Hello together, now that I have finished my job reviving my A/C, which was 'dead' over one decade long, I have mentioned it over various threads. But now, though all is working perfectly, one problem occured. The A/C belt makes nasty clicking noises after cold start. I isolated the noise with a quick squirt of belt dressing - now there's a sticky mess where all was clean and freshly installed :-( - and it immediately went away. I have read about many folks, who had or have this problem, but didn't find how to cure it. Do I need a new belt, though it is looking good? It is an old belt, which laid around over a decade too, but was just installed through just a short period. Or has it something to do with tension? I tensioned it fairly tight. Best Regards and thanks in advance Martin
1. Replace the very old belt. They're pretty inexpensive. Clean off all the belt dressing. 2. Don't overtighten the belt. Personally I use a deflection tension gauge. 3. It might still make a noise, but I see this commonly on other cars. Sometimes they get less noisy once warmed up. 4. Failing pulley or ac clutch can also make noise.
Have had this for years on cold start. Invited mechanic over to my place to hear it one morning. Of course it didn’t do it while he was here. 1st time is years ! Drove it again a week later and no noise..... maybe his mere presence cured it. I’ve retentioned the belt etc. with no luck. It’s a quirk.
I get the same thing when the weather is cold, it only last for a few minutes till things warm up. I asked my very expert indy mechanic and he told me it is caused by static on the belt and is quite normal. So I stopped worrying about it.
Thank you all, will try a new belt and if it reappears I will live with it. Drove around with A/C in fairly warm weather for S/W-Germany today and really appreciate it having A/C again. Thanks John, tensioner pulley bearings I have also replaced. As well as the big bearing in the A/C magnetic clutch. The pulley bearings are cheap and easily replacable. So I just did it as routine work. The big bearing in the A/C clutch was running rough. So I replaced it as well, when swapping compressors. I assume, the bearing in the clutch was damaged through permanent vibrations while driving around without belt over the many years. Best from Germany Martin
About all you can do design-wise is shim the AC compressor pulley axis to be as close to the crankshaft axis as possible - i.e., add as many shims, 6 (or better washers so they don't fall out), as you can while still maintaining enough engagement between the studs 3 and nuts 5 (or until you run out of slot on the idler pulley adjustment): https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/308-group/308gtb-gts/air-conditioning-compressor-and-controls.html This will increase the wrap angle of the belt going around the idler pulley. (It's just a poor belt path design -- having such a low wrap angle on the idler pulley allows the belt to easily move up one side of the V and then "snap" back down when it's cold and slick. Once the belt surfaces get warm, it has enough friction to not "snap" back down even it rides up one side of the V occasionally. The typical minimum recommended wrap angle for a V-belt pulley is something like ~60 degrees, and this design is nowhere close to that on the idler pulley.)
Thanks Steve, sounds interesting. I just had a look. I have already shimmed around 6mm. I could add around 3mm maintaining enough engagement of the nuts on the studs. But I wonder whether I have still enough tension travel on the pulley then (approx 20mm remaining travel at the moment) .... or my belt is currently overtightened. Regarding your addition, which explains the 'snap-effect', would you recommend also checking, whether tensioner pulley and compressor axis are properly aligned? Best Regards Martin
Certainly better alignment would minimize the V-belt wanting to ride up one side, or the other, of the idler pulley (and there are a bunch of tolerances in both the AC compressor pulley -to- crankshaft pulley alignment and the idler pulley -to- crankshaft pulley alignment), but it is just a poor design. As long as the idler adjustment isn't at the end of the slot, the more wrap that you can get on the idler pulley = the better, IMO (but even with everything aligned perfectly, and the wrap angle maximized, you might still have a cold noise problem). I'm in the camp saying: "eh, if it needs a shot of belt dressing every few months to keep the cold noise away, I'm good with that" . You can't habitually use a belt dressing, as it would soften/degrade the belt too much, but a couple/few times a year isn't a sin IMO.
I'm not familiar enough with earlier 308's - so.. - Martin, do you have a 2-belt or 3-belt accessory setup?
a 2-belt setup. But with the weak alternator of the early cars, I never had a problem with the one belt for both w/p and alternator. I see an advantage in the 2-belt setup. When the engine threatening w/p drive fails, the alternator light immediately comes up, what does not happen with the 3-belt setup The A/C-drive seems to be the same from the earliest GT4 up to the 328. Or not? Best Regards Martin
Aha. I've got the 3-belt (one each for alt, WP, and compressor). Earlier comments on the angles, deflection, etc - just had me wondering (as I've no idler pulley.)
So is your late QV-setup the same as the 328-setup? I see no idler pulley for the compressor drive, but one for the w/p-belt on the 328? (have no US 308 QV OM at hand and Euro QV shows still the same setup like mine). BTW. I was busy with the issue today. I made additional shims on my lathe approaching the compressor-distance to the bracket, so that the slot in the idler pulley for tensioning is at its end, with belt reasonable tight, but not overtightened. So I have the max. possible wrap angle. More wouldn't be possible, since the idler and w/p-pulley would then collide. First try showed the drive being silent. Will try again tomorrow. Of course, washers are better like Steve said, but for this I would have to pull the studs and I was not in the mood for that. And of course I will order a new belt, since I noticed after a look into my records, that it's not 12 but 20 years old Best Martin
So the US 308 QV got this setup earlier. On the Euro-cars it came not earlier than with the 328. Though you have the idler pulley now on the w/p-belt, it seems, that the wrap angle on the idler is much more than on my A/C-belt idler when tightened. Best Martin
I understand them being the same. Wrong? A look into my tech dictionary says: idler pulley = belt tensioner pulley (among further translations) Best Martin
The spare parts books indicate it's more related to the AC compressor used: Versions of 308QV and 328 that use the York (piston) AC Compressor = has the (adjustable) idler pulley for the AC belt adjustment. Versions of 308QV and 328 that use the rotary AC compressor = no idler pulley, and has the AC belt adjustment mechanism built into the AC compressor mount (which is far better and proves F realized that the early idler pulley style design wasn't so good ).
Just for the sake of conversion: If a pulley is involved in applying tension, I call it a "tensioner pulley". If a pulley does nothing but redirect the angle (but isn't adjustable), I call it an "idler pulley". IE - idle = doing nothing.
And Steve talks about idler pulleys as well. I'm lost. Lost in translation (good movie) Best from Germany Martin
Here's an example (not a Ferrari motor) An idler pulley (lower, left below the alternator). It re-directs the angle, but doesn't tension nor change anything but the belt direction: Image Unavailable, Please Login
After fiddling half the Sunday yesterday with this issue -making new shims, slowly approaching the best compressor-bracket distance, I just started my car after another cold night and same conditions like last week. Great! Belt drive is completely silent!! It seems, that the maximized wrap angle actually cured it. And I have a bit more tension now, though still far away from what the WSM says. My belt was not overtightened, what I first thought, but even too loose. FChat should collect such hints with a sticky thread with 'insider tips'. Best Regards and thanks a lot Martin
After reading this I come up with one question: How on earth do you confirm the angle between the compressor and the crank? I understand the theory but the angles are near impossible to see. Help me Obiwan, you're my only hope. Lester
With difficulty . The relatively large distance between the crankshaft-idler end and the AC compressor end works to make any angular (or offset) misalignment of the AC Compressor pulley less critical. Do you think that you have a specific problem in this area? The close distance between the crankshaft pulley and the idler puller is more fussy, but needing an offset tweak there would be more of a thing than needing an angle tweak.
Lester, perhaps I don't understand your question completely, but we are just talking about the wrap angle of the A/C belt on the tensioner/idler pulley -according to Steve- only used on York piston compressor applications. Like Steve said, in such applications a min. wrap angle of min. 60° is recommended. And even with the tensioner pulley at the end of its slot, we are far away from 60°. I would guess, I have now 20° at best now with the pulley slot fully used. This is, how it's looking now: Image Unavailable, Please Login Best from Germany Martin
