Glow plug duration resistor mod, it worked! starts easy!

[libtec]

Hello again.

I'm just sharing the info I gathered after doing a mod to the glow plug system on my 90 suburban based off suggestions from site members (thanks CleviteKid).

My original problem was that my glow plugs were cycling for around six to eight seconds when I first keyed the iginition in the morning. This only allowed enough time for the tip of the plugs to get red before the controller timed out and shut them off. While starting was not a terrible chore it seemed like it should happen a little quicker.

This is a direct quote from the post sent to me regarding a solution to the problem.

The center terminal (pin C) of the controller is where battery voltage enters the controller while the glow plugs are energized. This is the terminal that supplies battery power (and current flow) that passes through the main PTC thermistor. By inserting a 5-ohm 2-watt resistor in that lead, you can lengthen the glow cycles by 2-4 seconds (depending on ambient temperature).

The results I got from this mod were a glow duration of 12-13 seconds at +10F, compared to the 8 seconds max I was getting, this is a big boost. For the first time my truck started below the +20 mark without being plugged in and it started with out any extra cranking, nice and smooth.

This was a super easy mod to do, 10 minutes and a little bit of soldering. I took it one step further and ran into a two position switch on the dash so I can use the standard length glow time on summer days and switch to the extended length in the winter.

I just wanted to pass on some good info in-case anyone else is looking to get some extra "oomph" from their system. It's going to be right around zero F tonight and I'm going to do the no plug in test start in the morning. Thanks to the site members and again to the CK.

John.

[ZZ]

I also did this mod with the resistor using the 60's on my '90 Sierra. The results are well worth the while.

I would use the block heater with your cold temps. Your engine will have a lot less wear & tear on that 1st start of the day.

[GregCrabb]

I did it 2 years ago...now I get 18 seconds of glow for my '86...it definitely helps to start it on a +16F morning without the block heater! :D

[dieselbegreat]

Makes a big difference with those 60G's. :cool:

[84 C2B2]

Hi guys,

Any part number or store you can purchase this resistor from. My local Radio Shack rep gave me an airdale salute and pointed me down a nowhere lead.

Jerry

[jbell]

A pair of 10ohm 1 watt resistors in parallel will yield 2watt, 5ohm rating. RS should have that. Other than that, mouser.com should have anything you want.

[More Power]

Back before the 1985-93 GP article first appeared here in The Diesel Page, I experimented with a variety of resistor values before settling on a 5-ohm, which was then published in that 2000 article. A 5-ohm resistor extended glow times about 4-seconds - to a total of 12, which allowed normal and easy starts with the 18:1 6.5 project engine at low ambient temps.

In addition, my tests showed that if you're using the newer AC-60G or aftermarket plugs like Kennedy's, you can extend the glow cycle time beyond what the 5-ohm resistor will get you. Once I determined that an additional 4 seconds worked well, I didn't think it necessary to add more time.

Some members have been using a 10-ohm 2-watt with good results. In the end, the value is not all that critical, as long as you're somewhere close to the above mentioned values and you're using PTC (positive temperature coefficient) glow plugs. More resistance will increase the first glow cycle duration.

Don't do this with AC-9G or equivalent glow plugs (non-PTC). They may burn out and cause you some grief.

MP

[cruzer]

For the resistor I ended up at a tv/radio repair shop, since Radio Shack did not have. It was like under a dollar for the resistor IIRC. If not, it was suprizingly cheap.

[5.7L oldsdiesel]

I need to install a resistor on a 87'Chevy 6.2 that needs more glow plug duration.I'm going to use AC60G's on it.When i buy the resistor,is there a certain way it should be mounted?Can it be installed either way on the PIN C yellow wire,or must it be installed a certain way to get it to work properly?Can i still use the inhibit switch,or must i get rid of it for the resistor modification to work?If i eliminate the inhibit switch,i simply join both wires at the inhibit switch together?Also after soldering the resistor in place,can it be covered with electrical tape to prevent exposure to the elements?Sorry for all the questions.I've never done the modification before and i want to make sure i do it right.

Everyone's reply is much appreciated.

Thanks everyone.

[5.7L oldsdiesel]

Sorry for this next post guys.... smile.gif ,but if i wanted to increase preglow to 15 seconds,will the 5 ohm-2 watt resistor do or should i get a 10 ohm-2 watt resistor?15 seconds should get the AC60G's hot by that time,should'nt it?

Thanks everyone.Have a great day. smile.gif

[MTTwister]

5.7 Resistors can go in either way - it's Diodes that are critical. Not sure about the higher ohm's for the resistor - sounds like Jim didn't notice much difference. edit- But what the HAY - you're in Canada - you might need another 4 sec, go 10 Ohm. .
When you cut the wire to solder in the resistor - I would recommend slipping a length of Heat Shrink tubing over one cut wire - then cover the "mod" and shrink. If your really paranoid - you could put some RTV on the solder joints before doing the tubing thing - that would definitely keep out the corrosion.