Duramax smell

[Dez78n]

My husband has had diesels for years, and his current truck is a 2018 2500 HD with the duramax, so I am familiar with how a diesel engine smells. But my yukon often has a quite different, more oily (to me) smell when started in the morning and left to run to warm up. I thought it was just me, but he noticed it the other day and mentioned it as well. Has anyone else noticed this with theirs? I'd posted this in a FB group and one woman said her mechanic told her it was bc it was a "clean diesel" engine and it was burning off the emissions. Idk enough about engines to know if this is true or not, but you all seem pretty knowlegable, so I thought I'd ask here.

Other than this and the lightbulbs already being burnt out in the GMC emblem on the grill, I've had it about 6 weeks and love it!!! I was so worried it would be too large for me to drive, but other than the airport garage the other day, I've really not had any issues.

 

[Bill 1960]

Just a sidebar that idling a cold diesel is about the worst thing you can do to it. Very little waste heat in that state so it takes a long time to warm. Meanwhile the fuel washes down the oil from the cylinders and dilutes the oil because the rings and piston are cold and not yet sealing optimally.

Some designs have a high idle function to increase the revs and load the engine with some back pressure from the turbo to warm up more quickly. IDK if GM did that on these or not.

My guess is what you’re smelling is unburned fuel in the exhaust. Back in the days of the older design IDI diesels (the ones with glow plugs) they would smell of fuel and make smoke when cold.

 

[exp500]

Try a different fuel station.

 

[CTown Duramax]

Mine has a melted plastic smell in "regen" phase. I am told on this forum that regen phase burns the diesel particulate out of the particulate exhaust filter. I notice the smell after parking the Duramax in the garage. It is not a normal diesel smell. This only happens occasionally. I will have to take better notice whether it happens every tank or only from certain filling stations.

I am tanking what is marked at the pump as sub 20% bio diesel, but not from the same station. I guess (only a guess, no engineer or mechanic here) that the smell might be this bio diesel content creating the particulate that gets burned and has the smell. I have to start buying from the same station every time.

Story. Years ago, a friend was running a diesel VW camper van on used Fryolator oil from Chinese restaurants. When he'd shut off the engine, it would knock and sputter and make a cloud of white smoke. The whole neighborhood would smell of restaurant grease fire!

Please, somebody tell me if one big name company's diesel has less bio content than another, though I imagine the name on the sign is not the supplier of the fuel.

 

[CTown Duramax]

Just a sidebar that idling a cold diesel is about the worst thing you can do to it. Very little waste heat in that state so it takes a long time to warm. Meanwhile the fuel washes down the oil from the cylinders and dilutes the oil because the rings and piston are cold and not yet sealing optimally.
. . . .

So is it possible that using autostopstart is better for this engine? About 70 of my last 100 engine hours have been spent in slow stop and go traffic. My engine oil is dirty at 2,000 miles. The avg speed is about 20mph.

 

[Bill 1960]

So is it possible that using autostopstart is better for this engine? About 70 of my last 100 engine hours have been spent in slow stop and go traffic. My engine oil is dirty at 2,000 miles. The avg speed is about 20mph.

When the engine is at operating temperature the components have all expanded and the rings are sealing well. I don’t want to appear an expert with regard to start-stop of hot engines; I think it will be a while before the jury is in (if ever) on that question.

If you’re new to diesels, one thing to know is that dark is not the same as dirty. Because of the soot, diesels will blacken the oil almost immediately. Used oil analysis is really the only way to know how much life is left in oil. Blackstone is a well known name in that industry. I use oil analysis through NAPA which is cheaper. But it’s still about $20 per sample with postage costs.

All that said, UOA is one of those tools for people in the 1% that obsess over vehicle maintenance. For everyone else, the predictions from the engine computer are pretty accurate and I use them myself. Although some, like myself, will change it at 50% oil life remaining rather than go the max. Mostly because of the ”oil is cheap, engines are expensive “ rationale. However for most cars, and most drivers, just following the owner’s manual is going to result in the engine lasting longer than you’ll ever want to own the car.

 

[Stbentoak]

The jury is in for me. Auto stop start is not good feature for diesels. These engines are meant to run long and hot. Constant stop starting …. it’s not very refined in a diesel and when you are in traffic or traffic light situation, it’s a complete pain in the neck. First Thing I do when I get in the vehicle is poke that button and shut it off.

 

[steiny93]

This diesel engine will do a 'regen' activity which is when it cleans the 'diesel particulate filter'. The process for cleaning the filter is to get the exhaust hot and inject 'diesel exhaust fluid' (def) into the process to clean the filter. When this is occurring the tone of the exhaust will change (it will get a bit louder) and it will smell kind of plastic like, or maybe like burnt French fries.

If the regen activity doesn't fully complete enough times the truck will alert you and tell you to drive at highway speeds while it finishes.

Regarding warm ups, auto starts, etc just treat it like any other vehicle, if normal user behavior is going to make these fail then GM has a pile of work todo. They aren't as fragile as folks imply they are, we drive both our baby diesels no different then anything else and all is fine.

 

[steiny93]

I am tanking what is marked at the pump as sub 20% bio diesel

Does anyone know if the dmax has any published intel regarding bio diesel usage? Asking as in the ram ecoDiesel usage of bio diesel (above a certain percentage, I think it was 10% but I could be mistaken) flips you into a different maintenance schedule (basically sooner oil changes and fuel filter changes).

As such, I've been avoiding bio diesel in both our ecoDiesel and baby dMax.

 

[Stbentoak]

This diesel engine will do a 'regen' activity which is when it cleans the 'diesel particulate filter'. The process for cleaning the filter is to get the exhaust hot and inject 'diesel exhaust fluid' (def) into the process to clean the filter. When this is occurring the tone of the exhaust will change (it will get a bit louder) and it will smell kind of plastic like, or maybe like burnt French fries.

just as an FYI the above scenario is incorrect.DEF fluid is injected in a daily basis in the exhaust stream of your vehicle to convert harmful gases into water and hydrogen. It is not used in the function of regens. In regeneration the vehicle injects extra fuel into the exhaust stream to raise the temperature and burn off the DPF. That’s why mileage goes down during a regen….