355 front of engine rattle

On my 98 355 I get a major rattle from the front of the engine when the car is cold and idling, a noise kind of like a couple of small rocks in a coffee can or a metal bracket that is slapping around. It is really bad when the engine is cold and idling very low like when backing up and letting out the clutch and not really using the gas.... at that really low idle it rattles something fierce. I had my mechanic looking and everything seems to check out OK. They even thought it was the alternator tensioner bearing, but when they removed that it spun freely and the car still made the noise running without it. Since the sound goes away as the car is heated up, there is only a small window to try and diagnose the issue and it seems to come from the very front of the engine where you cannot get a good view. Any thoughts? It has us stymied.

 

Get a Stethoscope & pinpoint the EXACT area of the Rattle. Are you sure it is coming from the Front ?
Do you have OEM Headers & Cats ?

 

It has that rattle that made me think headers/cats also (they are OEM), and the fact that it goes away when hot like the broken cat "guts" expand and stop resonating, but it really sounds like it is coming from the front of the engine and not from a component of the exhaust. Is there a way to check the condition of the cats while in the car?

 

Have you had a service preformed recently. Belts sometimes can make noise until they get some temp.
Also headers, more specifically, air distirbution manifolds have been a problem with cracking. Noise cased by headers usually goes away when they get temp.

 

Sounds like possible cats breaking up (common problem). But usually this will throw a "check engine" light, as the pre and post O2 sensors will see a problem (although I have been told the OBDII needs to see two decently long drives (30+ minutes?) with the fault to throw the CE light). Do you see any white residue on the inside of your exhaust tail pipes? If you do, then you DEFINITELY have a problem with the cats....but this is not always shown on the exhaust tips. I had one failing, and no sign on the tips, just a "check engine" light.

 

I am due for the major service come spring, and I am sure at that point whatever is causing the commotion will be found, I just don't know if I am comfortable with it rattling until then. No residue on the exhaust tips and no check engine lights, so I don't *think* it is the cats....

 

belt tensioner bearings, loose AC compressor or alternator.

 

What you are describing sounds exactly like what mine was doing. My mechanic found that it was my AC compressor/clutch but it sounded like a bucket of bolts and only when cold. It would start up as soon as I started backing out of the garage. Nothing when I first start the car and let it idle, as soon as I hit reverse and started to move it made the noise.

 

Classic noise caused by bad hydrostatic timing belt tensioners.

 

I wouldnt' start the engine again if I was you. The last thing you need is for a bearing to freeze up.

 

Wow, good stuff and thanks all. I am going to print this thread and visit my mechanic next week to discuss it. The idea of a timing belt tensioner bearing (Rifledriver's thought) going is a scary one and I would guess replacing it would need to be done with the engine out of the car. Can you service the A/C compressor/clutch like Miniwerks believes it may be with the motor in the car? I want to investigate the least expensive route first.

 

I said nothing about a bearing. The tensioner is a different part.

 

FINALLY!! I own a 95 355B with 23,000 miles on it and am suffering with the EXACT same noise. It only 'rattles' when the engine is first started and when the engine is stone cold. The noise only lasts for a minute or so, then goes completly away until the next cold startup. It sounds very much like an alternator fan that has come loose and is 'tinging' and rattling around. (not like a deep bearing knock) When letting out the clutch it gets a lot louder. I'm certain it's not directly clutch related due to the source of the noise.....up front.
I'm sure that what ever is wrong with yours, is also what's wrong with mine too. I've been all over the shrouds and tied up wire harnesses, etc. in an effort to find this noise. Very irritating...and scary. Like you, by the time I get the car on a rack and get it up in the air...the noise is gone, and won't come back until the engine is completly cold.
vty,
Michael Scaglione
Classic Auto
Windber, Pa.

 

http://www.ferrarichat.com/forum/showthread.php?p=34597#post34597

 

Your not going to like what my problem turned out to be. I checked all the simple things out first. Then I took it to Barretti Farreri Service and it was the tensioner idler bearing was going out. When he took off the belts one idler was almost frozen. The rest is history. If that idler gives out you have lost your engine, about a $35,000. loss. Need to get it repaired soon. I hope Iam wrong.

Cliff. San Antonio, Texas

 

After discussion with my shop, we decided to just do the major service early and drop the engine. With the engine out and the service, they should be able to find the culprit. I will be sure to post the follow up, I should know something by the end of this week or the beginning of next.

 

Any update??

 

Nothing has jumped right out and said "I am the broken part" unfortunatly. It is not the bearings or tensionsers for the cam belts, they are fine and actually rather new. The driver's side belt was "scary" loose though, so it could of been that slapping around a bit but the noise seemed to be coming more from the passenger side. They dropped the oil pan and checked the oil pump, etc., all OK. The A/C compressor checks out OK. They pulled the clutch out and checked the bearing and that was OK. The last I heard was that they were taking off the valve covers to repaint them and check the valve buckets. Right now we are leaning towards is possible being that sloppy timing belt or possible the oil tank vibrating and rapping against something. I know, remote but they are doing a lot of CYA work. I just read an interesting thread posted either here or maybe in the Technical Q&A section about the same kind of noise from a 348 and someone said it could be a glazed belt and recommended pouring some water down to see if it temporarily stops then starts up again indicating a belt issue. Intersting. Anyway, I will post when I get the car back which I am hoping is soon. I am having additional items looked at (brakes, etc.) so it is taking a bit longer.

 

Tensioners have a recent manufacturers date and the bearings look and feel new (as they should be, as FoA did a major service not that many miles or time) ago. The clutch has been examined (went so far as to look at the centering bearing and the housing bearing, in case it was being transmitted forward), the A/C clutch bearing has no play and no roughness, the A/C compressor and alternator are tight and the mounts are not broken. We dropped the pan, looking at all drive systems and internal tensioners for the pump. Nothing. The driver's side t-belt was a touch loose, but not able to cause this noise! We have the cam covers off (to refinish them and to time the cams <grin>) and every thing checks to spec. The cats, manifolds and exhaust appear to be in good order (no leaks, discoloration, rattles or white discharge).

It sounds like "sheet metal" scraping more than a bearing shriek or something with a lower resonant frequency like a rotational mass. It has no musical tone.

The two things that still look screwy to me are that the sheet metal panel is not tight at the bulkhead forward of the motor and there is a shiny spot on the dry sump tank (mounted on the subframe) on the top forward edge where it looks like it's been rubbing some metal plumbing (mounted to the car). It only happens when the idle speed is 600-800 rpm (in gear and under load, backing out or moving forward from rest when it is stone cold) and only for 45 to 90 seconds.

It's going back together this week and we will keep the board posted.

-Peter

 

Peter -

Does the car have the updated alternator pulley, or the old style one?

 

Thanks for the updates, gentlemen!


Matt, you are in great hands with Sport Auto.

 

When you pulled the bottom pan did you also pull the front cover for the cam pully gears? Maybe it could be one of the bearings for those, kind of like the update for the 348 timing chain? Just throwing ideas out there.

 

Thanks, Ernie. Thanks, Daniel.

Ernie, first thing done was to put a dial indicator on the drive pulleys after the belts were off and measure axial movement (slop, for a better word <grin>). No problems... Also, any bearing failure would leave metal sharf and/or pieces in the front tray evident when you take it off. None there.

Daniel, before even suggesting pulling anything, as a matter of fact when we went to put on what we thought originally might be the problem, we removed the external drive belts (alt and a/c) and ran it. Still made the noise. No difference of any kind without any of the accessory driven pulleys connected.

It's going back in. We've satisfied ourselves that we're in good shape withen gine and what engine internals that are accessible with the engine out for service.

Keep you all posted...

 

You know what, now that I think of it, have a look at the thermostat. If it is the same one that they used in a 348 it could have broken. There is a clip that is on the top of it that will come off. I had that happen to my 348 and found it in the top tank of the right side radiator. So..........maybe the clip got hung up inside the water pump somehow and is causing the scraping sound? Again, just throwing ideas around.

 

Hello, what you are hearing is the multi groove belt that runs alt. slipping as alt. is trying to recharge battery. Fix is going to dayco brand belts which are designed to stop this kind of noise. End of story