erratic cranking, hard starting

[DonaldSmith]

1947 DeSoto, Carb cleaned, ignition sorted out, runs well when it starts.  A week-and-a-half to the DeSoto Convention. 

We can tow the sucker there and back, if we have to, but we should be able to start the car and drive it off the trailer to its designated parking spot.   

 

It'll crank sporadically, and maybe spin for a few seconds, stop, clunk, clunk  maybe catch and start, maybe not.  Great temptation to give it a small squirt of magic starter fluid.   

 

I've got a good accelerator pump squirt.  I try not to flood it, but i I do, the remedy is to keep cranking.  But it won't keep cranking. 

The battery is relatively new, larger size, Group 2.  I get 6.12 volts or more across the posts.  I put the battery on the maintainer but it says "standing by" (charged enough already).  

 

I've replaced the battery cables, since one cable got hot near the end after attempting to crank the engine. 

 

Am I looking at solenoid problems?  Can I get a good one, overnight or in a few days?  AB has one for Plymouth-Dodge - would it work on a DeSoto?  .   Can the solenoid be repaired?  By an amateur?

   

help 

 

[desoto1939]

Don Here is the selinoid switch that you need. The autolite number SS-4705  and you are correct the Dodge/Plymouth is a different unit.

 

These selinoid s are hard to find considering they were used from 1942-48.

 

Rich Hartung

 

 

[Plymouthy Adams]

don't guess...do a voltage drop test and know for sure where your issues lie....do consider looking again to ensure your timing may not be too high...do a current test to see if you starter is dragging due to worn rear bushing....you have a host of simple easy test with the most basic of tools, use them.  

[DonaldSmith]

Voltage Drop Test, Current Test - I'll look them up on the internet. 

 

Timing too high (too advanced?)  I will have to do the thumb-on-number-one and the light bulb. 

With my power steering pulley and belt, I cannot get my HF timing light to it the timing marks. 

 

It sounds like I'll be pulling the starter and taking it in somewhere.  

 

I printed an 8-page article on How To Test A Starter Solenoid (Step-by-Step Guide) and I'll be doing my homework this weekend. 

 

(Anyone got a spare starter?  Can I borrow it for a few weeks? ) 

 

 

 

 

[Sam Buchanan]

1 hour ago, DonaldSmith said:

 

I've replaced the battery cables, since one cable got hot near the end after attempting to crank the engine. 

 

 

Are your new cables correctly sized for 6v? You need mongo-sized cables, you won't find them in a big-box auto parts store.

 

 

[Bryan G]

The cover to my solenoid has a hole in the center top; not sure if this was common or if someone just added it. I keep a paper sticker over it. I've had times when it acted up and I could pull that sticker off and poke something like a toothpick in there and manually activate it. You could pull the cover off and do the same thing. It might just need a good cleaning inside. First, I'd triple check all connections and, as Sam said, make sure you have the right sized cables.

[DonaldSmith]

I've got No. 1 cables, available from Tractor Supply.  No. 1 is what Ma Mopar has called for.

Before I go to No. 1/0 cables, I'm going to do what Prof Plymouthy says, and do a voltage drop check on the cables and the starting circuit.   

I have quick disconnects at the battery posts that have served me well but may be suspect.  The test should tell me.  

 

If the cables, wiring and connections pass the test, then I'll get into testing the solenoid.  (I like Brian G's secret hole in the solenoid cover. for emergency situations.)      

[FarmerJon]

12 hours ago, DonaldSmith said:

Voltage Drop Test, Current Test - I'll look them up on the internet. 

 

Timing too high (too advanced?)  I will have to do the thumb-on-number-one and the light bulb. 

With my power steering pulley and belt, I cannot get my HF timing light to it the timing marks. 

 

It sounds like I'll be pulling the starter and taking it in somewhere.  

 

I printed an 8-page article on How To Test A Starter Solenoid (Step-by-Step Guide) and I'll be doing my homework this weekend. 

 

(Anyone got a spare starter?  Can I borrow it for a few weeks? ) 

 

 

 

 

Did you ever check your spark quality?

 

What is your base timing set at?

 

What do you mean "cranks sporadically" --- does it not always turn when you hit the starter button or stop turning mid-press?

How fast does it seem to turn it over?

 

When it is cranking, how long does it take to catch? 

 

To me, I would think those are two different issues.

If it randomly cranks/no cranks, ignition switch, Solenoid, starter, connections,  etc, Do the voltage drop and Current tests. 

 

If it turns over fine, with reasonable speed and strength, but the engine hardly wants to catch, I would keep chasing your tuning. 

I would think that timing would have to be 12*btdc+ before it would have trouble starting, and it would likely ping bad while driving.

I am running max timing without ping ( no timing pointer) and cold, my car starts on the first turn of the engine.

Are you still running the old, leaky resistor core spark plug wires?

[Kilgore47]

12 hours ago, Sam Buchanan said:

Are your new cables correctly sized for 6v? You need mongo-sized cables, you won't find them in a big-box auto parts store.

When I first got the P15 I used double 12 volt cables to get things going.  It worked but the engine still turned over slow.  Re wired the car and fixed all the grounds and got a set of 00 cables - still turned over slow.  I finally got a really expensive battery with a zillion cold cranking amps (6v Optima with 1000 CCA).   Turns over fast now.

[DonaldSmith]

Breaking News!  Cranking well! 

 

I went to do the requisite voltage drop test, and had to clip one of the leads to the starter case.  Where to get a good connection? 

 

Remember Ma Mopar's trick to keep you from grinding the starter when the engine is running? Anyone?  Anyone? 

She grounds the solenoid through the field of the generator.  When the engine is running, the field is no longer a ground.  

When I installed my alternator, I grounded that solenoid post to a bolt that attaches the solenoid to the starter. 

I removed the bolt, cleaned the surface, cleaned the bolt, and added a short plumber's strap to have something to clip a lead to.  Tightened the bolt.  

The blind pig stumbled on a truffle. 

When I connected my remote starter to do the voltage drop test, I noticed that the starter was cranking well! 

I pulled the accelerator linkage, flipped the ignition switch, and started the sucker! 

 

Professor Plymouthy gets the "Solved" accolade for urging me to go back to the basics. 

 

Now any minor rough running issues can be addressed.  Now drive, drive, dive. 

 

 

 

 

 

 

[Sam Buchanan]

Glad the starter is spinning better!

 

However.....I'm puzzled by how the solenoid ground could effect starter performance. Isn't the ground just a connection for the solenoid coil? The coil doesn't carry current to the starter--if no ground the solenoid won't energize and the starter won't run. A poor ground might be enough to energize the coil and close the starter cable contacts. But the coil doesn't impact starter running speed, it's either on or off.

 

I have to wonder if removing the bolt and cleaning it actually improved the starter ground (not solenoid ground) which allowed better spin. Is the bolt you removed one that attaches the starter to the bellhousing? You probably cleaned up the ground path for the starter which is a common remedy for a sluggish starter.

 

If I need some education, please do so. 

Edited July 15, 2023 by Sam Buchanan

[greg g]

Did tou do a compression  test

[kencombs]

25 minutes ago, Sam Buchanan said:

Glad the starter is spinning better!

 

However.....I'm puzzled by how the solenoid ground could effect starter performance. Isn't the ground just a connection for the solenoid coil? The coil doesn't carry current to the starter--if no ground the solenoid won't energize and the starter won't run. A poor ground might be enough to energize the coil and close the starter cable contacts. But the coil doesn't impact starter running speed, it's either on or off.

 

I have to wonder if removing the bolt and cleaning it actually improved the starter ground (not solenoid ground) which allowed better spin. Is the bolt you removed one that attaches the starter to the bellhousing? You probably cleaned up the ground path for the starter which is a common remedy for a sluggish starter.

 

If I need some education, please do so. 

I've seen similar issues with small tractors.   The wiring to the solenoid coil has to pass thru several safety switches first.  The wiring  was of marginal gauge to begin with, the  the switches contacts age,, the plugin connections all oxidize .  The result is the current arriving at the solenoid at to low a level to activate the pull-in coil.  Many makers offer a kit to place a little plugin relay near the starter.  It takes much less current to operate than the solenoid and when it closes it supplies power to the solenoid directly.  Same thing happens to some small diesels that have solenoid operated fuel shutoffs.

 

Long way of saying that a poor solenoid voltage (or ground) will not pass enough current to operate the plunger.   There is a surprising amount of amperage needed there.

[Sam Buchanan]

39 minutes ago, kencombs said:

I've seen similar issues with small tractors.   The wiring to the solenoid coil has to pass thru several safety switches first.  The wiring  was of marginal gauge to begin with, the  the switches contacts age,, the plugin connections all oxidize .  The result is the current arriving at the solenoid at to low a level to activate the pull-in coil.  Many makers offer a kit to place a little plugin relay near the starter.  It takes much less current to operate than the solenoid and when it closes it supplies power to the solenoid directly.  Same thing happens to some small diesels that have solenoid operated fuel shutoffs.

 

Long way of saying that a poor solenoid voltage (or ground) will not pass enough current to operate the plunger.   There is a surprising amount of amperage needed there.

 

Agreed. But Donald's car was cranking, just slowly. That means the solenoid was getting enough voltage to pull in and send current to the starter. What you are describing is different--not enough voltage to pull in the solenoid and the starter doesn't turn.

 

That is why I think Donald fixed his sluggish starter by improving the starter ground, not the solenoid ground.

[DonaldSmith]

The solenoid is a giant relay.  The light gauge circuit gets power from the starter button, and is grounded through the generator field.  Since I put in an alternator, I grounded this circuit to the bolt at the bracket that connects the solenoid to the starter body.  Quick and easy. I might redo it, and ground this circuit to the engine somewhere.   

The heavy gauge circuit gets power from the battery cable, and is grounded through the starter body to the engine, thence to the positive (ground) battery cable.   (10 points for using "thence" in a sentence.)

 

I get good cranking with my remote starter, with leads that I clip to the starter post of the solenoid and to the negative (live) post of the battery.  However, the starter circuit behind the instrument panel has some problems, maybe bad connections or a bad starter button or ignition switch.  It's a real bear to get at.  Waiting for better weather to back the car out to open the door wide.   I should check all the connections while I'm at it.  Ma Mopar had a real daisy chain of wires from one post to another.   

 

For getting to the Convention next week, I might just sneak in a stealth button somewhere, wired directly to the solenoid and clipped to a hot source.  Or I can get under the hood with m remote starter.  It looks like I have a make-do if necessary. 

 

[kencombs]

1 hour ago, Sam Buchanan said:

 

Agreed. But Donald's car was cranking, just slowly. That means the solenoid was getting enough voltage to pull in and send current to the starter. What you are describing is different--not enough voltage to pull in the solenoid and the starter doesn't turn.

 

That is why I think Donald fixed his sluggish starter by improving the starter ground, not the solenoid ground.

His description' crank sporadically, and maybe spin for a few seconds, stop, clunk, clunk  maybe catch and start'  sounded to me like solenoid releasing.  

Maybe I misunderstood the phrasing.  

What I've often seen looks and sound like bad battery cables, connections etc.  Weak sound of solenoid 'snapping' in and/or buzzing, maybe a half-hearted attempt roll over.   Relay fixed 'em.

[uncleaud]

 

First thing to try is to get rid of the quick disconnects at the battery. I had them on my Thunderbird and they caused all kinds of problems with the starter circuit.

[DonaldSmith]

Executive summary:  Car starts after some clunking.  Solenoid roulette? 

 

I double checked the starter circuits.  Even cleaned up the battery clamps and the quick disconnnects.  Tried the voltage drop tests, couldn't tell much.   Seems a bad connection would have a uniform effect on the starting.  Erratic operation may be the solenoid.  

 

(Someone said check the timing.  Less work for the starter if the engine wants to start right up.)  So I static-checked the timing.  OK, I can't turn the crankshaft by the fan belt; have to clunk it around.  Never stops where I want.  Is the rotor pointing to 7:00 on the compression stroke?  Thumb over No. 1 plug hole.  Rotor close enough. no way 180 degrees off.

 

Finally clunked the crankshaft to 10 degrees advanced.  Close enough.  Got the light bulb test.  Bulb went out near 10 degrees.  The timing was too far advanced,   

Wanted around 4 degrees advanced.  To take 6 degrees off, retarded the distributor about 3 degrees.  I eyeballed it.

 

Plugs sooty but back in.  (Someone told me to check the wires.)  At the distributor cap, Wires 2 and 6 looked burnt.  Pushed the wires all the way in.  Wire replacement slated. 

 

Primed the carb.  Set the fast idle and squirted a bit.  Crank, crank, repeat a few times.  Started up.  (Runs better with the timing right and plug wires all the way in.)   Vacuum gauge at 19, not bad.  

 

Crunch time:  With the engine starting better, do I play solenoid roulette, hoping that it gets no worse, or do I pull the starter and have a look at the solenoid?   A little over a week before the DeSoto Convention.   Maybe this afternoon I'll pull the starter. 

 

 

 

 

 

[desoto1939]

Don: On my 1939 Desoto that has the big 6 block my timing mark by the factory specs is 2 degrees before tdc.  You are stating that you are now set at 4 degress advanced. So I am assuming that you are set at 4 degrees after TDC. Is this correct.  I would assume maybe 2-4 degrees before TDC would be your proper setup for checking timing.

 

The timing mark will be rotating away  the driver side of the engine and this is where you would take the reading from the pointer. Which side are you taking the reading, driver side or passenger side when the engine is running.

 

Rich Hartung

 

[DonaldSmith]

I can't view the timing marks  from the left fender because of the power steering belt that I added.  Looking at the damper from the right fender, the marks come up an over.

I have the marks highlighted:  10 deg advance, the first to pass the pointer and the farthest from me; TDC; then 10 deg retarded, the last mark to pass.  

4 deg advanced has been recommended, by the wisdom of the forum, for gas with ethanol.   That's about where I have it.   It's running well.  I still have to listen for ping when going up a hill.  

 

I'll be trying to  get a timing light bright enough to shoot the marks from the right fender.   Then I can tweak the timing some more.  Maybe get the vacuum gauge to 22 or so.  

 

[desoto1939]

my 12 v sear timing light provides me with amble light to see the timing marks.  But i have the butterfly style hood and I keep the passenger side of the hood closed.  I also do the timing test in my garage and also turn off all other lights and do my testing when the sunlight is not so strong. Have curtains on my garage window to also limit the sun light.

 

Rich hartung

[Kilgore47]

On 7/17/2023 at 10:14 AM, DonaldSmith said:

At the distributor cap, Wires 2 and 6 looked burnt. 

If you found burnt wires at the distributor then the cap is damaged and should be replaced.  Pushing the wires back in will help but it will not fix the problem.  Those two cylinders are probably mis firing.  That's a third of your power.

[DonaldSmith]

Update:

 

I replaced the wires and the distributor cap.  I had a real lesson in "1 5 3 6 2 4", "Replace one wire at a time", "Don't fray the conductor", and crimp the terminal the "right way" (not assend to).

 

I bought a battery-powered strobe light from Summit Racing.  It works, if I'm patient.  Since I am shooting from the right side, the fan obscures the timing marks most of the time.  Eventually it works around the where I can see the marks.  I got the timing dialed in at 5 degrees advance, more or less.  Good enough.   

 

The car starts and drives well.  Some more shakedown before we go to the DeSoto Convention Thursday.