Sticking Solenoids

[Smokey Eddy]

I have a big solenoid for my glowplugs which is american made. It was very expensive ($60) so im a little peeved that im having issues with it. Sometimes it sticks and will not close when i switch it on.

I at first thought it was my switch, which too was supposed to be of high quality but im starting to doubt that, but if i open the hood and wrap it with my nuckles it clicks closed.
Anyone have any suggestions apart from just replacing it?
could the switch be sending too low a voltage to the solenoid to get it to close?
possible internal (of the switch) resistance?
The toggle switch has an incandecent light in it that made it glow orange when it was turned on but this light now seldom works.
Next time it's not clicking im going to get a wire and touch it to the battery to see if its the solenoid that isn't clicking or the switch that is gobbling up voltage that should be going to the solenoid.


Also, semi-related, can i run the stock wire that goes to the glow plug bus bar to my "on" input on the solenoid? That way my glow plugs should run off the stock relay with the KEY and switch on the added solenoid PLUS i'd have the option of forcing them on by flicking the switch. The reason for this is i don't much like the size of wire VW used originally to power the GPs.

[rabbitman]

When I pimped my plugs I used a big ford starter solenoid and ran the old buss bar wire to trigger it. I don't have a separate switch though.

Will it click consistently after you tap it? Your switch could be dying and sometimes not passing enough power.

[Vincent Waldon]

A couple of thoughts, FWTW:

I have a big solenoid for my glowplugs which is american made. It was very expensive ($60) so im a little peeved that im having issues with it. Sometimes it sticks and will not close when i switch it on.

There are two kinds of starter solenoids... the very common type rated for intermittent duty (ie 5-10 seconds bursts when turning over the car) and the less common type designed for "continuous" duty... ie longer than 5-10 seconds.  Dunno which kind you bought, but one way to tell:  when it comes on for 20-30 seconds on cold mornings is it getting really hot??  If so, it may simply not be up to the task of running glow plugs for the longer periods of time... may start out OK but degrade over time due to heat.

I'd also say that in generally the bigger they are the harder they fall... meaning... the bigger the solenoid the more metal it has to move etc... it's a mechanical part so will wear, jam, etc like any other mechanical part.

can i run the stock wire that goes to the glow plug bus bar to my "on" input on the solenoid?

Absolutely, and a great way to give yourself the best of both worlds.  The only thing that would give me pause is to carefully test what happens when you push the manual button during an automatic cycle... in a sense you're backfeeding power to the OEM glowplug relay... it may not care, or it may respond by latching on etc.

If you have any doubts a couple of diodes in series with the two lines you'll use to activate the solenoid will isolate your pushbutton from backfeeding the relay.  Holler if that makes no sense to ya and I'll bore you further.  ;-)

[Smokey Eddy]

I understood Vince
It doesn't get hot. I made sure i got one that was rated for in excess of what the plugs would draw and that's for constant power. It's very large, like ... half the size of a pop can. And you're right, the bigger they are the harder they fall and this one is BIG. When i first put it on and flicked it closed you could see dust coming off the car from it actuating. You can hear it from inside the car very clearly. If my memory serves my  right, which is usually doesn't, it's rated for 55 amps continuous power at 12V which is somewhere in the 650watts range. I concur that it's not getting a full 12V. I'll multimeter it when i get home. And im DEFINITELY joining the two systems. I'm just going to cross my fingers that it doesn't backfeed the relay. I'll test it first to see if it does and if so i'll grab a couple diodes.

just like this one actually except the body of the solenoid grounds to the frame so mine only has three wires. In this image i can only guess it's being used for a big winch.

[Smokey Eddy]

Will it click consistently after you tap it? Your switch could be dying and sometimes not passing enough power.

That's what im thinking because it worked wonderfully at first. Now it is getting frustrating.

[Luckypabst]

Those relays themselves draw a good bit of power to energize... It'll take a burly switch to keep up for very long.

Chris

[Vincent Waldon]

Those relays themselves draw a good bit of power to energize... It'll take a burly switch to keep up for very long.

Good point Chris... the bigger they are, the harder they fall... *and* the more power they need to energize !!

[Smokey Eddy]

ENERGIZE