I'm wondering if the timing belts will expand or contract when warmed up to normal operating temperature. I have just replaced my belts and I was quite happy with the tension.....but after driving a bit I have a new noise that appears only after the car is well warmed up. I just can't locate the source with my stethoscope. I'm trying to rule out possibilities. I have loosened up the water pump and AC belts but no change. I have noticed that after driving a few times the noise is seeming to quiet a bit.
What's the noise like? Loose AC and water pump belt can/will squeal as they slip and it is usually much worse when under load. The cam belts have teeth and won't slip like a V-belt.
Of course I changed the tensioners. The noise when hot is like the sound coming off of the Plenum when you rev the engine by hand in the engine compartment..... parked.....only louder and with more whirling sound.
What model, if it is 550 the AC/Alternator tensioner bearing has tendency to go bad and is not expensive. Just a suggestion. Sark
guess your 308 (?), a possibility: you did not put a little "extra"-pressure on the belt by manually moving those tensioner pulleys inward before tightening the pulley bolt, did you ? anyway, check the bearings of the lower cam drive pulleys - if the belt should really be too tight, those bearings - especially if you never changed them before - will be the first to go ... next you will see them "walking" and leaking ... after that, the white-ish smoke coming up your engine lid will be from the oil dropping down and burning on your right exhaust tube ask me how I know
Sorry didn't mention 308. When tensioning the belt I found the tightest point and marked it at the tensioner with a paint pen. Then I placed the cam locks on again and put some pressure on the crank before tightening the tensioner. (hoping to pull any extra slack out) It didn't look like that pressure moved the tensioner on either bank any tighter. The tension seemed good, a higher twang when flicked with the finger at the tightest point and a dull thud as loose points, and a twist of about 45 degrees, It seemed to me tighter than the last change, but I always felt I left them a little too loose the last time also. I guess I'll pull the rear cover and see how the tension looks. Loosing the drive bearings would be a pain in the ass for this old man.
i just solved my timing belt squeek, exactly the same issue as yours here's my whole procedure, for my 360. first, locate where the noise is coming from 2 methods, first method: warm up the car, then take off ALL belts except the timing belt, and see if it still is noisy. if yes, then that's the timing belt, if no, that's your aux belts. 2nd method: using a sprinkler, and while the engine's running, springle water into the suspicious belt, if the noise went away, then that's where's the noise's coming from. 2nd, now you know its your timing belt, you check the tension and u need a frequency tool for that, search for the forum and you'll find something cost your $300. 3rd, using that tool togheter with data the factory manual(combined 190-220 hz), u'll see that the belt is too loose, in my case I tightned it to the point the tensioner bearing is running out of play. i.e. can't tighten no more. the result is still too loose. thus I figured it must the be tensioner itself ( tensioner is the hydraulic thing, not the same as tensioner bearing) bought new tensioner, bang! problem resolved.
Wouldn't that only pull any slack out of the long run between the cam pulley and the drive pulley? It would not affect the pressure being put on the belt by the tensioner.......or would it?
I always used the book method of leaving the tensioner loose after the belt is on and turn the motor over by hand 4 times and then tighten the tensioner. Done. and never made noise. I only did 4 belt changes but all turned out OK.
That is not the correct procedure. As John mentioned, that would almost certainly put too much tension into the system. With everything locked statically, putting *extra* tension into one span of the belt means that when the locks are released, and the system is dynamic (operational), that increase in local tension gets spread over the entire belt eventually. Running a toothed belt too loose will cause increased "belt noise", but not increased bearing / pulley noise ---- the only things that cause that are either running the belt too tight or a faulty bearing / pulley / gear. .
The 308 spring is unreliable. The twist method is unreliable. The twang method is unreliable. The only way is the factory way with steager tensiometer. Good luck finding one of those. So pros have converted supposed steager readings into a variation of sonic tensioner readings. Those secrets are closely guarded. You won't find a pro here willing to give up those secrets. That said 30+ years of fixing Ferraris I still tension by hand which is totally unreliable but works for me. I have a sonic tester used it once. I can't even remember the final numbers I settled on for my 550. IMO unless you are a gorilla or a total hack it is hard to over tension a belt by hand so that a noise results fro over tensioning. The forces on these belts is amazing wizzing around up to 8000rpm. Your little hands are going to do much. DaveHelms got me all paranoid once about 550 belt tensions. I was driving and then pull the covers off to look for rubber and rubber dust indicating wear. There was none. I did that 3 more times over a number of hundreds of miles. All I did was waste my time looking. I would look elsewhere.
Do you use the twist the belt 90 degrees method? I've used that in my 924 and 928 for years with no issues..
+1 At least for the 2V cars. IIRC there is a slightly different procedure for the QV, where the tensioner should be tightened at certain flywheel positions. Best Regards Martin
No. It's the same for QVs. Put on the belt. Release the tensioner. Rotate the engine twice. Tighten tensioner. I am getting a kick out of this thread though. The 3x8 has been around for 40 years and no one has figured out how to replace the belts. The guy who services my car, Ferrari trained on these cars when they were new, told me that the biggest problem leading to belt issues is over tightening. Over stresses the bearings and can lead to cams seizing in the journals. I do know that on my first belt change (bought the car new) the factory installed belt on the front bank was sloppy loose, and I mean sloppy loose. But it never causes a problem In fact, when it came off the car it looked like new. The lettering on the outside of the belt was still legible, and it had some miles on it too. Image Unavailable, Please Login
Sorry to say but as a source of information this place is not a good choice. Signal to noise ratio is off the meter. I am just sorry so many get told the wrong thing and accept it. At the end of the day it does the reputation of the cars no good and it costs a lot of people money and frustration.
just compared both WSMs. You are of course correct. Sorry, must have been a different engine I had in my mind. Best Martin
Partly agree like for most similar places on the interweb. And sometimes there's the dreaded 'advanced car wrenching syndrome', when people discuss and plan their work by hours and days of sitting in front of the computer and don't touch one bolt. But partly disagree, because there are so many great threads, which encouraged DIY folks to do their own work with success. I'm a mechanical engineer, but wouldn't have dared at all to rebuild my steering rack, for example, without this place. You are an experienced Ferrari mechanic. But many are not, though being talented home mechanics. After all, this place saved me more frustration than it gave me. And when I compare FChat with the car related crap I find elsewhere, it once more justifies the fact, that FChat is the one and only place on the web, I pay a small amount of money for. For the subscription. Best Regards Martin
