Dyna Starter

wstokes

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My Rival 32 has a Volvo MD2B Diesal engine which is equipped with a Dyna Starter (some people refer to them as a starter-generator). I have had no trouble with this dyna starter but have noticed for the first time that it gets very hot when in operation. As there is no unusal noises coming from it, I.E. bad bearings etc., I am not sure how hot these things should get.
Does anyone know if this is normal?
 

pyrojames

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Err, never noticed mine getting hot. At least no hotter than any other part of the engine. Any funny smells? Hot wiring? Mine did chew up its front bearing many years ago, but then it wouldn't crank.
 

wstokes

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I never thought about replacing the Dyna Starter, but have noticed that periodicaly the engine won't crank over on the starting battery but will on the house battery. I thought that it was my battery cables (both batteries were fully charged) so I switched the batteries same result. In the meantime, I will probably take it off and have the unit serviced. To the best of my knowledge it has never been serviced.
 

VicS

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While it is under load eg by chaging the battery it is going to get pretty warm but if you decide that it is excessively hot the first thing you should check is whether the power is remaining on to operate the Dynastart in start mode. That I am sure will result in it being very hot.

It could be caused by a faulty start switch (push button?) or a faulty solenoid. Originally the solenoids were incorporated in the control box, but not in modern replacements which require a separate solenoid.

On reflection I think this is unlikely to be the trouble as if either start button or solenoid were faulty and energising the starter windings the engine would start, or at least be cranked,as soon as the battery isolator was closed, or the key operated ignition switch, if fitted, is turned on depending how that has been wired into the circuit. However it is worth a check.

If the starter side of things is Ok then you have to consider that the dynamo side is being overloaded or that the voltage regulation part of control box is faulty. Do you have an ammeter directly in the dynamo output (from the D+ terminal) that shows the current output of the dynamo? If so what is it reading.

Check the control box voltage regulation by measuring the volts output at either the D+ terminal or the B+ or 51/30 terminal of the control box or at the battery.

If you can find no external problems then it is probably a fault with the Dynastart itself such as a shorted turn(s) in the windings.

It depends how it has been wired but the charge/ run switch (if you have one) may enable you to run with the field supply to the dynamo disconnected. Alternatively disconnect the wire from the DF terminal of either control box or Dynastart. It really should run cool then.

It doesn't make any difference really but is a Bosch or a Siba
 

bluedragon

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I wouldn't assume it's faulty. I had a newly reconditioned unit two years ago, and it also became very hot after running for a while. Just speculation on my part, but unlike alternators the Dynastarts don't have a fan or cooling slots so perhaps it's not surprising that they get hot when charging? I've disconnected the output coils on mine now and use it only as a starter. It's a lot cooler, so supports the theory that it's the charge current.

PS - it might be an idea to take it to LSUK or one of the other specialist companies that rebuild Dynastarts and ask them to run a bench test if you're concerned.
 

William_H

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The best bet is to fit an ampmeter to see what charge current you can get. If it has a fault making it hot then it is unlikely to produce the expected amps output. olewill
 
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