-123-distributor.html?p=4577770

 

[Kosen500]

Thanks for the info, Peter. Very interesting to see your previous experience with the 123 system... Doesn't really make me want to spend 250 big ones on one. I'll have a tinker under the dizzy cap in the next few days and see what is moving incorrectly and why.

 

[JumpJet]

Having recently smoked my 123 system, I second Peter's reluctance to go that route. Everything is running great with my Pertronix (hall effect) setup, so why mess with it. If it falters, I've got a points setup and Swiftune condenser ready to go as a backup.

I would only upgrade to an electronic setup if you're willing to go 'all-in' on a distributor-less system with a crank position sensor and coil pack(s). Maybe for a super high performance motor or you're feeling adventurous and flush with $. It's not a necessity so much as the ability to finitely tune using modern methods.

 

[Franko500]

Sounds to me like its a "tappet" noise!
I would check those valve clearances again making sure you follow the correct process and have the right clearance.
There is a chance that you could have worn followers/pushrods/rockers as a result of incorrect clearances?

 

[Kosen500]

Hi Sean,

Yeah absolutely agree, my first instinct was that it sounded "tappety" but my lack of experience means that I'm not that sure. I'm pretty confident that the valve clearances were set correctly, as it was the first time I undertook such a procedure, I enlisted the help of my wife's uncle who has a lot of experience on old cars and bikes. He helped me, by 'help', I mean he watched me until he became so fidgety and keen that he kind of took over . The clearances were all over the shop and Rocky started and ran like a dream (bar that noise) after they were reset so it was definitely a step in the right direction. If valve train (I think that's how you guys that know what you're talking about call it!) related, any idea what the link with temperature would be? How do I go about checking the wear on followers/pushrods/rockers? As I hinted, I'm really learning as I go. I'm going to check valve clearances again (in a couple of months when I get back from work!), so will have it open. Just wondering if there are any red flags for wear that I could pick out while I'm at it.

Cheers for your help,

Andy.

 

[Fayray]

Maybe also check the rocker cover hasn't been over-tightened. The original cover is made of thin metal and if you keep tightening the two nuts holding it in place it will sink down to the point where it will foul the tappets. If this is the case you should see witness marks on the inside of the cover.
This happened to me but in my case the engine wouldn't run at all because I had gone way to far with the tightening. Took me an age to figure out the problem.

 

[the hobbler]

This may sound stupid, but it has happened to me. I had a ticking noise, road speed related, when the engine was hot and I was slowing down. The noise seemed to be coming from the rear of the car. I checked all the normal things--brake shoes to ensure that they weren't snagging, drive shaft couplings to make sure nothing was caught between the coupling and the wishbone and that there was no play in the coupling. What I DID find was that the gearbox oil level was low--had to put just over 1/3rd litre in it. Noise has gone!

 

[fiat500]

If we're considering all possible causes of a ticking noise which increases with speed, check that no small stones are trapped in the rear suspension arm and are catching on the aluminium drives haft connector.