Chrysler 340 V8 - loses power and stops when warm.

[woodwind]

Hello -
I really don't know where to turn - my Chrysler 340 V8 has a strange issue... maybe someone can help pull the thorn out of my paw? It is for a 1965 Luhrs single screw.
When my engine starts, it runs smoothly and everything is just fine. But after warming up, it starts to faulter and ultimately conks out. In this warm condition (which it reaches in about 10 - 15 minutes or so) it may be possible to start the engine, however it is unable to stay running under any load.
Here's what I've done so far... New Intake Manifold, New Edelbrook Carburator, New Ignition Module, New Coil, New Balast Resistor, New plugs & wires... Nothing has worked. Here is One curious thing - if I keep the key turned (as in starting the engine - turning the starter motor), the engine will run under load and stay running. Of course, that would burn out the starter motor eventually so that certainly isn't an option. It is very odd behavior and seems to suggest an electrical issue. Is there any kind of solenoid that will engage once the engine is warm? Something about engaging the starter motor seems to enable the ignition system to continue to run. Also, I do not suspect the ignition the switch since it runs fine for a while and I can't imagine that a switch would cause such behavior. I did see a little arching on one of the wires connecting to the coils - but I just wouldn't suspect such behavior from just that. I also don't believe its a choke issue either since the choke is vacuum driven.
I am absolutely stumped. Can anyone make any suggestions?

Thanks a bunch.

 

[Bondo]

Re: Chrysler 340 V8 - loses power and stops when warm.

I did see a little arching on one of the wires connecting to the coils -

Ayuh,.... Loose, Corroded wiring, most certainly Will cause such problems...

 

[woodwind]

Re: Chrysler 340 V8 - loses power and stops when warm.

Ayuh,.... Loose, Corroded wiring, most certainly Will cause such problems...

Aha ! Ok Bond-o... So you think that the wire with arching may be heating up and failing to drive the coil properly? Hmmm... Is there something that is bypassed while the ignition key is turned to the "engage-starter" position ? Now I'm just trying to determine which connections may be the source of the problem.


Thanks for your input.

 

[Maclin]

Re: Chrysler 340 V8 - loses power and stops when warm.

The ballast resistance circuit to the coil is bypassed and a full 12v is supplied to the coil when the key is in Start. This is to compensate for lower voltage available while cranking when the starter is drawing major current.

Your symptoms also mimic what happens if the coil is wired backwards. It will work for a little while then peters out.

Now, assuming wiring is correct, then If you have a tach wire on the negative terminal then remove it and run to see if it acts differently.

If no tach, or symptoms persist then more than likely something is needing attention in the positive circuit to the coil, either wiring or connections or resistor or ignition switch. There could also be problems in the triggering circuit (negative coil terminal) via wiring or connections.

What type of ignition are you running? The Chrysler style with 2 wires from the distributor to a separate ignition module/amplifier? If it is Chrysler then how many pins are in the module, 4 or 5?

What type of ballast resistance is used, a separate resistor unit or resistance wire? If a separate resistor, how many terminals does it have and what all terminals are wired in?

Do you have any type of noise suppression device, i.e. condensor/capacitor/filter, wired into the ignition circuit?

 

[woodwind]

Re: Chrysler 340 V8 - loses power and stops when warm.

What type of ignition are you running?
- Chrysler Electronic ignition module.
The Chrysler style with 2 wires from the distributor to a separate ignition module/amplifier?
- Yes
If it is Chrysler then how many pins are in the module, 4 or 5? 4 pins.
- The original one was 5 pins however I was told that this one would work just fine)
What type of ballast resistance is used, a separate resistor unit or resistance wire?
- A Separate resitor unit
If a separate resistor, how many terminals does it have and what all terminals are wired in?
- The Balast Resistor is a ceramic block with 4 terminal pins - all wired in

Do you have any type of noise suppression device, i.e. condensor/capacitor/filter, wired into the ignition circuit?
- No noise supression devices.

I will check to see if reversing the Coil wires works - its very possible they are reversed. However it is doing the same thing as before the coil was replaced. And it was running fine for a whole season with the coil connected as it is now.

One thing to note - After running the engine with the balast resistor bypassed with an allegator clip wire, it did improve the performance. Although it did not cure it 100%, it still kept the engine running under load.

Thanks for your advice Maclin - I will let you know how it goes.

 

[Maclin]

Re: Chrysler 340 V8 - loses power and stops when warm.

Don't just switch the wires on the coil unless they are wrong.

Verify that all wiring is in good condition, no cracked insulation or burned ends, that kind of thing.

For your application be sure the coil is designed for external ballast resistance.

Sometimes the pickup coil module inside the distributor can be faulty and not send good signals to the ignition module under all conditions (or temperatures). The gap between the pickup and the rotor wheel must be consistent.

The arcing you saw evidence of is certainly a factor. Be sure you have the proper coil wire boot, one that fits the coil neck and seals properly. Make sure the coil's neck is clean and dry, not greasy. The spark can arc from the coil tower to the terminals and steal spark away. There are taller neck coils available, probably non MoPar generic coil replacements. But if you have the correct fitting coil wire boot then this should not be a problem. If arcing continues to be a problem then you need to think about a different coil, that may change the style of boot needed for the coil wire.

The 4 wire ballast resistors have two separate resistors and circuits, one of the resistor's wiring goes into the module when the module plug has 5 wires. The 4 pin modules are a replacement and all of that is supposed to be compatible. That 5th wire was always somewhat of a mystery to me, has something to do with alternator load and temperature.

When bypassing the ballast resistor you need to make sure the resistor for the coil circuit is the one bypassed. The coil circuit resistor will have 2 brown wires on one terminal and just one on the other. The single brown wire comes from the ignition switch Run terminal. On the other terminal with 2 wires, one comes from the ignition switch Start terminal (or maybe from the starter relay), the other goes to the coil positive terminal. When bypassing the resistor be sure to use a large 10 gauge or even 8 gauge wire.

If you do go on a coil search the best coil I know of for that style of MoPar ignition is a Jacobs Energy coil. it is the same style, does not need a ballast resistor, has higher output and runs cooler. It can be wired with ballast resistor or not, but recommened to give it the full 12 volts with no external resistor.

The MoPar ballast resistors in that electronic ignition package carry a reputation for failing in the automotive world. I ran MoPars almost exclusively back in the day and had a bypass wire with male terminal ends in the glove box for emergencies, it got used a few times.

 

[woodwind]

Re: Chrysler 340 V8 - loses power and stops when warm.

Don't just switch the wires on the coil unless they are wrong.

Verify that all wiring is in good condition, no cracked insulation or burned ends, that kind of thing.

For your application be sure the coil is designed for external ballast resistance.

Sometimes the pickup coil module inside the distributor can be faulty and not send good signals to the ignition module under all conditions (or temperatures). The gap between the pickup and the rotor wheel must be consistent.

The arcing you saw evidence of is certainly a factor. Be sure you have the proper coil wire boot, one that fits the coil neck and seals properly. Make sure the coil's neck is clean and dry, not greasy. The spark can arc from the coil tower to the terminals and steal spark away. There are taller neck coils available, probably non MoPar generic coil replacements. But if you have the correct fitting coil wire boot then this should not be a problem. If arcing continues to be a problem then you need to think about a different coil, that may change the style of boot needed for the coil wire.

The 4 wire ballast resistors have two separate resistors and circuits, one of the resistor's wiring goes into the module when the module plug has 5 wires. The 4 pin modules are a replacement and all of that is supposed to be compatible. That 5th wire was always somewhat of a mystery to me, has something to do with alternator load and temperature.

When bypassing the ballast resistor you need to make sure the resistor for the coil circuit is the one bypassed. The coil circuit resistor will have 2 brown wires on one terminal and just one on the other. The single brown wire comes from the ignition switch Run terminal. On the other terminal with 2 wires, one comes from the ignition switch Start terminal (or maybe from the starter relay), the other goes to the coil positive terminal. When bypassing the resistor be sure to use a large 10 gauge or even 8 gauge wire.

If you do go on a coil search the best coil I know of for that style of MoPar ignition is a Jacobs Energy coil. it is the same style, does not need a ballast resistor, has higher output and runs cooler. It can be wired with ballast resistor or not, but recommened to give it the full 12 volts with no external resistor.

The MoPar ballast resistors in that electronic ignition package carry a reputation for failing in the automotive world. I ran MoPars almost exclusively back in the day and had a bypass wire with male terminal ends in the glove box for emergencies, it got used a few times.

Well... it looks like it may not be electrical after all. Here are the actions taken:
(review : already replaced electronic ignition, balast resistor, plugs, wires, and ignition coil)
- Measure voltage at inputs of balast resistors: all above 12V (seemed ok & was CONSTANT through the engine failure)
- Observe coil temp: gets hot but runs for a while with no apparent change in temperature of the coil
- Swapped out the coil: no change in behaviour
- Bypassed the balast resistors : worked for a little while longer however the engine conked out after another few minutes

Here is the curious one...
- REmoved center wire on distributor to observe if spark was present : spark was arcing perfectly well and engine actually started up and ran OK!
- Reconnected the center wire and engine did not start ; backfireing was observed while attempting to start the engine. :facepalm:

Apparently, the delay that the additional spark gap must introduce indicates that timing is the issue. As the engine heats, there is must be a mechanical element in the engine which causes the engine to get out of sync. After considering other posts that suggest the timing chain in a Chrysler engine could become worn and cause such behavior, I've all but concluded that the timing chain is the issue.

Perhaps I should not put more than 40 years on any one particular timing chain?

 

[Bondo]

Re: Chrysler 340 V8 - loses power and stops when warm.

Here is the curious one...
- REmoved center wire on distributor to observe if spark was present : spark was arcing perfectly well and engine actually started up and ran OK!
- Reconnected the center wire and engine did not start ; backfireing was observed while attempting to start the engine.

Ayuh,.... Replace the Cap, Rotor, Wires, 'n Plugs....

Obviously, there's a Problem, Downstream from the coil wire...

With the coil wire pulled, it causes a hotter spark to jump the gap, which jumps the problem spot as well...

 

[CoffeeHound]

Re: Chrysler 340 V8 - loses power and stops when warm.

Ayuh,.... Replace the Cap, Rotor, Wires, 'n Plugs....

Obviously, there's a Problem, Downstream from the coil wire...

With the coil wire pulled, it causes a hotter spark to jump the gap, which jumps the problem spot as well...

Oh geeesss -- Your post hit me right between the eyes --yesss !! To OP Replace Rotor and cap with matching set -- the length of rotor to the plug terminal is a hair too short !! BTDT on a ford engine !!

Let me know what you find !!

 

[CoffeeHound]

Re: Chrysler 340 V8 - loses power and stops when warm.

Oh geeesss -- Your post hit me right between the eyes --yesss !! To OP Replace Rotor and cap with matching set -- the length of rotor to the plug terminal is a hair too short !! BTDT on a ford engine !!

Let me know what you find !!

When cold the engine starts and runs,, as the cap gets warm it expands,, the rotor inside gets warm but does not expand as much due to it being mounted on the steel distribetor shaft.
Thereby moving the spark plug wire terminals in the cap away from the rotor and causing a wider gap than would be normal for the spark to jump across from the rotor to the spark plug wires.
]

 

[Bondo]

Re: Chrysler 340 V8 - loses power and stops when warm.

When cold the engine starts and runs,, as the cap gets warm it expands,, the rotor inside gets warm but does not expand as much due to it being mounted on the steel distribetor shaft.
Thereby moving the spark plug wire terminals in the cap away from the rotor and causing a wider gap than would be normal for the spark to jump across from the rotor to the spark plug wires.
]

Nope,... Not plausible,.... The spark will jump a 1/2"....

The bit of expansion or contraction is moot, 'n irrelevant...

The O/P's problem is the Cap, Rotor, Plug Wires, or Sparkplugs are JUNK... probably the wires...

 

[woodwind]

Re: Chrysler 340 V8 - loses power and stops when warm.

OK - If we replce all of these items (Cap, Rotor, Plug wires, & Spark plugs), then should we also replace the reluctor? I've heard that it is a good idea to replace that when replacing these other items.

Also, curious to know how the plugs could cause such behavior... (btw, they are platinum plugs. not sure if that's relevant).

And can anyone explain why the additional spark gap (on the center wire of the distributor) would enable the engine to run? Do you think it is indeed related to timing? or is added resistance a factor?

 

[Maclin]

Re: Chrysler 340 V8 - loses power and stops when warm.

I would replace the pickup coil in the distributor, the wiring insulation gets old and brittle from the heat and conductivity goes down and the reluctor and coil do not have a big signal to begin with. The reluctor is probably ok as it is a non-wear item. But if it has been replaced and was not clocked correctly then the signals sent to the ignition module will not be timed correctly in relation to the rotor position and poor performance will result. The same reluctor and coil is used in small blocks and big blocks and those distributors rotate in different directions so they mark one of the keyways with the rotation arrow, the rotation arrow is what direction the distributor rotates. If your distributor rotates in that direction then use thay keyway, if not use the other one, that kind of thing. I believe the rotation marked is for the small block, but take heed of the direction your distributor rotation if you decide to check this.

I have had platinum plugs act oddly on a car or two that did not have them as OEM specs. Had to go back to non-platinum on one of them, I did not ever really understand why.

I would go with good 7mm or 7.8mm resistor plug wires, more conventional spark plugs. If you want to upgrade the coil an MSD Blaster3 coil works well in the MoPars. The blaster 3 coil has a very tall tower, much less chance or arcing, and it is ok with the MoPar ballast. Get a good distributor cap with brass contacts and the ridges inside to minimize the chance for carbon traking inside the cap. Always get matching rotor at the same time.

Be sure to use a brass feeler gauge to set the reluctor to coil gap, .008" You can feel when it is set corrrectly when turning the distributor, the reluctor will try to center itself on the coil magnet as it passes by.

 

[Maclin]

Re: Chrysler 340 V8 - loses power and stops when warm.

"And can anyone explain why the additional spark gap (on the center wire of the distributor) would enable the engine to run? Do you think it is indeed related to timing? or is added resistance a factor? "

The extra gap allows the voltage to build up, and when the gap is finally bridged then, like a dam busting, the stuff downstream gets clobbered.

 

[Maclin]

Re: Chrysler 340 V8 - loses power and stops when warm.

Regarding my seemingly bipolar coil recommendations, Jacobs then MSD, I recommend Jacobs when wanting to rewire and not use the ballast, and MSD blaster3 when keeping closer to stock.

 

[woodwind]

Re: Chrysler 340 V8 - loses power and stops when warm.

Ok. The fix is in. This problem went away when I scraped off the carbon buildup on the center of the rotor.

After bringing the engine to the failing condition (ran fo about 15 mins), and moving wires around to see what happens, I found that pressing on the center Of the distributor cap (wire to the coil) worsened the condition, telling me that the problem was related to this area. Therefore, after scraping off the center of the rotor to cLean off what appeared to be carbon buildup, and observing much smoother running engine operation, I replaced the cap and rotor for good measure and the problem is now completely solved. As for the coil, I actually did instal a high performance coil and it performs nicely ( balast resistor is still in place). Thanks for all the support.

Now I need to crack my physics books and understand why a spark gap enabled the engine to operate. (a change of the load on the coil?).
One thing that does make sense is that the coefficient of resistivity of carbon is very different than that of brass - thus the misbehavior when the components become heated.




. ;3832264]Regarding my seemingly bipolar coil recommendations, Jacobs then MSD, I recommend Jacobs when wanting to rewire and not use the ballast, and MSD blaster3 when keeping closer to stock.[/QUOTE]

 

[Maclin]

Re: Chrysler 340 V8 - loses power and stops when warm.

The way that era of electronically signaled ignitions work the extra gap allows the voltage in the coil to build even longer, like water building up behind a dam. Then once the gap is arced (the dam breaks) then all heck breaks loose downstream.

 

[Maclin]

Re: Chrysler 340 V8 - loses power and stops when warm.

Oh yeah, glad you found the problem and got it fixed!

 

[woodwind]

Re: Chrysler 340 V8 - loses power and stops when warm - FIXED - Ground WIre to BlocK

Re: Chrysler 340 V8 - loses power and stops when warm - FIXED - Ground WIre to BlocK

Addendum - The real fix:

After further operation, intermittent behavior was still observed. Although it ran much better after replacing the Cap & Rotor, it would still conk out occasionally and force me to run the engine at slightly higher RPM to keep it running smoothly. So recognizing that it still was not completely fixed, I had attributed the slight rough behavior at this point to an aging, dirty carburator or bad gas. (We all know what the ethanol can do to boat engines...)

When Running the boat 10 minutes off of the dock, it failed and would not restart. Fortunately, being in a convoy saved the day and a friend provided a short 10 minute tow back to the dock... God Bless Him! He was fortuitously employed as a boat mechanic and he suggested that I check the GROUND WIRES FROM THE BATTERY TO THE ENGINE BLOCK because corrosion can be invisible and deceptive.

So the next day, I went directly to those connections on the engine block and sure enough found some oil, dirt, and paint underneath the connectors. Although they seemed tight enough, apparently the matter beneath the cable connector was significant. So I scraped and sanded these ground connectors down to a shiny brass finish, cleaned the surface on the block, cleaned the bolt itself (a bolt on the bell housing), and for good measure put on some dielectric grease before reconnecting it - tightly. (One difference - I put one of the cables directly onto one of the two bolts that fastens the starter motor - after cleaning it of course.) THAT DID THE TRICK !! All fixed.

The engine started right up and ran at just as low an RPM as I wanted. Now it runs perfectly at low idle with NO intermittent behaviour.


But I didn't stop there... I continued to clean off all of the positive connector terminals and replace some other connectors with questionable wires including battery terminals on the Battery 1-2 switch, and a wire feeding the main station ignition wires. Additionally, I replaced the starter solenoid also for good measure since the old one was somewhat corroded. Now the starter turns 10 times faster than it did before and it runs like a champ!

When I took the boat out for a test run and did my victory lap, it ran so well, our friends on the dock watching the boat cruising called me a lying sack of $#!+ for faking the breakdown...:facepalm:
I can say now definitively after a long drawn out episode of frustration and hard work that it is completely fixed. Thanks again for all the insights.


AMDG

 

[Maclin]

Re: Chrysler 340 V8 - loses power and stops when warm - FIXED - Ground WIre to BlocK

Re: Chrysler 340 V8 - loses power and stops when warm - FIXED - Ground WIre to BlocK

Sweet! The fundamentals get overlooked sometimes.