Engine hours vs Engine miles

I somewhat disagree. Hours are one factor to consider but a dyno is where you get the justification for an overhaul.

Hours don't tell about how the engine was loaded, or the power produced, it tells the running time and that can be loafing around for much of its life or really working hard.

Many times I will look at a truck to purchase or is part of a package, and many times I will see the ecm report with a huge amount of hours on it, then look at if it was overhauled or what work was done. Many times I will see that the ECM hours were never documented at the time of the overhaul to keep the records straight so the numbers are meaningless at that point. I understand for a few trucks, clearing the hours can't be done.

 

I agree a dyno will show more than an hours vs miles comparison but there is only one way to achieve roughly a million miles of hours on a 400k mile truck, idling.

 

If we're talking strictly OTR trucks, then yes. If the truck has PTO's then I'd have to disagree. It takes power to drive PTO's which in turn equals engine load. I spent my early years on hydrovacs. They may have low miles/high hours but those engines were working hard driving the PTO's and vacuum pumps. Plus there are a lot of applications such as off road work where the truck can only get up to 15-30 mph due to road conditions. Its pulling hard all the time, just not covering much ground.

 

Good point, NorthernMechanic, what a truck is used for is VERY important- kind of a far out example-When I drove a bed truck sometimes after a couple of days on a location my miles might be near zero. I sometimes spent as much time backing up as going forward. No wonder my neck was always sore! LOL! I used to jump at the chance to go down the road and make a recovery!

 

I've always wanted to try my hand on winch and bed trucks.

 

While that's true to a point, I have yet to see a PTO that delivered on a road truck more than 75 hp, I have also never seen a Dana 899 or 897 on a road truck except for an Oshkosh out west in a strip mine.

So the idea that these are working hard engines, I tend to say no they are not.

 

I was talking more about gravel hauling, lowbedding, logging, oilfield etc. Heavy loads on dirt roads. Just not possible to get up to highway speeds on dirt roads and hard pulls.

Stationary work with PTO you're going to have the RPM bumped up. No air flow to cool the engine so the fan is going to kick in from time to time. Eats up another 50-70HP. So while they may technically not be getting worked hard, its still working hard enough to keep the heat in the combustion chamber.

 

My average speed is 30mph.
Longest stretch i can drive without shifting is 35 miles.
Then there are the times i have to follow in line(runs up unwanted unavoideble idle time)
I accept that my engine will not last the same like a guy running the open plaines.
With the low mph also comes quite a bit off wear off the gearbox.(a lot off red lights so stopping and accerlating)
Still think a low miles second truck is a good buy?

 

It's pretty good work-I pretty much stick with winch/lowboy and scissor neck anymore, but still jump in a bed truck when we are short-haven't done poles in a while-pretty rusty there. They don't seem to use poles as much as they used to-I guess cranes have gotten mobile enough to get the job done. I always appreciated a good rigger-they can really make you look good on the job. It seems like winch work is picking up again, but I still fill in as a field mechanic to get hours-got to keep myself in beer and potato chips!