{Chrysler 300} Condenser / capacitor dance

[John Grady <jkg@xxxxxxxxxxxxxxxxx>]

Although I have written before about the junk capacitors we get today in tune up kits, and the need to keep any old ones with copper strap until at least checked , I got hit again yesterday with this , but a new manifestation of the same problem .
B block in question, good shape ran ok once started but extremely difficult to start . Just cranks not even a peep . Prior owner did not disclose , truck driver had to push it onto truck.  We had to push off a year ago . No attempt by engine to “catch “ at all . All primary  voltages and points fine . Great battery . “Theories “ Led to carb , accell pump , gas drying out while sitting , bad fuel pump , clogged filter ,bad gas , water ,  clogged sock , rust in tank  etc etc you name it —-still no start , only sometimes . Tank cleaned and good. But always started with ether .THAT Leads right  Back to fuel issues  etc . Neon tester shows spark ( ps— never arc coil or plug to ground —high voltage goes way  too high if you arc too far from ground can jump inside your  coil instead wrecking internal insulation . = An Intermittent coil short you have now caused! Or use an old plug with a permanent ground clip wire . 

Yesterday —10 minutes to start ,finally with  ether , drove 40 miles to MD , running perfect came out 10 minutes later no start again —still hot!! Just barely caught after 15 minutes wild pumping could see gas , must be flooded now etc etc .  You know !! Sick feeling . Ran  fine on way home including to 90 mph . Not a hiccup . Thinking was “ this thing just loves  gas ?” Crazy —-

So got into it . Thinking was still fuel . Neon light test on # 1 it flashes but Ed , my Helper remarked it looked weak . But that is subjective and viewed in sun , remember it ran  fine ! 
Capacitor had pentastar  stamped on end not the chinese stamped X ( those are terrible —Toss immediately  if you have one) . Decided to test this one anyway . Only 100k ohms ! Meter did Jump up but did not return to infinite ohms.  Means burned paper inside is  breaking down . Chinese go open , opposite thing  = no cap at all ( but sometimes  , only — of course ) .
So I had a Filco copper strap type , put in , it  starts instantly . 
Diagnosis : weak spark caused by failing cap lowers peak volts at plug enough when combined with starting volts drop , plugs simply will not fire the gas . But , ether yes , (? Easier to light?)  then volts rise and it runs fine . Think of the fun in store on a long trip !!!  Or if you stall it on highway stop .  
Definitely will progress to total failure in 2-3 k miles .
So check your old one —-should swing up on ohms and then infinite , using 100 meg scale analog meter . ( Triplett 630 are great, on ebay —despite special battery ) Forget digital meters for this , a sad joke . You cannot see a changing reading or make sense of it .  
 Old mopar caps are really good with strap if they pass this you are good .In the old days some were even oil filled . Oil insulation can repair itself . 
Values of caps are not critical — neither  is 6 or 12 v , all are about .27 uF not critical .
I have used external radio caps , .27 630 v Panasonic ( Japanese quality ) to end this where it can fit ( standby generator , randomly not starting —found  same cause)  
This is the 7 or 8 th  time for me . Erratic inconsistent nature of this WILL get to you , drive you nuts before it fails . You Tear carbs apart etc etc 
So if erratic non start , unexplainable , look here .. even it usually runs fine . 
John 
And save any old copper strap mopar cap after test .. don’t change unless proven defective on test . 
Sent from my iPhone

-- 
For archives go to http://www.forwardlook.net/300-archive/search.htm#querylang
--- 
You received this message because you are subscribed to the Google Groups "Chrysler 300 Club International" group.
To unsubscribe from this group and stop receiving emails from it, send an email to chrysler-300-club-international+unsubscribe@xxxxxxxxxxxxxxxx.
To view this discussion on the web visit https://groups.google.com/d/msgid/chrysler-300-club-international/4F36C781-E83B-4757-A7BB-1EB2BAC56B9C%40gradyresearch.com.