Coca Cola LJ Mack colors

[mowerman]

Glad you’re happy. It looks terrific.

[1961H67]

That looks about the same as what my Dad got for our H Model about 20 years ago, that will look great, I’ll check them out, I also found some at Restoration Specialty, I’ll do some measuring, Thanks again! 

[1961H67]

I have been hooking up all my air lines, most of the copper was good, replaced some with plastic. I put 110 shop air on the system,  I got all the leaks pretty much stopped, remember it’s not been used in 30 years. I have 1 issue,, when I press foot brake or pull hand valve I have a bad leak from the bottom ( exhaust) of  this valve on cross member in front of 5th wheel, my 2 parts LJs doesn't have it . The top line comes from the 2nd air tank ( pressure all the time) the other tees off line from foot valve to brakes ( delivery) . I’m not sure what it’s purpose is especially with constant air pressure hooked up. Any suggestions? 

 

[mowerman]

Shutterstat ????? Just a wild guess that what it looks like  I’m sure it’s not  Bob  

[mowerman]

Lol keep it coming I’m learning as you go along still got all this ahead of me … more snow yard is a sloppy mess  most be moving it in the garage for a while but I did start it Sunday let it run around 25 minutes 

[mowerman]

It actually looks like a distribution valve  for air brake system 

[terry]

Some kind of old style relay valve? Is it plumbed up properly?   terry

[67RModel]

Is there a part number on it. They are usually very faint and this case covered in thick paint. You may have to take it off and remove the paint see if there is a number on it. If there is you can probably figure it out that way. 

From your description it sounds like a relay valve to actuate something else when the brakes are applied. Since its connected to tank air at the top. The signal air from the brake valve probably opens a port inside the valve and allows the tank air (top line) to send air to something else via the port that is plugged (right port). Once the brake application is relapsed the air is exhausted through the bottom. A lot of relay valves are also regulated so the air sent to whatever it is controlling does not get full tank pressure.....just depends on what its controlling. 

[1961H67]

I dug through an old LJT manual this morning,, you’re probably correct, it talks of a relay valve but no picture. I have been the only one working/ using this truck for 45 years, and I never remember taking a line off, ( were the plug is ) the bottom line comes from a check valve that connects to the foot pedal and goes to front brakes , there is a tee off it before it gets to this valve the goes to service side of the tractor protection valve. ( top full air ) Relay valve in that location makes sense,, but it serves no purpose without another line??? I’ll keep looking for a better diagram . Thanks for all the advice! Hopefully someone can rattle my memory. 

[mechohaulic]

sounds like a front axle limiting valve that has been disconnected  possibly yrs back and never noticed. 

[1961H67]

Yea I thought of that also, I traced  the lines from foot pedal up to dash to limiting valve ( dail type) back to that check valve where the tee is to this valve. But you may be on the right track, that valve could have been plugged years ago, and just started leaking when I put air to it for the first time in 30 years. I was surprised that the foot valve and had valve were not leaking. 

[mechohaulic]

off the wall question; that wasn't a tractor  or had trailer lines to rear at some point. I don't see why there would have been a quick release  from dial control  to front tee'd in. quick release ok  not a tee towards rear

[mechohaulic]

the other two parts trucks don't have that valve. do either have a front axle limiting valve=dial or toggle on the dash (in the cab)?

[1961H67]

It was a factory tractor, both parts trucks have that same dial style front brake valve, put the older LJ (48 I think) doesn’t have a tractor protection valve, it has 2 ball valves that the trailer airlines hook to,, the other LJ has the same tractor protection valve,,, I’m going to get under it and make sure that “Relay “ valve isn’t in a different location ,, I’m now guessing maybe someone put the tee in going to tractor protection and plugged that right port ,, ?? Thanks for advice! 

[Mark T]

That couldn't be from sanders or something like that.... could it ?

[1961H67]

I’m not sure, I plugged the bottom line to it and the rear brakes worked normal, no leaks anywhere now, but the front is very slow, all lines under are copper and look original? 

[Mark T]

That little guy there looks like an old shuttle valve (maybe)

[1961H67]

I think you’re correct,, I haven’t had time to play with it today, That truck had about a 7 year period from the time the Welding Company traded it in to Peterbilt ( that’s when my friend bought it) until I started driving it ,and I knew some of the guys that worked for him ,,, So there is no telling what  they may have bypassed if it had a leak, I always remember the brakes weren’t that good,, but all the old H ‘s and B’s weren’t ether. 

[mowerman]

Hell, I forgot all about those front brake reducers I even have one on my DM…. Bob

[mechohaulic]

just not understanding why continual live air for brake system (front) other then going to TTP valve for trailer. as stated, many hands may have been in there. have seen such a cluster recently on a ford tractor /trailer combo. once a road truck; now a farm unit with limited road usage. lights on both units were sooo patched/ spliced. no one knew how to read the sockets for which color went where. there were back feeds, lights going on wrong time etc. goood pair cutting pliers . cut everything out and ran all new.

[mechohaulic]

On 2/8/2023 at 8:47 AM, Mark T said:

That little guy there looks like an old shuttle valve (maybe)

agree on the shuttle valve; but i think that's a different picture/valve then first post ?? like many/most of the topics on here it comes down to :: darn I wish I could be there to see it first-hand. 

[Mark T]

Just a wild guess,  truck didn't have an exhaust brake at some point ?    (I know little about those old ones, except they did exist)

[1961H67]

I did send 2 different pictures, the first is what we think is a relay valve , the second is a shuttle valve, the line goes from the shuttle valve to the bottom of the relay valve, I’m still thinking a line should be on the right bottom of the relay , just trying to find where the other end would have been. I’m thinking that maybe why the front brakes are very slow applying . Both my parts LJs are 48s and this is a 51 , The LT is a 55 . And they’re all different! I’m not sure when exhaust brakes came out, this one never had on according to the build sheet and the older drivers I talked to that drove it.  So if I see a LJ setting at a truck stop I’m crawling under it,,, Yeah that will be the day I’ll play the LOTTERY 

[mechohaulic]

with constant air into relay, bottom line from shuttle; i'm going with idea the plugged line went to a trailer protection valve/line.  you do have a trolley valve in the cab correct?? does it work ; it must go to rear axle since it may have been for a trailer when unit was a tractor.  i would put a gauge on line to front brakes check pressure . possibly the dash control isn't allowing full air to cans. 

[mechohaulic]

front brakes SHOULD NOT be connected to shutttle valve. shuttle valve will have one line from brake peddle valve . one line from cab trolley valve. and third will go to relay valve.  air from peddle/trolley should open  relay allowing constant air from top to feed plugged port.