Buying used without Blowby or dyno.

Last fill up with the truck in my avatar (93 CH) got 7.85mpg on 983 mi 113.8gal used

 

#### didn't realize that sorry

 

Wow!!! Good thing you did your homework, and pulled the valve covers. That’s crazy. It’s good to assume everything’s a scam. It’s easy to get that way, when Truck Shopping. I literally had to apologize once, for giving the Salesman such a hard time. He turned out to actually be an honest, decent Guy. Got a great deal. Actually apologized more than once, Lol. I had gotten pretty Cynical, after dealing with so many BS Salesman. Keep looking, good luck.

 

I’ve never heard of rusty cam and rockers. Must have gotten coolant in oil, even if they rebuilt the valve train, where’s the water/coolant coming from? EGR cooler? Or an after cooler? I don’t know anything about Mack’s. But chances are it’s not the first time it’s happened. Someone knows. Maybe @Goodysnap or one of the other real Mechanics on the Repair forum.

 

I would say the rust on components is likely due to condensation. Its not uncommon to see some rust on top end components. The rust is almost never in the path where parts or lubricated by oil or into machined surfaces. Its not a good sign. But if all the critical areas are inspected it might be a non issue.

Overhead cam engines are more prone to this. I am not at familiar with Mack. I wouldnt trust pete for your health check.

Take it to someone that works on the engine everyday.

 

I wonder how a WS would compare to the Mack, Ride, price, and Quality.

 

This! With only 300k on a 2016 I wouldn't be too worried. It sounds like you're doing your due diligence.

Here's what I did on mine. Found a dealer that had a lot of traded in trucks that were the same. Did a little digging and found out they all came from the same small fleet (100 or so trucks IIRC). Once I got serious on a certain truck I called that fleet with the VIN and asked for the maintenance dept. They were big enough to have an office guy who handled all that. He was super cool and gave me the entire history of my truck. I found out some things I never would've learned from the dealer.

When I'm ready for another truck I'll likely go back to the same dealer for a trade in from the same fleet.