6.2L rough start in cold temperatures

[Autonomy_Lost]

Now that it's starting to get cold (in the 30's), I noticed my 6.2L starts really rough. It starts up almost instantly, but sounds like it's not firing on all cylinders, actually shaking the vehicle for about the first 30 seconds. Eventually it smooths out and otherwise runs fine. I have no issues once it warms up, and I have no issues starting it in warmer temperatures.

I did add some Power Service Diesel Fuel Supplement Winterizer/Antigel on the last tank.

Also, according to the previous owner, the vehicle got new glow plugs and a smart start box in 2020.

I'm worried that when it gets down the the teens and single digits, it might not start at all.

Is this normal? Anything I can do to troubleshoot and/or fix this?

 

[98G]

If I were going to regularly operate it in cold temps, I'd install a block heater.

 

[FKAM]

Mine has always done the same in cold weather. What I do to mitigate it, is run a block heater during cold temps (near freezing) and if things get below freezing and stay there day and night I add a magnetic oil heater to the outside bottom of the oil pan that I remove before starting. it makes a big difference and eliminates almost all of the startup shaking in cold weather. I run the block and magnetic heaters about an hour or two before I plan to start it.

 

[Barrman]

Are you getting a dirty white smoke out the pipe while it is shaking and trying to wake up? That is usually an indication of not enough heat inside the combustion chamber. The glow plugs are supposed to glow before start up, which it reads like yours do just fine, then glow some more after start up to help the engine smooth out and stay running. Your glow plugs might be working just fine but your controller isn't doing the afterglow correct. The TM should cover how to check that.

 

[Autonomy_Lost]

Thanks, is there a go-to block heater that everyone recommends?

EDIT: Looks like I have to remove a freeze plug? Not too excited about doing that. I think I might just try the magnetic oil pan heater first.

EDIT again: Looks like a circulating tank heater is another interesting option, anyone have experience with that?

 

[Action]

I recently noticed that my cold advance sensor was broke in 2. It always ran smooth at start up (with it broken). I put in a good cold advance switch. Now it sounds louder for a couple minutes after cold start in cold weather.

 

[diesel dave]

It hasn’t been that cold yet in pa. I’ve never used block heaters ect and never had issues starting at 0. Yes,at colder temps they do knock and clatter a little more,but this is normal. Below 0 can get a little iffy with any diesel But we’re not there yet. I’d look at your entire starting system again.

 

[Autonomy_Lost]

It hasn’t been that cold yet in pa. I’ve never used block heaters ect and never had issues starting at 0. Yes,at colder temps they do knock and clatter a little more,but this is normal. Below 0 can get a little iffy with any diesel But we’re not there yet. I’d look at your entire starting system again.

Thanks, can you clarify something? You say "at colder temps they do knock and clatter a little" does that include temps in the 30's? I'm just trying to figure out if what I'm experiencing is normal.

BTW, I believe my glow plugs are working because I do see the voltage drop during the period that the wait light is illuminated. But then once it starts it looks like the alternator kicks on and goes to full voltage, so not sure about the after glow thing.

 

[JetbikeAnt]

Now that it's starting to get cold (in the 30's), I noticed my 6.2L starts really rough. It starts up almost instantly, but sounds like it's not firing on all cylinders, actually shaking the vehicle for about the first 30 seconds. Eventually it smooths out and otherwise runs fine. I have no issues once it warms up, and I have no issues starting it in warmer temperatures.

I did add some Power Service Diesel Fuel Supplement Winterizer/Antigel on the last tank.

Also, according to the previous owner, the vehicle got new glow plugs and a smart start box in 2020.

I'm worried that when it gets down the the teens and single digits, it might not start at all.

Is this normal? Anything I can do to troubleshoot and/or fix this?

There is a cold start advance that advance the timing during startup. This what you are hearing. I drove that truck until they salted the road's over the last couple of years. Its located just inside the Dog house on the passenger side of the Block. This is normal and you should have no worries in the cold months. There is also a procedure in the TM on hoe to check it. I also saw the engine was replaced. I forgot about the tag you found and I asked the same question here. I could not figure out the date. You got a better answer than I did. LOL. You can find that post as well if you search our threads.

 

[JetbikeAnt]

Thanks, can you clarify something? You say "at colder temps they do knock and clatter a little" does that include temps in the 30's? I'm just trying to figure out if what I'm experiencing is normal.

BTW, I believe my glow plugs are working because I do see the voltage drop during the period that the wait light is illuminated. But then once it starts it looks like the alternator kicks on and goes to full voltage, so not sure about the after glow thing.

If your Glow Plugs were shot you would have to crank the motor until she fired, then you would have a bunch of smoke that would dissipate as well.

 

[98G]

Thanks, can you clarify something? You say "at colder temps they do knock and clatter a little" does that include temps in the 30's? I'm just trying to figure out if what I'm experiencing is normal.

BTW, I believe my glow plugs are working because I do see the voltage drop during the period that the wait light is illuminated. But then once it starts it looks like the alternator kicks on and goes to full voltage, so not sure about the after glow thing.

If you send me your phone number or email I'll take video of my voltmeter during startup today and text it to you, showing afterglow.

 

[Action]

If you send me your phone number or email I'll take video of my voltmeter during startup today and text it to you, showing afterglow.

Newer PCBs dont move the voltmeter up and down like the older boxes. So, dont think something is wrong if you dont see what 98g is talking about.

 

[Mogman]

You could also have some bad glow plugs, that way some cylinders are hot enough to fire but not all of them, I would check them all individually with an ohm meter, they should all read very low resistance and all about the same.

 

[Autonomy_Lost]

If you send me your phone number or email I'll take video of my voltmeter during startup today and text it to you, showing afterglow.

Pm sent, thanks!

 

[Autonomy_Lost]

Newer PCBs dont move the voltmeter up and down like the older boxes. So, dont think something is wrong if you dont see what 98g is talking about.

Thanks, I do have a new smart start box.

 

[Autonomy_Lost]

There is a cold start advance that advance the timing during startup. This what you are hearing. I drove that truck until they salted the road's over the last couple of years. Its located just inside the Dog house on the passenger side of the Block. This is normal and you should have no worries in the cold months. There is also a procedure in the TM on hoe to check it. I also saw the engine was replaced. I forgot about the tag you found and I asked the same question here. I could not figure out the date. You got a better answer than I did. LOL. You can find that post as well if you search our threads.

Just putting it out there...there is a big difference between saying:

"I think this humvee had the engine replaced, but I'm not sure what year"

and

"This humvee had a brand new engine and transmission installed in 2006 and the odometer was reset to zero. Thats what this tag means where it says MWO 2006."

Come to find out the MWO was for seatbelts.

Every time I trust someone I get burnt.

 

[JetbikeAnt]

Just putting it out there...there is a big difference between saying:

"I think this humvee had the engine replaced, but I'm not sure what year"

and

"This humvee had a brand new engine and transmission installed in 2006 and the odometer was reset to zero. Thats what this tag means where it says MWO 2016."

Come to find out the MWO was for seatbelts.

Every time I trust someone I get burnt.

But it the end it did have the engine replaced. I'm talking about the Plate on the Block. As far as the Trans, my Mechanic changed the fluid and stated whoever worked on it sealed the pan with Silicone, which is a no no. That was fixed. I never really researched the MVO's. I just liked the cool tags. Personally, I would have liked to have the original engine installed (that would be unique) which I have not seen in our Trucks. Same for my Missel truck. Point is I miss talking with you. I thought when you found out it was replaced things would be cool again. Either way you have a Bad ass Truck.