Slow to start Volvo Penta.

[pandos]

My 1980 md21b has always been a great engine, but is slow to begin to start....

To be clear....

with full batteries and even with the two banks joined and having applied plenty of heater.... from the time you turn the key there seems to be a long delay before any noise is heard from the starter, it is quicker when the engine is hot but only marginally so, I think there is no delay if I jump the starter....

Is this a feature of the ignition system, or a sign of a failing solenoid, or something else....

 

[jiris]

My 1980 md21b has always been a great engine, but is slow to begin to start....

To be clear....

with full batteries and even with the two banks joined and having applied plenty of heater.... from the time you turn the key there seems to be a long delay before any noise is heard from the starter, it is quicker when the engine is hot but only marginally so, I think there is no delay if I jump the starter....

Is this a feature of the ignition system, or a sign of a failing solenoid, or something else....

I would check all connections, battery terminal especially, for corrosion. Some products of corrosion in the path of the current may have very high resistance initially. After some small current passes through them and heats them up, their resistance would drop dramatically. Checking temperature of the suspected spots immediately after a heavy start will pinpoint the location of the problem.

 

[lauriel]

Check fuel filter bowl is full before attempting to start. A small air leak can allow bowl to partially empty and cause difficult starting. From first hand experience.

 

[jiris]

Check fuel filter bowl is full before attempting to start. A small air leak can allow bowl to partially empty and cause difficult starting. From first hand experience.

Yep. that's exactly what stops starter motor from operating ;-).

 

[VicS]

+1 to clean and check all the connections ....... dont overlook the negative!

Check the that power is being applied to the solenoid coil connection ( white wire, I think) when you turn the key to the start position.

If it is, but nothing happens, the solenoid or the engagement mechanism is probably sticking.

If no power is being applied then you will have to trace back towards the switch to find the reason.

The fact that it cranks immediately if you "jump" it suggests the problem lies withe the switch , the wiring or even with the power supply to the panel.

 

[KellysEye]

I had that and it was a loose solenoid rivet.

 

[scottie]

Maybe worth checking the actual wire ends as well at this age

 

[pandos]

I had that and it was a loose solenoid rivet.

Elaborate please...




Thanks for the replies, the one about initial resistance also sounds plausible will check that...having thought about it, it may well be in the switch panel, as I think I had the starter off and checked a few years ago (almost no usage since).

It is not a fuel issue, the delay is prior to any attempt by the mechanicals to do anything, it is therefore purely electrical...

 

[jiris]

Elaborate please...




Thanks for the replies, the one about initial resistance also sounds plausible will check that...having thought about it, it may well be in the switch panel, as I think I had the starter off and checked a few years ago (almost no usage since).

It is not a fuel issue, the delay is prior to any attempt by the mechanicals to do anything, it is therefore purely electrical...

From the previous reply I thought you have it sorted out already - it seems like you have not. But my theory (tested in practice many times) is very probable as all fits 100%in the story. It would actually apply to some lose connections (rivet?) as well. The key is the delay in action and the fact (your observation) it gets smaller with temperature wile the connection is partly heated already. With the lose connection it is similar. It has a high resistance, but the material expands with temperature and connection gets tighter (depends on the materials used) and its resistance drops. Again, you would find the guilty parts being much warmer than the rest of the wiring after a heavy start.
The fact the delay still exists during jumpstart points very much towards the solenoid or negative end. Being shorter makes sense too; the total initial resistance of the circuit is lower and the faulty connection warm up faster. All fits like a glove

 

[pandos]

Thanks for the replies ,

Will explore in detail tomorrow..

 

[pandos]

Sorted... two shots of contact cleaner into the keyhole....