Glow plug light not going out completely

[PineappleGuy]

Two problems have arisen recently:

a)      the glow plug light is glowing dimly when the engine is running; and

b)      the engine is cutting out fairly frequently.

I’m wondering if they are related and that whatever the problem is eventually results in the stop solenoid dropping out, cutting off the fuel. I’ve attached the engine wiring diagram. Please can someone advise what is supposed to happen, what might be going on and where to look?

[Tony Brooks]

Regrettably that is only half the diagram, so I can't see where the warning lamp & ignition switch fits into things or anything to do with the domestic alternator. I can't see how the warning lamps connect.

 

The stop solenoid seems to need a "hold in" circuit and the way you talk about the frequent stopping makes me think about a loose connection, so have you checked, cleaned and tightened the connections inside the multi-plug(s) on the main engine wiring harness.

 

Your diagram seems to show two glow plug relays, one of which may be a timer/reduced power device. I simply don't know. 

 

I find it difficult to work out how a glow plug warning lamp can glow and not fully illuminate, so are you sure it is not one of the alternator warning lamps. They are far more likely to glow when a diode fails than a glow plug lamp. That would also compromise battery charging.

 

Not much help I am afraid, but check that multi-plug.

 

I think we had someone who sounded like a Barrus agent or employee as a member, but I can't find his post to ping him about this.

 

Edited February 9 by Tony Brooks

[PineappleGuy]

Thank you for the reply Tony. Sorry, I thought the table (top right) would contain sufficient extra information.

Regarding how the glow plugs are supposed to work, I was hoping for an explanation of what goes on inside HEATER RELAY, for example.

Also, I was wondering whether the GREY wire was a suspect as it goes to both the HEATER RELAY and the STOP SOLENOID Hold connection.

I'm not on the boat at the moment but a co-owner will be there soon so I'll ask him to examine a few connectors.

[matty40s]

Depending on how old the engine is, and its hour use...you may find the stop solenoid is sticking and maybe needs a good clean....possibly also adjusting if not adjusted since new.

[nicknorman]

That diagram is just the engine side of things. There will also be a wiring diagram for the panel. The grey wire is obviously important as you say. Worth bearing in mind that power for it is routed via the panel and ignition switch. So the flow of power is from the battery via starter solenoid, via F2, via the brown wire, via the multi-way connector, up to the ignition switch on the panel, back down via the multi-way connector, via the grey wire to the stop solenoid etc. So there is plenty of scope for bad connections! The multi-way connector is renown for being problematic due to corrosion etc, so that is perhaps the best place to start. Unplug it and check the contacts for corrosion. Also check the fuse F2 as sometimes they can corrode too.

 

As for the glow plug light, it’s difficult to suggest a cause as the panel wiring diagram, which includes the light, is not shown.

[Tony Brooks]

3 minutes ago, PineappleGuy said:

Thank you for the reply Tony. Sorry, I thought the table (top right) would contain sufficient extra information.

Regarding how the glow plugs are supposed to work, I was hoping for an explanation of what goes on inside HEATER RELAY, for example.

Also, I was wondering whether the GREY wire was a suspect as it goes to both the HEATER RELAY and the STOP SOLENOID Hold connection.

I'm not on the boat at the moment but a co-owner will be there soon so I'll ask him to examine a few connectors.

 

Without the other part of the diagram (the instrument panel) I can't check my supposition is correct, but I think the grey wire is a positive feed from the "ignition on" position on the ignition switch. I say this because it is connected to the IG alternator terminal that energises a six diode alternator.

 

An energise to run stop relay would need an ignition switched feed, so that adds up.

 

Note the Glow relay at the bottom of the diagram, a little off-centre. I think that this is a timer relay that times how long the glow plugs are energised for and then cuts them off. This is probably close to the instrument panel and to allow it to feed the glow pugs via a thin (cheap) cable it actually feeds the coil in the Heater relay (top of diagram). This will be close to or on the engine and switches thicker cables linking the man battery pos. terminal on the starter to the glow plugs. This is supposed to make it more reliable, as long as engine vibrations do nor wreck that relay.

 

I repeat, the first thing to check is the multi-plug on the engien harness.  These cause all sorts of problems across th whole range of engine makes.

[nicknorman]

It’s a little confusing but I think bottom mid-right “glow relay” is misnamed. It and the 1 second timer relay bottom left all seems to be part of the stop solenoid, the clue being in the 2 stop solenoid connections “pull” and “hold”. IMO when the starter is activated the “glow relay” puts voltage on the “pull” part of the start solenoid, which will be a low resistance high current high power winding to move the solenoid into the run position. After a second, the timer operates to disconnect this high current “pull” and just leave the lower current “hold” winding operating. All this to avoid excessive power drain and overheating of the solenoid.

 

The actual glow plug relay (near the top) is unrelated to all that stuff.

Edited February 9 by nicknorman

[Tony Brooks]

8 minutes ago, nicknorman said:

It’s a little confusing but I think bottom mid-right “glow relay” is misnamed. It and the 1 second timer relay bottom left all seems to be part of the stop solenoid, the clue being in the 2 stop solenoid connections “pull” and “hold”. IMO when the starter is activated the “glow relay” puts voltage on the “pull” part of the start solenoid, which will be a low resistance high current high power winding to move the solenoid into the run position. After a second, the timer operates to disconnect this high current “pull” and just leave the lower current “hold” winding operating. All this to avoid excessive power drain and overheating of the solenoid.

 

The actual glow plug relay (near the top) is unrelated to all that stuff.

 

That makes sense because I could not find a link wire between the two "heater" solenoids. I did not think Barrus would make that sort of cock up in the manual. 

[PineappleGuy]

Here is the other half of the wiring diagram. Can I draw attention to the first issue in my original post. Can someone explain how the glow plug light could come to be glowing dimly while the engine is running?

I'm assured that all the other warning lights are out. The engine is 9 months old and has done 200 hours. I looked up the GLOW RELAY part number and found a description "... By facilitating the preheating of the engine's glow plugs, it helps in achieving smooth and quick ignition..." so do you think it has been re-purposed by Barrus to work with the stop solenoid (and create confusion)?

Edited February 9 by PineappleGuy
Pressed the Post button before finishing the sentence

[Tony Brooks]

A glow plug warning lamp can not glow, it should be either on or off. However the heater relay shows an L terminal that typically becomes live when the relay is energised to supply the heaters. That would normally feed the warning lamp BUT the diagram shows the glow plug warning lamp is supplied from the ignition switch (as normal) but the lamp's negative seems to be the L terminal on the relay. Now speculation, The numbers on relays follow a standard:

Key Automotive Relay Terminal Numbers:

• 30: Common / Power Input (Fused 12V supply)
• 85: Coil Ground (Negative)
• 86: Coil Trigger / Signal (Positive input from switch)
• 87: Normally Open (NO) / High Current Output (Active when relay is on)
• 87a: Normally Closed (NC) / Low Current Output (Active when relay is off) 

This shows that the heater relay is wired back to front (see the relay next to it). I think that is deliberate to make the L terminal go negative when the relay is energised and that would make the warning lamp work as expected - only on when the glow plugs are energised.  

 

If the glow plug lamp glows then either there is a partial short circuit anywhere between the warning lamp negative side and the circuit's battery negative connection, or the relay does go fully open circuit for the L terminal when the relay is de-energised. I don't think any electronics are likely to be inside the relay so it makes no sense to me.

 

Try this test. While the lamp is glowing, try disconnecting that L terminal, it is likely to be a simple push on blade connection. If the lamp goes out then change the relay and hope it cures it. If the lamp stays on I don't THINK it can be a glow plug lamp,  whatever the symbols or manual may claim.

 

 

9 hours ago, PineappleGuy said:

The engine is 9 months old and has done 200 hours. I looked up the GLOW RELAY part number and found a description "... By facilitating the preheating of the engine's glow plugs, it helps in achieving smooth and quick ignition..." so do you think it has been re-purposed by Barrus to work with the stop solenoid (and create confusion)?

 

Why are you messing about with the forum. At name months the engine should still be under warrantee so get hold of Barrus and get them or their agent to sort it out. It seems needlessly complicated to me and I agree with Nick, that relay seems to have no wiring associated with the actual glow plugs, so we are trying to second guess what Barrus have been up to. They should also be able to answer your questions with certainty.

[Alan de Enfield]

1 hour ago, Tony Brooks said:

At name months the engine should still be under warrantee so get hold of Barrus and get them or their agent to sort it out.

 

 

Or, whoever fitted it.

[jonathanA]

1 hour ago, Tony Brooks said:

Key Automotive Relay Terminal Numbers:

• 30: Common / Power Input (Fused 12V supply)
• 85: Coil Ground (Negative)
• 86: Coil Trigger / Signal (Positive input from switch)
• 87: Normally Open (NO) / High Current Output (Active when relay is on)
• 87a: Normally Closed (NC) / Low Current Output (Active when relay is off) 

This shows that the heater relay is wired back to front (see the relay next to it). I think that is deliberate to make the L terminal go negative when the relay is energised and that would make the warning lamp work as expected - only on when the glow plugs are energised.  

I can't quite agree with that. it seems to me that the starter relay is wired 'backwards' in that its 86 is connected to Neg.  This makes me think that the glowplug relay is not just a simple relay and incorporates some other functions, which require the correct polarity supply, as normally a relay coil doesn't care.  my guess is that is has a timer built in and possibly the connection to the starter circuit (pin 50) disables the glowplugs during cranking ?  L being the lamp. There is no 'heat' position on the ignition switch so a timed glow plug operation would make sense.

 

searching on the part number RDG5279 shows picture of a nonstandard relay case and a price of around a £100 (!). 

 

I found this image purporting to be a 70A glowplug relay with the same pinout numbers but a different physical shape to the barrus one.

 

so quite a bit of guesswork and supposition on my part but seems to fit the situation.  Needlessly complicated i'd say ! The OP can tell us if the glow plug light comes on when the ignition is first switched on and then goes out after a few seconds.   (i.e is timed as i think or not)

Presumably it hasn't always had this/these faults - so did he/they do anything or when did it start ?

 

my guess would be this relay is acting up, causing the  dim glow, but that would not explain the engine stopping which seems more likely to do with the energise to run shenanigans that Nick describes.   

 

I agree disconnecting the glow plug light wire should be easy and as its on a separate bullet conenctor at the multiway plugs disconencting at that/those should help isolate any issue. Given its fed with +12V* any shorting to earth via rubbing on metalwork or even damp/crud on the connectors  could be causing the dim glow.

 

given the complication around the interaction of the starter, timer, other relay (labelled 'Glow Relay' )and the stop solenoid i'd be checking all those connections (white wire from starter, thru F1 etc). 

 

having said all that Tony is right phone call to Barrus or whoever fitted the engine to come and sort it.....

 

* fed with 12v when ignition on so dim glow could be an earthing fault.  if glows with ignition off i'm stumped !

Edited February 10 by jonathanA
added bit after *

[nicknorman]

Ah new information! So if it is a new engine it’s unlikely to be eg corrosion on the multiway plug.

 

The glow plug light wiring is pretty simple, a positive on one side of the bulb, other side going down to the heater relay thingy. It can only be either a partial wiring short in the loom (unlikely) or an internal fault with the glow plug relay. Which also seems fairly unlikely! But either way I can’t see how it could be related to the engine cutting out.

 

Can you give more details about the nature of the engine cutting out? Under load just cruising along? at idle? when selecting idle? or what? Does it stop dead or struggle a bit and then stop? Any smoke at the moment it stops?

 

How long has this problem been going on? Since new, just recently etc?

 

I am thinking new engine = debris left over from the installation in the fuel supply. That is just a guess though

 

But the main point is that as said, a new engine is covered by manufacturer’s warranty. Either the manufacturer or the installed needs to come out to fault find.

7 minutes ago, jonathanA said:

I can't quite agree with that. it seems to me that the starter relay is wired 'backwards' in that its 86 is connected to Neg.  This makes me think that the glowplug relay is not just a simple relay and incorporates some other functions, which require the correct polarity supply, as normally a relay coil doesn't care.  my guess is that is has a timer built in and possibly the connection to the starter circuit (pin 50) disables the glowplugs during cranking ?  L being the lamp. There is no 'heat' position on the ignition switch so a timed glow plug operation would make sense.

 

searching on the part number RDG5279 shows picture of a nonstandard relay case and a price of around a £100 (!). 

 

I found this image purporting to be a 70A glowplug relay with the same pinout numbers but a different physical shape to the barrus one.

 

so quite a bit of guesswork and supposition on my part but seems to fit the situation.  Needlessly complicated i'd say ! The OP can tell us if the glow plug light comes on when the ignition is first switched on and then goes out after a few seconds.   (i.e is timed as i think or not)

Presumably it hasn't always had this/these faults - so did he/they do anything or when did it start ?

 

my guess would be this relay is acting up, causing the  dim glow, but that would not explain the engine stopping which seems more likely to do with the energise to run shenanigans that Nick describes.   

 

I agree disconnecting the glow plug light wire should be easy and as its on a separate bullet conenctor at the multiway plugs disconencting at that/those should help isolate any issue. Given its fed with +12V* any shorting to earth via rubbing on metalwork or even damp/crud on the connectors  could be causing the dim glow.

 

given the complication around the interaction of the starter, timer, other relay (labelled 'Glow Relay' )and the stop solenoid i'd be checking all those connections (white wire from starter, thru F1 etc). 

 

having said all that Tony is right phone call to Barrus or whoever fitted the engine to come and sort it.....

 

* fed with 12v when ignition on so dim glow could be an earthing fault.  if glows with ignition off i'm stumped !

The diagram on the case (the square wave pulse) suggests a timer function as you say. So it’s more than just a relay.

[PineappleGuy]

Thank you everyone I really appreciate your analysis. Before responding on the technical issues, I’ll just say that we have spoken to Barrus and the engine fitter and so far they have not been persuaded to come and have a look, which is partly why I have turned to this forum for advice, as well as seeking to advance our knowledge, noting that the previous engine didn’t have glow plugs.

Reading the Shire 35 manual a bit further, it does indeed say “The glow plug light will come on when the ignition is first turned on for 5 – 8 seconds to indicate the heating system is operational. When the light goes out the engine can be started.”

So, I think we have a few specific things to work on, at least regarding the glow plug issue, but at the moment it seems from the above responses that the engine stopping is a separate issue. I can’t give definitive answers to Nick’s questions regarding how it stops but I’ll ask my friend to make a careful note when it happens to him! The engine restarts readily I gather and then dies a random time later. It only started to occur last Friday but it was the first time the boat had been out of the marina for a couple of months. The user had just got through Braunston Tunnel (!), which is a few hours from Wigrams Turn Marina.

She called RCR and the guy went through the fuel system and then, when it was getting dark, he noticed the glow plug lamp glowing dimly. Therefore, we don't know how long that has been happening. The RCR engineer didn’t investigate and didn’t suggest that perhaps the engine stopping could also be an electrical issue. Our user had further trouble with the engine cutting out the following day on the way back but carried on. On Sunday she did the final hour back to the Marina – the engine didn’t cut out and neither was the glow plug light glowing.

[Alan de Enfield]

54 minutes ago, PineappleGuy said:

..............the engine restarts readily I gather and then dies a random time later.

 

Would that time equate to something like a filter full of fuel ?

 

You may find a partly blocked filter, allowing the 'bowl' to fill but not fast enough to maintain the engine running, so its using the bowl full' and maybe a minute or two more, then the engine dies, the fuel re-fills the filter and off you go.

 

Check your filter element and fuel for black slime or 'jelly'.

[PineappleGuy]

I'm told that the engine ran continuously for nearly 4 hours at first on both Friday and Saturday. After that, it would run for a random length of time, between a couple of minutes and an hour.

I have also just learned that Barrus have made a slight modification to the control panel wiring (attached), namely a pair of resistors around the glow plug lamp - why? I don't know whether we have this version.

[Tony Brooks]

3 hours ago, Alan de Enfield said:

 

Would that time equate to something like a filter full of fuel ?

 

You may find a partly blocked filter, allowing the 'bowl' to fill but not fast enough to maintain the engine running, so its using the bowl full' and maybe a minute or two more, then the engine dies, the fuel re-fills the filter and off you go.

 

Check your filter element and fuel for black slime or 'jelly'.

 

That or a blocked tank filter seems a more likely explanation for the stopping. @PineappleGuy see what happens with the fuel filler cap off, but not when it is raining.

 

4 hours ago, PineappleGuy said:

I’ll just say that we have spoken to Barrus and the engine fitter and so far they have not been persuaded to come and have a look, which is partly why I have turned to this forum for advice,

 

I am afraid that you may need to get heavy with them and start writing letters. You could also suggest that their lack of interest is doing nothing for their good name on the forum, and some here are working inland engineers. I think that Barrus have gone down in my expectations, so in response to the change an RN engine to what, I would now say, avoid overcomplicated and disinterested Barrus  Shire engines that may well be supplied with incorrect circuit diagrams.

 

If this were my boat, I could see myself doing a bit of rewiring once it was out of warrantee.

Edited February 10 by Tony Brooks

[PineappleGuy]

For information, I have received the following from a contact at Barrus, clarifying the GLOW RELAY on the engine wiring diagram. Essentially, it is as Nick Norman deduced on Monday evening.

“[we decided] to fit an extra relay to operate a timer for the injection pump stop solenoid.  The stop solenoid has a pull in coil of about 20 amps, and a hold-in coil of about 1 amp.  If someone ran out of fuel and tried starting the engine with bleeding the fuel filters, the engine cranked and cranked, the pull-in coil was still energised and after about 40 or 50 seconds it burnt out.  By adding a timer, the coil was only pulled in for about 1 second and the hold-in coil took over.  The problem was then resolved.”

 

Regarding the glow plug light issue, one of the owners will try to have a look over the wiring next Friday. I expect that there are connectors dangling vulnerably behind the control panel.