New to me car: 400G intake manifold vacuum lines and electrical sensors

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Old November 13th, 2023, 08:35 PM
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New to me car: 400G intake manifold vacuum lines and electrical sensors

Hey everyone,

finally got my first Oldsmobile and actually drove it 500 miles home through the Sierra mountains.

I got home and started checking out some of the vacuum lines and was wondering if anyone can make some recommendations.

I noticed the advance is pulling port. The engine seems to run fine on that so I won’t mess with it.

the TVS vacuum tree is not being used. If it’s not capped, is that a vacuum leak source? What bolt size do you recommend I use to block off?

would also love to wire the vacuum lines correctly from the air cleaner solenoid. Not exactly sure of the function of that. The flap just stays open.

the tops sensor is broken, I think it’s an idiot light sensor, for maybe oil temp? I’d like to replace that.

and then on the topic of wiring, there are loose connections near the drivers side fender.

would love everyone’s input as I would like to keep driving this thing.







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Old November 13th, 2023, 08:43 PM
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Nice looking car.
I would recommend a factory service manual.
The fuel line is also not correct.

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Old November 13th, 2023, 08:53 PM
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The distributor is connected directly to a vacuum source, so the TVS can be left disconnected with no issues.
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Old November 14th, 2023, 02:33 AM
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The factory configuration used ported vacuum to operate the vacuum advance. Because of this, the factory vac advance can and initial timing are designed assuming no vacuum advance at idle. The TVS is intended as a safety feature. If the car starts to overheat, the TVS switches from ported to manifold vacuum at the distributor, which increases timing, increases idle speed, and lowers coolant temp. Bypassing it while continuing to use ported vacuum only serves to increase the risk that the car may overheat on a hot day in traffic. Unfortunately, people who don't take the time to understand why the part is there simply disconnect it out of ignorance.
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Old November 14th, 2023, 06:13 AM
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Originally Posted by joe_padavano
The factory configuration used ported vacuum to operate the vacuum advance. Because of this, the factory vac advance can and initial timing are designed assuming no vacuum advance at idle. The TVS is intended as a safety feature. If the car starts to overheat, the TVS switches from ported to manifold vacuum at the distributor, which increases timing, increases idle speed, and lowers coolant temp. Bypassing it while continuing to use ported vacuum only serves to increase the risk that the car may overheat on a hot day in traffic. Unfortunately, people who don't take the time to understand why the part is there simply disconnect it out of ignorance.
I read a lot of your comments explaining how the bypass works. In a few of them you stated if the engine operates fine on port, then probably best to leave it. Especially if port and manifold vacuum are the same at throttle opening.

do you have any advice on that sensor that is broken off in the manifold?
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Old November 14th, 2023, 07:31 AM
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The broken sensor is just the switch for the HOT light. They are available everywhere.
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Old November 14th, 2023, 08:05 AM
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Good luck with the new ride!

Changing the rubber fuel line between the fuel pump and the carburetor back to original steel fuel line would be a priority on my list. If the rubber hose leaks it will put gasoline on a hot engine. If the heat doesn't cause ignition/fire, spark from a leaky plug wire, coil or armature from an alternator could be enough.
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Old November 14th, 2023, 08:35 AM
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Originally Posted by Sugar Bear
Good luck with the new ride!

Changing the rubber fuel line between the fuel pump and the carburetor back to original steel fuel line would be a priority on my list. If the rubber hose leaks it will put gasoline on a hot engine. If the heat doesn't cause ignition/fire, spark from a leaky plug wire, coil or armature from an alternator could be enough.

I agree. Looking for that part now. Those are compression fittings and don’t need any tape on them, correct?
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Old November 14th, 2023, 08:36 AM
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Originally Posted by joe_padavano
The broken sensor is just the switch for the HOT light. They are available everywhere.

would something like this work?

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Old November 14th, 2023, 09:05 AM
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Not compression fittings.

Double flared ends with tubing nuts. Put anti-seize between the nuts and the lines. Tape on the threads is ok to prevent seizing but it shouldn't be needed to prevent leaks, the seal is at the flare, not the threads.
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Old November 14th, 2023, 11:26 AM
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Originally Posted by Sugar Bear
Not compression fittings.

Double flared ends with tubing nuts. Put anti-seize between the nuts and the lines. Tape on the threads is ok to prevent seizing but it shouldn't be needed to prevent leaks, the seal is at the flare, not the threads.
thank you
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Old November 14th, 2023, 11:42 AM
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Originally Posted by Pitbull2o08
I agree. Looking for that part now. Those are compression fittings and don’t need any tape on them, correct?
Steel fuel lines are available reproduction. Try Fusick Automotive or Inline Tube. Both are strongly Oldsmobile oriented.

With these available, there's no reason to put yourself thru the aggravation of trying to make those tight bends and double flares.

Last edited by rocketraider; November 14th, 2023 at 11:44 AM.
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Old November 14th, 2023, 02:49 PM
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Originally Posted by rocketraider
With these available, there's no reason to put yourself thru the aggravation of trying to make those tight bends and double flares.
Oh, yes there is. I got a carb to pump fuel line from ILT and although the flares and fittings are good, I am now having to buy a tube bending tool to modify the line so it'll fit. Maybe I should have tried Fusick.
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Old November 14th, 2023, 04:33 PM
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Originally Posted by BangScreech4-4-2
Oh, yes there is. I got a carb to pump fuel line from ILT and although the flares and fittings are good, I am now having to buy a tube bending tool to modify the line so it'll fit. Maybe I should have tried Fusick.
Ditto my experience w/ ILT. Thankfully a friend owns a tube bending device.
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Old November 14th, 2023, 04:42 PM
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Originally Posted by BangScreech4-4-2
Oh, yes there is. I got a carb to pump fuel line from ILT and although the flares and fittings are good, I am now having to buy a tube bending tool to modify the line so it'll fit. Maybe I should have tried Fusick.
I've heard that the aftermarket pump-to-carb lines are poorly formed, and mine was no different, but not too far off. My replacement line (Fusick) was about an inch off from correct orientation at the carb when connected to the pump. What I did was attach well at the pump, with the line in it's closest approximation to carb inlet. I gently bent the line closer to the carb inlet. I then unbolted the carb from intake. Next I lifted the carb and slightly rotated it to align with the fuel line, connected the line to the carb and sealed correctly, then lowered the carb back onto the intake while carefully massaging the "factory" bends and bolted in place. This way the connections at the pump and carb both lined up and sealed correctly to the line. Connecting the line first, then moving the carb to correct installation location, while "massaging," allowed me to get it all together with no leaks. Then after everything was torqued into place, I gently "plied" the hard line to, in my mind, relieve some of the stress. Five years later, no leaks. I can unbolt the line from either the pump or the carb and the ends of the line remain in the port/connector(s) on the carb and pump. Reconnecting later, and still no leaks.

Last edited by BackInTheGame; November 14th, 2023 at 04:45 PM.
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Old November 14th, 2023, 04:43 PM
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Does anyone know why there’s a positive terminal on the drivers fender?
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Old November 14th, 2023, 09:20 PM
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Oldsmobile used a junction block and horn relay mounted on the fenderwell. Battery (+) cable runs to the starter solenoid, but it has a 10 gage wire running from the battery (+) terminal to the junction block post. This powers the whole car.

You need a 1969 factory Olds Chassis Service Manual. It has the wiring diagrams and plenty of other things that will help you understand and service your car.
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Old November 14th, 2023, 10:06 PM
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Originally Posted by rocketraider
Oldsmobile used a junction block and horn relay mounted on the fenderwell. Battery (+) cable runs to the starter solenoid, but it has a 10 gage wire running from the battery (+) terminal to the junction block post. This powers the whole car.

You need a 1969 factory Olds Chassis Service Manual. It has the wiring diagrams and plenty of other things that will help you understand and service your car.

yeah I’m reaching out now to some people that might have an original one. Thank you
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Old November 15th, 2023, 04:10 AM
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Originally Posted by Bernhard
I would recommend a factory service manual.

Originally Posted by rocketraider
You need a 1969 factory Olds Chassis Service Manual. It has the wiring diagrams and plenty of other things that will help you understand and service your car.
Originally Posted by Pitbull2o08
yeah I’m reaching out now to some people that might have an original one. Thank you
You want the one pictured, not a Chilton's or a Haynes.
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Old November 15th, 2023, 06:12 AM
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Many original used OEM CSM manuals available, some w/ free shipping, some in worse/better condition. Do your research...

https://www.ebay.com/itm/16637673770...evt=1&mkcid=28

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