So I'm looking at a 1959 98, current owner says "it's a positive ground" , I raised hood and looks like that's way he has hooked it up. Battery un hooked but look like he did have it hooked up like that..
My question what damage has been done, how bad is he did that , says it was running before ?

 

Positive ground was common practice for awhile..

 

Pretty sure neg ground came about 6 years earlier. 1953. Unless there are solid state components in it, there will probably be no damage, other than possibly the regulator. Sometimes there is a stamping on the voltage regulator base indicating the ground ie 12V N If there is a part number stamped on the regulator base you can look it up to determine what ground it is set up for.

 

Positive ground was popular amongst British cars and motorcycles. I thought 12V negative ground was the standard back to at least 1955. 6V was standard to about 1953, if I remember correctly.

 

No way that car is positive ground. Fords were positive ground until some point in the 50'.s Olds was not. This is pretty common knowledge.

 

A google search turned this up for what its worth.

The 1958 Oldsmobile 98 uses a 12-volt, negative-ground electrical system. A large positive cable runs from the battery to the starter solenoid, while a ground strap connects the negative terminal to the engine block. The alternator/generator and lighting circuits connect through the regulator and starter relay.
Key 1958 Oldsmobile 98 Battery Circuit Components:

• Battery: 12-Volt, typically Group 24 or 27.
• Positive Cable (+): Direct connection to the starter solenoid.
• Negative Cable (-): Ground connection to the engine block or frame.
• Charging System: Generator or early Alternator with a voltage regulator.

For detailed, full-color routing, specifically labeled wiring diagrams for the 1958 Oldsmobile are available from vendors like Classic Industries or eBay.
120258L | 1958 Oldsmobile; Color Wiring Diagram ; 11X17
120258L - 1958 Oldsmobile; Color Wiring Diagram ; 11X17 * Product #: 120258L. * CATEGORY: Wiring Diagrams. * SHIP TYPE: Standard |

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A google search turned this AI up for what its worth.

The 1958 Oldsmobile 98 uses a 12-volt, negative-ground electrical system. A large positive cable runs from the battery to the starter solenoid, while a ground strap connects the negative terminal to the engine block. The alternator/generator and lighting circuits connect through the regulator and starter relay.
Key 1958 Oldsmobile 98 Battery Circuit Components:

• Battery: 12-Volt, typically Group 24 or 27.
• Positive Cable (+): Direct connection to the starter solenoid.
• Negative Cable (-): Ground connection to the engine block or frame.
• Charging System: Generator or early Alternator with a voltage regulator.

For detailed, full-color routing, specifically labeled wiring diagrams for the 1958 Oldsmobile are available from vendors like Classic Industries or eBay.
120258L | 1958 Oldsmobile; Color Wiring Diagram ; 11X17
120258L - 1958 Oldsmobile; Color Wiring Diagram ; 11X17 * Product #: 120258L. * CATEGORY: Wiring Diagrams. * SHIP TYPE: Standard |

 

This info is from Motor's Auto Repair Manual.
All Oldsmobiles from at least 1949 and up are negative ground
1949 thru 1952 Olds were 6 volt, 1953 and up are 12 volt.
Buicks (except 1953 Special) and Cadillacs are the same way.
Chevys and Pontiacs from at least 1949 and up are negative ground.
1949 thru 1954 were 6 volt. 1955 and up were 12 volt
Fords, Mercury's and Lincolns were positive ground and 6 volts from at least 1948 thru 1955 .
1956 and up were 12 volt and negative ground.
Chrysler had positive ground from 1949 thru 1955
1956 and up were negative ground.
1949 thru 1955 were mostly 6 volt except a few 1953 thru 1955 models with 12 volts
All 1956 and up were 12 volts

 

Everything I'm seeing says it's supposed to be a negative ground, looking at it it was hooked up positive ground my questions are would it have run that way.? And what would be the damage ? The owner lives out of town and I'm going by what he said

 

Yes, it is possible someone (PO) changed wiring from (-) ground to (+) ground. Absolutely, it would have run that way. The battery GROUND dictates polarity.
There would likely be no damage if performed correctly. If this car has an Ammeter, it's likely to have the sensor wires (on back of ammeter gauge) reversed on the terminals.
Generally, if using the same OEM IGN COIL you'd reverse the distributor & key switch positions then momentarily flash the GEN/ALT so as to match polarity. The only caveat to this I'm aware of might be the use of a positive ground aftermarket Pertronix IGN COIL. Pertronix sold or still sells a positive ground IGN COIL (it's possible there are others).

On a NEGATIVE grounded battery system:
"DIST" (-) terminal on coil goes to distributor.
"BAT" (+) terminal on coil goes to key switch.

On a POSITIVE grounded battery system:
"DIST" (-) terminal on coil goes to key switch.
"BAT" (+) terminal on coil goes to distributor.

You can find many articles regarding conversions from (-) ground to (+) ground - for a variety of reasons. Here is a simple to read dialogue:

Ignition Coil wiring hookup... Battery ground dictates.

 

If it were me, I'd stay away from this car. It may not have been the current owner, but apparently someone along the way converted it to positive ground for some reason. Who knows what else has been done to the car that might make it difficult to service, or even figure out what was done in the first place. You could be buying a four-wheel headache.

At least, I'd ask the seller point blank, this car was negative ground when new. Why is it positive ground now?

 

99% chance he'll say, "I have no idea." This should reinforce your advice and OP's likely decision to stay away.

 

Pictures of the car might help establish if the car is worth pursuing. The fact it's supposedly employing a (+) ground would not dissuade me from pursuing the car if it meets other expectations. You have the option to reverse polarity back to (-) ground if you desire. This isn't a big deal, IMO.

 

My point was that this might NOT be the only significant modification done to the car. For all we know, it's been converted to right-hand drive.

IF the positive ground is the only significant modification, then, yes, probably not a big deal to live with it or convert it back. But this remains to be seen.

 

In another thread, the OP claims the brakes don't work. That would make me wonder how you can drive it and know the transmission is good and shifts into all gears. He also claims the car is "mice infested". Mice DO chew up wiring. Mice also chew up cloth interiors. This isn't just a matter of wrong polarity, as Jaunty points out.
https://classicoldsmobile.com/forums...0/#post1668050

 

I didn't know this OP was same OP as the other thread. As everyone points out...OP has considerable items to address

 

A few mothballs in the inside and under the hood when the car was "parked" would have prevented this disaster.

 

So I knew the previous owner before he passed away.. The car only has 10,000 miles since 1983. It sat in a garage. I looked at it probably 15 years ago. The son has it now. And it's up for sale. I'm supposed to meet him on the 21st and he continually says it's a positive ground car although everything I've read and everything from Oldsmobile says otherwise I have documented oil changes from 1982. It was on the road and registered till 2000
I'm not sure I can convince him it's not positive ground. I guess I will let him start the car that way. It's his car so I guess he can do what he wants
But nothing has been rigged or changed except for new paint done to the car. I'm not sure what year that was done

 

Looks like an OE Delco voltage regulator. Ask him to get the numbers stamped on the reg mounting base. From that you can probably determine the intended polarity.

 

This thread is really a waste of everybody's time. We all know all 59 Oldsmobiles were negative ground from the factory. There would be no reason in the world to convert the car to positive ground if that was even possible. Really. What a waste of time.

 

OP wants to know if damage could have occurred if the car was run on reverse polarity. The answer is probably none, but it is possible the ignition points and the regulator points may be damaged. If the regulator points are run on reverse polarity, it may have caused the points to stick in the past or possibly in the future. If the regulator cutout points stick, it could cause the generator to fry. Have you ever noticed how a set of points will have a tit on one point and a divot on the other point? There is a reason for that. Direction of current flow (polarity). Yes a condenser will minimize that but not eliminate the transfer of material from one point to the other. Running it backwards can cause bad voltage readings, premature regulator failure, or unwanted smoke when the car is shut off. The regulator in his picture has a fuse connected between the battery wire and the bat reg terminal. I would check that fuse. If it is open, then the regulator points may have already stuck. Look at the regulator stamp. If it is 12VN then connect it neg ground. Before you connect the battery, clean the regulator and ign points.

 

Thank you stellar, exactly what I wanted to know. Everything I see on car is 100% original.. hopefully get this worked with seller ...