Perkins cold start aid wiring

[Water Dragon]

I'm installing a cold start aid (flame plug) in my Perkins 4.108. The parts diagram shows an adapter that screws into the intake, and a terminal ring between the flame plug and the adapter. Is the terminal supposed to be wired to ground? Does it not just ground through the engine block?

[a64pilot]

If by flame plug, your talking regular glow plug, then yes it grounds through the block, or all that I have ever worked on did.
There are some Diesel burning actual flame heaters in existence, by chance do you have one of those?

[Lepke]

It grounds thru the block, but the manufacturer may want a separate ground to ensure full voltage to the plug. I've only seen flame plugs on bigger diesels.
A small amount of diesel drips on the plug and flames instantly. It creates more hot air than a glow plug and uses less current.

[Water Dragon]

Originally Posted by a64pilot

There are some Diesel burning actual flame heaters in existence, by chance do you have one of those?

Yes, it's an actual flame heater that ignites a diesel drip.

[a64pilot]

Originally Posted by Water Dragon

Yes, it's an actual flame heater that ignites a diesel drip.

I thought it might be as there was only one, yes that ought to work.
I’ve only seen them in motors meant for really, really cold ops.
There is no better ground than the engine, and this isn’t a high amp device. Even if it has a point for the ground, I’d connect it to the block myself.

[sailor_ed]

I had one of these hooked up on a 4-107. Nifty little device. If I remember right it had just one +12v lead and relied on the engine for ground. The tab should be electrically isolated from the engine and this may be easily verified with an ohm meter.

Do you have a reservoir set up?

[Water Dragon]

Yes, it has a tab on the flame plug itself, but the parts diagram also shows a separate ring with a tab on it that you install like a washer under the plug. But I'll check if it has good ground through the block, and if so, maybe I don't need that ring, which is $40 for basically a washer!

I have a plastic reservoir and fittings to connect a 1/4 inch fuel hose to the flame plug.

[sailor_ed]

The heat coil is not polarity sensitive so there is little you can do wrong if it glows and doesn't blow a fuse all is good. :-) BTW no flame appeared in mine, just smoke, until I turned the engine over. Fun to look down intake while this happens!

I'm not sure what information you have but there used to be a reservoir that fed off the return line. Not really necessary though.

Ed

[Water Dragon]

I know there's a kit that feeds fuel to the reservoir automatically, but it costs $300, and I think I can put together something that works just as well for a lot less. I'll just have to fill the reservoir manually when it gets low

[a64pilot]

Make sure of course that you fit a good fuel off valve to the tank, like maybe a motorcycle petcock or something fuel rated.

[Argyle38]

Originally Posted by Water Dragon

I'm installing a cold start aid (flame plug) in my Perkins 4.108. The parts diagram shows an adapter that screws into the intake, and a terminal ring between the flame plug and the adapter. Is the terminal supposed to be wired to ground? Does it not just ground through the engine block?

The adapter is not conductive. I'm not sure why but that's the way it is. It's glass reinforced nylon I believe. So you need the lead between the starting aid and a bolt that attaches the intake manifold to the head, to complete the connection to ground.

Here's a link to the replacement adapter. Says clearly that it isolates the glow plug (so the separate ground lead is required).

https://www.parts4engines.com/perkin...wplug-adapter/

Here's a link to the glow plug itself, just to make sure we're talking about the same thing.

https://www.parts4engines.com/perkin...g-thermostart/

[atraitees]

Side question:I have just finished a refit from a 30hp 310 to the 4108. I'm finishing up the wiring prep. If I'm staying in the warmer lats, do I need the flame heater? I would actually prefer to leave it disconnected.

[sailor_ed]

There are a lot of threads on the 4-108,107 cold start aid but all are quite old and many are incomplete so I will try to clear the air a bit. (I confess I have not read them all, if I duplicate please forgive me.)

Most boats with these engines probably do not even have an operational heater as in most conditions if the engine is in good condition they are not necessary. However, in cold weather or when the engine starts to develop low compression they are a help. This Youtube video shows one in operation:

Video

https://www.youtube.com/watch?v=KNhC-svEjUg

The essentials are that the heater is energized until a bit of smoke from vaporized fuel is noticed and then the engine is turned over. The rush of air will cause the device to burst into flame which will warm the air going to the cylinders. Some call these "bonfire" heaters.

Here is how they operate: applying 12volts causes a heater coil to glow cherry red. This in turn heats a bi-metallic strip or coil (I am unsure) causing it to bend and open a small valve allowing fuel to enter. The inrush of air and the cherry red coil cause it to ignight.

Argyle:According to www.asap-supplies.com the nylon insert bush is for "providing electrical insulation for the heater plug on insulated earth return Perkins 4108 marine diesel engines". So the usual negative ground boat engine installation would not need this and a single wire (as in the video) would be sufficient.

A good work-around is a lit propane torch held horizontally over the inlet while cranking. Watch for surrounding flammables!

Fair winds and an operational engine!

Ed

[atraitees]

Originally Posted by sailor_ed

There are a lot of threads on the 4-108,107 cold start aid but all are quite old and many are incomplete so I will try to clear the air a bit. (I confess I have not read them all, if I duplicate please forgive me.)

Most boats with these engines probably do not even have an operational heater as in most conditions if the engine is in good condition they are not necessary. However, in cold weather or when the engine starts to develop low compression they are a help. This Youtube video shows one in operation:

Video

The essentials are that the heater is energized until a bit of smoke from vaporized fuel is noticed and then the engine is turned over. The rush of air will cause the device to burst into flame which will warm the air going to the cylinders. Some call these "bonfire" heaters.

Here is how they operate: applying 12volts causes a heater coil to glow cherry red. This in turn heats a bi-metallic strip or coil (I am unsure) causing it to bend and open a small valve allowing fuel to enter. The inrush of air and the cherry red coil cause it to ignight.

Argyle:According to www.asap-supplies.com the nylon insert bush is for "providing electrical insulation for the heater plug on insulated earth return Perkins 4108 marine diesel engines". So the usual negative ground boat engine installation would not need this and a single wire (as in the video) would be sufficient.

A good work-around is a lit propane torch held horizontally over the inlet while cranking. Watch for surrounding flammables!

Fair winds and an operational engine!

Ed

Ed, thanks so much for replying. This explains a lot. After watching that video I will test the operation of it and just put it on a second push switch. This way I have full control over it. Well, it sounds good anyway. Lol... I'm honestly hoping I'll never need it but... that's not how true sailors plan, is it.. haha

Thx and Fair winds,
Chuck

[lonesoldier0408]

Due to the distance, between power source and unit, I would put a relay in the circuit. Smaller gauge for triggering the higher amperage coil circuit. Also a heavier gauge wire for the coil element power source.