Driving with failed glow plugs?

[PNW_Steve]

Hello Everyone,

I am considering the purchase of a rig with a 7.3 diesel. The glow plugs are failed. I have no idea if it is the glow plugs, harness or relay at this point.

If I buy it I will have a 800 mile drive home from the Bay area to Seattle. Interstate driving and warm weather.

What are the potential problems driving a 7.3 equipped rig with failed glow plugs?

My Cummins 5.9 does not run the grid heaters (instead of glow plugs) in warm weather and has no issues but I know very little about the 7.3's.

Am I safe to drive it in this condition?

Thanks

S.

[Brad_SwiftFur]

The primary thing the glow plugs do is make it easier to start, especially when cool, and in cooler weather. Once running and warmed up, the glow plugs don't do much of anything.

[PNW_Steve]

Originally Posted by Brad_SwiftFur

The primary thing the glow plugs do is make it easier to start, especially when cool, and in cooler weather. Once running and warmed up, the glow plugs don't do much of anything.

That is my understanding.

My Cummins has grid heaters instead of glow plugs but they perform a similar function. In warm weather they don't run or only run for a very short period. I know that if they failed I probably would not notice until the weather cools somewhat.

What I don't know is how the Ford would behave in similar circumstances and if there are any other potential ill effects.

Thanks for the reply.

S.

[somewhereinusa]

Glow plug/grid heaters are only for starting. Actually glow plugs are off once the glow timer times off, before you engage starter.

[PNW_Steve]

Originally Posted by somewhereinusa

Glow plug/grid heaters are only for starting. Actually glow plugs are off once the glow timer times off, before you engage starter.

That is my understanding.

My Cummins has grid heaters instead of glow plugs but they perform a similar function. In warm weather they don't run or only run for a very short period. I know that if they failed I probably would not notice until the weather cools somewhat.

What I don't know is how the Ford would behave in similar circumstances and if there are any other potential ill effects.

Thanks for the reply.

S.

[somewhereinusa]

You don't want glow plugs on anything to be on when the engine is running, it will cause preignition. Like pinging in a gas engine.

[PNW_Steve]

Originally Posted by somewhereinusa

You don't want glow plugs on anything to be on when the engine is running, it will cause preignition. Like pinging in a gas engine.

Shouldn't be a problem on this one as they don't work.

Anyone aware of any potential issues with running the rig 800 miles without them in reasonably warm weather?

I wouldn't think that there is but there are things that I don't know and I prefer not finding out that I was wrong the hard (expensive) way.

Thanks.

[porkchopsandwiches]

Should be no issues running that 800 miles in warm weather. Or even cold weather once the engine is started. You'll be fine, they're off when the engine is running.

[EastCoastCB]

Cal's shorty should be fine. Tell him I sent you and get a big discount!

[roach711]

Originally Posted by somewhereinusa

You don't want glow plugs on anything to be on when the engine is running, it will cause preignition. Like pinging in a gas engine.

As I understand it, glow plugs on the 7.3L do stay on for 30 seconds or so after the engine has started. When watching my digital battery monitor I see my starting bank voltage staying down around 11 volts until I get out the driveway, then it pops up to 14.x volts.

As everyone here said, no problem driving with dead glows. It may be harder to start but once you're running it's all good.

If your bus has OBDII diagnostics many auto parts stores will scan your error codes for free.