hmmwv white smoke

[jww8161]

anyone have any idea's what's wrong when your 6.5l in a M998 is smoking white and running rough?

 

[DatGuyC]

white smoke sounds like coolant in the cylinder, might have a blown head gasket or a cracked cylinder wall.

 

[tomelroy]

what is the outside temperature? Does it go away after it warms up? Is it hard starting?

 

[Retiredwarhorses]

White smoke on startup is unburnt excess fuel...99% of the time due too bad glow plugs or faulty PCB/EESS etc...
if it's still there after startup and driving at temp....more likely an excess fuel issue like a bad injector, bad pump, or worse....a blown head gasket. You first need to determine if the white smoke is fuel or glycol being burnt off....the 2 are quite distinct in odor.

 

[SublimeMudTime]

You first need to determine if the white smoke is fuel or glycol being burnt off....the 2 are quite distinct in odor.

I have not had to do this myself but I've heard you can route the exhaust into a bucket of water and let it run for a minute or so. After killing the engine and letting the water settle you can look for signs of fuel on the surface of the water in the form of a rainbow like shimmer...

I have seen that effect at a boat dock with spilled gasoline.

 

[infidel got me]

Is it using coolant(are you adding coolant to it regularly) like that guy c asked does the rough idle go away after it warms up? You can do a block test on it to confirm a bad head gasket, but you should be able to smell a blown gasket. Need a little more info to diag. properly.

 

[GMVguy]

If the white smoke issue occurs with hard starting, replace your glow plugs. It's a quick, 45-minute job and fixed the problem for me. She starts right up like a brand new truck now!

 

[Bubba4635]

HMMWV Head Gasket/Head Pulley Tool

White smoke on startup is unburnt excess fuel...99% of the time due too bad glow plugs or faulty PCB/EESS etc...
if it's still there after startup and driving at temp....more likely an excess fuel issue like a bad injector, bad pump, or worse....a blown head gasket. You first need to determine if the white smoke is fuel or glycol being burnt off....the 2 are quite distinct in odor.

I just purchase a M1038 with a 6.5L engine, the vehicle started up once and had a lot of white smoke, I shut it down and it would not start again and it was having problems turning over. I check the oil and found that it was mixing with the coolant. I change the oil and filter and it still didn't start. I believe that water is in the cylinder causing the engine not to turnover. Also, how can I get a head pulley tool? I believe that the head gasket or gaskets are blown and needs to be replace. If you or anybody has any advice on how to repair this vehicle, please let me know.

 

[Dock Rocker]

I just purchase a M1038 with a 6.5L engine, the vehicle started up once and had a lot of white smoke, I shut it down and it would not start again and it was having problems turning over. I check the oil and found that it was mixing with the coolant. I change the oil and filter and it still didn't start. I believe that water is in the cylinder causing the engine not to turnover. Also, how can I get a head pulley tool? I believe that the head gasket or gaskets are blown and needs to be replace. If you or anybody has any advice on how to repair this vehicle, please let me know.

The first thing would do is confirm the problem. There are specific troubleshooting steps for this in the TM’s. If you don’t feel like you can pull it off or don’t have the tools take it to a shop that works on diesel trucks. Don’t take it to one that works on 18 wheelers, find one that works on f-250’s and such. Ask around and make sure they have a good reputation and stand by their work.

They can confirm a head gasket leak via a pressure test in the cooling system. If it fails the pressure test then you need a new head gasket.

If the head gasket is gone then have them pull the head and check the engine out. If you have been trying to crank in a hydro-locked motor you may have bent a rod. Let them know they need to check the bottom end. If there is sever head damage or a bent rod i would just find another 6.5 and replace it. If it’s just a head gasket then put a new one on and run it.


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[Sintorion]

I just purchase a M1038 with a 6.5L engine, the vehicle started up once and had a lot of white smoke, I shut it down and it would not start again and it was having problems turning over. I check the oil and found that it was mixing with the coolant. I change the oil and filter and it still didn't start. I believe that water is in the cylinder causing the engine not to turnover. Also, how can I get a head pulley tool? I believe that the head gasket or gaskets are blown and needs to be replace. If you or anybody has any advice on how to repair this vehicle, please let me know.

I would start with a coolant tester and see what you are protected too. It has been ungodly cold and if your coolant mixture was light, you could have frozen the block. That could mean more than just a head gasket. Obviously worst case anyway. Hope it is something as simple as glow plugs. Do you have a block heater?

 

[Bubba4635]

Reply to Sintorion

I would start with a coolant tester and see what you are protected too. It has been ungodly cold and if your coolant mixture was light, you could have frozen the block. That could mean more than just a head gasket. Obviously worst case anyway. Hope it is something as simple as glow plugs. Do you have a block heater?

Thanks Sintorion for your speedy reply. My coolant mixture is good, and yes the weather has been cold!

 

[luke2pl]

anyone have any idea's what's wrong when your 6.5l in a M998 is smoking white and running rough?

What was it?
Was it cylinder heads? or injectors

dealing with same thing now on my m1123 6.5

 

[mgFray]

White smoke is usually coolant in the combustion. At best head gasket leak, maybe head cracked, but could be catastrophic if the block has cracked. Only way to know, check the coolant for combustion gases and check the exhaust for coolant. (There are test kits for each.)

If it is coolant, check your oil. If you've got coolant in the oil, something VERY bad likely happened.

You'll have to pull the heads and inspect the block, heads and head gasket to figure out how fatal this is... but the key, stop driving it, stop running the engine until you figure out if it's coolant!

 

[luke2pl]

White smoke is usually coolant in the combustion. At best head gasket leak, maybe head cracked, but could be catastrophic if the block has cracked. Only way to know, check the coolant for combustion gases and check the exhaust for coolant. (There are test kits for each.)

If it is coolant, check your oil. If you've got coolant in the oil, something VERY bad likely happened.

You'll have to pull the heads and inspect the block, heads and head gasket to figure out how fatal this is... but the key, stop driving it, stop running the engine until you figure out if it's coolant!

no coolant leaking. Smells like diesel read that it could be injector pump and PTS. No sweet smell or blue smoke. Smokes at start up once warm never does it again.

 

[Mogman]

no coolant leaking. Smells like diesel read that it could be injector pump and PTS. No sweet smell or blue smoke. Smokes at start up once warm never does it again.

That sounds like you have some bad glow plugs or possibly a bad EESS box, test each glow plug disconnected for low resistance (about 2.5 OHMS or so) the bad ones will be obvious.

 

[luke2pl]

That sounds like you have some bad glow plugs or possibly a bad EESS box, test each glow plug disconnected for low resistance (about 2.5 OHMS or so) the bad ones will be obvious.

Got smart box from black dog customs. Glow plugs are good. The only thing I can think off is injectors or injector pump or TPS sensor that controls everything. It does idle rough when cold. When it warms up smoke is gone. Takes about 30 to 50 seconds in 60 degree whether. I did not change injectors or injector pump. The only two things left. Coolant is stable no leak. It does not bubble up so looks like it’s stable. It looks and smell like access unburned fuel. Which leads me toward either injectors or injection pump. Some times runs really good. Did notice a little jerk some times which leads me to believe it’s too much fuel supplied might be bad injector. PCB is good for it replaced with Black dog customs box.