IH 7020 air break issue

I picked up a 74’ IH 2070 Fleetstar grain truck. Great runner. Working on the stoping part. I’m new to air brakes but not troubleshooting. So I’m starting at the beginning. It has 60 psi at an idle but comes up to just over 100 at road speed. So I’m now looking for the compressor. And to my surprise it’s not belt driven off the engine.
It has an Eaton 5/10 trans with a splitter behind it and a twin screw. Which I haven’t been able to figure out how to lock in. (The dash isn’t exactly labeled anymore lol) but I’m having a hard time tracing air lines other that to somewhere under the left side of the cab. I want to check pressure at the compressor.
There seems to be a large unit comming off the engine on the left side but with the huge frame rail can’t tell what’s going on there. Any help fellas ?? I would think it would have larger lines going into the cab but haven’t found them yet.
Thanks Dave D-C Acres

Usually when the air is like that you have a leak and you may be surprised how small seeming of a leak can do that so start by listening for leaks with the engine off I like to have an air hose plumbed in to the tank so you can air it up that way to check for leaks and stuff

Does it have a detroit motor?

What engine? Detroits were belt drive off the back end mostly....

Jonas302 said:

Usually when the air is like that you have a leak and you may be surprised how small seeming of a leak can do that so start by listening for leaks with the engine off I like to have an air hose plumbed in to the tank so you can air it up that way to check for leaks and stuff

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Thanks. Jonas302. It has a quick coupler on a tank under the battery’s but it’s heavily corroded so I’ll have to replace that first. I was thinking the brake air tanks are the ones on each side between the cab and fuel tanks. But I will investigate that when the weather breaks. I figured that coupler was to charge the break system.

lantraxco said:

What engine? Detroits were belt drive off the back end mostly....

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Yes it has a Detroit 6-71. The only belts on the front of the engine drive the fan and alternator.

I’m not sure if this will make any difference. But it must of started life as a semi tractor. As it has the air and elect connections on the back of the cab but the air is pipe plugged off, and elect wires are cut on the inside.
Thanks for your help guys.

Bendix has some great videos on air brake systems;

https://www.heavyequipmentforums.co...tems-and-diagnostics.85958/page-5#post-930346

Excellent. I’ll check it out. Thanks. Dave

I have a 1970 Fleetstar 2000 with a 6-71 detroit in it. FWIW I'm 90% sure the alternator on mine is belt driven on the back side on the drivers side. I will go and take a few pics of mine and report back. Your is a few years newer but its possible it has alot of similarities to mine.

bam1968 said:

I have a 1970 Fleetstar 2000 with a 6-71 detroit in it. FWIW I'm 90% sure the alternator on mine is belt driven on the back side on the drivers side. I will go and take a few pics of mine and report back. Your is a few years newer but its possible it has alot of similarities to mine.

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Ok thank you. I appreciate that. There arnt too many of these left. Lol.

I found a You Tube channel called “Smart Drive Test” it’s an instructor who explains things about semi’s very well.

Oh boy.