Paccar MX Engine ???

i have driven one and like it. it has the old cat growl to it. they get could fuel mileage, some say little weak on pulling side but i did not have a problem with it. i am getting ready to buy a truck with that engine and i think you will like the motor i know i did. i have no quarls about it what so ever. are you getting one as a company driver or buying one? they are quieter on the idle side than all of the other engines out there. i believe you would like it.

 

It's a quiet engine, especially in a T-680. Ive never seen a quieter combo than this. It's good for the fuel mileage, but it could use a little more pull. My fiance and I have agreed on that since we've both been in a 700 with the Paccar MX. Part of the problem could also be how much HP TransAm has cut back though. I feel it's not a bad engine, but it's definitely not a CAT, lol.

 

I had one in a 660. Did not want to pull a hill and acceleration was lagging. I wished I still had my old cummins

 

I have a 455 hp MX with a 13 speed in my T700. Kind of a dog from a stand still (pulls the same loaded or empty). My Detroit 60 pulled hills a little better but the MX has a better mid-range. I'm getting high 6's - low 7's for mileage pulling 40,000-48,000 lbs in the mountainous states. I keep it between 1200 and 1425 rpms and keep the boost below 20 lbs. Your mileage will vary depending on how you drive, I cruise around at 60-65mph. You will get better mileage by not using the cruise except on the absolute flat since any sort of hill will immediately push the boost up to 30-35 lbs. I never added oil until I hit around 80,000 miles, and even then I only add maybe a 1/2 gal per month. It has needed coolant ever since I've had it (brand new). I add about a gallon every 2 weeks.

EDIT- quiet is an understatement. This truck is quieter than my wife's Subaru.

 

Check all of your hose clamps under the hood. All of mine were loose from the factory. Once I tightened them all down mine quit loosing coolant

 

I had to put a gallon of coolant in my 700 every five days. There was never any sign of a leak. I even had it in the shop and it still kept sucking coolant. Im hoping my 680 proves to be a sipper rather than a guzzler.

 

Brand new my 660 had a coolant leak and an oil leak, both on the turbo

 

Find where the coolant is going ! If its not leaking out , it's going in. Water on top of the piston is bad news. Water In oil also bad. Glad to hear same positive reviews! Have heard bunch of bad reviews.