Glow Plugs

[Steveh24]

I've got a strange problem with my glow plug system on my boat.

I have a VW Marine engine and it has a small control panel mounted to the side of the engine that controls some of the electrics, one of the systems is for the the Glow Plugs and consists of a big 50A fuse and a relay, the problem I have is that when I turn on the ignition the glow plug heater work fine and the engine starts quite quickly, but as soon as the engine has started the fuse blows and the red warning light comes on the glow plug heating system will not work until I replace the fuse..

This is very annoying and I'm wondering what the fault is, cound the relay be faulty although it meters out ok, there is either a short somewhere or more than 50A is being sent through the fuse while the engine is turning.

 

[Steveh24]

Forgot to mention that I've just replaced all the glow plugs, although I couldn't find anything wrong with any of the old ones.

 

[Wolf]

It sounds to me as if you've got a short circuit in the glow plugs electrics circuit.

 

[Steveh24]

It sounds to me as if you've got a short circuit in the glow plugs electrics circuit.

That could be difficult to fix as it's on a PCB

 

[Trampster]

I can't offer much help Steve - never had a boat and not great experience with Diesels.
I would think that there must be something in that circuit (probably a timer) that turns the Gloplugs off. I know that the few Diesels I have come across, you ususally had to leave the ignition on for a certain number of seconds before turnng on the starter.
My old Diesel pickup was a swine to start in really cold weather, and you some times had to cycle the Gloplugs 2 or 3 times before it would start.
For a 50 amp fuse to blow, as Wolfie said, it sure sounds like there is a fault in that board and it's shorting the battery direct to ground.
Either that, or damage to the wiring loom somewhere.
Is there any possibility that the VW engine is used in other applications, like a car or van? Might pay you to do some digging, and if it's used elsewhere, try some of the VW forums. Other than that, it's chancing a 2nd hand board from somewhere or enlist the help of a Marine electrical engineer.

You might find some info on this forum:

Glow Plug circirt blowing fuse - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

Glow Plug circirt blowing fuse - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

vwdiesel.net

Or these: Lots of reults that might help from a Google search.

Need help -- Fuse 34 blows weekly

This problem first started about three weeks ago when after a slightly stumbling start (40 deg), the CEL came on and the GPL flashed. The car ran but limped home where I did a scan, got the codes, and posted my problem (link here). Greengeeker keenly noted in that thread that all of the codes...

forums.tdiclub.com

HOW-TO: Troubleshoot Your Glow-Plugs - VinceWaldon.com

On a cold mornings the heat of compression alone is not enough to get our beloved diesels going; they need some additional heat that is generated by 4 glowplugs.

vincewaldon.com

 

[Steveh24]

I can't offer much help Steve - never had a boat and not great experience with Diesels.
I would think that there must be something in that circuit (probably a timer) that turns the Gloplugs off. I know that the few Diesels I have come across, you ususally had to leave the ignition on for a certain number of seconds before turnng on the starter.
My old Diesel pickup was a swine to start in really cold weather, and you some times had to cycle the Gloplugs 2 or 3 times before it would start.
For a 50 amp fuse to blow, as Wolfie said, it sure sounds like there is a fault in that board and it's shorting the battery direct to ground.
Is there any possibility that the VW engine is used in other applications, like a van? Might pay you to do some digging, and if it's used elsewhere, try some of the VW forums. Other than that, it's chancing a 2nd hand board from somewhere or enlist the help of a Marine electrical engineer.

You might find some info on this forum:

Glow Plug circirt blowing fuse - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

Glow Plug circirt blowing fuse - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

vwdiesel.net

Or this one:

Need help -- Fuse 34 blows weekly

This problem first started about three weeks ago when after a slightly stumbling start (40 deg), the CEL came on and the GPL flashed. The car ran but limped home where I did a scan, got the codes, and posted my problem (link here). Greengeeker keenly noted in that thread that all of the codes...

forums.tdiclub.com

Thanks for the help

It's certainly a strange problem, the glow plug heating system works fine while the fuse is intact, once it's heating cycle has completed the engine starts up without any problem, but I can see that once the engine is started the Red light on the control panel is on and the fuse has blown.

I still have the Relay I can replace to see if that's the problem, I can also try removing each cap on the glow plug to see if it's a lead that's shorting, if not then it has to be the board and I do have the part number so can try looking around for a secondhand board.

 

[Steveh24]

After much playing around I found that what I thought was the Glow Plug Relay wasn't and having now fitted a replacement, the system seems to be working normally with no blown fuses when the engine starts ...... Happy days.

 

[Mr Fish]

Was going to say @GPSguru is your man, but looks like it’s sorted?

 

[GPSguru]

After much playing around I found that what I thought was the Glow Plug Relay wasn't and having now fitted a replacement, the system seems to be working normally with no blown fuses when the engine starts ...... Happy days.

Yes, it is a relay timer, and they are known to cause issues. It sounds like the timer side if the relay was faulty. Those relays are a fairly standard item and used in older vehicles and plant. Modern cars have the glowplugs controlled by the ecu, where it looks at the ambient temp, and the coolant temp to decide ‘if’ and how long.

 

[Steveh24]

Yes, it is a relay timer, and they are known to cause issues. It sounds like the timer side if the relay was faulty. Those relays are a fairly standard item and used in older vehicles and plant. Modern cars have the glowplugs controlled by the ecu, where it looks at the ambient temp, and the coolant temp to decide ‘if’ and how long.

Thanks for the info