Help diagnosing starting issue poss glow plugs

[PCSB]

Sorry for what may be a long post, just trying to give all the relevant info ...

 

Our engine is taking quite a few attempts to get going from cold. It cranks no slower than previously and it can take multiple attempts at around 5 to 10 seconds each time. Eventually it splutters into life. It starts very quickly when its warm and even several hours after running. Even 8 hours later it starts within 2 or 3 seconds. It runs very smoothly with no hunting.

 

The engine is a canaline 42 (Kioti base engine). The starter battery shows anywhere from 12.8v to 13.2v, haven't tested it whilst cranking as I don't have enough hands but next time I'll look at the display in the engine console. 

 

I've measured the amps dranw, when switching on I can see 2 or so amps being drawn but no amps when switching to glow position. I'm getting voltage at the thin wires that lead to the relay and the same voltage to the main power feed to the relay. When switched I am seeing the same voltage on the feed to glow plug side of the relay. I've since replaced that relay with a new one of the same spec (70Amp) and get the same results - I did this because I've had the relay fail before so had a spare.

 

My suspicion is the glow plugs may have failed or something along the feed to them. What is the best way to confirm this? Is it a case of removing them and seeing if they glow?

 

I'd like to confirm that is the case before shelling out for new ones athey are £42.39 each plus VAT and shipping.

 

I cannot see any fuses inline with the circuit after the relay and it seems as though its just the feed from the relay to the plugs.

 

I've checked fuel lines for leaks etc and there are none, the air filter is fine - I've removed it to confirm. 

 

As always advice is much appreciated.

 

TIA

Paul.

 

 

 

[magnetman]

Is it not just because the weather is really very cold? 

 

I don't think it would start at all if the glow plugs were not working. 

[PCSB]

 

1 minute ago, magnetman said:

Is it not just because the weather is really very cold? 

 

I don't think it would start at all if the glow plugs were not working. 

I don't believe that to be the case. Last winter when we were frozen in the engine started just fine. The glow plugs normally pull around 40 amps or so, there is no current draw.

 

[Tonka]

2 minutes ago, PCSB said:

 

I don't believe that to be the case. Last winter when we were frozen in the engine started just fine. The glow plugs normally pull around 40 amps or so, there is no current draw.

 

Is there a relay or a dodgy switch position which the power to the heaters go through 

[PCSB]

4 minutes ago, Tonka said:

Is there a relay or a dodgy switch position which the power to the heaters go through 

Yes there is a relay, just replaced with a new one. I'm getting voltage to the relay and from it. Thinking on I wonder if checking the resistance of the glow plus will determine if they are knackered. Just need to find what they should be ...

 

ETA: the old and new relays show the same thing

Thinking on, I suspect a good glow plug will have a low resistance (1 to maybe 5 or 10 ohms ??) and knackered ones much higher?

 

Edited January 10 by PCSB

[jim mitchell]

The wire or wires  feeding the glowplug/s from the relay should be detachable from the plugs without having to remove the plugs themselves so what voltage is detected if any at the actual plug when switched to the heating position one or more maybe broken or detached in some way.

As you say you should be drawing around 40- 60 amps but are seeing nothing - all the plugs may have failed at once but its unlikely  i would check the wiring out thoughly.

 

Glowplugs are usually around 1 ohm resistence on 12v units.

 

A continuity test between the relay and the plugs (would show a wire fault)

 

[magnetman]

So the engine will start with no glowplugs. 

[PCSB]

3 minutes ago, jim mitchell said:

The wire or wires  feeding the glowplug/s from the relay should be detachable from the plugs without having to remove the plugs themselves so what voltage is detected if any at the actual plug when switched to the heating position one or more maybe broken or detached in some way.

As you say you should be drawing around 40- 60 amps but are seeing nothing - all the plugs may have failed at once but its unlikely  i would check the wiring out thoughly.

 

Glowplugs are usually around 1 ohm resistence on 12v units.

 

A continuity test between the relay and the plugs (would show a wire fault)

 

Thanks Jim, I'll do that tomorrow when I have daylight.

1 minute ago, magnetman said:

So the engine will start with no glowplugs. 

Yes, in the summer a lot easier than in the winter. 

[jim mitchell]

5 minutes ago, PCSB said:

Thanks Jim, I'll do that tomorrow when I have daylight.

If you are happy checking resistances correctly - double check the relay when it closes , if the resistance is high bad connections etc you could get Volts but still not get any appreciable current 12V  across 1K   =0.012 Amps that would flow so heaters would be ineffective.

[PCSB]

3 minutes ago, jim mitchell said:

If you are happy checking resistances correctly - double check the relay when it closes , if the resistance is high bad connections etc you could get Volts but still not get any appreciable current 12V  across 1K   =0.012 Amps that would flow so heaters would be ineffective.

Will do, thanks again.

[David Mack]

I assume the plugs are wired in parallel, so the failure of one or two plugs would not affect starting too much. Since simultaneous failure of all the plugs is unlikely that would suggest a fault in the wiring common to all the plugs. So with someone holding the ignition switch in the heat position (or can you wedge the switch in that position) check the voltage at the heater plugs. If battery voltage then the plugs have gone open circuit, if 0 volts it's a fault further back in the wiring.

Do you have a multiplug and socket connection in the wiring between the engine and the control panel? These are often a source of engine electric problems.

[PCSB]

9 minutes ago, David Mack said:

I assume the plugs are wired in parallel, so the failure of one or two plugs would not affect starting too much. Since simultaneous failure of all the plugs is unlikely that would suggest a fault in the wiring common to all the plugs. So with someone holding the ignition switch in the heat position (or can you wedge the switch in that position) check the voltage at the heater plugs. If battery voltage then the plugs have gone open circuit, if 0 volts it's a fault further back in the wiring.

Do you have a multiplug and socket connection in the wiring between the engine and the control panel? These are often a source of engine electric problems.

I do have a multiplug between control panel and the engine so will check it best I can. Thanks for the advice re voltage at the plugs too.

[magnetman]

Multiplugs in wiring looms very often cause problems. 

 

 

[MtB]

1 hour ago, PCSB said:

 

I don't believe that to be the case. Last winter when we were frozen in the engine started just fine. The glow plugs normally pull around 40 amps or so, there is no current draw.

 

 

If by this you mean the glow plugs used to draw 40A but draw zero Amps now, then this is the root of the problem. You need to trace why no current is being drawn. Do you have a multi-meter? 

 

 

[PCSB]

8 minutes ago, MtB said:

 

If by this you mean the glow plugs used to draw 40A but draw zero Amps now, then this is the root of the problem. You need to trace why no current is being drawn. Do you have a multi-meter? 

 

 

Yep exactly that, that is why I'm after advice on how to diagnose/trace the fault or confirm the plugs are u/s. I do have a multi-meter and will be following the advice of Jim and David tomorrow.

Edited January 10 by PCSB
speeling

[MtB]

3 minutes ago, PCSB said:

Yep exactly that, that is why I'm after advice on how to diagnose/trace the fault or confirm the plugs are u/s. I do have a multi-meter and will be following the advice of Jim and David tomorrow.

 

Ah ok, I only skimmed the thread. I think there was some doubt about the cold resistance of a glow plug. I happen to have one on my desk and a multimeter too. The resistance of this one at room temp measures about 6 Ohms. But I'm not sure that is a credible result as it seems too high. I'm pretty sure my vintage diesel plugs draw about 15A each. 

[PCSB]

1 minute ago, MtB said:

 

Ah ok, I only skimmed the thread. I think there was some doubt about the cold resistance of a glow plug. I happen to have one on my desk and a multimeter too. The resistance of this one at room temp measures about 6 Ohms. But I'm not sure that is a credible result as it seems too high. I'm pretty sure my vintage diesel plugs draw about 15A each. 

When the original relay failed I measured the current drawn after fitting the new one (this was two years ago) and iirc it was just over 40 amps. So roughly 10 amps each. I'll know more tomorrow, if the resistance is much over 1 Ohm it would suggest they are fubar'd if the resistance checks out its likely to be a wiring fault. Fingers crossed I can find out tomorrow.

[Tonka]

12 hours ago, MtB said:

 

Ah ok, I only skimmed the thread. I think there was some doubt about the cold resistance of a glow plug. I happen to have one on my desk and a multimeter too. The resistance of this one at room temp measures about 6 Ohms. But I'm not sure that is a credible result as it seems too high. I'm pretty sure my vintage diesel plugs draw about 15A each. 

I thought vintage engines didn't have glowplugs and were hand start.

[blackrose]

11 minutes ago, Tonka said:

I thought vintage engines didn't have glowplugs and were hand start.

 

There are plenty of vintage engines with starter motors. It depends on one's definition of "vintage" I guess. 

[Tonka]

9 minutes ago, blackrose said:

 

There are plenty of vintage engines with starter motors. It depends on one's definition of "vintage" I guess. 

But if it designed to be hand start then that implies no battery is present so the engine would be designed not to have glow plugs

[GUMPY]

Simple diagnosis without removing the plugs is to remove the wire from the glow plug and measure between the tip of the plug and the base, The resistance of a glow plug should be between 1Ω and 6Ω depending on the manufacturer.

My suspicion is that last winter you may have not had the full compliment working even though it was starting ok and this winter the last couple have failed.

[Momac]

14 hours ago, PCSB said:

 

 

I'd like to confirm that is the case before shelling out for new ones athey are £42.39 each plus VAT and shipping.

 

Seems a bit pricey . Do you have the part number ?

https://www.sparkplugs.co.uk/ngk/marine/glow-plugs

 

 

[Tacet]

You could connect the glow plugs directly to the battery (probably best to disconnect the permanent wiring) and see if it makes a difference.

[PCSB]

2 hours ago, GUMPY said:

Simple diagnosis without removing the plugs is to remove the wire from the glow plug and measure between the tip of the plug and the base, The resistance of a glow plug should be between 1Ω and 6Ω depending on the manufacturer.

My suspicion is that last winter you may have not had the full compliment working even though it was starting ok and this winter the last couple have failed.

That is my plan, and I'm worried you may be right too.

1 hour ago, Momac said:

Seems a bit pricey . Do you have the part number ?

https://www.sparkplugs.co.uk/ngk/marine/glow-plugs

 

 

Eye watering would be how I describe it! I do have a part number so will try your link, many thanks.

37 minutes ago, Tacet said:

You could connect the glow plugs directly to the battery (probably best to disconnect the permanent wiring) and see if it makes a difference.

I'll try and diagnose first and take it from there.

[ditchcrawler]

2 hours ago, GUMPY said:

Simple diagnosis without removing the plugs is to remove the wire from the glow plug and measure between the tip of the plug and the base, The resistance of a glow plug should be between 1Ω and 6Ω depending on the manufacturer.

My suspicion is that last winter you may have not had the full compliment working even though it was starting ok and this winter the last couple have failed.

When we had an old Vauxhall diesel car just one plug down and almost impossible to start