What is wrong with this GLOW PLUG diagram? (1 Viewer)

[JohnPro992]

Hi all,

another minor problem with my BJ45, I have been starting it by glowing the plugs for about 15 seconds. Everything is manual, and the timer is my brain ... 15 seconds is really becoming too long for a daily driver.

I attached a diagram for how it is all wired up at the moment. The dashboard light is simply a bulb to tell me their is power on the glow plug rail. It has no sophistication whatsoever. In fact it would probably burn out my plugs since I cant see when they are glowed, I estimated 15 seconds after pulling 1 off and checking to see how long it glowed.

I junked the 20.5 volt plugs and bought 8.5 volts thinking it would glow faster, turns out they are for 12 volt diesels, mine is 24 volt system.

They certainly glow faster but everytime I connect the 4th glow plug it blows the fuse or sparks fly and it glows red and melts the fuse lol

It glows 3 plugs beautifully though.

I was thinking perhaps if I had a controller, I can still use these plugs and connect the 4th? They glow in 3 seconds, I wouldn't know myself if my land cruiser could glow that quick.

Based on the diagram of my current vehicle, what is wrong? (dont say everything haha) and what is lacking in my setup? A controller? A relay? A timer? I really dont know how these were designed originally.

Thank you!

EDIT: I posted a photo of the dashboard when I got the car, it was empty so I decided to fill in all the holes and start from scratch, "thus the engine stop" I opted for manual engine off rather than the EDIC.

 

[RufusTheDufus]

Nothing wrong with the diagram. You need a bigger fuse and wires that can handle the current. Those 8.5v plugs are going to draw somewhere between 15 and 20 amps each initially. As they heat up their internal resistance goes way up and the current drops.

Look up an online parallel resistance calculator. Those 8.5v plugs are likely only .5 ohm to maybe 1.2 ohms each depending on brand. This is just like four resistors wired in parallel.


I think you would be much better off with 14.5v plugs or even 20v. You're going to kill 8.5v plugs quickly feeding them 24v.

 

[Elkhorn1]

I just compared it to the diagram under FAQs in " 3b glow system" and I agree, it's fine. I'm a little confused bc I think the glow indicator light should not be in the relay circuit ( I think it should be in parallel with the wire controlling the relay) but otherwise it's how mine is done, just 12v

 

[lostmarbles]

It may take a lot of reading, but have a good look at this thread:

https://forum.ih8mud.com/threads/which-plugs-should-i-be-running-b-2b-3b-h-and-2h-diesels.471567/

Feeding 8.5V plugs directly with 24V (as per your diagram) would produce so much current that it would blow that fuse immediately (and would even blow one twice that size immediately too).

 

[JohnPro992]

@RufusTheDufus thank you very much! I realize now. So I will try searching for the 14.5v

@Elkhorn1 an FAQ? Sorry to be posting content that has already been answered, I havent fully appreciated the content of ih8mud yet, im still fairly new here. hehe I connected that dash light up to my custom dash led panel, it was easier for me to do it this way and i would know that if my light gets power the glow plugs would too

@lostmarbles I did take a look at that excellent thread but only after i bought the 8.5v plugs. Very informative but it is what got me thinking my diagram is wrong. My car has no controller, timer relays etc. I didnt get past the first page though as a lot of info was scattered. so basically my answers are in there amongst the pages? and yes that is exactly what its doing, blows in an instant, yet 3 plugs glow fine, I have very solid wires and heavy duty solenoid. regardless I will go with all your advice, my system should have14.5 volt glow plugs

 

[RufusTheDufus]

I wouldn't say your system should have 14.5 plugs. They will just work better than the 8.5v ones. With no current limiting device in series from the solenoid you should really have 20v-ish glow plugs for any kind of reliability. You will burn them up, just less quickly than 8.5v plugs.

 

[bj40green]

Nothing wrong with your diagram but you should use 23V glow plugs because what you have there is similar to a "fixed delay" system but lacking a time controller. Your diagram is known as a "Wilson switch" set up. The difference is that your finger on the momentary switch is your timer.

14V plugs are used in a "super glow" 24V system where the glow time and glow current is regulated by a timer and a current sensor.

That fuse is there to do what......? A better option would be to make (or buy) a fusible link. A fusible link can handle the initial run-in current and protects your wiring is case the glow relay (solenoid) gets stuck in the on/closed position.

Rudi

 

[Elkhorn1]

At the top of the page when you go to " diesel tech and 24 volt systems " forum are a number of topic which always appear, regardless of posting date. The last of these is FAQ's. Click on it then read 3B glow system.

 

[JohnPro992]

Guys I really appreciate your info, for reliability I should go back to 20.5 volts, any way to cut down the 18 second glow time?

Should I buy a superglow kit? where could i find one online?

My dad keeps insisting on giving me an inline fuse holder, to clarify a fusible link is different to inline fuse right? Fuseable links dont have fuses? Its designed to melt first before the wiring? I first noticed fuseable links on an 88 vette.

 

[roscoFJ73]

Most glow systems glow for for 5-10 seconds after it starts, so the 18 second glow time is not abnormal. Its just a PITA sitting there holding a switch.
A simple adjustable timer and the correct voltage plugs is all you need.
Fusible links do the same job as a fuse but I think fusible links are less susceptible to corrosion and they probably handle a short term overload a bit longer,but thats only my uneducated guess.

 

[bj40green]

0 seconds, 5 seconds, 10 seconds...... it all depends how warm/hot the engine is.
I live in the tropics. I only need to glow for 7 seconds for a smokeless start year round.
If you're in a colder climate you may need to glow longer in the winter and shorter in the summer.
Or don't have to glow at all when the engine is still warm/hot.

Google for glow plug timer. Note: You have to set the glow time on these units. If you need more glow time on a cold day you have to activate the circuit 2 or 3 times.

With a Wilson Switch set up you are fully in control of the glow time depending on the the weather and how warm/hot your engine is.

Fuse or fusible link.... what you want but don't cry when the fuse blows on a cold morning when you have to glow extra and you don't have a spare. There is a reason why these circuits are protected with a fusible link and not a single fuse.

Rudi

 

[Tapage]

0 seconds, 5 seconds, 10 seconds...... it all depends how warm/hot the engine is.i

Ditto .. where are you located ..?

Back in the day when Tencha was my DD, I only need to glow her for the initial morning start up .. and no more glow during the day ..

 

[JohnPro992]

I live in the tropics right on the equator, all year round its hot. I now glow for 12 seconds with new 20.5 glow plugs. I actually wanted a wilson switch rather than electrical relays and timers, it just seems "reliable"

Since superglow seems difficult and complex with pre glow and after glow and more things to go wrong.

A little viewport thing on the dash that glows in sync with the glow plugs is just as good, i still dont know what to buy or how to install it. Ill try finding a wilson switch diagram here on ih8mud.

also i noticed sometimes i glow for 12 seconds and it idles rough, I glow few seconds more and it idles smooth.

 

[JohnPro992]

Okay guys thanks to @lostmarbles thread regarding glow plugs I have realized this is a lot more tricky than I thought. Firstly the wilson switch does not glow in sync with the glow plugs. If you put 14.5 volt plugs the glow controller with wilson switch setup will still glow at the rate of the 20.5 plugs?

So i am thinking i'll just make a nice looking bracket and put a 5th glow plug in the cabin. They will glow at the same rate and i dont need to measure coils and stuff to get the timing right. I will boost the wiring to cater for an extra plug.

Only draw back is the cabin is much cooler than the engine bay so once the car has warmed up they may not be in sync anymore But the 14.5 volt plugs should glow in less than 5 seconds so I think there is no issue with that.

It seems very difficult to have an accurate manual method with glow plugs.

Other option, just stick a adjustable timer inbetween solenoid and glow plugs and hope they are glowing orange everytime at the set time interval.

 

[RufusTheDufus]

Any idea how hot the tip of the glow plug gets? Where would you mount the glow plug so it doesn't start a fire? That's what they're designed to do, start fires.

 

[JohnPro992]

I'd have the bracket like a deep cone, only the glow plug threads would be in contact with the bracket and none heat conductive material between bracket and dash panel And a little circular glass viewport Behind a drilled hole. Kinda like the headlight housings.

Thought about it a lot, maybe too mucn now. The whole design is screwed, I'm just going to put a 15 second timer from solenoid to glow plug, so the way its wired once the timer shuts off and dash light comes off with it i'll crank. If the plugs burn out quickly then I'll just replace them, cheap enough anyway :-(

I'm just thankful for the information regarding 8.5 plugs and 24 volt systems, at least im on the right track, the rest is a fun type trial and error

 

[RufusTheDufus]

one of these might work for you.

 

[JohnPro992]

thanks @RufusTheDufus ! Yep that will be my solution for now :-D a fixed timer setup.