MD2040 Starting trouble

[lustyd]

Hi all, looking for some experts to comment on my thought processes on a slow to start engine (VP MD2040). I'll start with the general statement that the boat is very dry with no corrosion or visible issues and everything is in good condition.

Since buying the boat the engine has been slow to start when using just the start battery. It springs into life when joining start and domestic banks, there's no smoke and it runs very well. As such I suspected the start battery despite it having a reasonably easy life and being well charged. Same issue with the new battery after replacement.
Voltage drops low when cranking, even with banks in parallel. This causes all the electronics to grumble and beep if they're on.
Next, I suspected the glow plugs so used a clamp meter to confirm they draw suitable current (they do) so I think I've ruled these out. Also, the engine responds in an identical way whether I use glow or not so although I will use it, it doesn't seem needed.
I checked the relays, a known issue with the engine. Relays were fine and good connection on all contacts, very secure in their box.
I checked connectivity from the engine to the battery. Contacts seem clean and there is good continuity on all connections. Cables are all suitably large and seem in good condition with no visible corrosion at all. Engine is next to the battery so runs are short

This leads me to suspect the starter itself. Possibly brushes, or some fault in the windings. Given the costs and effort it seems easier to start with a new starter as a test. Is this a reasonable next step or did I miss something?

 

[jamie N]

I'd a similar problem, and removed the starter to have it tested it an autoparts retailer; in Inverness they're Dingbro. They tested it and condemned it. I was able to get a replacement at a good price from Germany for my Ruggerini, which fitted and started without issue.
However, did the previous owner have the same grief, or is it a developing thing?

 

[ghostlymoron]

I'm not familiar with the md2040 but have had several inboard diesels including an early VP. Your problem sounds like a poor connection somewhere and although you say you've checked continuity, I would undo, wire brush and clean all connections to/from battery, ignition switch and starter. It's rare for a starter motor to give up so thoroughly check wiring first. You can be fooled into thinking it's good if you only test with a digital meter. It can show healthy voltage but will drop when actually turning the starter.
Your engine should start without paralleling with the house battery.
Incidentally, if you do need a starter motor, try your local tractor dealer as many marine ones are identical to VP/YANMAR etc.

 

[BobsFolly]

I wonder are the glow plugs not in great condition? Do you have the same symptoms starting the engine when it's warmed up?
My glow plugs were 'working ' but badly coked up and my md2020 was very slow to start up when cold.
Initially I took the 2 out I could access easily and cleaned em up a bit, worked fine ever since !

 

[Tranona]

It is a Perkins engine. Starter motor here parts4engines.com/volvo-penta-md2040-starter-motor/

 

[Boater Sam]

I would inspect the negative connections between starter, engine and battery. Often overlooked but they are the other half of the circuit. Crimps that look OK may not be............
Is there a battery management shunt in the battery negative ? Is it designed to take the starter current? Some are not.
Battery isolator switches are notorious for poor contact especially the nasty red key ones.
If the starter is the problem Lancashire Rotating Electricals would be my choice of fixer. They really know whats what and try to please.

 

[lustyd]

I wonder are the glow plugs not in great condition? Do you have the same symptoms starting the engine when it's warmed up?
My glow plugs were 'working ' but badly coked up and my md2020 was very slow to start up when cold.
Initially I took the 2 out I could access easily and cleaned em up a bit, worked fine ever since !

Yes I should also have said it's the same warm or cold pretty much and whether I glow or not so pretty sure the plugs aren't the fault here.

 

[lustyd]

Is there a battery management shunt in the battery negative ? Is it designed to take the starter current? Some are not.
Battery isolator switches are notorious for poor contact especially the nasty red key ones.
If the starter is the problem Lancashire Rotating Electricals would be my choice of fixer. They really know whats what and try to please.

I tested the negative and all good, no corrosion anywhere. Yes there is a shunt but that was added and didn't change anything. It's not part of the engine circuit unless the parallel switch or VSR connect things up.
A new starter is only £150 by the look of it so if I go that route I'll swap and then maybe get the old fixed as a spare depending on cost.

 

[lustyd]

It is a Perkins engine. Starter motor here parts4engines.com/volvo-penta-md2040-starter-motor/

Thanks, very useful. I'm planning to check the model this weekend if the consensus is to swap. The MD2040 has various starters associated on various websites. They have differing numbers of teeth and power ratings so I want to check what I actually have. Some sites suggest the whole 20x0 range use the same but the manual says different as the 2040 has different gearing which makes me nervous enough to check properly

 

[Boater Sam]

I tested the negative and all good, no corrosion anywhere. Yes there is a shunt but that was added and didn't change anything. It's not part of the engine circuit unless the parallel switch or VSR connect things up.
A new starter is only £150 by the look of it so if I go that route I'll swap and then maybe get the old fixed as a spare depending on cost.

Try LRE for a price on a new starter too, they are very good.

 

[jac]

If it starts fine using both banks, would that suggest that the engine and starter itself are fine. My initial thiought would be a starter battery that is perhaps not up to the job

 

[lustyd]

If it starts fine using both banks, would that suggest that the engine and starter itself are fine. My initial thiought would be a starter battery that is perhaps not up to the job

In theory it's a common symptom of worn brushes or a short in a winding. I say in theory because I have zero practical experience troubleshooting this! Brushes are a consumable item and need replacing periodically anyway. Windings can sometimes short, which can cause voltage drop which in turn causes heat which gradually kills the starter. Joining the batteries gives the ability to supply enough amps to overcome the voltage drop. That's the theory at least.

New battery is definitely OK, as I suspect was the one I replaced and the other spare I tested.

 

[lustyd]

Just closing this thread out. Today I cleaned all of the contacts which improved things a bit. It looks like there was never a great connection due to paint on various bits. This completely fixed the short beep when stopping the engine and made it sound for several seconds like normal. The engine still had trouble starting though so I fitted my new starter and the engine starts better than any I’ve used previously now. Looks like the poor connection damaged the old starter. All fixed now though so thanks all for the help and advice.

 

[david_bagshaw]

I would inspect the negative connections between starter, engine and battery. Often overlooked but they are the other half of the circuit. Crimps that look OK may not be............
Is there a battery management shunt in the battery negative ? Is it designed to take the starter current? Some are not.
Battery isolator switches are notorious for poor contact especially the nasty red key ones.
If the starter is the problem Lancashire Rotating Electricals would be my choice of fixer. They really know whats what and try to please.

I have used Lanc rotating Elecs for an old alternator, deffo can recommend.

 

[Bilgediver]

I'm not familiar with the md2040 but have had several inboard diesels including an early VP. Your problem sounds like a poor connection somewhere and although you say you've checked continuity, I would undo, wire brush and clean all connections to/from battery, ignition switch and starter. It's rare for a starter motor to give up so thoroughly check wiring first. You can be fooled into thinking it's good if you only test with a digital meter. It can show healthy voltage but will drop when actually turning the starter.
Your engine should start without paralleling with the house battery.
Incidentally, if you do need a starter motor, try your local tractor dealer as many marine ones are identical to VP/YANMAR etc.

If going for alternates then remember to count the teeth on the pinion. The starter can appear the same but can be supplied with slightly different pinions.

 

[Boater Sam]

Just closing this thread out. Today I cleaned all of the contacts which improved things a bit. It looks like there was never a great connection due to paint on various bits. This completely fixed the short beep when stopping the engine and made it sound for several seconds like normal. The engine still had trouble starting though so I fitted my new starter and the engine starts better than any I’ve used previously now. Looks like the poor connection damaged the old starter. All fixed now though so thanks all for the help and advice.

What many do not realise is that trying to start with a low battery or bad connection/s actually causes the starter motor to draw more current than normal. This deteriorates the windings and brush gear.
It is because the motor which is an inductor is not spinning fast enough to develop the back emf leading to reducing the current in normal operation..