14 replies to this topic

[AEM]

Hi all,

Need a bit of help please, I've come back from being away and my '66 Cooper S wont start, 1330cc, +ve with a dynamo. 

it turns over very slowly and slows down after a few seconds. 

I've checked and charged the battery and used another one in parallel and on it's own.

Check and tightened the battery connections and solenoid connections.

When cranking the voltage on the starter side of the solenoid drops to approximately 9 volts, so there isn't enough current available from the battery hence the voltage dropping so much and slow turning?

Before I remove the starter is there anything I've overlooked?

I've read somewhere that the solenoids can cause a voltage drop?

I need to get it running for Brooklands on Sunday but only have tomorrow and Friday afternoon/evening to get it up and running.

All helpful suggestions welcomed.

Thanks in advance.

 

 

[Dan]

Volt drop to 9v under cranking is perfectly normal, it's why ballasted ignition was invented. It shouldn't need to be cranking for more than a few seconds in order for you to see it slow down, a healthy A series should catch at the first turn or two. How fast will it turn with the plugs out? How long has it been sitting? Is there a spark?

[carbon]

+1 for Dan's comment.

 

What you are measuring at the starter side of the solenoid is 9V, that does not mean you have a 3V drop across the solenoid.

 

If you measured the battery voltage at the terminals when cranking over starter you would likely be just above 9 volts, as a lot of the volt drop is battery internal resistance.

 

Typical volt drop from battery terminal to starter terminal is about 0.5V when cranking a 1275 lump if all is correctly connected.

[carbon]

2 suggestions :

- first check the earth strap is in good condition, and where it bolts to the body has metal to metal contact not just paint

- second check the end of the lead connected to the starter motor, where the 1/4 nut connects the terminal. There is insulation sleeve on the end of this cable and if the sleeve has stretched it can get caught beween nut and cable causing a 'high' resistance

[AEM]

Thanks Dan and carbon,

Perhaps I termed it incorrectly when I stated that the drop was across the solenoid, that's where I measured the voltage on each side of the contacts, but not simultaneously, that'd need two volt meters, I'm working solo so accessing and reading the voltmeter is tricky when operating the starter via the key switch.

It has almost caught a couple of times, so whatever is causing this is intermittent or on the margin of being OK.

I haven't tried without the plugs in, will give that a try, it has been stood for a while, I did try to start it a before I went away, it wouldn't start, same issue, so I removed the battery and charged it off the car as it'd been used somewhat.

The earth connections are tight but I'll check for paint and rust etc. the cable to the starter is tight, but the terminal it's self does move slightly? I can see an insulating washer on the threaded terminal, the cable is connected beyond that between two nuts on the 'free' end.

I've lost the light etc now and it's getting a bit cold too!

I'll be back on it again in the morning.

[carbon]

If it's close to firing then the other suggestion I would make is fuel.

 

If possible get the 'overwintered' fuel out of the system and put in a couple of gallons of fresh 99 octane (one for each tank).

 

Once it's running you can then blend the old fuel back in.

[AEM]

If it's close to firing then the other suggestion I would make is fuel.
If possible get the 'overwintered' fuel out of the system and put in a couple of gallons of fresh 99 octane (one for each tank).
Once it's running you can then blend the old fuel back in.

I think the fuel is OK, not had an issue before, it's got a full tank of 98/99 octane and Castrol Valvemaster +, also I don't think that would account for the slow cranking that happens most of the time? It was only almost fast enough on two occasions out of numerous tries.
Tomorrow I'll pull the plugs and try cranking it like that, check for a spark and warm the plugs before refitting, also I'll jump it from my 4x4 As that has more CCA to add, then take it from there.
I'll keep you posted.
Thanks again.

[KernowCooper]

Can you do a volt drop test on the different connections, place the volt meter on a 20v scale and place one terminal on the battery centre post and on the terminal itself, work your way forward on all the conections,including the earths. if you start seeing 1v+ then that connection needs looking at

 

Are you sure your battery is not sulphated ?

 

Also check what voltage reading you have on the coil + terminal, I'd be interested to know what your getting there?

 

If all these points check out and your sure you have a good earth then the starter is where I'd be looking at next

Edited by KernowCooper, 25 March 2015 - 09:07 PM.

[AEM]

Thanks for the post,

 

Can you do a volt drop test on the different connections, place the volt meter on a 20v scale and place one terminal on the battery centre post and on the terminal itself, work your way forward on all the connections,including the earths. if you start seeing 1v+ then that connection needs looking at

Are you sure your battery is not sulphated ?

Also check what voltage reading you have on the coil + terminal, I'd be interested to know what your getting there?

If all these points check out and your sure you have a good earth then the starter is where I'd be looking at next

Hi thanks for the post.

I'm pretty sure that the battery is good, it looked OK when I removed the caps, yes, it's not a seal for life/death type, plus I've added another in parallel and it was just the same.

I'll check the coil voltage and leads/connections from the battery and earth side.

One thing else I'll try which I remember from my late father, who was an auto electrician for 40 years, is to connect the earth from the battery straight to the engine, not quite so easy when the battery is the opposite end of the car!

Thanks again, I'll try all the suggestions in the morning and report back.

[ChopperHarris]

try a live with a jump lead from the connection on the solenoid to the starter terminal ,thereby bypassing the solenoid, if it spins over then the solenoid is at fault....out of gear!

[AEM]

try a live with a jump lead from the connection on the solenoid to the starter terminal ,thereby bypassing the solenoid, if it spins over then the solenoid is at fault....out of gear!

Good though, I'll try that too, thanks.

[Swift_General]

try a live with a jump lead from the connection on the solenoid to the starter terminal ,thereby bypassing the solenoid, if it spins over then the solenoid is at fault....out of gear!

Good though, I'll try that too, thanks.

Or just place your voltmeter accross the terminals of the solenoid whilst cranking. That will tell you if there is any appreciable voltage drop within the solenoid.

[AEM]

Update!!!!!!!!!!!!!!!!!!!!!!!!!

Well it's up and running!

I didn't really do anything else to it after last night other than check the engine earth continuity and the battery voltage on the solenoid, 12.7VDC.

First time it turned over at full cranking speed and almost fired up, second time successfully fired up and ran without a problem!

I don't think this issue is resolved, it just gone away, but at least I have some things to try to sort it out.

Thanks to everyone who made suggestions all very helpful and banked for future use.

I'll let it cool off and try it again later and again tomorrow after work, then again on Saturday evening.

I will now hopefully be at Brooklands on Sunday, looking forward to it, hope it's sunny and warm.

Thanks again, TMF you're the best.

[ChopperHarris]

good news

[AEM]

good news

Indeed, I'll be keeping ny fingers crossed for Sunday morning though!