Expert advice welcome (really)! ... I have started hearing an irregular sharpish tap seeming to come from under left bank cam top-cover (firewall side), close to belts end. Only occurs at startup from dead cold (at least 1-2 days since last run). Can be quite irregular (as in tap-tap-tapatapatap-tap, etc) running between 1 & maybe 5 cycles per sec during fast idle (1200rpm). The noise is loud enough to hear lightly in the cabin, but usually only lasts for 5 - 10 secs, 20 max as slowly goes away. It may take a sec or 2 to actually begin, and oil pressure is always right up ~ instantly. Motor is an '87 3.2 with a good few miles. No other problems (smoke on overrun, etc). Car is run min 2 hours every week & has always been F-shop serviced on schedule. A local independent mech with some F-experience hasn't actually heard it but said *sticky valves* => need to drop motor & redo that head (as too close to firewall to do in-situ). Expensive. So, are there any other thoughts? My first one was how can the valves stick with 40+kg of spring load on them? Could it be the followers/tappet shims? Would popping the cam cover tell me anything? If it DOES end up being a top-end recon, do the valves themselves usually need replacing (assuming not burned), or do the bronze guides get most of the wear? (I'm doing a worst-case budget) Many thanks ...
Cam, we've just had a 87 mondial 3.2 cab in with similar symptons, turned out to be a slighlty sticking exhaust valve, whilst we removed the head to sort it out you may want to try de-coking the head with it in place & changing the oil to see if this makes any difference, if this doesnt help your best bet is to take it to a specialist to help with diagnosis (an hour or two of pro labour time may save you days of time and lots of parts trying to work it out)
Exhaust leak. Either missing a nut on the header flange (lower ones seem to fall off often) or one of the sample tubes broken off. Get a piece of hose (garden or heater) and listen through it to locate the source. Other possibilty is the alt. belt is loose. These snap rather than squeel. Start by snugging it a little bit when cold and see if the problem is gone when you start it. The belt snap is louder and harsher than the exhaust leak noise but they both fit your explination of the sound and how it goes away quickly. Dave
This is a very good place to look. Especially if the car has the emmission air rail in place but the system not functioning. These thin air rails will rot out quickly and give a very noticable tapping noise. Just carefully reach down and surround the rail with your hand and feel around. You will feel the leak if you find one.
ahh the dreaded tapping noise. i had one that drove me nuts, it started only at start up and once warm was gone then it progressed to the point of being all the time and would get louder as the engine rev'd. i checked everything, belts, exhaust bolts and the air injection system. nothing, also ran a stethascope on the valve train, nope. then i decided to take a step back while the car was idleing and regroup, in doing so i stood in just the right spot and noticed that the EGR tube from the exhaust had a washer or something loose and had fallen to the exhaust pipe. upon further investigation i found this...the PO had to have the car smogged to be sold to me. the shop had dissconected the EGR to get it to pass smog, what they did was unsrew the retaining nut to the bottom of the EGR valve and it fell down to the exhaust pipe. the nut would rattle against the pipe and the nipple end of the EGR port would rattle against the exhaust feed pipe. so all the time this anoying and expensive sound was a loose nut. so as you can see, it can be the oddest things sometimes.
OK, lots of options here. A few questions ... If sticky valve-train (= worst case?), would the sharp tapping (almost like a "cracking" sound) be caused by contact with piston & valve, or is it that the valve doesn't quite close and so it has excessive cam clearance on that valve? Second, how can I decoke "in-situ"? If exhaust, since it goes away after 10 secs would I still be able to locate it as an exhaust leak after then? It doesn't give me much time, & once its gone I have to wait until next day!
Before everybody gets nuts about spending $$$ start with the simple first... most likely in my opinion - its your belts... making a slapping noise - not your timing belts, but the ACC belts... if it does it on start up and then goes away... most likely those... spray some belt dressing - pep boys $5.00 and see if that makes it go away .. if not then start looking elsewhere.. my expreience has bee that most of those noises are easy & cheap.... if your Ferrari has a real mechanical problem ... you'll know it a stuck or sticking valve would result in some form of driving performance issues.. stumble, hesitation, smoking etc.. higher temps etc...
easy way to spot a sticky valve is to put a vacumm gauge on the plenum and see if the needle reacts. any hanes/chilton manual will have a chart of needle behavoir for the vacumm gauge. cheap and easy start. cheers'
I agree, it is probably the AC Belt. Mine make a clacking sound when cold..I put some belt dressing on it temporarily and it completley eliminated the sound. Also, WD 40 works... A lot of 308,328 motors have done this.. Good Luck
Also that the timing belts can create static discharges under certain conditions and I have heard they can be quite loud. Also, do not the later 3.2 motors have hydraulic followers? If so, it could simply be a dirty cam follower. In that case the oil change/flush recommendation could help.
WHAT?!? I've never heard of that one! Nope, just like your 308's. Inverted buckets with shims on top. My vote is first, belts (the Polyflex belts start their racket after a short delay and are active for a shorter time than exhaust leaks) and second, exhaust leaks. Always look for the simple stuff first... -Peter
again, WD40 is bad for rubber, and gaskets. its also VERY BAD FOR ELECTRICAL COMPONENTS. i WOULD NOT go spraying it in your engine compartment!!!
Mine had similar symptoms. I soon noticed the dreaded water pump weeping (right before I started weeping!). After replacing the pump and belt it went away.
This is TOTALLY TRUE. The test is to run the car (while it is making the noise) in a completely dark garage. If you see sparks (that are not from bad plug extenders, etc.) this is the cause of the sound. I would not have believed it myself, but it is true - I have seen it when troubleshooting the same noise on my gt4 (#10704). A
now remember boys and girls, let's NOT do this in our own garage! try night where there is little or no light saturation. a shop garage has ventilation home garages don't.
Yep, it seems to have been the accessory belts. Funny how something rubber sounds so much like steel tapping on steel! Water pump belt seemed right on spec (5mm flex under ~ 3kg side-force, as judged by my "thumb-O-meter"), so I didn't change anything there, but did snug-up the AC and ALT belts slightly. Also I cleaned with a cloth the pulley grooves and belt friction faces as best as I could, and buffed them up a bit with fine paper to remove any glaze. I noticed that the AC pulley inner faces (where the belt runs) seemed to have lots of small dark blemishes on them, which may have contributed to the belt sticking in the groove on "exit". Sat the car for a week & when started ..... perfect, no tapping. I'm pretty confident that was the cause (will be continuing this post if not ...). Much cheaper than doing the heads! Thanks to all.
