I think Ii have a problem with my glow plugs - Lots of white smoke & wont start

darkostoj

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I have a 93 M998 and it just got cold here in Detroit and it won't start.

No matter how many times I cycle the the switch to the "ON" position and cycle the glow plugs it won't fire, but it pumps out a ton of white smoke from the exhaust.

The WAIT light will come on for about 5-10 seconds then turn off.

Any ideas on where to start?

Thanks!
 

papakb

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Just watch your voltmeter and see if it dips when the wait light is on. If it doesn't it's time for some new glow plugs.
 

MarkM

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I had to change out the temp sensor in the block. When cold the injection pump advances the timing for the injectors. Mine starts fine now and the sensor was like 35 bucks and easy to change.

Mark
 

snowtrac nome

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glow plugs should cycle about 15 seconds sounds like you have a few bad ones. change them all out before you swell up the remaining good ones you have.
 

papakb

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Mark, be careful with your terminology.

The sensor in the right rear of the block is called the "cold advance sensor" and advanced the IP when the block is cold. You can test it when the block is cold by disconnecting it. You should hear the advance solenoid in the top of the injector pump click.

The sensor tucked in behind the alternator on the left front of the engine is the "temp sensor" and is only for the instrument panel temp gauge.

The 3rd sensor is the one on the water crossover manifold on the top of the engine and it's for the control box. Depending on your control box it's either a "glow plug controller" or a "temp sensor controller".
 
Last edited:

snowtrac nome

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western alaska
I remember a ps article back when they were having control box issues, where ps wanted operators to count off 15 seconds, if the wait light stayed on longer than maintenance was supposed to replace the box. Now things may have changed with the latest boxes since I retired there for a while the Humvee series was going through different boxes pretty regularly I remember seeing 3 different types when I was in Iraq.
 

jackson76550

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sealy tx
while we are being careful, you will hear the pump click regardless of what you do with the cold advance switch located on the rear of the passenger side head. the injection pump solenoid clicks.


Mark, be careful with your terminology.

The sensor in the right rear of the block is called the "cold advance sensor" and advanced the IP when the block is cold. You can test it when the block is cold by disconnecting it. You should hear the advance solenoid in the top of the injector pump click.

The sensor tucked in behind the alternator on the left front of the engine is the "temp sensor" and is only for the instrument panel temp gauge.

The 3rd sensor is the one on the water crossover manifold on the top of the engine and it's for the control box. Depending on your control box it's either a "glow plug controller" or a "temp sensor controller".
 
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