Hey ya'll,

I've got a '92 F-350 with the 7.3 non-turbo I picked up recently to use as a farm truck. It's maintenance history is questionable, but I've started to correct some of the issues one-by-one. Need a little help now though.

Here's the scenario... put the key in to start, I get the battery light and "wait to start" light. My first question is, does the battery light always come on pre-crank with the glow plug wait light? or is that my first sign of an issue? If I wait a couple seconds the wait light goes out and I can hear what sounds like something electrical charging. After a good 10-15 seconds it stops and I get a very slight "click, click, click" and a small bounce on the voltage gauge. I already replaced all 8 glow plugs, the wiring harness and two batteries - because they were all necessary anyway and the truck *does* start right up without hesitation, but it doesn't seem like its totally gone away.

The other part I'll mention is that the ignition cylinder doesn't have a distinctive "click" when you turn the positions, it feels very "mushy" to me.

Any thoughts on what to check? I would prefer to diagnose at this point than just throw money at new parts.

 

Sometimes, the glow plug relay can make a buzzing noise when first engaged. Especially on a relay that hasn't been used properly for some time. Mine did the same in the beginning from sitting for many months before I exercised it back into shape. The noise has gone away.

What glow plugs? Beru? motorcraft? Sounds like it's working ok. After the glow plugs warm up, my only problem is with these later model glow plug controllers is one rule is the glow plugs will continue to heat for up to 2 minutes during warm up. I'm ok with that if the glow plugs are designed to handle the long warm up.

What I don't like is the ticking on and off. I feel that's a sign of a mismatch of the controller to plug or plug failure. I feel this ticking on/off can cause quicker failures in glow plugs, though the beru and motorcraft, most say, are more reliable for this. My opinion is the ticking causes surge current to the plugs, not allowing them to fully heat, where the plugs are designed to increase resistance and lower current while on and heating.

 

Thanks for the response!

I went with the Beru ZD-9's and did all 8 plugs. This seemed like the recommended method. It had a rough start previously, but after it fires right up.

So if I'm reading this correctly some amount of "tick" is normal if you dont crank after the "wait to start" light goes out? I was understanding that any ticking was bad.

 

No, ticking is normal glow response when you dont' crank. The controller detects warmup and then ticks them to keep them warm and not overheat. The idea is to crank as soon as wait to start goes out. The fuel immediately cools the plugs and supposedly the controller can detect and keep the plugs on to fire the engine and run the emissions clean during initial 2 minute startup.

Your plugs are fine. My problem is too much ticking I think can be bad or a sign of problems or a defective controller. But yours sounds like they're operating fine. The quicker you get the engine started after initial glow, the better, I think and i think you should have less tick or no tick after the engine is started. Manual says the plug controller may continue up to 2 minutes of after glow during warmup before the controller cuts out that time could be much shorter.

 

Awesome. Thanks for the info eagleye! this is my first diesel and its hard to figure out sometimes what is normal and what is broken just from reading and watching the videos.

You guys have been a huge help already.

 

Yeah, the controller will cycle(resulting in the battery gauge jumping) for about 2 minutes after key on. Whether you start the engine or not; it'll act as an 'after glow' if the engine is started.

Also, chances are, you have 1 dead glow plug. What I've noticed is that with 1 dead plug, it'll still start, but will short-cycle the plugs. If all are working, it'll click on, stay on for perhaps 1/2 second, then off. If one or more is dead it'll click-click as the controller instantly turns it back off again thinking the plugs too 'warm' already.

 

the cycling of the glow plugs is normal behavior. it is designed to keep the plugs hot for faster cylinder warm up. by cycling, the controller only sends power to the glow plugs for a short time so they stay warm, instead of glowing red hot like they do for startup.

 

Great info guys. After reading up on "afterglow" (wasn't aware of this term) I think all is working normally. Unless it starts giving me issues turning over I'm not going to worry about it anymore.