60G Controller Questions

[Burbinator]

Out here on the Islands north of Seattle we're already seeing low- to mid-50's at night. On top of that, I've noticed a slow increase in white smoke from the tailpipes of my Suburban, and slightly longer start times with rougher idle. As I know its not a fuel problem, I'm upgrading the GPs to 60G's since they're due.

Some time ago, I seem to recall someone mentioning that by cutting a wire on the plug near the GP controller and placing a 5 Ohm resistor inline will give an additional 5 seconds or so of glow time, and probably more as the temperature drops. In looking over the schematic for the wiring harness, I'm pretty sure the splice for the resistor is going to be on the pin 'C' line.

My question is: will the resistor splice be enough to safely 'convert' the stock GP controller for use with the 60G's while not sacrificing controller longevity, and does the addition of the resistor actually increase glow time in a cold motor as the temperature drops? Or is a secondary unit built from a starter solenoid with a switch as a backup/booster system absolutely mandatory from the start when installing 60G's?

[DmaxMaverick]

The resistor will "adjust" the impedance from the glow inhibitor (temp sensor), essentially lying about the actual temp. It won't hurt the system. An alternative is to install a manual switch to increase the glow time, as necessary.

9G plugs (the OEM's) are fast and hot, but are prone to burn-out (among other problems) with longer glow times. The 60G plugs will handle any reasonable glow time. The controllers last, or they don't. Increasing glow time won't effect them to any noticeable degree.

There's a wiring diagram in my signature under "truck stuff pics", for 1985. This is the same system used for all 1985 and up 6.2L, in regards to the GP's.

I prefer 11G plugs, myself (if you can find them). They are as hot as 9G plugs, but won't swell when they fail. They won't last as long as 60G plugs, but don't require any modification, and are relatively reliable. You can also use a "quick heat" plug, such as Kennedy.com sells. I've used them in 6.5's, and they have served me well. As good as 11G plugs, IMO.

[Robyn]

If you are seeing white smoke at even 40F there may be other issues creeping into the picture.

The 60G plugs will work quite well even with the stock glow controller.

The issue is probably your injectors getting tired. How many miles on the injectors???

If the injectors are near or over 100,000 miles they are on the way out.

What happens is the Pop pressure starts to fall off and the nozzles wear out.

The spray pattern becomes more of a PEE STREAM rather than a cone of fine mist.

Once this happens, the ability of the glow plugs to get the fire lit when the engine is cold becomes more difficult.

Its amazing what a fresh set of injectors (or having yours rebuilt) will do to the cold start ability as well as mileage and power.

A good set of 60G plugs and some fresh injectors will get the old girl back up on the step.

The practice of lengthening the glow cycle, in many cases is a bandaid for a set of failing injectors (and in some cases the IP too)

What year is your truck ???

Hope this helps.

After rebuilding the 6.5 in my 95 Dually truck it starts real well even in the colder temps. 60G plugs with the stock controller. No smoke at all.

Robyn

[Burbinator]

Thanks Dmax and Robyn! The info is great. And by the way, its a '87 with 6.2 and about half a million miles on it, or close to it. :)

Thankfully, the problem isn't as serious as it sounds. I am just planning ahead for fall to spring, and am taking into account longevity and durability factors for the glow plugs. I agree with Dmax that 11G's are quite good. But 60G's are more stable and last longer from what I see, and that's important to me. I've never had much luck with quick heats, and tend to stay away from them aside from the fact that its not something I really need. Besides, I can grab new 60G's for under $9 each, so I might as well upgrade to the best I can get.

I don't think it's always a good idea to run a stock GP controller with 60G's, though. From what I see, and from what other moderators have written, it takes a little longer for the 60G's to run up the heat as opposed to the 11G's. I'd rather take a little time and be sure of the work instead of being caught in a hard start/no start scenario because the glow plugs just aren't hot enough. Later on, before it gets really cold I'll go ahead and fab an auxillary booster system to manually heat the glow plugs as well. Right now I'm just looking to keep the Suburban up and running when changing to 60G's without any problems and without doing a lot of work for the moment; bolt-in replacements and about 5 minutes or less with a soldering gun and some shrink wrap works for me.

As for white smoke and rough idle, that's not a problem that comes on instantly in my experience. And, I don't think its always an injector problem. Even if it is, I can grab a set of rebuilts (Mylex) for under $19 each. As for my situation, the glow plugs haven't been changed in quite some time, and I noted down in my maintenance log a gradual increase in start time and decrease in cold idle quality, along with a slow increase in white smoke.

I've been tinkering with the fuel system and getting rid of the nonsense that the previous owner wrought on my old Suburban. I'm just about finished rehabing the fuel tank and lines, and fabing the new fuel delivery and filtration system (Stanadyne FM100 gear for a secondary and final fuel filter system with sensor modules to work with the factory wiring harness, and a carter vane-type electric pump). While I've been working on the fuel system, I've made it a point to notice black or green discoloration or slime that would point to a serious problem, and I've not seen any. However, when I snatched the old intake manifold off to change to an EGR-free dual plane from another motor I have for a future rebuild (longer runners as opposed to an open plenum design, which is better for mileage and towing IMO) there was a little black discoloration in the old plena and their runners. But that seemed to be more normal blow-by residue than anything else. When I changed intake manifolds I replaced the old CDR valve and built a manometer and tested the replacement to make sure I'm not getting excessive blow-by into the air/fuel mix through the runners still, and its within spec. So I'm gonna have to rule the injectors out for now--not to mention that the motor was running fine before and after the manifold swap.

However, about a month ago I started to notice a slight amount of soot in the tailpipes as opposed to tarry nastiness, and from what I've seen that's more of a glow plug system going away. And that's why I decided to R+R the old glow plugs. Granted, the injectors are due, but they still got some life in 'em Robyn! :D