Where is the voltage regulator??
 

1977 911S......I cooked my Optima battery yesterday....replaced it with a new one and after arriving home after a 1 hr drive, the new battery was boiling. Removed it from the car so it wouldnt explode in the trunk. Ok...I am suspecting that the "overcharging" is caused by faulty voltage regulator. Where the hell is it? There is a spot between the Perma-Tune and the platic cover for the relays on the left sidewall of the engine bay but I cannot find a voltage regulator anywhere? HELP!!!

Roger

Inside center of engine fan

So...do I go ahead and pull the fan out next?

Roger

Mine was attached to the alternator, but the replacement voltage regulator was installed in the rear engine compartment electrical panel. Not sure where it originally was...

Voltage Regulator Location.....
 

Roger,

The location of the voltage regulator for your car is located just to the right of the fuse panel in the engine compartment. However, if your alternator has been converted to have the integrated VR, then it is now located on the back of the alternator behind the fan.

Tony

Tony is correct. I just went through this upgrade. If your alternator has not been upgraded, and it's in good shape... the voltage regulator is MUCH cheaper and easier to replace. Simple plug and play. Let me know if you need pictures of where it's located but as Tony mentioned you should be able to find it just to the right of the fuse panel. Mine had a black housing but the replacement ($40) was in a silver housing.

Tony...it must be behind the alternator because there is nothing mounted on the wall next to the fuse panel. Looks like an empty space where it used to be.

Roger

Clint....sure...if you have pictures that would be great. Would you think that my problem is most likely with the regulator? I hope that's all. That poor battery must have gotten 18 volts for about an hr. Really was hissing and leaking.

Roger

Well, it sounds like you've confirmed that your alternator has been upgraded and has the internal (built in) regulator. When you remove your alternator you'll see it on the back side. I'll try to find a picture of mine and post here in a bit. From what I've learned... it's very common for the voltage regulator to go out which is one of the reasons it used to be external and easy to get to... that way you didn't have to replace the whole alternator. I'm not quite sure why they went away from this but I'm sure there are several advantages of the internal regulator... which is why Porsche went to that design and it's typically consider an upgrade for our older year cars.

As far as just replacing the regulator, I don't "think" that you can simply pull the old off and replace but maybe some others can correct me. From what I understand you'd have to take yours in for a rebuild or buy a new one. I bought my Valeo rebuilt for $140 but you can probably take your core in and have it done for much less.

I'll try to snap some shots tonight and post pictures tomorrow of my external voltage regulator and where it was pulled from.

Subscribed

I have an '86 with the Valeo alternator & regulator and just did this chore. If yours is the same, the VR mounts to the back of the alternator and a new one can be purchased separately from Pelican. Replacing it is easy. On the other hand, getting the alternator out is a major PIA so since it's 20 years old I had it rebuilt "while I was in there" - cost $110. There is also an excellent tech article on this by Wil Ferch that explains every step in detail. I highly recommend reading that before you start.

Thanks for the recommendation on my Tech Article.

Here it is for ease of use ---> http://www.pelicanparts.com/techarticles/911_volt_reg_replace/911_volt_reg_replace.htm

It links to another article with pics, too.

- Wil

Roger - How did you suspect that the new battery was boiling? Did you just do a visual because - or were there tell-tale signs?

Kato

Re: This thread I posted yesterday:
http://forums.pelicanparts.com/porsche-911-technical-forum/359495-help-hot-battery-barfed-my-trunk.html