I am working on a club member's car, and I have a rather strange electrical issue.
The car is a bone stock 91+. I swapped engines in the car a few years back and it has been fully maintained.
Here is the background. A year or so ago, his alternator went out, so he bought another one from a local parts house. It may or may not be related, but since then, he has gone through 3 or 4 radiators. THe radiators keep generating leaks. I did not swap his alternator or radiators (other than the first one with the engine), but he has had a local shop do the radiators, and last time, they commented on how the coolant smelled like burned electrical parts. They thought the car had a short or some other electrical issue that was corroding/burning a hole in the radiator and the car had problems with overheating.
The owner got frustrated, so the car has sat for almost a year now, and I am just helping him out. Unfortunately, I do not know where the leaks were being generated in the radiator.
Here is what i have found.
1) His battery was 100% dead. I was able to bring it back to life and it is now holding voltage. It is a 2 year old Spiral cell (Red Top branded for a different company).
2) His new alternator was dead and putting out 0 volts. I took an old used alternator from our parts and put it on his car. I noticed that his new radiator had a very small pulley, so I am inclined to think that is was a SLO alternator, and the smaller pulley made it overspin. I would bet that is why the relatively new alternator is dead.
3) After changing alternators and charging his battery, his charging system seems to function normally, and the car is not overheating (the cooling fan comes on and off as it is supposed to, so I would think the CCRM, temp sensors and fan are all in good condition).
I would bet his overheating problem is related to the bad alternator not putting out the correct voltage (messing up the fan and CCRM), but I have no way of verifying this.
On a normal car, I would say the car is now fine, and he just needs a new alternator of the correct style.
BUT
His comment on the radiators failing worries me. To double check everything, I started looking for stray voltage, floating ground, etc. I am measuring all over the engine and components, and I get a very consistent 0 volts. It seems very constant and well grounded. I measured between the radiator core and the ground terminal and I got -.57 to -.61 volts. I thought it strange that I am getting NEGATIVE voltage. I am actually measuring voltage below the voltage of the negative battery terminal.
I started measuring around to other components, and came up with the same -.6V The only component that measured any odd voltage was the radiator core, and it was relative to everything. The radiator cap actually measured -.26 V and it is totally isolated from everything by the plastic radiator neck??
While I am measuring, I would periodically get 0V from the radiator, and then I would go back, and it was back to -.6V I don't know why it is doing this, and I never saw it change from 0 to -.6 while I was in one place. It was only between moving the probes, and even then, it woudl usually go back to -.6V if I came back to the radiator later. I get the -.6 V with the car running or with the KOEO. I did not check the voltage when the key was off because I went in for dinner.
Since it is negative voltage (don't know where that could come from in the electrical system, and because it seems isolated to the radiator, I am wondering if I am seeing some sort of a dielectric reaction??
What are your thoughts, and what would you recommend I do?
Thanks
- Mike
The car is a bone stock 91+. I swapped engines in the car a few years back and it has been fully maintained.
Here is the background. A year or so ago, his alternator went out, so he bought another one from a local parts house. It may or may not be related, but since then, he has gone through 3 or 4 radiators. THe radiators keep generating leaks. I did not swap his alternator or radiators (other than the first one with the engine), but he has had a local shop do the radiators, and last time, they commented on how the coolant smelled like burned electrical parts. They thought the car had a short or some other electrical issue that was corroding/burning a hole in the radiator and the car had problems with overheating.
The owner got frustrated, so the car has sat for almost a year now, and I am just helping him out. Unfortunately, I do not know where the leaks were being generated in the radiator.
Here is what i have found.
1) His battery was 100% dead. I was able to bring it back to life and it is now holding voltage. It is a 2 year old Spiral cell (Red Top branded for a different company).
2) His new alternator was dead and putting out 0 volts. I took an old used alternator from our parts and put it on his car. I noticed that his new radiator had a very small pulley, so I am inclined to think that is was a SLO alternator, and the smaller pulley made it overspin. I would bet that is why the relatively new alternator is dead.
3) After changing alternators and charging his battery, his charging system seems to function normally, and the car is not overheating (the cooling fan comes on and off as it is supposed to, so I would think the CCRM, temp sensors and fan are all in good condition).
I would bet his overheating problem is related to the bad alternator not putting out the correct voltage (messing up the fan and CCRM), but I have no way of verifying this.
On a normal car, I would say the car is now fine, and he just needs a new alternator of the correct style.
BUT
His comment on the radiators failing worries me. To double check everything, I started looking for stray voltage, floating ground, etc. I am measuring all over the engine and components, and I get a very consistent 0 volts. It seems very constant and well grounded. I measured between the radiator core and the ground terminal and I got -.57 to -.61 volts. I thought it strange that I am getting NEGATIVE voltage. I am actually measuring voltage below the voltage of the negative battery terminal.
I started measuring around to other components, and came up with the same -.6V The only component that measured any odd voltage was the radiator core, and it was relative to everything. The radiator cap actually measured -.26 V and it is totally isolated from everything by the plastic radiator neck??
While I am measuring, I would periodically get 0V from the radiator, and then I would go back, and it was back to -.6V I don't know why it is doing this, and I never saw it change from 0 to -.6 while I was in one place. It was only between moving the probes, and even then, it woudl usually go back to -.6V if I came back to the radiator later. I get the -.6 V with the car running or with the KOEO. I did not check the voltage when the key was off because I went in for dinner.
Since it is negative voltage (don't know where that could come from in the electrical system, and because it seems isolated to the radiator, I am wondering if I am seeing some sort of a dielectric reaction??
What are your thoughts, and what would you recommend I do?
Thanks
- Mike
