Why weak starting at times?

[Discseven]

'85 3.2. New alternator 3 months ago. Over weekend... left headlights on and drained battery. Did not work to push start--never experienced that before. Cable jumped, and that did not work immediately. Had to leave cables connected for a while before starter would crank. Since then, starting power has been weak at times... normal at times.

Checked bat voltage... static = 12v. Running = 13.5v. Checked water level = OK.

EDITS - ADDED DETAILS: "Weak start" means slow cranking compared to normal. Bat connections and ground to car are tight... recently cleaned. Engine ground strap... 2 years since terminals & strap cleaned. Starter, replaced about 2 years ago. Battery age: 6 yrs. Has been drained 2 times in lifetime.

Ideas...?

[boyt911sc]

Karl,

Have your battery checked and analyzed. An ideal battery charge for cold starting is between 12.3 - 12.8 volts (static). Your battery could be getting old and should be able to deliver high current during the start phase. A good way to determine your battery's condition is have it checked using a battery analyzer. The print out would tell you more about your battery's health. Keep us posted.

Tony

[83-911SC cab]

I'm no electrical genius here just know enough to be a danger to myself and my cars....but I would check Batt voltage to see what it drops to when you are cranking engine...also how old is batt..heard somewhere the batt voltage shouldn't drop much below 10.5 volts while cranking or it might be sluggish...maybe the drain to dead might have damaged a cell in the batt?? Good luck with finding your issue..I'm sure many smarter people than me will chime in on this..

[Discseven]

Originally Posted by boyt911sc

Karl,

Have your battery checked and analyzed. An ideal battery charge for cold starting is between 12.3 - 12.8 volts (static). Your battery could be getting old and should be able to deliver high current during the start phase. A good way to determine your battery's condition is have it checked using a battery analyzer. The print out would tell you more about your battery's health. Keep us posted.

Tony

TY for input Tony. Just Google'd to see if I want to buy analyzer. $300 - $1,400. Pass on that. Will have tested.

[356graham]

Assuming "weak start" means that it cranks slowly sometimes.

The fact that it experiences weak start only sometimes might point to a bad connection, but do check the battery also.

- Alternator is working. Charging voltage proves that.

- Starts OK sometimes - indicates that your battery might be OK, otherwise it would be weak all the time. It isn't good to run a non-deep-cycle battery all the way down, but it that situation it is normal for it to take some time on jumper cables before you can start the car. Age of the battery can be a factor also. How old is the battery? There should be a date on it. I've had batteries last as little as 3 years and as long as 9 years.

- If battery checks out OK, that leaves connections which are a relatively cheap fix.

Remove, clean and replace all connections at the battery terminals, including the connection from negative terminal to the body (ground strap) and also the ground strap from the body to the transmission. While under the car you can check the connections at the starter - both the heavy positive cable to the solenoid (careful with your wrench -it is a hot + connection) and also the smaller wire that connects from the ignition switch to the starter solenoid. I've seen that connection get corroded and cause weak starts (though that particular problem mostly results in the starter not engaging at all).

Hope you find the problem.

[DRACO A5OG]

+1 have you battery checked. Pull it out and take it to couple of FLAPS to confirm it's condition and look for visual cracks or swelling. I wrote coupe because some FLAPS are not consistent with their results. Ask me how I know.

If you have AAA road side service they can give you a print out diagnosis.

"12. volts" is way too low

[Discseven]

Originally Posted by 356graham

Assuming "weak start" means that it cranks slowly sometimes.

The fact that it experiences weak start only sometimes might point to a bad connection, but do check the battery also.

- Alternator is working. Charging voltage proves that.

- Starts OK sometimes - indicates that your battery might be OK, otherwise it would be weak all the time. It isn't good to run a non-deep-cycle battery all the way down, but it that situation it is normal for it to take some time on jumper cables before you can start the car. Age of the battery can be a factor also. How old is the battery? There should be a date on it. I've had batteries last as little as 3 years and as long as 9 years.

- If battery checks out OK, that leaves connections which are a relatively cheap fix.

Remove, clean and replace all connections at the battery terminals, including the connection from negative terminal to the body (ground strap) and also the ground strap from the body to the transmission. While under the car you can check the connections at the starter - both the heavy positive cable to the solenoid (careful with your wrench -it is a hot + connection) and also the smaller wire that connects from the ignition switch to the starter solenoid. I've seen that connection get corroded and cause weak starts (though that particular problem mostly results in the starter not engaging at all).

Hope you find the problem.

Yes, "weak start" = slow cranking.

• Battery age... forgot. Sticker on bat I'll check.
• Bat connections and ground to car are tight... recently cleaned.
• Engine ground strap... 2 years since terminals & strap cleaned--will check connections.
• Starter, replaced about 2 years ago. Will check connections.

TY for input Jeff. Will edit original post to note status notes you raised.

[Discseven]

Originally Posted by 83-911SC cab

I'm no electrical genius here just know enough to be a danger to myself and my cars....but I would check Batt voltage to see what it drops to when you are cranking engine...also how old is batt..heard somewhere the batt voltage shouldn't drop much below 10.5 volts while cranking or it might be sluggish...maybe the drain to dead might have damaged a cell in the batt?? Good luck with finding your issue..I'm sure many smarter people than me will chime in on this..

Have not checked voltage when cranking. Need to get son over to partner on that. TY for note "83."

[Discseven]

Originally Posted by DRACO A5OG

+1 have you battery checked. Pull it out and take it to couple of FLAPS to confirm it's condition and look for visual cracks or swelling. I wrote coupe because some FLAPS are not consistent with their results. Ask me how I know.

If you have AAA road side service they can give you a print out diagnosis.

"12. volts" is way too low

Amusing... when I have AAA, never need them. Then I cancel membership. Then I need them. Sensing membership-voodoo. Gona see if I can find issue... if not, will FLAP around. TY for input Jim.

Thought 12v static reading was normal. (?)

[Justin@Athens]

Fully discharging the battery like that dramatically reduces its overall lifespan and in many cases will kill a battery--in that, even when fully recharged it will dissipate back below 12v in a weeks time of non-use.

You may be in that situation. Your alternator may be keeping it alive in effect.

Have the battery load tested, but I am even skeptical of the test equipment used at Autozone and the like.

I agree with others on checking connections, particularly at the battery to body, and transmission to body locations.

[Dave Colangelo]

Being from Miami I doubt its cold (thats a factor up here in the north east sometimes).

Bricking a battery can be bad for them and as mentioned can reduce the life span.

On top of all that 12V does not mean that the battery can deliver the current needed to crank the motor as it should. People often mistake having 12V as having a good battery. If you look on your battery you will see a value for CCA (cold cranking amps) that is the total amount of amps your battery is capable of delivering (at about 12V) when the starter relay is clicked on. In reality you get less than this at the starter motor due to the natural resistance of the wires but that is neither here nor there. As a batter losses life it really looses the ability to deliver that original CCA value. Think about an engine that is losing life, it will always spin at 800 when idling but it may not deliver the power needed anymore. Bottom line, get the battery load tested, or if its old, swap it out.

Regards
Dave

[Discseven]

Originally Posted by Justin@Athens

Fully discharging the battery like that dramatically reduces its overall lifespan and in many cases will kill a battery--in that, even when fully recharged it will dissipate back below 12v in a weeks time of non-use.

You may be in that situation. Your alternator may be keeping it alive in effect.

Have the battery load tested, but I am even skeptical of the test equipment used at Autozone and the like.

I agree with others on checking connections, particularly at the battery to body, and transmission to body locations.

Never knew effect of discharging bat. TY for insight Justin. Yeah... not sure I trust any entity testing batteries that's selling them. Calling on mechanical friends to see who might have tester.

[HawgRyder]

When you check for voltage drop...do a check at the battery...and then do one at the starter....to see if there is a drop in the wiring or connections.
Also...feel the wires...if any feel warm or hot...it's a bad wire or connector.
Bob

[Discseven]

Originally Posted by Dave Colangelo

Being from Miami I doubt its cold (thats a factor up here in the north east sometimes).

Bricking a battery can be bad for them and as mentioned can reduce the life span.

On top of all that 12V does not mean that the battery can deliver the current needed to crank the motor as it should. People often mistake having 12V as having a good battery. If you look on your battery you will see a value for CCA (cold cranking amps) that is the total amount of amps your battery is capable of delivering (at about 12V) when the starter relay is clicked on. In reality you get less than this at the starter motor due to the natural resistance of the wires but that is neither here nor there. As a batter losses life it really looses the ability to deliver that original CCA value. Think about an engine that is losing life, it will always spin at 800 when idling but it may not deliver the power needed anymore. Bottom line, get the battery load tested, or if its old, swap it out.

Regards
Dave

Appreciate the detail Dave. TY.

[Discseven]

Originally Posted by HawgRyder

When you check for voltage drop...do a check at the battery...and then do one at the starter....to see if there is a drop in the wiring or connections.
Also...feel the wires...if any feel warm or hot...it's a bad wire or connector.
Bob

At the starter... Good one Bob! TY for input.

[AVIMAX]

I agree with everyone who suggested to have the battery tested. I had a similar problem over the summer, slow cranking but voltage at battery was OK and when running/charging was OK. I took the battery to be checked, test showed CCA = 90, should be something like 850. Put in a new battery, and all back to normal. 6 year old battery is probably getting to the end of it's life.

[Discseven]

TY for +1 on bat test AVI.

[Discseven]

Connected friend's battery known to be in good condition and... powerful start up. Given known work that's been done relative to key electrical connections... plus ALL input from you guys, my draining it (which I never considered detrimental before now)... seemed reasonable bat was done. Had it tested. Failed. Receipt for new monster-size DieHard below. Seems expensive. Was in hurry so convenience to get new bat in immediately was worth premium.

Pelican brain trust strikes again > problem solved. TY!

[Bob Kontak]

Originally Posted by Discseven

Receipt for new monster-size DieHard below.

Remember when I changed out to "The Monster". I posted a thread on how I was setting trees on fire with my headlights.

[Discseven]

Originally Posted by Bob Kontak

Remember when I changed out to "The Monster". I posted a thread on how I was setting trees on fire with my headlights.

Have some bushes to trim... will try headlightriming. Gotta check in with your front-end progress Bob.