Glow plug by-pass switch on toyota 3L engine (1 Viewer)

[GreatOutdoor]

Hello All,
The glow plug resistor died on my old Hilux 1991 (3L engine with super glow plus system). I'm planning on installing a by-pass switch. I want to use a switch to control the original first relay. The currant output at the glow plug bus bar is more than 12 volt (12-12.6v). My glow plug are 12-11 volt type (toyota no. 19850-54090). Is there a real risk to burn the glow plug?
Thanks to all!
Cheers!

 

[Dprio34]

As long as you don't hold the manual switch longer than 4-5 seconds at a time when it is really cold, I would say the risk is minimal.
I use 4 seconds to stay on the safe side. Here is a chart based on OAT and Time.

 

[GreatOutdoor]

Thank's for the table. I imagine this is for 11 volt glow plug running at full 12 volt power?

I read this on the net. It based on a 12 volt system. What shall I understand fro this:

With 12v glow plugs the glow plugs would probably take 30-40
seconds to get fully hot.

With 10.5v plugs, the max heat will be reached after about 15
seconds.

With 6v. plugs, the max heat will be reached in 1.5~2 seconds, and
thus the odds of burning them out with a manual system are pretty
high.

 

[Dprio34]

@GreatOutdoor , you are welcome. I'm not sure how cold it gets in your area, but I always do a 4 second count between -5 to +5 Celsius, and it is enough for my engine to fire right up on the colder days. Yea, I have a full 12 volts going to the glow plugs.

I'm not claiming to be an expert on how long it takes to reach "fully hot" on all glow plugs, but I've seen videos where the plugs glow hot in a few seconds and the 30-40 second range seems excessively long. I personally wouldn't hold beyond 5 seconds based on that chart and this video.