1939 Buick Special Model 41

[MHT30]

How do you stop the starter re-engaging when you are driving?

 

Example: driving 30 mph, then you push the gas pedal past 50% the starter wants to start and you hear a grinding.

 

What is the mechanism that adjusts this, or stops it wanting to re start?

 

Edited September 13, 2023 by MHT30 (see edit history)

[MCHinson]

How is your generator? How about your voltage regulator? Any vacuum leak? Originally on Buicks of this era, system was designed so that the accelerator would engage the starter when the generator is not charging and the engine vacuum is not present, i.e., voltage from the generator when running prevents the starter from engaging and engine vacuum generated by a running engine prevents the starter from engaging. I would suggest you try the trouble shooting steps in the 1938 Buick Shop Manual to see what is wrong. Most likely there is a generator or voltage regulator or wiring problem causing this.  

[Ben Bruce aka First Born]

Matt is correct, of course.   Another way is to install a push button instead of the "foot feed" start. 

 

  Ben

[Bloo]

Two things keep it from re-engaging, vacuum and generator charging. There is a little relay on the back of the starter. It needs hot and ground to engage the starter. Hot comes from the pedal switch and a vacuum switch. Ground comes from the charging system. @MCHinson has it right. Look in the shop manual and see what has been changed or miswired. The fact that it comes in under acceleration sounds like the charging system side.

 

The factory setup is sort of a double safety. If the car is idling or running under light load the vacuum is high and the vacuum switch disables the starter. It doesn't matter if the generator is charging or not. If you are under acceleration vacuum is low, but the generator is charging, and that disables the starter.

 

The little wire coming up from the relay on the starter originally connected to a "GRD" terminal on a 5 terminal regulator. "GRD" isn't exactly ground, it is a contact in the regulator that is only grounded when the generator is NOT charging. If you have a 4 terminal regulator you should still have this "GRD" terminal. If you have a 3 terminal regulator, you could try hooking that little wire to the GEN terminal. Buick did it this way on some newer models. It might work. I strongly suggest looking closely at the wiring diagram in the shop manual so you can see exactly what I am talking about.

 

[MHT30]

Thanks guys, I will start digging in.

[dodge28]

I had a 41  Buick Century . The way to start was to push the gas pedal to the floor and also the clutch pedal at the same time. The gas pedal has an electrical attachment at the carb linkage. I suspect the 38 may have the same set up. If it is there is an adjustment  for it. I am subject to correction here . Sometimes my 88 year brain falters.

 

[1939_Buick]

20 hours ago, MHT30 said:

How do you stop the starter re-engaging when you are driving?

Example: driving 30 mph, then you push the gas pedal past 50% the starter wants to start and you hear a grinding.

What is the mechanism that adjusts this, or stops it wanting to re start?

Download the 1942 Buick shop manual for free. All of it section by section.

Or click the pdf link to pay $9.95.

http://www.oldcarmanualproject.com/manuals/Buick/1942/Shop Manual/

It is very comprehensive and has information that can be used with all straight 8’s.

It has more information than was included in older “Shop Manuals” before 1942

Has a good section on the carb vacuumn starter switch.  Including sections 12-08 to 12-14 (Chapter 13 in the web site)

Edited September 11, 2023 by 1939_Buick (see edit history)

[critterpainter]

The clutch does NOT need to be depressed. Just shift to neutral before starting the engine.   Pressing in the clutch adds needless load on the starter and puts wear on the engine thrust bearing surfaces.   Pre government intervention cars instructed the operator to shift a manual transmission into neutral for most makes.   

[EmTee]

The 1938 Buick shop manual suggests depressing the clutch when starting in cold weather in order to remove the transmission load from the starter when the transmission oil is like molasses...

 

Edited September 12, 2023 by EmTee (see edit history)

[drhach]

On 9/11/2023 at 9:27 PM, critterpainter said:

The clutch does NOT need to be depressed. Just shift to neutral before starting the engine.   Pressing in the clutch adds needless load on the starter and puts wear on the engine thrust bearing surfaces.   Pre government intervention cars instructed the operator to shift a manual transmission into neutral for most makes.   

Well, actually page one of section 12-1 of the 1942 Shop manual says:

 

"Always depress the clutch pedal when starting in cold weather to release load caused by heavy lubricant in transmission. Service stations should give this instruction to owners."

 

I always push in the clutch when I start the car. It's less mass for the starter to spin. I just noticed EmTee beat me to the punch on that one. 

 

Edited September 13, 2023 by drhach (see edit history)

[MHT30]

I have the 37-39 Shop Manual.

 

Could a voltage regulator cause this problem?  I am running an alternator, not generator. My VR does not have a wire connected to the right side. For some reason it was removed and taped to the side of the harness.

[Bloo]

33 minutes ago, MHT30 said:

I am running an alternator, not generator.

That's why it's grinding. That doesn't work. If you want it to work, you have to come up with some way to disconnect the ground from the starter relay whenever the engine is turning. That appears to be the center wire on top. You could conceivably use an oil pressure switch, although that seems a little shaky to me. Maybe you could use the idiot light wire from the alternator to trip another relay to take the starter relay ground away.

 

[MCHinson]

If you have an alternator rather than the original generator, I would suggest you simply disconnect the original accelerator starting circuit and replace it with a push button starter switch. I would either switch everything back to how it was originally, or convert it to the starting system to a push button mounted  on the bottom of the dash rail. 

[critterpainter]

On 9/12/2023 at 7:12 AM, drhach said:

Well, actually page one of section 12-1 of the 1942 Shop manual says:

 

"Always depress the clutch pedal when starting in cold weather to release load caused by heavy lubricant in transmission. Service stations should give this instruction to owners."

 

I always push in the clutch when I start the car. It's less mass for the starter to spin. I just noticed EmTee beat me to the punch on that one. 

 

My bad.   I grew up in an area where 18 degrees was considered COLD.   Those of you in the -20 would have a different reality. Then do push the clutch in.

[drhach]

18 Degrees? That's when we put on our shorts