How To: Upgrade the regulator & rectifier on the 355 alternator (with pictures)

After much investigation it was determined that one of the NEW replacement components was bad as we obtained readings with car running at 1100 RPM. Voltage readings were:
1. 12.76V Black wire
2. 12.39V Cream colored wire
3. 2.00V Brown wire with green stripe

According to Romaine Electric here in Seattle, the tech said there is no way either of the two components I replaced could enhance the output of the Alternator. The only thing that can do that is a revised stator assembly (which is basically a different alternator). The rectifier and the regulator simply manage the power that is there and can't improve it if it isn't there as they are effectively passive devices. Clearly if either of those parts are damaged original stock from heat or something then you would see a return to original performance.

Bottom Line - I wish I had never touched my perfectly working alternator to attempt an alteration.

 

Say what?!?!?!

You mean to tell me that there was nothing wrong with your alternator in the first place?

Oh Dave.....tisk, tisk, tisk. You have got to know "If it ain't broke don't fix it".

But on a better note, thanks for the update. Glad to here your light problem got fixed. SO I guess the brown and green wire is the wire for the light, no?

 

I've been following this thread since its inception, not to mention the countless other threads surrounding 355 alternator failures. I'm in the midst of diagnosing another battery light issue myself. Battery checks out okay and I replaced the VR and rectifier 2 months ago.

I'm starting to think I may have a loose wire someplace. The battery light is intermittant and flickers randomly throughout the rev band.

In the mean time, I'm interested to see where this thread goes. Good luck to all.

 

Have you checked to make sure your alternator belt isn't loose?

 

Yeah- tension was fine. I did a search and found the sticky thread with interchangable parts. I just ordered a new alternator from Autozone for about $100.

 

I don' know whether there is a unique bad part or a tainted lot. Its made by Regitar USA This is the part with the cooling fins and the 3 prong plug recepticle. I replaced with the original factory part and light went out. This is the first time I've been that stupid to remove a perfectly fine part to try to upgrade it. I even had it tested to make sure it was good but apparently they didn't test the sense line and didn't tell me. Shame on me, I should know better. I have a PE liscense in ME - I feel like those pilots who over flew MSP!!

 

I feel bad for leading Aeroengineman down this road. I purchased three sets of regulators and rectifiers from Holcome about a year or so ago. Myself and JH355 both successfully did the swap "in car" and had no problems. Unfortunately the same cannot be said for Aeroengineman...in spite of him taking the extra precaution of having his alternator tested after the swap, and still getting the battery light coming on.

In the end, I am suspect of whether the VRH2005-4DG that Aeroengineman got was truly a direct equivalent to the VRH2005-4A. I got three regulators, and two where 4A and one was the 4DG that Aeroengineman got. I checked with Holcome, and as mentioned in another thread, they said they are essentially direct equivalents, the only difference being the "load response control" differs by a few milliseconds....this is the delay before the charging voltage is sent to the battery, according to Holcome. As soon as Aeroengineman stated he was having an issue, I immediately contacted Holcome to recomfirm the 4DG is equivalent to the 4A and they went so far as to contact Regitar for me to be certain.

I guess my point is the part may indeed be defective, but there may also be an issue with the presume equivalency of the 4DG and 4A. I ordered three 4A's, but Holcome did not have three in stock and substituted the 4DG.

 

Dave:

You're a good man to spend the time researching this. Also, thanks for the information concerning the 4DG versus 4A issue. I ordered two (2) and I have already upgraded my alternator in situ. Both of my parts read - VRH2005-4A. This is valuable information for those who order in the future. Even though they are regarded as "essentially equivalent", I'd still opt for the 4A.

Now, if we could just figure-out the correct part numbers for the rotor, brushes and stator....

Best regards,

Scott