Scorer128 Posted July 17, 2019 Share Posted July 17, 2019 I am working through a nightmare I’m hoping someone here can help. I inherited my Daddy’s 1980 U model. I believe it was once a single bogie tractor converted to a six wheel dump. It has spent its last thirty years as a home for wayward rodents and waiting for its next job. Well I plan to use her to pull an equipment trailer and do small hauls but ..... the exhaust was hacked (my guess for parts) and melted the ground cable, airlines and frame wires causing a short that melted the wires and air lines in the dash. I think it sounds worse than it really is but I don’t remember the original layout of the exhaust. Or the size because there’s currently 4 5 and 6 inch pipe on it The r model wiring schematic I found for the most part helps me just that I can’t see any of the colors so I plan on re-wiring new harness. If anyone can give me the airline lay out, the exhaust layout and any help with familiarizing myself with a 1980 U model, it would be greatly appreciated. I plan on using this girl for many years to come in honor of my dad. I don’t plan on doing a complete re-store but would like to get close to original. Thank you advance for your help happy Trucking!! Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/ Share on other sites More sharing options...
HarryS Posted July 17, 2019 Share Posted July 17, 2019 Hats off to you on a worthy project. Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428146 Share on other sites More sharing options...
Scorer128 Posted July 17, 2019 Author Share Posted July 17, 2019 Thank you. Encouragement is probably the most of what I need. 😃 Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428150 Share on other sites More sharing options...
j hancock Posted July 17, 2019 Share Posted July 17, 2019 Here is a scan for the brake system. Shows where things go but routing them away from heat will be up to you! Grand Rock has exhaust for a Mack DM which as close as they get to a U model. Check page 166. I would get OEM from the turbo down for sure and then make what might be needed whether you have heat to your dump box or not. http://grpipes.com/sites/default/files/catalogs/files/GrandRock2018v2i2.pdf 1 Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428151 Share on other sites More sharing options...
Scorer128 Posted July 17, 2019 Author Share Posted July 17, 2019 Thank you very much. Every bit of info helps. As you’ve stated deflecting exhaust heat is a concern. Any suggestions that will try to keep heat from the goings on in the frame rails? Or do you think that wasn’t necessarily a u model issue -but the lack of proper exhaust piping -which allowed the heat direct access ?? Knowing that will help decide how to proceed in that area Thank you again for your help !! Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428152 Share on other sites More sharing options...
JoeH Posted July 17, 2019 Share Posted July 17, 2019 (edited) Not sure how/why your wiring got cooked by the exhaust. Exhaust should be 4 inch diameter from turbo to exhaust tip. Exhaust elbows down off the turbo, goes between flywheel housing and the frame; should be a clamp that bolts the exhaust to a machined hole on the flywheel housing; exhaust then goes along underneath the frame, til it hooks up to a goofy looking muffler behind the passenger fuel tank, muffler outlet is 4" diameter straight out the top. Any air lines/wires in the frame rails should have been clamped to the inside of the frame, with the exception of a copper tube that comes off the air compressor and is clamped to the transmission before it changes over to a braided stainless steel hose going to the wet tank. Edited July 17, 2019 by JoeH Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428173 Share on other sites More sharing options...
JoeH Posted July 17, 2019 Share Posted July 17, 2019 (edited) You will want to use flexible exhaust tubing to run for a couple feet along the underside of the frame. This allows the system to flex as the engine torques and the truck frame twists going down the road. Pictures please!! We love to help but we love looking at trucks too!! 😎 Here's my dad's U model he used to plow with, we're getting it running for yard work. It's a little older than yours, used to be a single axle tractor too! Edited July 17, 2019 by JoeH Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428174 Share on other sites More sharing options...
Scorer128 Posted July 18, 2019 Author Share Posted July 18, 2019 (edited) the Pipe was blowing exhaust directly into frame rail. I have a couple pics I’m trying to get uploaded. Please bare with me Edited July 19, 2019 by Scorer128 Image too large 1 Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428223 Share on other sites More sharing options...
JoeH Posted July 18, 2019 Share Posted July 18, 2019 You usually have to go into edit mode and change the aspect ratio to dumb the picture file size down. That's the only way I can post. Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428245 Share on other sites More sharing options...
Scorer128 Posted July 19, 2019 Author Share Posted July 19, 2019 Y Quote Link to comment https://www.bigmacktrucks.com/topic/58170-1980-u-model/#findComment-428258 Share on other sites More sharing options...
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