Hard Start - Glowplugs?

[jchristie]

Took this video of my truck starting yesterday. It seems to be getting progressively worse. Yesterday was a colder morning which I think aided in it being a harder start, and it was the first time I noticed white smoke after it starting. Could this be a glowplug issue? I got this truck recently, so I don't know if/when the glow plugs were changed. If so, the motorcraft plugs are the way to go (from the threads I've read), correct?

If you watch the video, you'll also notice the voltmeter gauge jumping back and forth until finally settles. This does throw my theory off about the glowplugs although I don't know if they're connected.

https://www.youtube.com/watch?v=W6JY7fHkfDM


Thanks in advance.

 

[bbjordan]

It is possible that a glow plug or two have failed. It's easy enough to check the GPs for continuity. The fewer GPs working, the shorter the glow time. The GP controller uses the total resistance of the GPs to determine how warm the engine is to calculate how long to glow the plugs. The higher the resistance, the warmer the GP controller thinks it is. A failed GP will raise the total resistance (since the resistors (GPs) are in parallel) making the controller think the engine is warmer than it actually is. This results in a shorter glow time = harder starting and white smoke from the cold cylinder with the failed GP.

As for the voltmeter jumping back and forth, that is normal. The GP controller cycles the GP for a few seconds to help reduce engine emissons.

 

[icanfixall]

Agreed that maybe a couple glow plugs have failed. That will easily cause white smoke during starts. Reason is you have a couple of cylinders that are not hot enough to fire the diesel. It takes 942 degrees to ignite diesel. These idi diesels are like any other diesel engine. They ignite the fuel by the temp of the compressed air in the cylinders. So the faster the engine cranks the hotter the air will be. Thats simple science in action.

 

[riotwarrior]

A disconnected OR failed gp will cause that.

Check gp connections and if disconnected reconnect see if situation improves.

Al

 

[jchristie]

Great. I'll check glow plug connections first and then, if the problem persists, I'll check continuity. I ask this out of inexperience, but is it a common practice to replace all glow plugs if one is bad or can you replace them on at a time?

 

[DaveBen]

I would, as they are heaters and do go out after X number of hours. I don't have any idea of how many hours, but I have found if one or two go out, just repalce them all. Use only Motorcraft or Beru glowplugs. Others swell up making removal very hard.

Dave

 

[OLDBULL8]

Observing your Video. It looks to me that your battery voltage is low when you first turn the key ON.

The GP cycle looks like it is about the right length of time for a 40*F temp. The GP's will cycle ON/OFF just like your volt meter is showing.

Once the engine has started, it's showing that the Alternator is full charging. I don't think you have a GP problem, more than likely a battery problem.

Next time, before you start, check the battery voltage with a volt meter, it should read at least 12.3 to 12.5 volts.

It would be a good thing to check the battery posts for corrosion, clean them off.

The Glow plugs pull a Hi amperage when there ON, that drags the battery voltage down resulting in a longer than usual start time, the colder the temperature, does contribute to that. Batteries loose some of there CCA ability the colder it gets.

 

[jchristie]

The only reason I did not consider the batteries is because I replaced both of them a month ago. Now, I guess there could be a poor connection on one of the terminals. @OLDBULL8, is your theory void if those batteries are new? I will check the volts before starting next time to verify I don't have a bad battery.

 

[OLDBULL8]

There are a lot of things that will cause a long crank to start. Personally I don't think you have a starting problem at all.
A three second start is not that bad. If you take all things into consideration. A starter on a diesel takes 500 to 800 amps just to get the engine to turn over the first revolution basically.

A gas engine only takes 150 to 300 amps to start, depending on it's CID.

Considerations of starting length.
The ambient temperature.
The viscosity of the crankcase oil.
The length of glow plug cycle. One or more bad ones will result in a short GP cycle, like 1 or 2 seconds.
The starter condition. Worn bearings, if not ball bearings.
The starter solenoid contacts condition.
The battery positive and negative connections. Are the cable ends/connectors corrode free.
The battery cables condition, are they corroded internally.
The battery negative connection to engine.
The battery positive connection on the starter.
The age of the batteries themselves.
The compression of the engine.
The fuel supply. Is it air free.
The efficiency of the IP.
The efficiency of the injectors.
Maybe a few other things.