Smoke on start up (not glow plugs)

[thompsoncustom]

My humvee has started to smoke on start up quite a lot for the first 3 seconds and then cleans up and is fine.

Things I've checked so far:

Glow plugs have 22.9v going to them when the Wait light is on.
All glow plugs Ohm good but 1 is bad (open) on the rear drivers side cylinder.
Vent line and filter are clear back to the tank.

So that 1 plug has been bad for a couple month and you could just see some smoke if you were looking but now there is a huge cloud and heavy smoke for 3 second. Smoke smells like fuel so I'm thinking maybe one of the injectors is leaking into the cylinder. I'm thinking of pulling all the glow plugs and using a bore scope to see which cylinder looks washed to identify the injector.

Any other tips on what I should check, after starting humvee runs and idles good.

 

[Milcommoguy]

IMO... Fix the one glow plug, then move on to the other checks if necessary. First time cold start with one plug out can produce a puff of smoke like you describe.

Simple stuff easy, then get all dirty. CAMO

 

[Barrman]

What color is the smoke?

Fluffy white is coolant.

Blue is oil.

Dirty white is cold cylinders not firing. Glow plugs.

Black is too much fuel.

 

[thompsoncustom]

IMO... Fix the one glow plug, then move on to the other checks if necessary. First time cold start with one plug out can produce a puff of smoke like you describe.

Simple stuff easy, then get all dirty. CAMO

Pretty positive it's not the glow plug just from the amount of smoke but your right might as well replace it to rule it out 100% I have 4 other diesels but no other experience with a humvee maybe they are super sensitive to dropping one plug? I'll try to get a video of it in the morning.

OEM plugs on the way

 

[Pstyckiewicz]

Where do you park it? How long does it sit between starting up. Could be moisture/condensation building up in exhaust. Or somthing burning off that gets in there?

 

[thompsoncustom]

Where do you park it? How long does it sit between starting up. Could be moisture/condensation building up in exhaust. Or somthing burning off that gets in there?

Just in the drive way, gets started and drove around town almost everyday. Went to take a video of the smoke this morning and it wasn't all that bad. Started it again this after noon and there was probably twice as much smoke as this morning.

I did some looking last night and it does seem the 6.5 really doesn't like losing even 1 glow plug so maybe that's all it is when the plugs get here i'll install them and give a update.

 

[Mogman]

You could be losing more glow plugs.
There is a theory that when any plug opens up the voltage/current to all of the other plugs rises causing a cascade effect of plug failures

 

[thompsoncustom]

went to start it today has been sitting for over 24hrs.
https://youtube.com/shorts/mT5Rx9aV57Y?feature=share

didn't want to start without giving it some throttle then started right up.

 

[Mogman]

First you should read the operator TM, you will find some interesting things in there including that every time you turn the run switch off you must wait at least 90 seconds before going back to run or you can fry your glow plugs.

 

[Thunderbirds]

went to start it today has been sitting for over 24hrs.
https://youtube.com/shorts/mT5Rx9aV57Y?feature=share

didn't want to start without giving it some throttle then started right up.

I'm assuming it died on it's own, you didn't turn it off, correct?

In the TM 9-2320-280-10 (I usually start here), table 3-1, page 3-4 there is a troubleshooting guide. Have you tried draining the fuel filter in case you had some water collect in there:

6. ENGINE STARTS BUT MISFIRES, RUNS ROUGH, OR LACKS POWER
Step 1. Check for water in fuel filter by draining.
Drain fuel filter (para. 3-10).
Step 2. Check for restricted air cleaner.
If emergency situation exists, clean air cleaner element (para. 3-15).
If emergency situation does not exist, notify unit maintenance.
Step 3. Other causes.
Notify unit maintenance.

 

[thompsoncustom]

First you should read the operator TM, you will find some interesting things in there including that every time you turn the run switch off you must wait at least 90 seconds before going back to run or you can fry your glow plugs.

lol I figured you guys would catch that got a little to ansie.

I'm assuming it died on it's own, you didn't turn it off, correct?

In the TM 9-2320-280-10 (I usually start here), table 3-1, page 3-4 there is a troubleshooting guide. Have you tried draining the fuel filter in case you had some water collect in there:

6. ENGINE STARTS BUT MISFIRES, RUNS ROUGH, OR LACKS POWER
Step 1. Check for water in fuel filter by draining.
Drain fuel filter (para. 3-10).
Step 2. Check for restricted air cleaner.
If emergency situation exists, clean air cleaner element (para. 3-15).
If emergency situation does not exist, notify unit maintenance.
Step 3. Other causes.
Notify unit maintenance.

ya it died on its own. normally if started everyday it starts just smoking a lot now, always starts better with more rpm tho.

I have drained the fuel filter and there was no water and the air filter has been cleaned.

 

[Mogman]

You should also check to see if the cold advance solenoid is getting 24V and that the coil is not open.

 

[thompsoncustom]

You should also check to see if the cold advance solenoid is getting 24V and that the coil is not open.

ok I will look into that then but I assume it's working. engine is extra rattley for the first 2mins then all of a sudden it gets quite which I assume is the advance shutting off.

 

[TOBASH]

Clean up the oil catch we call a catalytic converter.

Back pressure from that causes issues.

HummerH1 and I cleaned our multiple units up and they run like scalded dogs. MPG also improves.

 

[thompsoncustom]

Clean up the oil catch we call a catalytic converter.

Back pressure from that causes issues.

HummerH1 and I cleaned our multiple units up and they run like scalded dogs. MPG also improves.

thanks for the tip that's a easy one to test I'll unbolt it and see if it starts better. also I would just remove the cat and muffler don't need them in my state.

 

[thompsoncustom]

well glow plugs came today so I replaced the bad one real quick and started it for the first time today. still smokes a lot maybe a tad better, haven't had time to test anything else

 

[thompsoncustom]

well finally cooled down enough I was able to take the cat pipe off and modify that. Was a little tricker getting the exhaust out being pushed up into the tunnel but I just used the torch to put a nice bench on my wrench and then it went pretty smooth.

I'll have to start it in the morning and see if it made any difference in the smoking on start up.

 

[Mogman]

If it was the cat it should also smoke excessively at highway speeds and have low power

 

[thompsoncustom]

If it was the cat it should also smoke excessively at highway speeds and have low power

ya wasn't the cat still smokes the same.

I ohmed the plugs ealier but I didn't check to make sure I was getting 24v to all of them just one spot on the harness.

 

[Mogman]

I suppose it is possible they could ohm out OK when cold but open when power hits them.
Did you replace all of these at one time?