Warm Engine Re-start

[arran]

When recently attempting a warm re-start (Volvo MD5A) there was no power supply to our engine. On investigation all cables etc were o.k but the engine was VERY warm (we had been under power for about 3 Hours). After 10 Mins (presumably after the engine had cooled?!) a power supply was restored and the engine started.

I traweled this forum and read with interest your excellent advice on possible causes of overheating. Ours was caused by a faulty thermostat now replaced the engine is no longer overheating. However a warm re-start is still causing problems.

Your advice and oppinions as to what may be causing the power to cut out would be very welcome.


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[Jools_of_Top_Cat]

When you say no power, do your warning lights come on when the key is turned and then no start, or turn key and everything dead?

if the no start but power on then it sounds like your

starter solinoid is sticking
dry joint on starter panel (extreem)
battery goosed (more extreem)

Do you get a click when you get a no start, or is it just silence?

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk/Honda_00.html>Honda Formula 4-Stroke racing</A>

 

[Robin]

I might be wrong it's been some time since I read this, but some Volvos have master fuses in a black box on the engine, the box also contains spare ones and/or unused connectors. Either the fuse or the contact goes, hence no start, I think the cure was to swap the fuse over or maybe the wires so a different fuse connector is used. It may be that the contact is poor when the engine is hot and eventually cures itself. Use with care but it is worth a quick check, if my memory serves it was quite a common complaint.

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[arran]

Thanks for your reply - I turn the key and everything is dead - no electricity!

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[arran]

Thanks for your reply - that was my inkling too. Perhaps a poor connection or something. Were the faults you talk about specific to early volvo engines?

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[Robin]

It depends how early! It was around 10 -12 years ago for sure so +/- from there. I remember reading it in PBO or maybe Westerly Owners mag. Because around that time we fitted a new Volvo MD22L in our old boat, and despite this being basically a Perkins Prima painted green, it did have this Volvo black box on it and as a result I filed it in a brain cell. As I said I think there was an easy work around, either moving the leads and fuse to a blank fuse carrier that is there or something similar. Maybe it was a part of a printed circuit that corrodes or cracks with vibration/heat?, I remember the article mentioning there was a ready made 'spare' in the box unused.

Like I said I might be wrong but it's worth a try and easy to check.

Good luck!

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[arran]

Thanks. There is a plastic box a litttle too close for comfort to the cylinder head. I'll check that out.

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[Robin]

That's the one!

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[alan]

Just to add my twohappence worth: this little balck box also contains the start motor relay and the glow plug relay (or at least it does on the 2020). On the black box you will find there is one wire connected to a spade terminal and 3 or for spare terminals. When the key is turned you should have 12v on all terminals and you can connect the wire to any of them; each of these terminals is fused and it is Volvo's way of providing spare fuses. I would suspect a duff connection either at the wire female terminal itself or at the spade terminal on the black box; when hot the metal is expanding and breaking the connection, when cold it is re-making.
Good luck. If it is any help I have a wiring diagram for the MD2020 from the workshop manual and I can also point you to a cheap source for Volvo workshop manuals ($20).

<hr width=100% size=1>Alan Cloke

 

[arran]

That's really helpful. We have already experienced electrical problems due to the age of the wiring (20 Years). As you suggest I suspect that the problem is a combination of old wiring and this black box. A workshop mannual and wiring diagrams would be very useful so if you have any addresses where they can be obtained (at sub Volvo prices!) I would be very gratful. Thanks once again for taking the time to post.

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[alan]

Workshop manuals and spare parts for most makes of engines can be obtained from "MarineEngine.com" :

www.marineengine.com

e-mail: info@marineengine.com

Fax: 1-802 301 1034 (USA)

Hope that helps.

Alan.

<hr width=100% size=1>Alan Cloke

 

[idoltyme]

check your issolaters and other conectons

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