355 Top alternator bolt

I find it easier as well as removing the aux belt if i take the alternator out with the engine in. Also remove the aux lower tensioner pulley so you can get your hand up to the front of the top of the alternator. The rear nut can be got at via an extension bar on a ratchet, its getting to the top front thats a bugger to get at without removing the belt tensiomer i find.
Of the top of my head i am sure its a 17mm nut and bolt. Its tight up behind the alternator, buts its easy once you have done it once.
Regarding the lower bolt, i have seen them placed in from the bulkhead /fuel tank side while the engine was out. Naturally this makes it impossible to remove with the engine in. However it sounds like you have the lower sorted.

 

Yes nut and bolt, but also each side of the bracket that holds the top of the alternator, there are two plastic inserts that go in each side, the bolt passes through both.

 

I have found this diagram to show you the plastic inserts #4. I am telling you about the inserts because they can easily be pushed out because they are not tight fitting.
Also you cam see the nut and bolt set up.
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So how was the out come mate?

 

Please keep us informed about the pulley experiment. Sounds interesting.

 

I think the rpm may kill the alternator bearings but should not affect the electrics/electronics. As the rpm goes higher, the regulator reduces the current through the exciter coil (the coil on the rotor) and still maintains the correct voltage of the alternator output. At idle, the regulator has to push maximum current through the exciter coil to maintain a good output voltage so, as far as the regulator and the exciter coil are concerned, they are most loaded at idle.

 

On the 348, the alternators probably fail due to very high start-up current drawn by the two radiator fans that come on simultaneously. The alternator is especially vulnerable if, at the time the two radiator fans come on, it happens that the oil cooler and the AC condenser fans are on. The alternator is also more likely to fail if the battery is not at its closer to full state of charge as the battery will not be able to "cushion" the high current draw at the fans start-up. Typically, fans that draw 15-20 Amp when running will draw some 50-60 Amps on start-up (x 2 is up to 120 Amps, in addition to what is already being drawn by other car consumers). This Amp spike certainly exceeds the alternator's capacity and, sooner or later, will blow its diodes. The latest version of the 348 alternator that provides 140 Amps is probably more capable to withstand the Amp spikes. I noticed this on my 348 soon after I bought it - at the rad fans start-up, the dash lights would "blink" (dim) significantly and the engine would "feel" this sudden big load. To eliminate these big sudden loads on the alternator, I have installed PWM fan motor controllers for the two rad fans and for the AC condenser fan. These controllers provide for "soft start" of the fan motors - when the fan motor is switched on, the controllers provide for gradual acceleration of the fan from zero to full speed over 2-3 seconds thus avoiding the high start-up amperes.

On the 355, difficult to tell. The cooling fans do not start simultaneously and there is less of them (4 powerful fans on the 348, how many on the 355?). Perhaps it is the heat that kills them. Do 355 alternators, like the 348 ones, have a cowling at the front that scoops cool air?

 

I think some means of directing cool air to the alternator is quite important. For example, my Jaguar XJ8 has quite elaborate air scoop and duct to direct good cool air blow to the alternator. The alternator is Denso of similar size and amps as the 348/355 ones.

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Bob my heat shield is slotted so you only have too loosen bolts to get it off.