I revved my Testarossa to the redline today and it ejected its alternator belt. I’m new to these cars. Is it just a matter of loosening the alternator and putting on a new belt, or is there a recommended sequence of dismantling that needs to happen before I can get that far? I have searched but can’t find an answer to this question. Many thanks.
easy to do, but not easy to reach just loosen the alternator, put on new belt and adjust. don´t know if you have an airpump also driven by a belt?
How long since your last major? Fairly recent? It is easy to install the alternator with the alignment shim misplaced or missing. If it was loose enough to be thrown, you would have likely been hearing a squeal on startup or when revving the engine.
@vincenzo The last major was this past spring, before I bought it. There hasn’t been any squealing. @Steve Magnusson I have the ribbed belt. It is now split longitudinally. I don’t know if it split first then flew off, or if the split is collateral damage. The belt that came off is a Dayco 4PK 812. I can’t find any evidence that that is even the correct belt. Is it? It’s very hard to find, and is never described as a Testarossa alternator belt. What’s the correct part for me? Thank you so much for the help.
The multi-ribbed belt is the "improved" design. It is a big alternator (120A) so maybe make sure that the Shop didn't/don't use a substitute belt that fits but really isn't the same specification, and, of course, give the alternator rotor some spins/feel by hand just as a quicky sanity check for the bearing condition.
I think the belt broke because of an alignment problem. @vincenzo refers to an alignment shim. Where is it in this diagram? View attachment 3204909
And those goes behind the alternator bracket to push the alternator a little closer to the firewall, or the other way around?
Well, I didn’t get too far before getting stuck. To get the alternator belt on, I have to first remove the AC compressor belt. With great difficulty, I loosened the pivot bolt on the compressor. When I wrenched on the tension adjustment bolt, I expected the compressor to move and the bolt to stay put. Instead the compressor stayed put and the bolt backed out. How do I get the compressor to budge? It won’t move for me. On the alternator side, I can’t even reach the pivot bolt. I have a wide variety of wrenches, but don’t see how any of them will let me put leverage on that one. Any hints?
I solved that one, actually, using the two-wrench trick. It won’t move, though (the alternator, that is). I have loosened the pivot bolts and tensioner bolts on both the alternator and compressor, but can’t get either to budge. I’m trying to avoid removing their fasteners completely, including the ones attaching the alternator/compressor to their respective tension adjustment devices, but maybe that’s what I need to do…? In theory I think I’ve done all the hard part. Now just wiggle the things, put on new belts, and then put it back together, but I just CANNOT get them to move enough for me to get belts on and off. Edit: I think I know what I’m doing wrong … I have not loosened the nut 26. I’m going to try that. I didn’t think I’d need to, but…
Yeah, I didn’t understand how those tension adjusters work, and therefore didn’t understand what I need to loosen. I worked it out. The new belts are loosely in their proper places now … just gotta do the whole thing in reverse now.
Likely a too simplistic statement…. but it may be of value for others… If high forces appear to be required, re-think the process! It was a hard learned lesson for me as a kid.
I don't think it was mentioned that fitting is much easier from under the car. I've replaced the alternator twice in my ownership. An unpleasant job.
Having a lift sure helped. I found that I must be under the car in order to: - reach the alternator pivot bolt - get belts on/off the crank pulley - check the belts’ tension
I did the work on axle stands, using a jack to slightly lift the engine once the left side engine mounts were loosened.
Bad news. The alternator belt I put on snapped, and the AC belt that had to be temporarily removed to get the alternator belt on also snapped. Obviously I put them on incorrectly. Please don’t shame me, I feel stupid enough. I’d read three alternative methods for tensioning the belts: 1) Use a Borroughs tension checker 2) Use a Kriket tension checker 3 Just tighten them as much as you can without power tools I don’t have a Borroughs tension checker. I’m willing to buy one. I have a Kriket tool but found it useless in the confines of the belt area. So I did #3. How likely is it that my incorrect tensioning alone was the cause for these belts fraying and snapping over the course of 100 miles? What else should I consider? How can I make sure this doesn’t happen again?
you not need a tensioner checker. you have to see if the 2 disks where the belt is on are exactly in a row. I never had until now a belt snapped on a flat 12 when installed correctly. I think you have a little missalignment
They were too tight if they snapped. I couldn't get an accurate reading with the kirkit. Of course, with the engine out, it would be a breeze. The trick is to barely be able to rotate the flat of the belt 90 degrees with moderate effort. Check this in the middle of the span between the two pulleys. To get the feel try this with another vehicle with an automatic tensioner. Then get it close with your Testarossa. Leave the access panel off and drive the car a couple of times. You just need a few heat cycles so you can recheck the tension and tighten it a bit more. Don't do a high rpm run until the belt's tension remains consistent.
