Battery - question on voltage 1984 3.2

[198491132]

Good Day,

I have been trouble shooting a no start issue, that seems to have led me to the battery. No start is - engine turns over but does not fire. After I gentle touch, push together, and move around the three wires (CHT and flywheels sensor connectors) the car starts. I have done this six times over the past year or so. After that all is fine.

So I drop my meter on the battery terminals. (14 year old Optima 34/78). Reads 12.6 with no load. Drops down on occasion below 11, I even saw 10 and an 8 volt reading once during cranking. Even with the low reading the engine would still crank over and start.

No engine on, flashers only - battery drains down in 120 seconds, after several starts. So I believe that it is bad.

How can the starter engage with that momentary low reading? Could the low voltage be effecting the intermittent not start?

Thanks for your thoughts...

Dave

[pete3799]

Your 14 year old battery would be the first thing i'd replace.

[darrin]

or at least get it load tested (can get this for free at most local autoparts stores)

Note your observation about a potential bad contact among your CHT/sensors -- has your cht sensor been replaced? these were originally single wire units and were later updated to two wire units. My original single wire CHT failure many years ago manifest as a similar no start situation --

[198491132]

yes , I have replaced all the sensors myself. Once I get the new battery in, I will continue playing with the sensor terminals. I just don't understand the 8-10 volt intermittent reading drop during cranking and how the engine kept spinning. I suppose flywheel momentum maybe.

[old man neri]

So during cranking you saw a voltage drop? Perfectly normal. The starter is a huge load, one would expect to see a voltage drop. Think back to years ago, remember seeing cars head lights dim when they were starting their engines at night? Same thing. Your situation might be exacerbated by the age/condition of your battery. Dirty and corroded terminals, grounds, and starter connections could as well.

As for your connector issue I believe that is unrelated to your old battery. It could be as simple as a dirty connector.

[198491132]

Installing new battery today......should hold a charge a bit longer then 3-5 minutes with flashers on. Still cranks though after all these years, Optima 34/78.

Thanks for the response, I just never knew the drop was so low. Will work on the connectors again today as well. Will try some contact cleaner and reseat them. I have done this in the past. Perhaps one is worn or wire maybe damaged.