1938 Buick Vacuum Starter Switch Adjustment Help!

[1938BuickLimited90]

Hello all, 

My 1938 Buick Limited 90 series has a vacuum actuated switch connected to the carb that when you push the gas pedal with the ignition turned on starts the vehicle. I have replaced this switch twice in the last year with NOS units that I have sourced and they never seem to work right. Sometimes it works intermittently and other times it does not work at all. Then sometimes it cranks once and then will not crank again using the pedal. I have already had the starter rebuilt so I know it is not that, plus if you take a jumper wire and jump the two leads that come off the switch that go directly to the starter the car starts right up. Has anyone else had this issue with their car or have any helpful advice? There are instructions in the original packaging that state how to install and adjust the switch but I am not sure what the adjustment instructions are actually telling me to do. Any helpful advice would be appreciated!

Thanks!

Stefano

[neil morse]

This really isn't an answer to your question, but I'm throwing it out there anyway.  On my '41, a previous owner had disabled the switch on the carb and installed a starter button under the dash.  The wiring is very simple -- just as you say -- the starter button is simply wired to the two leads that come off the carb switch.  I would probably not have made this modification if it hadn't already been made before I bought the car.  I believe in keeping things completely stock.  However, I have to say that I'm in no hurry to change my car back to the carb switch.  I know they can be troublesome, particularly when they don't operate as they should and cause the Bendix gear to stay engaged with the ring gear on the flywheel after the engine starts.  I've seen some pictures of ring gears where the front quarter inch or so is completely worn away on every tooth!

 

Buick used the accelerator/starter system for years, and I'm sure there are folks here on the forum who will help you get yours working.  But you might want to consider just bypassing it and going with a starter button.

[Ben Bruce aka First Born]

Stefano, Neil is spot on.  I drove these cars when a teenager in the 1950s. The switches were a constant problem even then. Dad almost always installed a pushbutton for reliability.   My 1950 has a push button.

 

  Ben

[1938BuickLimited90]

Hi guys thank you for your responses! I was definitely considering bypassing the switch at this point because it has given me so many issues. Can anyone send pictures of their push button starts that were installed so I can get some ideas on where to mount it? 

Thanks again!

[1938BuickLimited90]

Hi guys thank you for your responses! I was definitely considering bypassing the switch at this point because it has given me so many issues. Can anyone send pictures of their push button starts that were installed so I can get some ideas on where to mount it? 

Thanks again!

[1938BuickLimited90]

I really would have liked to keep it stock but I have gotten stuck one too many times because of this issue and it appears even just replacing the unit with a NOS one does not remedy the problem

[MCHinson]

Do you have a 1938 Buick Shop Manual? The vacuum switch is only one part of that circuit. There are several potential problem areas that could be causing erratic operation. Review Chapter 12 of the Shop Manual. The circuit includes the vacuum switch, the solenoid, the solenoid relay, the voltage regulator, and the generator windings. Troubleshooting all of the circuit, I suspect you will find something else that needs adjustment, or at least cleaning. If all of the circuit is returned to original condition, it should start reliably.

 

If you want to add an auxiliary switch, you can add a push button to the bottom of the dash rail (there are a couple of holes there from the factory unless you are already using them for other switches) and you can add wiring to trigger the solenoid relay from an added switch.

[1938BuickLimited90]

1 hour ago, MCHinson said:

Do you have a 1938 Buick Shop Manual? The vacuum switch is only one part of that circuit. There are several potential problem areas that could be causing erratic operation. Review Chapter 12 of the Shop Manual. The circuit includes the vacuum switch, the solenoid, the solenoid relay, the voltage regulator, and the generator windings. Troubleshooting all of the circuit, I suspect you will find something else that needs adjustment, or at least cleaning. If all of the circuit is returned to original condition, it should start reliably.

 

If you want to add an auxiliary switch, you can add a push button to the bottom of the dash rail (there are a couple of holes there from the factory unless you are already using them for other switches) and you can add wiring to trigger the solenoid relay from an added switch.

I do happen to have a shop manual, I believe that the issue does stem from that vacuum solenoid on the carb because I have looked into all the other pieces and everything seems to be working just fine. Plus I have replaced or had the rest rebuilt within the last year. There are instructions on how to adjust the starter switch if it does not work properly after installing but I cannot seem to make sense of the instructions and how to adjust it (if that makes any sense). If I bypass the switch the car starts up just fine everytime. 

I think at this point I will just add a push button start switch

[Ben Bruce aka First Born]

The simplest way, if not the neatest, is run the wires that are now attached to the vacuum switch back through the cowl ,  adding wire if necessary.  The push button simply replaces the vacuum switch.  

 

  Ben

[Eddie-O]

I’ve had this problem with my 41 Special on and off for years. Once in a great while the same thing would happen to me. About once or twice a year. Since I am a purest and want the car “as built” I refused to put a start button on the dash. Tried to source a new switch with no luck ( let me know where you got your replacement switch from ) . The fix is simple though. Open the hood and tap the switch LIGHTLY with a small hammer or wrench a couple of times and voila. She’ll start right up from the pedal. Works every time. Since it happens only on a few occasions I leave well enough alone. I believe the spring inside or plunger sticks from time to time. If I drive the car regularly it never happens. Just when not in use for awhile it will stick on occasion. When someone asks if something’s wrong I just say I’m putting the battery cut off back on. Try it and see if it works for you. Good luck.

[1938BuickLimited90]

46 minutes ago, Eddie-O said:

I’ve had this problem with my 41 Special on and off for years. Once in a great while the same thing would happen to me. About once or twice a year. Since I am a purest and want the car “as built” I refused to put a start button on the dash. Tried to source a new switch with no luck ( let me know where you got your replacement switch from ) . The fix is simple though. Open the hood and tap the switch LIGHTLY with a small hammer or wrench a couple of times and voila. She’ll start right up from the pedal. Works every time. Since it happens only on a few occasions I leave well enough alone. I believe the spring inside or plunger sticks from time to time. If I drive the car regularly it never happens. Just when not in use for awhile it will stick on occasion. When someone asks if something’s wrong I just say I’m putting the battery cut off back on. Try it and see if it works for you. Good luck.

Thanks for the advice! I got my starter switches from ebay and from another member on the forum who had reached out to me about having one. Not sure if a 41 is the same as a 38 would be but they are out there, just can be pretty pricey especially if they are NOS

[Shootey]

3 hours ago, Eddie-O said:

The fix is simple though. Open the hood and tap the switch LIG

Do you do the tap before you first start the car or in the field when the throttle starter won’t work after having driven the car?

[edinmass]

The switch on our 34 is original and works fine………..I agree with the above. Check the rest of the circuit. It’s a neat set up, and worth getting it right. Showing people you start the car by putting your foot to the floor on the accelerator is fun……..

[EmTee]

You could go ahead and wire a pushbutton in parallel with the original vacuum switch, which I think you may prefer to do.  That way, when the vacuum switch balks, you can simply use the pushbutton to get going and fiddle with the vacuum switch when you get home.  Just run wires from the vacuum switch terminals back through the cowl to the momentary dashboard switch.  Ensure the wires are protected with a grommet (or use an existing penetration) where they pass through the firewall.

[Eddie-O]

Like your issue, at times it will turn over once then won’t work on the second try. Open the hood with ignition off and do the tap trick. Go back and turn on ignition and step on the pedal. She’ll spin over just fine. My car can go on weeks or even all season after with no problems and work as it should. Some times it never fails from spring to fall. Just fickle at times. Like other posts, I like my cars as built and it is neat to show people how the car starts. If you can’t start it the first time you try the tap method, just do it again. It does work! Let me know how it works for you and good luck.

[1938BuickLimited90]

3 hours ago, Eddie-O said:

Like your issue, at times it will turn over once then won’t work on the second try. Open the hood with ignition off and do the tap trick. Go back and turn on ignition and step on the pedal. She’ll spin over just fine. My car can go on weeks or even all season after with no problems and work as it should. Some times it never fails from spring to fall. Just fickle at times. Like other posts, I like my cars as built and it is neat to show people how the car starts. If you can’t start it the first time you try the tap method, just do it again. It does work! Let me know how it works for you and good luck.

Ill try it and see what happens thank you!

[1938BuickLimited90]

3 hours ago, EmTee said:

You could go ahead and wire a pushbutton in parallel with the original vacuum switch, which I think you may prefer to do.  That way, when the vacuum switch balks, you can simply use the pushbutton to get going and fiddle with the vacuum switch when you get home.  Just run wires from the vacuum switch terminals back through the cowl to the momentary dashboard switch.  Ensure the wires are protected with a grommet (or use an existing penetration) where they pass through the firewall.

That sounds like not a bad idea to have both, I think it would be wise to do this, thank you for the advice

[DonMicheletti]

That starter / choke mechanism is a real Goldberg.

It may be that some of the complicated mechanism in the housing is gummed up and not letting things work right.

There is a pushrod inside that does the actual switch operation. It may have worn and has become too short. I had that happen on one of my '38's. I made a new, longer pushrod to solve the problem.

 

I like thing working as they should too.

[1938BuickLimited90]

1 hour ago, DonMicheletti said:

That starter / choke mechanism is a real Goldberg.

It may be that some of the complicated mechanism in the housing is gummed up and not letting things work right.

There is a pushrod inside that does the actual switch operation. It may have worn and has become too short. I had that happen on one of my '38's. I made a new, longer pushrod to solve the problem.

 

I like thing working as they should too.

I will check that out thank you! The funny thing is that sometimes if you get out of the car and yank on the throttle rod hard enough that connects to the carb the switch will then work, very odd. Never had an issue with this in all the years of owning this car until the last year, can be so frustrating! I just want to drive it 

[neil morse]

On 10/11/2023 at 5:58 AM, 1938BuickLimited90 said:

Can anyone send pictures of their push button starts that were installed so I can get some ideas on where to mount it? 

In another thread, someone suggested that people have to drill through the engine-turned panel to install a starter button.  That's simply not true.  In fact, that would be a very difficult way to try to do it since those panels are not at all easy to remove and there is very little room behind them.  There is plenty of space install a starter button on the underside of the dash.  Here's a photo of what a previous owner did on my '41.  I'm assuming that the '40 dash has the same basic design.

 

[Talarico8447]

 

 

Here's my solution. I also like to keep my cars the way they came from the factory so when my vacuum switch acts up I just hook up my Snap On remote starter button to the switch terminals and presto! I keep it handy in the trunk. It always seems to happen If you're at a high profile event or have guests in the car. 🙄

Edited October 23, 2023 by Talarico8447 (see edit history)