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Slow Cranking (2)


Guest Gargoil

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Guest Gargoil

Hi Gents.

I am new to the forum, so please excuse any etiquette faux pas I might commit.

I have a 2.1 pinto, recently bought from Chris Russ who is/was a member of this forum, I can say I am delighted with it, it needs a little tinkering with and that is one of the aspects I am delighted with.

What I would like to get to grips with is the slow cranking speeds when cold, and when I say cold, I mean 10 degrees C and lower.

Searching through the help on line, one of the causes could be the connections to the starter motor. I checked these today and they seem fine, no resistance to speak of in the ccts, I cleaned all the connections but to no avail. It still cranks over slowly. The battery is good, so is it going to be the starter? I also noticed in some threads that there should be an earth strap between engine and chassis. Is that going to make a difference?

Thanks in advance for any help.

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Welcome aboard. :)

Get along to your local meet that's this Weds, plenty of learned peeps there to chat with.

 

http://www.rhocar.org/index.php?showtopic=38195&hl=

 

The engine earth is paramount to getting a good cranking speed so if it's thin, corroded or even missing start with sorting this.

Also, batteries are susceptible to the cold if a cell or 2 isn't tip top. How have you checked the battery?

 

Nick.

 

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Guest Gargoil

Thanks Shaft.

I do intend to get to some of the meetings, Wednesdays are a problem for me at the moment though.

I am reasonably sure the battery is ok, it's new and the symptoms are identical with the old battery or new battery installed. True, it would be nice to have a bigger 12v supply, but as you will know, space is at a premium. I am not sure the engine has a strap to the chassis, I have only seen the one from engine to the battery negative terminal, so that is something to check tomorrow. It would be nice, if that was the problem.....

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Guest chris brown

As Nick says make sure the earth between engine, chassis and battery are all good and man enough for the job. Then check the voltage of the battery both off load and under cranking, it should be 12 to 12.5volts off load but shouldn't drop below about 10volts under cranking. Also check the voltage with the engine running it should be between 13.8 and 14.2volts. I mention this as the problem could be a poor (failing) battery or alternator, all easy to check and alot cheaper than replacing the starter but if all the above are good then it does sound like the starter is at fault.

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Guest Gargoil

That's the first thing on my list tomorrow DanE.

While you're available, I know that membership starts in Jan, I presume I will have to wait to fully join until then?

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for battery check turn everything on lights heater if you have one turn engine over I if voltage drops below 11 battery problem otherwise as hankworht said just high compretion and starter motor struggling defo needs good earth strap from engine to chasis

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Earth straps from

block to chassis

Starter motor bolt on bellhousing to battery

Another strap from bellhousing bolt to chassis

There is also an earth strap from centre of gearbox mount to chassis

All this gives the battery half a chance of delivering full amps

If you running 2.1 and a decent cam you'll have spark advance at cranking

I use Megajolt and can program less advance at cranking with more advance once it catches

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Guest Alan_builder

Hello and welcome,

 

 

You say

"no resistance to speak of in the ccts"

Unless you measured that resistance by passing 100 amps you have fooled yourself. With only 12v to push the current the increase in resistance found by a bad connection when 100 amps flow is not found by a meter at 10mA. 0.01 ohms gives 1v drop at 100A which is about your cranking current. That's why Chris Brown said measure volts in several conditions.

 

 

Making good earth connections to the starter motor body is essential.

 

 

The starter solenoid connections could be corroded. The change from series to parallel wiring for cranking within the solenoid could be corroded.

Some starters have a wire you can get to so you can measure the voltage at the starter windings.

 

 

Lastly there are many starters with differing torques, obviously you need the high powered one not the one from a 1300. So worth a check on the part number.

 

Good luck

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Guest Gargoil

Hi again.

A small update.

I tried using a set of jump leads as a temporary engine to chassis connection, but with no difference when starting. I noted the voltage drop while cranking, which went down to 10.1V but then up to 11.5ish as the starter spun round quicker. The battery measured 12.7V (at rest) and when charging measured at 13.8V. I then hooked up a second battery and the results were pretty much the same. So even with more power, the starter isn't working the way it should. I did notice that when starting, it is reluctant to turn over at first but sometimes it seems to free itself and turn over more quickly. One of the lads at work suggested feeling for any temperature changes, as an indication that if something is getting warm, there is going to be a certain amount of resistance involved. So, negative cable from battery to engine block, cold. Positive from battery to solenoid slightly warm. Solenoid cold. Starter warm. From that it would seem the starter motor has a lot of internal resistance.

 

However looking for the cheaper and easier options first, the battery to motor strap goes to one of the bell housing bolts, not the starter motor mounting bolt. I can't find a strap from motor to chassis and the negative terminal to chassis is what looks to be a bit of 10mm. So I will be ordering some new cable (is 135 amp enough?) and a few ring terminals and getting these straps as they should be, before I go any further.

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You should also measure the volts at the starter motor and and the battery when cranking, as this will give you the voltage drop accross the cables. From that you could calculate the resistance. Having said that, it's not something simple like the starter motor is dry as a bone or dirty and needs greasing. I have had motors do this when cold, the muck/carbon build up mixed with the grease becomes like glue when cold.

 

Nige

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Guest Gargoil

You should also measure the volts at the starter motor and and the battery when cranking, as this will give you the voltage drop accross the cables. From that you could calculate the resistance. Having said that, it's not something simple like the starter motor is dry as a bone or dirty and needs greasing. I have had motors do this when cold, the muck/carbon build up mixed with the grease becomes like glue when cold.

 

Nige

It's possible Nige. It could be a combination of all the faults mentioned here.
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Guest Gargoil

cheapest option is to check the ignition timing. Too much advance causes the engine to slow and stop irregularly as it tries to start.

The timing was checked recently, but it might be worth my while investing in a strobe and checking it myself.
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