How often to replace Glow Plugs?
 

First, I was having the dealer service the truck the other day and as the Fuel Heater failed and would not let the truck start despite cranking hard. The tech told me all I had to do is disconnect it and it started right up - just a tip to everyone. While we were in there he also replaced the Glow Plug Relay as it was showing signs of rust, etc. Easy enough to do.

He then said I should consider replacing the glow plugs - even advised to do it perhaps every year. That seems to be quite frequent in my mind.

How often do you all replace the plugs? I live in northern MA and we do get our cold spells up here. Is there a way to tell when the glow plugs are on their way out. Like hard starts, etc.

Well, mine are 10 years old and still working great..
You can ohm check them from the 9 pin connector on top of each valve cover to see if they are working.. SEE:
https://www.ford-trucks.com/forums/8...and-p1316.html

Glow plugs should be replaced when they fail, once a year is pretty excessive.

Mine are original factory plugs with over 130k miles and 10 years on them.

Every year:rolleyes: Local dealer charged an old guy 800 to replace his. Felt sorry for him, but I had no way of helping. His truck only had bout 50k on it.

:-missingt And they wonder how they got the nickname "Stealership".

I would say it depends. If you start and stop it many times a day, probably a couple of years. If you start it and leave it run all day, much longer. Each time you start it, you wear it out a little more. So, miles are not an issue since it isn't turned on soon after the truck starts.

After the engine is warm, the glow plug circuit is not turned on.. so they are not being used as much as you might think..

And they wonder why the big three automakers is having a hard time!

Depending on temperature. I've got 279k on my original glow plugs, so I'd say I've started it more than most here. Of course living in Texas, I don't need the glow plugs as often as others.

I'd say do the ohm test and only replace them when they're bad. Make sure to re-torque the rockers & injectors while you're in there doing that.

I thought it glowed before the crank and a little after it gets started for emissions purposes? IIRC, the call it the Afterglow???:confused:

Just do it when they go bad. It will make the truck hard to start when cold when they do go bad.

Only when the engine is cold. If the engine is already at or near operating temps when you crank it, the glow plugs never turn on (neither before or after the engine starts). The WTS light on the dash operates completely independant of the glow plugs.

If the engine is cold, then the glow plug operation is controlled by the PCM, and the length of time is determined by the oil temps, ambient air temps, and baro sensor. At that time will the glow plugs engage before you crank, and will continue to stay on after the truck has started. This can be just a few seconds, or as long as 2 minutes, depending on temps and altitude.

So if you start and stop your truck all day long, the glow plugs are probably only activating once the entire day.





As for when to replace them, once a year is waaaaaaayyyy excessive. I have 120K miles on my truck and still have the original glow plugs. I do have one or two that are on their way out, but the truck still starts fine so I've been too lazy to change them out yet.

Also, there's no sense in changing out one or two at a time. Change them all if you already have the valve covers off. You'll want to do that job as few times as possible, since it's kind of a pain anyway. But only dive in there once you've determined that enough glow plugs are burnt up, and it's getting harder to start.