2007 Volvo Vnl 780

I am buying a volvo 13 speed, ISX 500 with 370k miles on it....
before...it used to do 7.5 to 7.9 mpg..wonderful...extremely economical...

but now, for some reason, it is only doing 5.6 to 5.8 mpg...it is smoking a little bit and i noticed a little lost of power when i use cruise control on the last gear...

anybody know from you experience, what could the problem be?
thanx

 

First thing I would have checked is your cac (charge air cooler). Going through a similar problem with my truck, it has a cat in it, and thats whats wrong with it.

 

what is a charge air cooler? im sorry...im just not in this business for a long time to know all the truck parts?

thanks bro!

 

it is intercooler, air to air heat exchanger.

it looks like a radiator installed behind it.

When turbine compresses air with 1-2 bar pressure, air is too hot and engine looses some power.

When intercooler is bad, some air leaks and boost pressure is lower... less power, less miles per galon

 

Yes its in front of the main radiator.The hose that comes off the turbo and runs to the front of the truck attaches to it. Its not a big deal to have it checked any shop can do it.

 

The Volvo D12 is a 12 liter engine. Compared to the Cummins ISX 15 liter the Volvo engine is weak.

And the autoshift transmissions have been nothing but trouble from day one.

Why do you want an auto shift? Is your girlfriend going to drive the truck?

You will have more control over the power of the engine with a manual gearbox. And it will be easier to manage in the winter on snow and ice, and in the wet conditions.

The autoshift transmissions were developed for the megacompanies that hire rookie drivers that tear up clutches, driveshafts and axles.

I drove an 05 Volvo with the ISX engine, and now am in an 07 Volvo with the D12. Both rigs have 13 speed gearboxes.

The ISX never left me wanting for power, and if I kept the speed at or below 65 I could get 7 to 8 mpg.

The D12 is a gizzy. Even when pulling an empty trailer I have to downshift for small hills. I had a load of wire on reels recently, 40,000lbs. Running West on I-20 out in West Texas (can you say flatlands?) with a headwind the #### thing would barely make 45 mph, and got about 4 mpg.

When the exhaust gasses pass through the turbo they heat it up, and some of that heat is passed to the intake side of the turbo.

The charge air cooler (CAC) cools the intake air charge after it leaves the turbocharger, before going into the engine.

A cooler air intake charge is more dense, and thereby will allow more air to be forced into the combustion chamber, and make more power.

The CAC can develop cracks, and then leak. When that happens the air charge that was compressed by the turbo is no longer compressed, and the engine will not be able to produce the same amount of power.

One thing that strikes me is that you don't seem very knowledgeable about big trucks. If you want to be an owner operator, you should at least know a bit about trucks and how they work.

Otherwise dishonest repair shops will take advantage of you.

Good luck.

 

At the last company I worked for they had 04-06 Volvos with the D12s, and we never really had engine problems, but I can't speak for the rest of the trucks...

 

Have the egr valve checked. Also could be a Turbo actuator.

 

Hello.

You have to look of the facts

1- is the truck going to give you the service that you need?
2- is fuel economy?
3- is the parts are available and prices?
4- what engine do you want?
5- what transmission do you want?
6- what truck do you want?
once you considered this facts make your decision.
Now, this is my experience of driven for the last 12 years, now days you can not go out there and by a truck only because looks nice or everybody prefer to drive that particular truck.
I used to own a peterbilt 379 with cat c15 475hp and eaton fuller 13 speed, bat experience with that truck all ways broken down, and poor fuel economy 4.75 to 5.0 miles to a gallon, even the oil changes were more expensive for that engine.
I have a Freightliner FLD120 1998 with Detroit 12.7 60 series and 1.6 million miles on it, and very good fuel economy, MT 9.0 Loaded 6.5 miles to a gallon, parts are cheap and you can find them almost everywhere, but your best option is ask drivers that owns a VOLVO truck, not some one who is yest a driver, I guarantee you they are going to say there are piece of junk. The big roll in buying a truck it is taking in considerations fuel prices.

 

I have a 2007 Volvo 780 with the D12 engine and a 13 speed transmission.

The truck has 589,000 miles on it, 130,000+ miles since i bought it. Had two new EGR valves when I purchased it. Changes have supposedly been made to their design/operation to help them last longer.

The only major issue I have had with it is replacing the EGR cooler(approx $2,800) other than that no engine issues. The tech that worked on my truck said to replace the vibration dampener every 100,000 miles to minimize the chance of the cooler cracking as the most common cause of an EGR cooler failing is vibration. If this is true it is very cheap preventative maintenance. Otherwise, I have not found parts to be expensive. Have yet to add a drop of oil to the engine(Change at about 15,000.)

Also had a couple items replaced under warranty shortly after purchasing the truck.

When I was looking for a truck I hoped to find one with a Cummins engine but there just wasn't anything decent available. I can't say this particular truck has been awesome, but overall not too bad. And it seems Cummins engines have many of the same problems as a Volvo.

The only thing in regards to service I see as a potential problem is how long it may take to get a Volvo in for service work. When i have needed minor work done out on the road I have been told more than once it could be two to three days before they could get to it. So down the road I went.