Starter circuit help

DrGonzoMIA

DrGonzoMIA

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Hi all

Been having trouble with starter cranking too slow to fire engine. Thought it was an old, clapped starter so installed a new one but same problem so must be down to wiring. It's a 1979 Leyland 6/98 5.7l diesel. The wiring circuit confuses me a tad as I can't seem to locate a starter relay any where which I would like to test. Should it have a relay somewhere ? Or do some older systems not have one? Seems to be getting the correct t current at starter as tested with a multimeter. And I grounded the starter with a jump cable to don't think bad ground is the problem. Must be a relay, fuse or wire? Thanks in advance for any info.
 
If starter is turning their won't be a relay in the main cable so can only be a battery fault or starter or could be a bad connection to main starter cable
 
My starters were running slow and removing, cleaning and refitting all the battery terminals solved the problem. Even after sitting for a while they spin much faster than before. Worth going over (if you haven't before) before digging in too much into anything else.
 
yes, suspect a battery terminal or a cable clamp

connect the voltmeter to the starter, and measure the VOLTAGE during cranking,
most probably this is dropping

and then move your voltmeter connections closer to, or ON the batt terminals, and do the same again, (measure during carnking)
this way, you can find where the voltage drops
 
Thanks all. I will give everything a good looking over and cleaning. Just a bit difficult to do any tests while I'm by myself as can't crank it and sort multimeter out too. I tried jumping battery from another decent one and problem persisted so hopefully it is just a case of cleaning everything up. Thanks
 
best way of checking when you are on your own is to have a very long set of test leads for your multimeter so you can crank and view the voltages at the starter motor terminals.
Don’t think there were any relays the starter circuit, at least not in the vehicle based units I have worked on with that engine.
just check you are getting a good voltage between the big power in cable to the starter and the starter negative or body of the starter whilst you are cranking the starter.
It is a pre engaged starter so you have a low power feed to the starter solenoid unit and a high power feed direct to the starter.
Best to check on the big stud on the motor body that is connected to the solenoid with the positive lead and the negative directly on a starter motor mounting bolt.
 
Did a few more multimeter checks and all looks good. Took all cables off, cleaned everything and re installed. Still no joy. Connected starter to battery directly with jump leads. Seemed to run slightly faster but not enough to fire. I'm starting to think the problem may not be electrical....
Any easy mechanical things I can check ? Looked at a few forums as you do...but probably just confusing the issue more. Its a great, old, dirty 5.7 leyland 6/98. Mechanical lifter pump. Which I hear can go ? Anything I can check with raw, wet exhaust ? Oil looks good so don't think anything has mixed ? ? head scratcher...
 
DrGonzoMIA said:
Did a few more multimeter checks and all looks good. Took all cables off, cleaned everything and re installed. Still no joy. Connected starter to battery directly with jump leads. Seemed to run slightly faster but not enough to fire. I'm starting to think the problem may not be electrical....
Any easy mechanical things I can check ? Looked at a few forums as you do...but probably just confusing the issue more. Its a great, old, dirty 5.7 leyland 6/98. Mechanical lifter pump. Which I hear can go ? Anything I can check with raw, wet exhaust ? Oil looks good so don't think anything has mixed ? ? head scratcher...
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When was the last time it cranked fast when starting? If it cranks very slow then very very unlikely to be any of those other things you mentioned. What battery are you using and how old is it? What is the CCA? If all the cables have been checked and you have swapped the starter motor then the battery is the next thing to concentrate on.

www.solocoastalsailing.co.uk
 
I'll check battery specs. But it was new when I bought the boat 5 months ago. And I've kept it topped up. It's never started great to be honest. But has always fired until recently. Probably last time I had it running was a month ago. I also tried jumping it off leisure batteries. And another battery that is showing good voltage. But problem persists. Worried about knackering it up by keeping on trying to start it dry with poss no fluids getting around it.
 
Have you fuel at the injector? To test, full throttle, make sure the stop lever is in the run position, slacken one high pressure fuel line to one injector, crank engine and you should see fuel coming out the slackened fitting.
you won’t damage the engine trying to start it as long as you have good oil level. May be worth closing the water inlet seacock if it has one just in case any water back feeds into a cylinder.
 
DrGonzoMIA said:
I'll check battery specs. But it was new when I bought the boat 5 months ago. And I've kept it topped up. It's never started great to be honest. But has always fired until recently. Probably last time I had it running was a month ago. I also tried jumping it off leisure batteries. And another battery that is showing good voltage. But problem persists. Worried about knackering it up by keeping on trying to start it dry with poss no fluids getting around it.
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Until you have a good cranking speed its not worth pursuing anything else that may assist starting, they can come later. Check the CCA rating (cold cranking amps) on your battery. Leisure batteries are not usually the best for cranking anyway and battery voltage does not indicate it is a good battery for cranking.

www.solocoastalsailing.co.uk
 
Hopefully got help tomorrow to test any drain. Battery is a pretty new 126ah 800 cca one. That would do they trick wouldn't it ? Pretty beefy truck battery by the looks.
 
DrGonzoMIA said:
Hopefully got help tomorrow to test any drain. Battery is a pretty new 126ah 800 cca one. That would do they trick wouldn't it ? Pretty beefy truck battery by the looks.
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In my limited experience 800cca is the minimum for a 5.7 litre diesel. I use a 1000cca on my 3.5 litre diesel. Good luck for tomorrow. Do you have a battery charger permanently connected? If not, when you arrive and before you start and before you turn anything on, check the voltage at the battery terminals. A good charged battery should give 12.7 volts.
 
So narrowing a few things down today. But also confusion is rising. Battery seems fine. Had a mechanic put a drop test on and it checked out. Fuel is getting to injectors as we cracked a nut. Suspicions are now internal on engine, not enough cca (which surely can't be as jumping off others is no different) or new starter is faulty.
So...tool new starter off, connected battery cables, jumped terminals. It spins up but the gear and rod do not push out and engage. Which makes it more confusing as it actually turns over the engine. All be it slowly. How is the possible if it doesn't engage ? Unless it has some purchase on the flywheel without being engaged ? Tested old starter. And exactly same. It spins but gear does not shoot out and engage....wtf
 
That was the old bendix type if my memory serves me well, my starter as has been said, engages the solenoid forcing the gear to mesh with the flywheel and also closing contacts to power the motor, I suppose it is best to mesh before power unlike the old bendix type that often caused wear on the gears!
 
Mmmm, I didn't realise they varied in type too much. It's certainly an old engine but now not sure which type it is. I just assumed that when there was power to it, it would stick out and do its thing. But unless the small electrical connector is hooked up to the ignition it wouldn't engage ? Thanks all for all help thus far
 
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