When would you worry about miles

[Ricky Beals]

Some of these 90’s model rd688 are showing 200,000 to 300,000 miles on odometer. You would think they have rolled over. At what point is the mileage to great of a risk. Say a 1.2 million mile Mack rd688 that has had motor rebuilt.  At what point does it become cost prohibitive with the transmission and rearends

Edited January 17, 2022 by Ricky Beals

[Joey Mack]

Tough one to answer because of the un-known's..  I guess if the seller would allow you to drain a little gear and tranny oil(before the truck is cranked/moved) into a clean pan through a small kitchen strainer to look for chunk's, and oil condition, you can take it from there. I have seen many of these trucks with over 1 million. it ay be hard to get good maintenance records, because the truck may have been owned by several people.. I hope some more opinion's are posted... jojo

[Onyx610]

To add to Joeys comment on draining some oil, you could also get an oil analysis done on it too. 

[JoeH]

Mileage never really bothers me.  Frame condition does.  I've seen a couple otherwise perfect trucks have horizontal flex cracks from where the dump body rests at the very front.  Rust Jacking is the other big problem. There's always spare engines and transmissions to be had. But you have to have good bones to put it in.

[JoeH]

It's never cost prohibitive due to rears and trans.  You can have a cutoff from a junk yard for 2k with good differentials.  Rebuilt 8LL is 3-5k I think plus install. What you save on truck cost will far outweigh those "incidental" costs you might incur in 5 years.  If you can pick up a mid 90's mechanical e7 then you are into about the best Mack possible.  No aging computer and related wiring harness.  I have a 1995 RD688S with 272k miles and 22,000 hours. In the 7-8k hours we've owned it we had the valve covers off once just to check adjustment.  And replaced the oil pan as the old one had fatigue cracks.  And the truck got a clutch.  Engine brake is a joke but I wouldnt trade the truck for anything.

[JoeH]

Not sure how familiar you are with Mack model numbers, but a 688 is a 350 hp standard fuel setup with about a 400rpm powerband.  A 690 is a 300 hp Maxidyne that makes 90%+ of it's peak torque from about 900-1100 rpms all the way to the governor.  Hence the 690 gets away with a 5 to 7 speed trans.  You simply don't need in between gears because you're engine pulls so far down.  An engine brake is perfect on the 690 for shifting up hills, cuts the shift time down to 1/3. 

[mrsmackpaul]

Back to the question 

 

I dont worry about miles, if your gunna buy second hand its a gamble whether it has 3 miles or 3 million miles

It can go kahput in a heart beat and leave you out of pocket big time

First thing that has to be right with out  a question is the chassis, if it's stuffed its like building a house on crook foundations 

Next for me is cab

Then drive line

The reason I  say this is drive line parts are plentiful were as cab parts run out of stock quick no matter what the brand as they are updated  all the time but drive lines stay fairly similar for mamy years

 

Paul 

Edited January 18, 2022 by mrsmackpaul

[67RModel]

Its one of those universally unanswerable questions. It depends heavily on region, type of truck, future usage of truck, budget, cash flow, and your mechanical skill. For instance I would be more uneasy about a steel body dump truck with 500,000 miles that spend its entire life in Pennsylvania versus a highway road tractor with 500,000 that ran the interstate between Arizona and New Mexico. For me regardless of type of truck I seek out an example that has no rust or corrosion and good sturdy frame rails for the application. After that I look for the powertrain that meets my specifications and then evaluate the mileage after these criteria are met. If a truck has been maintained and cared for higher miles should not necessarily scare you away. There will come a time however, where everything will need worked on or replaced its just a matter of when. Also, with 20+ year old trucks there is no guarantee the ecm mileage is correct either. The ecm could have just as easily been replaced as odometer gauge at this point.....

[tjc transport]

actually, i would be more suspect of a high mile over the road truck than a local run truck.

the local truck is most likely very well maintained by the same mechanic who has it in garage at least once a week.. 

the over the road truck on  the other hand usually gets service when thought of, or when it breaks,  by a truck stop monkey who will most likely never see it again.

[Ricky Beals]

Thanks guys for the response. I initially was going to look at a 2001 rd688. Truck has 1.2 million miles with 30,000 hrs. Motor has been rebuilt in last three years. Guy who is selling it knows it’s two previous owners. Said it was maintenance since new. I think he is dropping money into it and made the decision to sell. This truck is about a three hour drive from me. I then saw the low hour 690s for sale in close proximity. Looking at both today. 
 

i live in a small town and trips to haul are about 50 mile round trip. I also plan on using truck off road to build a pond and build roads on property.

Edited January 19, 2022 by Ricky Beals

[67RModel]

11 minutes ago, Ricky Beals said:

i live in a small town and trips to haul are about 50 mile round trip. I also plan on using truck off road to build a pond and build roads on property.

That is about the exact use case that 690s was specd for....

[JoeH]

I have 2001 in my head as the ideal year for a Mack motor.  Rebuilt engine in the last three years? If the frame is clean I'd take it if the wiring harnesses look clean.  2001 is the first year they moved the engine computer to the left side, away from heat and possible pinch against frame rail.  Emissions BS with the ASET engines started sneaking into the trucks in 2003 and was in all 2004 trucks.

[OldRedMack]

2001 had the cam issues, ours has a cam job done every 3-4 years.  Our 2, 94 rd with mechanical engines have well over a million miles and God only knows how many hours and we have never been into the engines.  Still work every day going on 30 years as dump trucks.