1958 Plymouth Belvedere - over charging to 16v to 17v

[WikedPlymouth]

My 1958 Plymouth Belvedere has the 318 engine with a generator. The car is now running well, except for some blow by, but I've noticed on the aftermarket gauges I added that at anything above idle the battery is getting around 16 volts. Some times it even goes up to 17 volts. I've checked this with a digital meter on the battery. I know this is not good for the battery and wondering if it's just a bad voltage regulator or if there is anything else I should check? Thanks in advance.

 

[Sixpactogo]

That would be my guess. The regulator's job is to regulate the voltage between 13.8-14.2 volts. As long as you have a digital meter, check the case ground on your regulator. If it is not grounded properly, it don't have a good reference to regulate by. Over 15 volts will boil the water out of your battery.

 

[Big_John]

If it's the stock voltage regulator, it should be adjustable.

 

[WikedPlymouth]

Are there any write ups on how to adjust the voltage of the voltage regulator or is it obvious when you remove the cover from the voltage regulator?

 

[Big_John]

Are there any write ups on how to adjust the voltage of the voltage regulator or is it obvious when you remove the cover from the voltage regulator?

If it's the original regulator, the FSM covers this. If it's a replacement, there may be an adjustment screw under the cover that will be obvious.

Thinking about it, you may have some stuck points in the regulator too... In which case, a replacement might be the best option, but it's worth pulling the cover and inspecting.

If you don't have an FSM, download a copy here: MyMopar

 

[CBODY67]

With the factory calibration, perhaps just cleaning the contact points might make it act more normally?

CBODY67

 

[Toolmanmike]

Bad grounds and excessive resistance through electrical connectors can cause overcharging.

 

[WikedPlymouth]

Thanks for all the helpful comments. I will remove the regulator cover this weekend and check the contacts etc. Might as well tinker with it first rather than just throw parts at it. I do have a FSM and should have looked there first. Thanks again for all the help!!

 

[WikedPlymouth]

Well, I took a look at the voltage regulator today. The cover looks to be riveted on so I could not remove it. I guess I could try to drill out the rivets. Anyways, I did clean up all the contacts and especially the ground wire that appears to be coming from the generator and goes around a brass grommet on one of the regulator to fender bolts. Cleaned everything up and will test tomorrow to see if it made any difference. If not, should I try and drill out the rivets holding the box cover on to clean the contacts? Being riveted, does that mean its an aftermarket unit or original? Thanks!!

 

[WikedPlymouth]

Went out and started the car. At idle (around 700 rpms) voltage is about 12.8v. At anything around 1k rpms or higher it goes up to 17v. I did check the engine to body ground. The wire looks old and could be replaced, but it is making contact between the block and firewall. I will replace the ground strap and the voltage regulator and hope that fixes it. Does anyone know if a Standard Motor Products VR15 is the correct voltage regulator? Thanks.

 

[WikedPlymouth]

Well, decided to drill out the rivets holding the cover on. I cleaned all the contacts but it did not make any difference. I did not see any way to adjust the voltage regulator. I did start the car and run it. The contact points would start to move as the engine revved up but then close quickly. Not sure if its working right or not but ordered a new regulator and will hope that fixes it.

 

[CBODY67]

The FSM indicates a "bending method" to adjust the voltage supplied at various temperatures. Kind of a "bend and try" method.

Which is why the externally adjustable voltage regulators were introduced, even by Mopar. Mainly for people who did a lot of town driving and shorter trips, but might also go on long trips (where continued higher charging levels could be an issue as to longer term battery life).

CBODY67

 

[Rusty Muffler]

Dare I say on my 66 Fury ebay had a solid state replacement (no contacts) that looks stock on the outside and has worked perfectly since. Inexpensive too.

 

[WikedPlymouth]

Got the new voltage regulator and installed it. Also cleaned up the original engine to body ground strap and added a second one for good measure. Car now charges correctly and there is no over charging and the lights do not get brighter as you rev the car. Thanks for all the help.

 

[Sixpactogo]

Got the new voltage regulator and installed it. Also cleaned up the original engine to body ground strap and added a second one for good measure. Car now charges correctly and there is no over charging and the lights do not get brighter as you rev the car. Thanks for all the help.

Persistence pays dividends. Glad you had success.