Mikesbucketlistmack

What is anyone's opinion of using Mobil 15W-40 synthetic blend oil in my 1980 R611ST ? Or should I just stick to conventional diesel oil like Shell Rotella T-4 ? The truck is rarely driven and only taken out a few times a year and stored during the winter.

I'm contemplating changing the coolant conditioner on my 1981 R612. I've had the truck over 10 years and barely drive it 50 miles per year. It has only 65,000 miles on it. Do you think the coolant conditioner should be changed and if I take it off while the truck is off will I get a bath of antifreeze ? Thanks !

Terry, I can't see a picture of the mirrors, but are you talking about the ones with the half bulldogs on them in the front ?

I think we ALL got it. Did she ask you how's your Peter-bilt ?

Try Utica Mack in Utica , NY. I've never had a problem with them.

Okay, Jim. I'll try all those. I couldn't find any other fuses so hopefully that won't be an issue though it would be an easy fix. Thanks, Mike

The switch I took out was "short", and I replaced it with one the exactly same size.

Hi Gents ! I got a 1981 single axle R 600 dump with back up light/alarm issues that is causing me to pull my hair out (the little I got left 😲) trying to get them to work. They worked fine since I've owned the truck the past several years. About a month ago they stopped working. I found that the ground wire at the rear of the truck had come loose. I reconnected it and the worked again. The next time I took the truck out they stopped working again. I rechecked the ground wire and it was fine. I pulled the fuse in the glove compartment and tested it with a continuity tester and it was good. I then checked the back up switch on top of the transmission. The terminals were all corroded so I replaced it with a brand new one. I tried the lights /alarm again and they worked for a second and then stopped. I checked all the wiring at the rear of the truck and at the 3rd terminal under the driver's side of the hood and all connections are firm and good. Does anyone have any ideas or am I missing another fuse or something else ? Any help would be appreciated because I can't get it inspected without the lights and alarm working. Thanks !

Okay, thanks. That's what i was thinking, too. I'm going to try that and let you know.

What exactly am I looking for with the ohmmeter and to which terminals do I attach the leads ?

Check any big city's Post Office Vehicle Maintenance facility near you. They will direct you to where they do sell the used ones off at times. I used to drive for them in the 90s. I had a brand new single axle MR, automatic. They special ordered them WITHOUT air conditioning or radios. They were pretty good with a trailer on but don't ever bob tail one in the rain. They were also terrible on snow and ice. I don't know if there are any more Mack MRs out there. I think that they have gone to all conventionals now or are just renting tractors from Ryder.

Thanks, Ron. I finally got some time and disovered that a strange looking unlabeled button on the dash works the city horn. Someone must have reconnected it when the steering wheel button failed a long time ago.