What is a stem seal?

48 minutes ago, Dolfinz said:

What is a stem seal?

It is the orange rubber piece in your last photo. This goes at the base of your valve in the head to block oil from seeping into your combustion chamber. Example:

 

This isnt a 280z exactly but it will give you the idea of the order of operations 🙂 :

Edited November 24, 20213 yr by Barefootdan

So, it's been a few months since we last discussed this due to my working on other things.  Now that those are completed I still have to resolve the alternator issue.  I replaced the voltage regulator and with the key on I still have no +12v at the F terminal.  See my last question regarding if the motor has to be running for the F wire to get +12.  Reading back through the posts to this point I'm not sure what to try next.  Perhaps someone can advise me further on how to isolate the problem?  I'm running out of ideas.

I had a similar problem 10 years ago in my race car.  The +12V wire from the ignition was gone (a teammate inadvertently removed the wire while cleaning up the harness), so it wasn't charging.  After a lot of head scratching before we figured out that several feet of the wire was missing from the middle of the harness, we ran a new wire from the ignition on to the alternator and it charged fine again.  

The wiring diagram (available online) will show you the color of the wire and the end connections.  Do a continuity test from one end to the other and see if the wire itself is bad.  Worst case, run a new wire.

Yes, you should see 12VDC to ground at the white black white with the ignition on. 

To check, unplug the voltage regulator from the engine harness. Put the key in ON. Measure voltage to ground at the black/white wire on the engine harness. You should see 12VDC. With the VR unplugged, you can also use the ohmmeter function to measure resistance at the two pins marked below. There should be about 0 ohms (continuity). 

If the car will start and run, test the voltage at the battery with the car running. It should be running around 14 VDC or a little more. That is a better test.

 

So I can just run a new wire from the ignition switch to the F terminal on the alternator?  I was previously advised against it as it would bypass the voltage regulator.

24 minutes ago, Dolfinz said:

So I can just run a new wire from the ignition switch to the F terminal on the alternator?  I was previously advised against it as it would bypass the voltage regulator.

No! That is not the right solution. Run the tests I posted. Figure out what is wrong and fix it. You will get better results.

Steve,

I performed the suggested tests.  On the wiring harness the white wire is hot regardless of key position.  With key ON no other wires get hot including the black/white.  As for the continuity on the VR connector, I have 3 ohms between those 2 terminals.  Next steps to determine why black/white wire isn't getting hot with key ON?

 

18 minutes ago, Dolfinz said:

Steve,

I performed the suggested tests.  On the wiring harness the white wire is hot regardless of key position.  With key ON no other wires get hot including the black/white.  As for the continuity on the VR connector, I have 3 ohms between those 2 terminals.  Next steps to determine why black/white wire isn't getting hot with key ON?

 

So the white wire has the battery sensing voltage. It should have 12VDC to ground full time, so that's good.

The black/white wire in the engine harness should have 12VDC to ground when the key is ON. It branches off the wire that goes from connector C-7 under the dash all of the way to the ballast resistor. Corrosion could have built up where Nissan spliced it into the wiring harness, but that seems strange for an AZ car. Just for fun, unplug the black/white wire from the condenser under the voltage regulator and test again at the voltage regulator connector and the bullet connector that was connected to the condenser.

The ballast resistor is located under the VR.  Where is the condenser?

A few more thoughts.  I was reviewing the manual transmission whole car harnesses wiring diagram and it appears that the black/wht wire beyond the C-7 connector at the fire wall, inside the engine compartment, only goes to the VR and condenser correct?  There appear to be other places it goes from the ignition switch that aren't in the engine compartment that are apparently working; since it runs.  From my recent experience troubleshooting and repairing my gauge issues I had to bypass the firewall connectors, thus I am very suspect of those connectors. I am curious to see if the condenser has voltage or continuity to the harness plug at the VR, but as previously stated I have no idea where it is. At this point I think I may need to bypass C-7 as I did for the other connectors related to the gauges and connect the blk/wht wire from the dash harness directly to the same in the engine harness.  Open to other thoughts.

3 hours ago, Dolfinz said:

A few more thoughts.  I was reviewing the manual transmission whole car harnesses wiring diagram and it appears that the black/wht wire beyond the C-7 connector at the fire wall, inside the engine compartment, only goes to the VR and condenser correct?  There appear to be other places it goes from the ignition switch that aren't in the engine compartment that are apparently working; since it runs.  From my recent experience troubleshooting and repairing my gauge issues I had to bypass the firewall connectors, thus I am very suspect of those connectors. I am curious to see if the condenser has voltage or continuity to the harness plug at the VR, but as previously stated I have no idea where it is. At this point I think I may need to bypass C-7 as I did for the other connectors related to the gauges and connect the blk/wht wire from the dash harness directly to the same in the engine harness.  Open to other thoughts.

 

On 4/6/2022 at 8:27 PM, SteveJ said:

So the white wire has the battery sensing voltage. It should have 12VDC to ground full time, so that's good.

The black/white wire in the engine harness should have 12VDC to ground when the key is ON. It branches off the wire that goes from connector C-7 under the dash all of the way to the ballast resistor. Corrosion could have built up where Nissan spliced it into the wiring harness, but that seems strange for an AZ car. Just for fun, unplug the black/white wire from the condenser under the voltage regulator and test again at the voltage regulator connector and the bullet connector that was connected to the condenser.

 

Edited April 8, 20222 yr by SteveJ