355 technical views

OK, 99 355F1 goes in for cambelt service( running perfectly) at f dealer at the same time the cats are replaced with tubi sport and it already has tubi manifolds and exhaust.

When i get it back i notice a rattle/ vibration at idle ONLY ( it goes after 1500 rpm)say 5 mins after startup and it goes when the engine is hot.
so NO noise when cold- only after 5 mins and then until engine is hot- when hot NO noise!

Back to the garage who disconnect all anc drive belts- noise is still there. It seems to be comming from the front near the bulkhead.

The noise seemed to me most prominent in the lower sump area so it was thought the oil chain tensioner my be at fault. Sump is removed and the tensioner appears to be only half way over the chain- new tensioner fitted - which ferrari have modified by the way for all you 355 owners out there!! but this was not the problem.

So engine comes out again and it seems 1 of the tensioner bearings is running a bit noisy after installation of new belts so both of these are replaced together with new belts and new pulley.

The noise is still there! and its best described as a vibration as though the exhust was somehow fouling the chassis.

The noise is NOT the following

exhaust bypass valve
cats
manifolds
tensioners
oil pump chain tensioner
alternator/power steer air con
loose conrod bolts ect

The whole episode is cosying a fortune- where do i look now?? any ideas?

The timing is correct and in anycase weve had 2 sets of belts and timed every time with same results!

It does not appear to be valve noise ( ie hyd tappett) so its not bleeddown.
HELP!

 

It sounds like an isolation problem. How are the engine mounts/transmission mounts? You say it's towards the gas tank..Any way it could be a bad fuel pump? I have heard some that you would swear the car was going to fall apart!

 

Ran across this same type of condition on another 355.

Found that the left side timing belt tensioner was weak and that the bearing for the alternator/water pump belt tensioner was bad and noisy.

Replaced that faulty parts with new belts and the problem was solved.

Check those componets, belt tension, and possibly as tbakowsky said, Check the mounts.

best regards, Jim

 

As i said in my post the aux parts- ie alternator and w/pump were isolated - so its not that. Both tensioner bearings replaced and new belts.

I presume if it was the tensioner rather than the tensioner bearing that you would hear it from cold and when hot and also above idle

 

Have you checked the exhaust mounts? I had a vibration like yours and it was traced to a loose mount. Might be worth a try ? This sounds v expensive, BTW