Hello everyone,

I purchased a 2008 KR with a 6.4 with 125k a few days ago. So far I love the truck, but I have a few questions.

1) How long should it take for the heater to blow warm air in the morning? I have the truck plugged in for at least 3 hours before leaving. It's been unusually cold here, -4 this morning, but it took around 15 min to blow WARM air. I fired the truck up, waited about 30 seconds and then rolled out.

2) If I let the truck idle for anymore than 2 minutes (ballpark) it will go from around 800 RPM to 1200RPM. Once I step on the brake, it will drop back down to what seems like normal. Is this normal behavior?

3) I reset the average MPG, and with only around 100 miles driven, the truck is averaging 9.5 MPG. I'm not worried about MPG that much, I didnt buy the truck to get great gas mileage, but damn...

Thanks in advance everyone. I haven't posted in 6 years since my 71 F250 rebuild!

 

The high idle is normal. Diesels lose heat idling, so they high idle to build or maintain heat better.

unfortunately, the 6.4 is notorious for low fuel economy, especially for a diesel. Deleting the emissions equipment will most likely improve fuel consumption, but is also illegal. Some areas do not test emissions on diesels, so you could "get away with it" if you live in such an area. Deletes will also help the longevity of the engine.

Diesels can also take a while to warm up. They have huge cooling systems and generate less heat when unloaded, compared to gassers.

 

sometimes the mileage counter is not very accurate. if you want to get the mileage accurate you have to do math on how much you are actually using. also there are tunes that can help with gas mileage. I suggest looking into it. Gearboxz has the plus tune which is designed around towing and fuel efficiency. also it is a very good priced.

 

I was getting sub 10 mpg high way on my 2010 6.4 with 87K miles.

I had 4 rocker tips worn to the bone, 14 slightly bent push rods, the rest of the rocker tips were worn, but not to the bone.


I replaced all the rockers, push rods, and saddles. my mpg high way is at 22 mpg, according to the lie o meter.

cost in parts was 800 bucks. lots of labor....almost 2 months working a few hours on the weekend.

 

A diesel needs at least 5-10 min warmup before moving, especially in those temps. My 2 cents.

 

Look on the manufacturers door plate, axle code will provide hint to rear end gearing. My F450 has 4:30 gearing and pulls 13mpg calculated by hand with DPF in place.

 

1. Allright fellas, fair question. He lives in Texas. He had -4 degrees. The correct political answer would be from us living in the Nothern portion of the world...........til hell really freezes over to warm up.

They don't warm up.

2. Your touch of the pedal anywhere will drop it back into driveability mode and disable the high idle. Totally Normal.

3. Nationally they produce diesel with a different blend for winter. You will loose mpg's due to this mix. Anyone who tells you that this is just in the North is bonkers. They have a decided switch date and that's to accommodate OTR commerce. (semi drivers). (everywhere).

3a. I've had a few and not sure if anything I said is correct. (Pretty sure tho)

Salute,

Denny