UPDATE!

Started from scratch and redid every test. lights started working again so I'm guessing the plug wasnt seated well, or the pin to the board is coming loose.

Got the car up to 200 on the new gauge. Rallye gauge lifted abot 1/8 of an inch at the temp. Measured resistance on the sender, had 130 at that temp. Going to put the old sender back in it and see.

Hi all,

I'm racking my brain and thoroughly stuck. I've searched the threads and cannot find anything similar to my issue, but I think they have given me enough insight to give you all as much data as possible and I would greatly appreciate any help!

1968 Oldsmobile 442, 400, 4 speed, original wiring, original Rallye Pack with Tic Toc Tac, points distributor.

Issues:
- Rallye temp gauge is pegged BELOW the C, not pegged to H, when key is in RUN or ACC. It stays this way when engine is fully warmed up.

- No dash light to speedo cluster. All other lights operational.

- Coil gets really warm when ignition is on but engine is not running. Pretty sure this is normal and the points are probably closed. But trying to include all 'symptoms'.

Work done that may be cause:

- Installed Bosch 3 gauge cluster with Temp, Oil PSI and Voltmeter. Mostly for temp so I could see a number in relation to rallye gauge.
* Used the ash tray light to feed the new gauge lights
* Used the radio power for temporary Voltmeter feed
* Oil PSI is fed from copper tube off a tee with original sender and new sender in the tee.
* Moved and replaced the rallye temp sensor to 2nd port on intake (Eddie 2151) and put the new bosch sensor in port closest to head for depth clearance.

- Installed new vacuum advance on the distributor, old one wasn't moving under vacuum.
* Also added some length to the coil negative -> distributor wire as it was tight when I got to the right timing position. Connection is soldered and insulated.
* One thing to note that I need to fix, previous ownership plugged the solid black carb idle stop wire to the distributor. So I know I need to switch it back to the black with brown stripe wire, assuming its still good.

Troubleshooting steps so far:
- For the rallye temp gauge issue:
* Checked continuity of green wire. GOOD
* Checked for good ground of sending unit. GOOD
* Checked resistance in both old and new rallye sending units. #1 is 650 ish at 80 degrees, #2 is 623 at 80 degrees, and both are around 225 at 150 degrees.
* Check and replace grounding jumper between gauge pods. Added ground from jumper to dash, because grounding. PROBLEM?
* Checked voltage at sending units. 12 +/- .5 volts with engine OFF, key ON. PROBLEM?
* Grounded out the sending unit wire and rally gauge went to full H. GOOD?
* Not able to check the gauge independent of the car for now as I dont have the right tools, but I can pull it and check continuity and resistance if needed.

- For the speedo dash lights
* Ground jumper checked and added another jumper to the dash just in case as stated above.
* Bulbs checked. Replaced ones that were questionable.
* Turn signal indicators both work
* Lights in the bosch pod all work and respond to dimmer.
* Both othe pods have dash lights.

Also made sure the new gauge pod has a good ground. All gauges work great. Voltmeter is steady showing 12 ish with engine off and between 13 and 14 volts nice and steady when running.

I'm sure I missed something and I will provide any other info you need besides my social security number and date of birth. Like I said, brain is properly racked and fried on this.

Thanks all in advance!

 

You didn't use teflon tape on the sender threads?
Also . I'm not a fan of having oil plumbed into the interior, when I do have to use it, I put wire heatshink tubing over the copper , so if it leaks other than at fiting it slows the leak from spraying everywhere.
Kinda like home oil heat copper tubing with the plastic cover that is code now.

 

Ground for the sensor is good. I didn't use teflon, but did use a light coating of high tack on the sending unit, which is something I've always done.

I agree about oil in the car. I have heat shrink on all the friction points for that reason, but didn't do the whole line. Good thing to consider when I clean up the bay this winter.

I've had the car for a year now and am just getting started on the cleanup. I think first order of business this winter is a new wiring harness. I'll either go with American Autowire, which I have really enjoyed their kit on other cars, or replace with factory style. Not sure yet. Electrical and I have a love hate relationship.