[Sam Warren]

I am having a problem with my 400 Turbo leaking fluid, it seems to be leaking at the point of entry from my speedometer cable into the speedometer driven gear housing but it is not the larger O ring that inserts into the transmission housing, when I detached the cable I did not have any kind of gasket or O ring. Is there one supposed to be there ?

Thank you

["QUICK-SILVER"]

If it's leaking where the cable attaches, most likely needs a new driven gear seal.

Clay

[Sam Warren]

Thank you, I replaced it once but maybe it was bad, I'll try it again

[stevep]

Make sure that the driven gear shaft is not chewed up.

[Sam Warren]

I am going to try to uplaod some pics of my driven gear assembly, are there any seals inside this housing that can be replaced other then the outer O ring ?, This assembly has me stumped as I have never seen this on this year model. Thanks in advance

[Andretti]

I've never seen an housing like that, does it have cruise control? Pretty high tech speed sensor for the time. I remember the aftermarket Cruise Control Kits sold back then using a magnet clamped to the driveshaft and a cheap tin bracket (usually screwed right thru the floor) holding the sensor.

A common leak with the non cruise adapter housing occurs at the end seal under the speedo cable nut. Fluid walks thru the shaft and past that small seal.

[Sam Warren]

No cruise control, This car was ordered and sold in California, sent to Hawaii and then back to California where it made its way to Arkansas.. It looks like I can remove the inner shaft but no way to disassemble the housing to see if there are any inner o-rings or seals that can be replaced. Thanks for all the help and comments

[Andretti]

Don't think you'd need to disassemble anything further to replace that shaft seal. An angled hook tool to pull it out and you'll see the new seal presses back in. Some use a small 'C' clip on the outer side but it'll seal fine without it.

So the mystery is, what's the single wire speed sensor used for?

[Sam Warren]

Good question, this is a pic I took underneath the car where the single wire ties into another sensor of some sort at the transmission then feed up somewhere. I will trace the wires and see where they go. Thank you

[stevep]

That is for spark control and I have never seen a repair for them when they leak

[Sam Warren]

What does the spark control do ?, sorry if this is a stupid question

[stevep]

I believe that it retards the timing at a certain speed. We ALWAYS eliminated them when they leaked. You have to get a non spark control gear, bracket and adapter.

[Kenth]

The 1972 Pontiac CCS System: This year's CCS set up was redesigned. A new Speed Control Spark Advance operation was added by combining bits of the older TCS and CEC set ups. The new acronym for Speed Control Spark Advance is SCS.
The SCS system has a vacuum advance solenoid valve and temperature sensing switch. The TCS switch is replaced with a speed control spark (SCS) switch. The SCS allow vacuum spark advance to road speed above 38 mph. The TCS/SCS temp sending switch was moved from the top of intake manifold to the right of the rear cylinder head between plugs 6 and 8. The switch was recalibrated to allow vacuum advance at engine temps below 95 deg F and above 230 deg F.