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stalling problem...and the wisdom of crowds

Started by savemy67, October 13, 2015, 05:25:32 PM

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savemy67

Hello all,

Five days ago I posted the following message on the Restoration Corner section of this forum.  I am only posting it here as a new topic in the hope of getting more viewers and responses (I have received no responses to the post in the Restoration Corner section as of this writing).  Many of you have a great deal of experience with Cadillacs, but like me, none of us has as much experience as the collective wisdom of the thousands of members of the CLC.  I would enjoy distilling the responses from a dozen or more of you in my efforts to resolve my stalling problem.  Thanks for reading.

Christopher Winter

"Hello all,

1967 Sedan DeVille, 429, TH400, A/C, 90,000 miles.

Over the past several months I have done many repairs on my car - wheel bearings, brakes, exhaust, power antenna, lighting, distributor, and most recently I repaired the fuel tank sending unit which is now back in the tank, and the tank is back in the car with a working fuel gauge in the dash.  I replaced all the ignition components except the coil, but I am confident that the coil is OK.  My timing is set to factory spec, and my timing light indicates that my mechanical and vacuum advance are working (when I rebuilt my distributor, my lung-powered vacuum pump sensed that the vacuum advance was working but weak, it ultimately failed, so I replaced it).

My car starts immediately, and it idles very well.  When the engine is warm, and the choke is off, the curb idle speed is a little above the factory spec.  Vacuum and oil pressure are steady at about 20 inches of Hg and 30 PSI respectively. Even after I removed and replaced my gas tank, the car started in less than 5 seconds.  This indicates to me that my fuel pump seems to be operating OK.  My car has air conditioning, so it has a fuel return line from the fuel filter bowl to the tank, and the tank is vented.  I believe the fuel pump was replaced by the previous owner, and I know the previous owner had the carburetor rebuilt.  Typically, when I start my car, I let it run at idle for about a half hour or more.  The temperature gauge moves to about the first quarter hash mark and stays there.  When I tested the coolant temperature without a radiator cap, the coolant temperature was about 150 degrees F.

I put my car in a dead-level position and checked the transmission fluid after the engine had warmed up, and after shifting the car through the gears.  The transmission fluid level as indicated by the dipstick was where it should be.  The parking break vacuum release works as it should.  When I put a new exhaust system on the car (from the Y pipe back), I fished a stiff wire up the Y pipe to see if the heat riser was stuck in the closed position.  The wire penetrated the pipe a few inches further than the location of the heat riser, indicating to me that the heat rise, even though it is stuck, is open.

Despite all my good efforts, my car has a problem.  When I drive the car (after it has warmed up in the driveway for a half hour or so) it accelerates smoothly and shifts smoothly through all three forward speeds.  After about 5 to 10 miles of driving, either on neighborhood streets at about 30 to 40 MPH, or on the highway/beltway at 50 to 60 MPH, when I come to a stop-sign or traffic light, the car stalls.  Downshifting is relatively smooth, but when the car has down-shifted to 1st, and as it almost comes to a complete stop, the car bucks - sometimes a little, sometimes a lot.  The bucking reminds me of driving a standard shift car and forgetting to step on the clutch when coming to a stop.  If, before the car comes to a complete stop, I shift into neutral, I can usually keep the car running.

When the car stalls, if I immediately try to start it again, it will either restart and stall, or it wont restart.  If I wait a few minutes (about five), the car will restart but I have to put the car in neutral and keep the RPMs slightly elevated to get going.  This problem has occurred 4 times.  The weather was not particularly hot on the days when the car had this problem (much to my chagrin, one of the 4 times was when I was on my way to a meeting of the CLC Potomac Region).

I have considered that I might have a fuel problem (including the possibility that the carburetor was not correctly rebuilt), and that I might have a torque converter or transmission problem.  I have considered vapor lock, but the fuel lines are in good condition and they are well away from the exhaust, and the car does not get terribly hot.  If anyone has any thoughts about my predicament, I would appreciate hearing from you.

During the upcoming Winter, if there are a few mild days, I am considering rebuilding several of the car's components including: alternator, starter, power steering pump, steering gear box, exhaust heat riser, and maybe the carburetor and transmission if these last two components are indicted as the possible cause of my stalling issue.  I may post this message as a separate thread in the Technical/Authenticity portion of the forum in the hope of getting more viewers and responses.  Thanks for reading."

Christopher Winter

Christopher Winter
1967 Sedan DeVille hardtop

Jeff Rosansky CLC #28373

What is the reason you let it idle for half an hour? Will it not run if you just start it and go? If it will run, then do that. See if the problem duplicates itself with a cold engine, cold oil and cold trans fluid.
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Scot Minesinger

Chris,

Started writing this at 6pm and got interrupted, so some of my writing might be duplication or contradict since discovered facts - sorry if that happened.

Three areas come to mind:

1.  The car I believe has a switch pitch torque convertor where the pitch of the blades change in response to throttle.  This may be controlled by carb linkage-I'm not sure.  Who ever re-built the carb may not have realized the essential linkage and connection procedure.   For sure the switch pitch was around in 66, and not in 68, so do not know if 66 or 67 was last year.  If the car slows down and the pitch does not change it may be trying to require too much engine power that is just not there during idle, thus stalling the car, and when you shift to neutral the problem is mitigated.

2.  The Cadillac does have or should have a dash pot that keeps the throttle from slamming shut when you let off the gas and prevents it from stalling.  This can also get messed in adjustment if the carburetor is removed - read shop manual and be sure it is adjusted properly.

3.  The carb may need to be rebuilt, although you say it idles and accelerates well, so seems like maybe not, but I cannot be sure.  I think Greg wrote something like 90% of my carb problems are electrical.  I suffered an ignition issue that seemed like a carb issue, so as a precaution it may be good to change the condenser, those are often not made well.

Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Scot Minesinger

Thanks, I second Jeff's suggestion, start it, let it warm up for a minute max and drive it gently until it is warmed up.  Why does it run for half an hour in park before driving it?

BTW hope to see you again at Capital Cadillac on the 24th, and maybe with your 67!
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Ralph Messina CLC 4937

#4
Christopher,

If it feels like the engine is pulling against the brakes as though you really didn't step on the clutch, I'd follow Scott's suggestion about the transmission variable pitch circuit. There's a plunger type switch on the passenger side of the carb that senses throttle position and signals the stator to switch pitch. There is a section in the shop manual that provides tests and diagnosis. The bad news is if it is the switch,  it is a '67 only part.

Ralph

Correction: That should be driver's side of the carb
1966 Fleetwood Brougham-with a new caretaker http://bit.ly/1GCn8I4
1966 Eldorado-with a new caretaker  http://bit.ly/1OrxLoY
2018 GMC Yukon

bcroe

A 67 is definitely a switch pitch.  The control is a 3 terminal switch next to the carb linkage. 
These are not particularly rugged.  If its not putting the trans in high stall autodial (12V applied
to the top terminal on the left side of the trans), that is at least part of the problem. 

You could use a test light, or run a "click test".  In a quiet garage with windows open, turn on
the ignition.  Now press down on the gas pedal and you should hear a "click" from the trans as
it changes from high stall (12V applied) to low stall (no voltage applied).  Continuing to press
down, you should hear 2 more clicks from the kickdown and switch pitch solenoids as you
approach WOT.  Releasing the pedal, you should hearth sequence in reverse. 

I don't care for the mechanical control, which only functions at idle & near WOT (if it even works
at all).  I use an electronic pitch control which is far more reliable & works over all situations. 
Bruce Roe

Julien Abrahams

Before you start checking the switch pitch solenoids, make sure that the car is warmed up (drive it until the idle drops).
I would like to second the suggestions already given with regard to the switch pitch of the transmission. Another tip: instead of sitting in the car with the windows down, you can also open the hood, turn on the ignition and then, under the hood, move the throttle rod by hand (slowly). Listen for three clicks when you open the throttle from idle to WOT. Of course, shut off the engine otherwise you can't hear the solenoids clicking.
1954 Cadillac series 62
1967 Cadillac Sedan De Ville HT
1969 Austin Healey Sprite
1979 Opel Kadett

"Cadillac Kid" Greg Surfas 15364

Christopher,
Your switch pitch transmission, if it is still that is intended to go into "higher" stall position when the car is stopped, in drive and idling.  It does so to "
loosen" up the converter and allow a higher stall speed. The mechanism that does this is an electrical circuit from the brake switch that provides a signal to the converter through the previously mentioned switch on the carburetor.  I would recommend you get a factory service manual wich includes the electrical diagram of this function, and trace it out.  There are several possibilities for malfunction.
If you check out the function of the switch as others have suggested above and find your kick-down switch good AND someone has not removed the switch pitch transmission (or its function) I would suspect a disconnect in the brake light circuit.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

bcroe

Quote from: Julien Abrahams on October 14, 2015, 03:49:54 AM
Before you start checking the switch pitch solenoids, make sure that the car is warmed up (drive it until the idle drops).
I would like to second the suggestions already given with regard to the switch pitch of the transmission. Another tip: instead of sitting in the car with the windows down, you can also open the hood, turn on the ignition and then, under the hood, move the throttle rod by hand (slowly). Listen for three clicks when you open the throttle from idle to WOT.

Actually, for the final test, I recommend that you NOT operate the throttle under the hood by hand. 
The reason is, there is a lot of slop in a throttle linkage, and even though it works by hand, it
MAY NOT work consistently by the gas pedal. 

If the car stalls when in neutral, its not caused by the trans. 

Typically the circuit is quite simple; a single wire from a trans fuse to the switch, and 2 wires from
the switch to the trans.  However, I don't have the 67 Cad drawings showing if there is anything
else involved.  Bruce Roe

savemy67

Hello All,

Thanks for replying.  So far there seems to be a consensus around the variable pitch stator.  My '67 does have the variable stator transmission.  What it does not have is a functioning kickdown/stator switch.  My thread in the Restoration Corner section of this forum has a post about my trying to repair the switch.  So, the switch is not connected.

I have had the shop manual since I have owned the car.  There are several tests for the switch spelled out in the manual, but the tests assume the switch is attached and intact.  My switch is broken internally so the only test I can do is to apply 12 volts to the wires connected to the solenoids in the transmission.  When I do this for each wire, I hear one click when I apply voltage, and one click when I disconnect voltage.  Of course, just because the solenoids click does not mean the valves in the transmission are working.

Jeff and Scot - there is no particular reason I let the car idle for 20 to 30 minutes other than to bring it to operating temperature.  Sometimes I check other things while the car is warming up to temperature.  I hesitate to drive it cold (or drive it at all) knowing there is a good possibility I will get stranded.

Scot - I have adjusted the throttle dashpot so the throttle does not slam shut.  I plan to be at the PR CLC show at Capitol Cadillac, but propbably not with my car.

Ralph - yes, the '67 switch is a one year only - difficult to find at an affordable (for me) price.

Bruce - your test description is as the manual states, but my switch is broken and not in the car, hence my click test as described above.  The car does not stall in neutral, only drive (I have not tried in reverse).

Julien - the click test you describe is as the manual advises, but my switch is disconnected.  The test procedures in the manual appear to be done without the transmission operating, and hence no hydraulic pressure at the stator valve.

Greg - I have studied the wiring diagram on pages 12-80 and 12-81 of the '67 shop manual but I do not see where the brake circuit interfaces with the kickdown/stator switch circuit.  The stop light switch has two terminals.  One terminal has an 18 gauge drk grn wire from the fuse panel, and the other terminal has a 16 gauge blk wht wire that goes through the turn signal switch in the steering column, then out to the lighting wiring harness.  The kickdown/stator switch, according to the diagram, is fed by a 12 volt wire from the fuse panel (18 gauge org blk), and feeds two wires (18 gauge wht, and 18 gauge org) to the solenoids in the transmission.  I could not find any trace involving the brake circuit.

I may have to bite the bullet and buy or rig a switch so I can see if the transmission responds to the action of the switch.  If there are any other theories out there, please chime in.  Thanks to those of you who have replied so far.

Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

"Cadillac Kid" Greg Surfas 15364

Chris,
If you need a switch, PM me.  I got an extra one when I converted my 66 to a '67 quadrajet.
Look at the wiring diagram closely.  There is (I believe) a 18 ga. white wire that goes to the kickdown switch.  It comes from the "down stream" side of the brake light circuit (brake light switch) through a diode.  It is in the factory service manual abeit kind of hard to spot.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

bcroe

Quote from: savemy67
Thanks for replying.  So far there seems to be a consensus around the variable pitch stator.  My '67 does have the variable stator transmission.  What it does not have is a functioning kickdown/stator switch.  My thread in the Restoration Corner section of this forum has a post about my trying to repair the switch.  So, the switch is not connected.

I have had the shop manual since I have owned the car.  There are several tests for the switch spelled out in the manual, but the tests assume the switch is attached and intact.  My switch is broken internally so the only test I can do is to apply 12 volts to the wires connected to the solenoids in the transmission.  When I do this for each wire, I hear one click when I apply voltage, and one click when I disconnect voltage.  Of course, just because the solenoids click does not mean the valves in the transmission are working.

I may have to bite the bullet and buy or rig a switch so I can see if the transmission responds to the action of the switch.  If there are any other theories out there, please chime in.  Thanks to those of you who have replied so far.
Christopher Winter 

You can check the switch pitch function.  With the brakes applied in gear, apply 12V to the
upper trans terminal and the engine should speed up.  This will be more pronounced if
you add a little throttle. 

I guess you can live with it the way it is, or fix it.  You might be able to restore the problematic
factory setup, which offers no performance benefit, or use something avoiding the throttle
linkage problems or/and improve the cars all around performance.  I have an album SWITCH
PITCH TRANSMISSIONS on my PHOTOBUCKET which shows some ways people have
done this.  The simplest involves hooking it to the brake switch.  Any time this is done, you
need to unhook it while using 4 way flashers, or they will also "flash" the trans.  Some sense
torque by checking manifold vacuum.  Some use timers to improve acceleration and smooth
shifts.  There is a flow diagram of the one I use on my cars.  I got tired of regular 3 speeds
and converted all 5 to switch pitch. 

    http://s93.photobucket.com/albums/L71/bcroe/

  click on an Album
  click on a picture to enlarge + description

BRUCE ROE                                  bcroe@juno.com

Julien Abrahams

Also check whether it also stalls in reverse. Then it could have something to do with the pump pressure of the transmission.
1954 Cadillac series 62
1967 Cadillac Sedan De Ville HT
1969 Austin Healey Sprite
1979 Opel Kadett

savemy67

Hello all,

I followed up on Bruce's suggestion to apply 12 volts to the stator solenoid while the car was in gear.  I connected a remote starter switch to the stator solenoid wiring and placed it in the car where I could reach it.  I connected a tachometer and set it on the hood of the car in front of the windshield so I could observe it.

I started the car and let the engine warm up.  I moved the gearshift lever through the gears a few times.  I applied the brake, put the car in D(rive) and raised the engine RPMs to 800.  I hit the remote starter switch, energizing the stator solenoid, and the engine RPMs increased to 1000.  When I released the remote starter switch and de-energized the stator solenoid, the engine RPMS returned to 800.

To me, this test indicates that the stator solenoid and stator valve in the transmission pump are working.  Without the kickdown/stator switch installed, the pitch in the variable pitch stator is positioned at its low angle.  I believe this makes the torque converter operate at its low stall speed.  If I theorize based on the test (and as Scot mentioned), there may be a problem with the torque converter that is not allowing the impeller and the turbine to slip enough when the car comes to a stop.  This is just a theory.  There are a few more items on the transmission I can inspect before deciding to rebuild it.

Julien - I have a 0 - 300 PSI pressure gauge that I need to plumb into the test port on the side of my transmission.  The gauge and the test procedures in the manual will tell me if the hydraulics in the transmission are OK - something I should do anyway.

Bruce - I sent you a PM re this thread, and some questions about what I read on your photobucket site.

Greg - I took a few more looks at the wiring diagram on page 12-80 of the '67 shop manual.  I even bought a 3x page magnifier.  I did find another trace connected to the stator solenoid wiring.  The trace indicates an 18 gauge wht wire that runs from the solenoid switch terminal (at the carburetor), through a rectifier, to the grounded mounting strap of the coil mounted condenser.  The wiring on my car is the same as the diagram indicates.  I could not find any trace connected to the brake/stop-light circuit.

My car is nearly half a century old (I am jealous because my car is younger than me!), so I expect that my car will have some mechanical mysteries that need to be solved.  However, the solution to some mysteries can be elusive.  I know my car essentially sat in a garage for about a dozen years.  This could not have been good for fluids and seals, etc., so if I ultimately rebuild the transmission in my car, I don't think that endeavor will be a net loss.  At least that endeavor will eliminate the transmission as a factor in any subsequent mysterious issues.

Thanks to all who replied.

Christopher Winter

Christopher Winter
1967 Sedan DeVille hardtop

55 cadi

I am having very similar issues, and I put a glass fuel filter and I am seeing some sediment in the fuel filter glass, I replaced the tank new and the fuel pump new, and rebuilt the carb clean,  but I didn't do the gas line from tank to front pump, so what I fount is getting sediment from line back into the clean carb and clogging small areas.

So you might want to blow out or replace the fuel lines, and rebuild the carb again, or more like clean it out again, and add a fuel filter before the carb.

Just a possability.

Jason
1955 Cadillac sedan series 62
1966 mustang convertible w/pony PAC, now in Sweden
2005 Cadillac deville

bcroe

Quote from: savemy67Without the kickdown/stator switch installed, the pitch in the variable pitch stator is positioned at its low angle.  I believe this makes the torque converter operate at its low stall speed.  If I theorize based on the test (and as Scot mentioned), there may be a problem with the torque converter that is not allowing the impeller and the turbine to slip enough when the car comes to a stop.  This is just a theory.  There are a few more items on the transmission I can inspect before deciding to rebuild it.

Julien - I have a 0 - 300 PSI pressure gauge that I need to plumb into the test port on the side of my transmission.  The gauge and the test procedures in the manual will tell me if the hydraulics in the transmission are OK - something I should do anyway.

Bruce - I sent you a PM re this thread, and some questions about what I read on your photobucket site.

Greg - I took a few more looks at the wiring diagram on page 12-80 of the '67 shop manual.  I even bought a 3x page magnifier.  I did find another trace connected to the stator solenoid wiring.  The trace indicates an 18 gauge wht wire that runs from the solenoid switch terminal (at the carburetor), through a rectifier, to the grounded mounting strap of the coil mounted condenser.  The wiring on my car is the same as the diagram indicates.  I could not find any trace connected to the brake/stop-light circuit.

My car is nearly half a century old (I am jealous because my car is younger than me!), so I expect that my car will have some mechanical mysteries that need to be solved.  However, the solution to some mysteries can be elusive.  I know my car essentially sat in a garage for about a dozen years.  This could not have been good for fluids and seals, etc., so if I ultimately rebuild the transmission in my car, I don't think that endeavor will be a net loss.  At least that endeavor will eliminate the transmission as a factor in any subsequent mysterious issues.
Christopher Winter   

Yes if the converter doesn't go to high stall when stopped, it will put more drag on the engine. 

If the solenoid is connected to a diode whose other terminal is tied to the grounding strap, it
must be non conducting when the solenoid is activated.  In that case its purpose is to absorb
the solenoid kickback pulse when power is removed.  Probably the reason is to avoid noise
in the radio (from a quick arc at the switch); not used on other brands. 

Not related to the stalling issue (stopped when nothing in the trans is turning), its good to be
concerned with its half century age.  I have a similar age switch pitch trans in all 5 of my cars. 
There was a picture of some of seals I have taken from such a transmissions, failing (very
typical).  Any trans that age needs at least a $30 "soft" sealing kit to preclude a serious failure. 
The hard parts might be fine and I would not replace anything not requiring it.  Bruce Roe

Scot Minesinger

Chris,

The fuel lines rust from the inside out.  The newer metal fuel lines have a copper type compound ( cannot be copper, an element or galvanic corrosion would result) with steel jacket.  I just presumed you replaced them.  It is one of the first things I do when bringing a Cadillac from the 60's or 70's back to mechanical perfection that has primarily original components.  Recommend that you replace them if you have not already.  It is quite a job (made easier by removing body to frame bushing above axle).  Takes a full day.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Fred Pennington 25635

Chris, I had a similar problem on 65 deVille Conv.  The car would randomly stall and would start after waiting a minute or two.
After exhausting every seemingly possible cause we found there is a screen or sock on the fuel pick up tube inside the fuel tank.
They get clog and or deteriorate over time.
It is common on new cars to replace them when changing in tank fuel pumps.
But on our older cars they are not given a thought.
I could not find one for the 65 ( didn't look all that hard ) so we just removed it.
Relied on the fuel filter at the carb.

Never had another problem .

Good Luck 
Fred Pennington, CLC 25635
1940, LaSalle 5019
1940 LaSalle 5019 parts car
1968 Ford Bronco
1973 Mustang Convertible
2012 Shelby GT500

Scot Minesinger

Those socks in fuel tanks for the 65 thru 70 Cadillacs are sold by USA Parts, and likely other suppliers.  Cost is low.  I always replace those too as a precaution on old cars.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

savemy67

Hello all (and Jason, Scot, and Fred),

A couple of weeks ago I repaired (successfully) the fuel sending unit in my car.  This entailed dropping the fuel tank to remove the sending unit.  I inspected the tank and it was clean as a whistle.  The fuel lines and the fuel pump appear to have been replaced by the previous owner.  All these parts are corrosion free with new rubber connecting hoses and new clamps.  I have the factory glass bowl and filter and there has never been any sediment in it.  When I repaired the fuel sending unit, it appeared to have also been replaced by the previous owner, and the filter sock was clean and I could inhale and exhale air through the sock via the fuel pick-up tube.

When I replaced my fuel tank, and put a few gallons of gas in the tank, the car started within a few seconds, and idled fine, so I think my fuel system is OK.  I know the carb was rebuilt by the previous owner, but it is possible that it was not rebuilt correctly, nor that it was adjusted accurately, although I never have trouble starting the car or getting it to idle.

I will probably concentrate on reviewing the carb adjustments, but I can only go so far on these because my air conditioning is not connected and some of the carb adjustments for air conditioned cars are supposed to be done with the air conditioning operating.  I am not sure what effect a non-working air conditioner will have on the carb settings.  Has anyone not been able to get the carb adjustments correct with a non-working air conditioner?  Thanks for your replies.

Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop