Manual glow plug button good temp fix?

[Cubey]

My 87 6.9 (with the 7.3 glow plug system) seems to have developed one or more bad glow plugs this summer. Somewhere in the 40s, it has problems starting and the WTS light is only ever on for a maximum of about 3 seconds, no matter how cold it is.

At about 50 degrees or above it's "okay". When warmed up it's perfect, so it's probably not fuel related. This morning when it was 50 degrees out, it stuttered a tiny bit but didn't stall or need any excessive cranking.

Back in February, I didn't have such problems, so it's obviously developed during the summer when they didn't really matter, but the system fired them up anyway, as it tends to do. I do recall seeing the WTS light on longer back then so I don't think it's a problem elsewhere, except maybe poor connections to the harness.

While I haven't actually dug out my multimeter and checked the resistance of the plugs, I've already done a lot of reading up on the subject. My conclusion is that it's probably one or more bag glow plugs, based on the behavior. The relay clicks normally after WTS turns off.

Due to trying to pay down debt right now, I'm trying to skimp by as much as I can. I couldn't when it came to needing a new alternator last month, but on this, it's possible.

I am considering just wiring up a momentary push button, but without the WTS light since you have to chop off the wire from the controller, which I'd rather not do. I'd rather have it fixed properly, but if I can wait to spend the $75 on a new full set of plugs, that is best. $10 for some wire and a switch is much more fitting to my budget right now.

If I can put off new plugs until next fall, that would be great. In summer it doesn't need them hardly, so there's no point replacing them in July. I realize there's no guarantee this will work or for very long depending on how bad the plugs are, but since I'm not in areas any colder than upper 20s at night, it might get me by. While it may not start up perfectly, anything is better than tons of cranking that I have to do now on colder days.

Any thoughts?

 

[snicklas]

If you have a 7.3 style solid state controller, you can add an “override” manual push button without any modification. This is how I have my 92 wired, since the controller doesn’t want to work every time. It either runs the plugs fine, or doesn’t do anything at all. For the nothing at all times I have a push button override.

The way the 7.3 controller works, the controller supplies a ground to the relay on the white wire. If you add a wire to the terminal with the white wire, on the relay (it will be one of the small terminals with the 1/4” sized nuts, not the 9/16 sized nuts (approximate size not necessarily actual wrench size)) through a momentary push button to ground, this will energize the relay and run the plugs as long as you are pushing the button. You are now controlling how long they run, not the controller, so keep that in mind.....

My truck has been set up like this for a few months.

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[Cubey]

The mods I read said to disconnect the white wire and chop off the WTS harness connector, moving it to the white white's terminal, along with the wire gong to your manual switch. I'm not sure why, though. What you said does make more sense.

This is the diagram I was seeing (and others basically just like it, just drawn by someone else) and basing my hesitation on chopping up the wires. It's in the next to last post here:
https://www.oilburners.net/threads/hard-start.33925/

 

[Cubey]

Oh and yes, I've read that 15 seconds is the absolute maximum time to run the glow plugs without burning them up. 5-10 seconds is all I would ever need at coldest. That's why you use momentary switch, not a fixed on/off switch.

 

[u2slow]

I ran manual glow plugs on my '84 Suburban, and '97 E350. It was a permanent fix.

 

[jwalterus]

I ran manual glow plugs on my '84 Suburban, and '97 E350. It was a permanent fix.

Heck, I don't even have my controller hooked up anymore, mine's only there so I can run power through the wavy bar.
I have a pushbutton on a constant-duty rated solenoid, and have for a few years now.

 

[Cubey]

What wire gauge is needed to wire up the switch? Probably 14 or 16?

 

[u2slow]

What wire gauge is needed to wire up the switch? Probably 14 or 16?

Large enough to carry the energizing current for the solenoid... like 1-2 amps. I don't wire anything smaller than 16ga. 14ga or bigger if other stuff gets tapped onto the circuit later.

 

[franklin2]

I ran manual glow plugs on my '84 Suburban, and '97 E350. It was a permanent fix.

The pushbutton is a permanent fix on my 89 also. I don't need the aggravation of the automated controller when it decides to throw a fit and not work. I think they could have done a better job in their design of the controller. Like using a separate temp sensor for the engine, instead of monitoring the current draw of the glowplugs for temperature feedback.

 

[u2slow]

Automotive mfr's really went out of their way to automate something that never needed to be. It's about selling the diesel engine option to dummies. A 'pre-heat' momentary button shows up on all kinds of small diesel equipment.

 

[Hydro-idi]

A better option would be to go to Azone and buy a lifetime warranty GPC. I dont normally recommend electronics from Azone but I have had good luck with their glow plug controllers.
10 min fix. The 7.3 style gp system will be better than any push button jerry rigged setup.

 

[Hydro-idi]

http://m.autozone.com/ignition-tune...low-plug-controller/539986_199783_0?location=

 

[Cubey]

I already have a 7.3 style controller that works... as mentioned in my first post.

So I’m not sure why you are suggesting I replace it.

 

[Hydro-idi]

I already have a 7.3 style controller that works... as mentioned in my first post.

So I’m not sure why you are suggesting I replace it.

Oh, thought it was not working properly for you.

 

[IDIBRONCO]

Assuming that you have some glow plugs burned out, the more you use your truck without all 8 glow plugs working, the faster the rest will burn out. You will soon be without any working glow plugs.