Worrying engine noise Mondial T

Hello

I am writing in this Q&A lounge in order to get some advice regarding a chattering noise on my Mondial T. There are some more details regarding this car in its topic here: http://www.ferrarichat.com/forum/mondial/531210-another-mondial-t-potential-buyer-thread-5.html

Long story short: I bought this car as a mechanical rebuild project whith lots of doubt regarding very bad idle/running/exhaust smoke and a small gearbox noise. I noticed a chattering noise on idle when I checked it and when I was running it then myself on idle but was not really worried since this noise can almost not be heard outside idle; was quite random/erratic and was very obvious at very low (600rpm or so) when the car was almost stalling (thought about some broken or loose stuff in the engine bay). After having improved greatly the engine running issues, I have been warned by an ex mechanic working on Ferraris that he is thinking it is a "beginning" (but already quite important) big end bearing issue and that the noise/rpm relationship is not mandatory (didn't know that).

I would then like to get your opinion on this noise if you think it is indeed a big en bearing or if you have any other ides about 3.4 specific stuff.

https://youtu.be/pIvqp-U2RMY
https://youtu.be/v4LWa5EPrqc

(have more records if needed!)

Thanks in advance

 

does not sound good at all....

I would check from underneath.

Remove accessory belts and see if it goes away.

something is loose.

regards, Jim

 

Jim's right. Maybe use a mechanic's stethoscope to isolate it. Doesn't sound like a bottom end issue. Something definitely loose.

 

Not a big end issue. Probably not even the motor. That does however not mean it will be an easy or cheap fix. It needs further diagnosis more than anything at this point.
Does the noise go away with the clutch depressed and a gear engaged? If not, it could still be an exhaust resonance of some kind. If yes the noise does stop, it is probably a problem in the intermediate gearing or gearbox. Like this issue: http://www.ferrarichat.com/forum/technical-q/214922-mondial-intermediate-gear-failure.html
Agree with Bruce, get a helper to methodically go over the engine and gearbox using a stethoscope to pinpoint the location of the noise. In the end, it will need to be taken apart to know for sure what is the problem.

 

Sounds like possibly the chain guides. What was the 'mechanical' repairs?

 

Hello

Thanks for your replies. Will try to check asap with a stethoscope around the oil sump to see if it comes from here.

I have just corrected a stupid engine tuning (CO resistance+idle by-pass+one spark plug SAE fitting) but nothing else for now. The car had his major 3 years ago (2000 miles) with also a new clutch, starter, starter ring and clutch release bearing.

 

Dont start that engine again. To much bad sound. It can be loose con rod bearing, mean bearing or broken con rod. Starting engine can brake something inrepairable or even a hole in the crank case.

Guido

 

Just another opinion- - - - - - -

Ferrari builds good motors. Really good motors! Having said that, what trauma could that motor have experienced to cause a significant failure?..If it's idling low, and you suspect the mixture is way off, this could damage the cats, and if they were badly damaged, they would rattle about in the exhaust. Also, you mentioned a major service was done, so idler pulleys and belts would be suspect. Clutch work - - - I don't see how, if something were loose on the rotating parts, centrifugal force would stabilize it when spinning, unless something was left in the bell housing?? A socket?? Or some tool left behind somewhere?? If you really fear it's motor major mechanical issues, do an oil change and inspect the oil for debris. Also, open the oil filter and look there for signs of damage. If something in the motor was letting go, I would suspect you'd see something. (But again, these motors are pretty strong) Hose attachments transferring vibration to other assemblies etc.??

Don't panic, be patient. Beautiful car. Best wishes for getting her fixed to enjoy in the new year!

 

I agree that it doesn't sound like a bottom end issue. An oil analysis can confirm if it's a connecting rod bearing or not.

 

Hello

Yes I am quite convinced that the engine of these years are very strong (not the gearbox however!).
What could explain some bottom end damage is that the engine ran for at least these 3 years/2000miles with this nasty mixture (it was REALLY rich) and that depending on the level of short/long journey there may be a quite high level of gasoline dilution in the oil. Further, the oil is three years old but due to the very low mileage even if it is not good I don't think this could do so bad things quickly, provided that I have had a look at the cams and they are not so bad, some small pitting marks but should have been more shot if the oil was so bad to kill the bearings? (pics here: http://www.ferrarichat.com/forum/145026630-post18.html)

This car is one early Euro Mondial T so there is no cats from the factory

I am indeed considering doing an oil analysis. Think I will firstly try to have a look around the aux belts to see if I can see something strange. Then will see if I start the engine a little bit to listen it or if I just simply open the conrods caps to check the bearings. From what I have understand and be told, this can be done without major troubles with the engine in, isn' it?

Had an another friend that had a big end bearing shot on a motorbike. He was only getting the noise on idle and not when revving. So he kept using it and revving it since it was not doing any noise until the noise was there also when revving and he then discovered a shot crankshaft/big end bearings..

Thanks

 

Not a broken rod, or rod bearing.

I spun a rod bearing once on a Chevy. The motor made a thump, thump, thump noise. This was the sound of the piston hitting the head. Root cause was an out of round crankshaft. A broken rod would have poked through the crankcase already. I've seen that happen too.

The video sounds a little like pre-ignition.

 

Okay, I have a fair amount of experience with the 3.4. One of the problem areas with the 3.4 is that the timing belt "fence" on the main pulley is simply spot welded in place. These spot welds can tend to break leaving the fence to rattle and carry-on similar to what your car sounds like. The fix is to respot-weld the pulley fence and drive.

Next on my list would be waterpump bearing play. Again- similar noises can be found. This too goes for a failed tensioner.

Hope that helps.

 

I would check the tensioners just completed mine on a 89 T with 30k miles they were shot the first indication was black ground up plastic in the oil pan. Check the drain plug and strain the oil if you find any pull the pan. If they are bad you will need to pull the motor the front cover needs to come off . The pan can be removed with the motor in the car. And needs to be removed to pull the front cover. Just be careful if the chain slips by by valves.

 

I thought these cars had belts, not chains ?

 

The cams are driven by a single belt via a cog just above the crank front pulley. That cog and the oil pump are driven by short chains via sprockets on the front of the crank.

HTH.

 

I see. Ferrari Mondial t 3.4 Cabriolet Mechanical Table 006 Timing, Controls

I'm liking the older motors ever more.

 

To me this sounds like an ignition fault. Pre-ignition maybe ? Either way - it does not sound good and I would for sure worry until it's resolved.

 

IF you are going to start the engine again try this.
Get a small piece of hose 3-4 feet long, put one end in your ear and touch the other to the suspect area.
I had a noise and tried the stethoscope all over for an hour, I was dazed and confused everything was making noise.
Mechanic found the one (1) leaking exhaust gasket in less than a minute this way.

 

That hose method works for gas leaks but less well for bearing, chain or gear noises.
It is true that everything makes noise.
I would not worry about some rich idle diluting the oil, it has to be a combination of really rich to the point of misfiring and many cold starts/cold running over quite some time or miles before that becomes significant.
I had a look at your cam pictures. The edge pattern is quite normal, almost every engine with this cam construction has lobes like this, also across car brands. Same with the pitting, I also saw this before in Lamborghini and Alfa engines. It looks like there has been some corrosion, doesn't it. I have seen it often enough to declare it normal - or at least no cause for concern of imminent doom. The flanks of the lobes caught my eye, those seem rougher than most. But again, as long as the lobe tips are OK I would not be worried.

Have you checked whether the noise is still present with clutch depressed?

 

Hello and happy Christmas here

The 3.4 timing belt fence indeed does not very strong! (http://www.ricambiamerica.com/media/catalog/product/cache/1/image/940x587/282d9b6de90e9a421ff861fcca42a84b/1/4/144488_2_1.jpg) that is a good idea..


I haven't had the time to look back at the car recently. I will keep you in touch as soon as I have news. However, with the idea of limiting engine running until new data, I will firstly try to have a look underneath after having removed the small metal protection under the sump and to listen to the sump noise together while testing the depressed clutch.

166&456, yes I have had advice from some people regarding my cams and the conclusion are the same as yours. The flanks are indeed not very nice, it is not important but quite strange to see this.


I will keep you in touch as soon as I have time to have a look. Thanks for the help

 

Well I am no expert but it sounds more like a loose guard or something. I had a similar sounding rattle on my 308 and it ended up being an exhaust manifold shroud that was loose, allowing it to rattle against the frame.

 

Hello

Had a quick look yesterday. No difference in noise between clutch engaged/disengaged in neutral. Tried to listen to the oil sump with a stethoscope but hard to say to be honest, and the fact that the noise is not always here complicates it!

Did not found any obvious loose stuff for now, aux belts tension are OK, ... will try again asap!

 

You have to be sure that the gearbox is stopped, the only way to be sure is with a gear engaged while clutch is depressed.
I had another listen. I know I was adamant that it was not a big end, somehow I am now less sure of that. Yet if it is a big end it really sounds unlike any I heard before, it is still more something resonating than anything else, so an exhaust resonance is still likely to me. The noises will sound different on camera versus real life. Big-ends are usually mostly heard at light throttle when driving, sudden acceleration when idling or some revs while idling (though that is usually the piston hitting the head making the most noise - like this: https://www.youtube.com/watch?v=k0_TJ-FStfU . It could also be bad piston slap... but for both diagnoses, I am missing the rhythmic noise usually present. Is there a cylinder that you can point it to by methodically removing the plug leads (look around for vids how to do that and be very careful to insulate yourself very, very well from electric shocks!).

Are cam cover bearings an issue on these, like the video in here: http://www.ferrarichat.com/forum/456-550-575-sponsored-bradan/336022-what-cost-belt-service.html While the failed bearing sound is drowned out by a lot by other noises, it does have similarities to my ears.

 

Hello Thanks for your reply

Yeah I will do it again since yesterday it was not safe enough to play putting the car in gear!

Here is a further video made before solving the idle issue which gives an another idea about the noise: https://youtu.be/McgI3kt6aDE

Honestly for me it was not a big end noise, just this friend that told me he had a similar noise on a 360 and it was indeed big end bearings.

Have an another friend owner of a M3 E46 who is obviously into big ends stuff and I have the feeling that all these things regarding oil analysis is not really reliable. Think that if you don't have a previous oil analysis as a reference this is not telling you a lot, is it?


I can try to disconnect cylinders yes, but to be honest not really happy with removing the HT (safety obv and also electronics reliability!) but I will try to do this by disconnecting injectors since it is quite simple on this car.

I have checked a very short video I made when checking the car and it was already doing the noise (the PO did 100km in between), thinking that if it was a big end it would already be killed but...

I had a look at the 456 noise, humm I would be quite scarred to film this! I assume when you are saying cam cover bearings you are just talking about cam belt tensioner/idlers?

 

Hmm. I am afraid that video does hint much more towards big end bearing or piston noise. It is always very difficult to assess from a video because of different harmonics etc.
Injectors are probably a better idea to identify cylinder noise yes - some ECUs will set codes if you do that but this car won't.
I am not sure how difficult it is on these cars to inspect big ends superficially, on many cars it is possible to remove the oil pan and feel some or most of the bearings, if you identify which one it is before that by the injector method, you know which one to look at most.
On the other end you want to minimise wear if there really is a big end issue you need to minimise testing. And if a service is due anyway, perhaps bite the bullet and take it all apart and see. Sometimes your time is better spent that way rather than searching and testing for days. The per-cylinder check is still worth doing though, even if it is just to verify where you expect to find a problem.

Big end bearing failure can slowly progress over thousands of miles after it is first audible before it becomes catastrophic - provided the motor is not stressed, because internal stresses are highly exponential with RPM. If it stressed, it usually becomes fatal in seconds. You can of course take it up to 7000 rpm a few times, then you will know for sure if it is a big end... (please don't)

The 456 video shows one of the two cam drive bearings having failed, as a result the drive gear of the timing belt is rattling about. Not an uncommon thing on these motors as those bearings are relatively small and quite stressed, especially if the timing belt is overtightened.