[jmdub85]

Does the 3.0 have variable valve timing? Mine is in the shop and they are saying the cam phasers are bad but I can't find any reference to the diesel even having cam phasers.

 

[Dunrollin]

I never heard of them on the 3.0 diesel. I went to the Coffee Table Book on our engine and did word searches for several terms but no hits. I also did a search for cam phasers for a 3.0 and came up with nothing.

I see you posted this earlier:

Truck is currently at the dealer being looked at for a rattle from the engine that last 2-3 seconds at startup after the truck has sat for a couple hours or more. Sound is like shaking a can full of marbles (very similar sound to my 5.4 that had bad timing chains and tensioners).

Hopefully you can get this solved promptly. Please continue to keep us informed on your progress as this is a problem I don't recall hearing of before. Best of luck and may you be back in the driver's seat soon.

 

[Reinharm]

I never heard of them on the 3.0 diesel. I went to the Coffee Table Book on our engine and did word searches for several terms but no hits. I also did a search for cam phasers for a 3.0 and came up with nothing.

I see you posted this earlier: Hopefully you can get this solved promptly. Please continue to keep us informed on your progress as this is a problem I don't recall hearing of before. Best of luck and may you be back in the driver's seat soon.

Maybe time to get a 2nd opinion...

 

[j.phil9]

Does the 3.0 have variable valve timing? Mine is in the shop and they are saying the cam phasers are bad but I can't find any reference to the diesel even having cam phasers.

Like most diesels on the market today, the 3.0 PS does not have variable valve timing (neither does the 6.7 for that matter). I will try and simplify the reason as follows: VVT was created to help gasoline engines provide more power and better fuel economy.

For a gasoline engine to be efficient, the goal would be for the engine to operate at a stoichiometric air-fuel ratio of ~14.7:1. This allows the fuel in the combustion chamber to completely burn. However, to produce more power, we need more fuel; more fuel requires more air. As the gasoline engines RPM increases, volumetric efficiency decreases due to losses from the throttle valve (gasoline engine speed is controlled by the amount of air inducted, sometimes referred to as pumping losses) and high RPM (time that the inducted amount of air has to enter the combustion chamber). To combat these 2 losses, VVT was created to vary the duration the valves remain open and closed to increase the volumetric efficiency over the RPM band of the engine to keep it operating as close to the stoichiometric air-fuel ratio as possible under differing load demands.

Conversely, a Diesel engine does not have a throttle valve (engine RPM is controlled by the amount of fuel that is injected into the combustion chamber). Additionally, a diesel engine produces much more power at a lower RPM range and typically has a much lower maximum RPM. This drastically increases the volumetric efficiency of a Diesel engine (no pumping losses due to a throttle valve and maximum power production and lower RPM). Efficiency is also increased in modern diesels by operating with forced air induction. This makes Diesel engines run much more lean than their gasoline counter parts (meaning the engine has more oxygen in the combustion chamber than is required for a complete burn) essentially making VVT a complexity on the engine that will produce very little benefit. And this is why the Diesel engine is considered to be more efficient than the gasoline engine.

This is not an exhaustive explanation, I tired to hit the high points and keep it fairly easy to understand. The mechanic was probably mistaken (as the 3.5EB has had rattling problems with the cam phasers) but the 3.0 PS does not have cam phasers (the cams are belt direct drive).

Hope this helps answer your question.

 

[jmperlik]

@j.phil9 - first-things-first, let me welcome you to the forums with your first post!

I was pretty sure that our 3.0L V6 Diesel engines do not have VVT but like @Dunrollin, I could not find a reputable source to quote, so I kept quiet since I didn't know for sure.

Your explanation is more exhaustive than I could have provided and very well presented. Keep up with these types of contributions as this is why I like our little corner of the internets where we have built a pretty strong knowledge base with members like you.

Welcome aboard!