Restoration of 1953 Mack 85LS

[Mack85LS]

Good morning!

I've recently acquired an antique Mack truck—a 1953 Mack 85LS (as shown below).

Since it’s an old truck that sat idle for quite a long time, it’s not in its glorious state. However, I’m confident that with my skills, I’ll be able to restore it to its former glory.

I would love to give it a fresh paint job and a new lease on life so that it turns heads and makes people want to take a ride. However, I’m not very familiar with antique trucks, and since I live outside the United States, I don’t know much about the original equipment used for this model.

I’ve already started disassembling my "patient" part by part, carefully documenting each component’s purpose and where it belongs. However, I’ve come across two parts that I absolutely cannot identify, and I need help figuring out what they are or where I should look for guidance.

For starters, this is how future beauty looks right now:

I know it ain't much, but it’s honest work! So far, I’ve identified all the parts except these two, and I’ve also determined that the engine is a Thermodyne 707A gas motor. Interestingly, despite only 8,000 miles driven, the oil looks like someone just filled it with fresh oil.

Now, after this long introduction, here’s the first part I can’t identify. It’s located on the right side of the engine, as shown below:

Hold on I will give you a better view:

I really don’t want to damage this part since it still has its original seals, and I’m worried it might be something important. Unfortunately, I haven’t been able to figure out what it is or what it does, which is why I’m seeking help or guidance.

The second part I’m clueless about is located behind the water pump system, near the left rear tire:

And the only thing visible is this number:

 

So far, I’m relieved that these parts are the only things stopping me from making further progress on the restoration. I am able to provide an additional information about this truck if it's needed for you to help me.

If you’re still reading this and I haven’t bored you to death, thank you! I’d be incredibly grateful for any help you can provide with these issues. If you don’t recognize these parts either, any guidance—such as where to look for information, any available manuals for the engine or truck, or recommendations for who to contact—would mean a lot to me. It would help me bring this truck back to life and make it the only fully restored and working model of its kind in the country where I live.

Thank you in advance, and I wish you a wonderful day!
(P.S. If anyone is interested, I’ll keep you updated on the progress)

[mowerman]

i think second photo is a water pump believe first photo is just was is says RPM governor could be wrong,,,im sure other guys will chime in and by all means,,keep the photos coming,,,,were all interested thanks bob

[70mackMB]

Mack85LS, Welcome to BMT    You sure know how to do a first post. l'm sure someone will jump in and answer your questions. Contact the Mack Museum with the info of your truck and a donation. They will send you back a wealth of information about it.

  https://www.macktruckshistoricalmuseum.org/historical-research     .....Hippy

 

[cruiseliner64]

Welcome to the group.Yes please do keep us informed about the progress of your Mack.I cant help identify the parts but Im sure there are some here who will be able to help you.the first part looks like an engine governer to limit RPM.but not 100% sure.the second looks to be a brake servo of some type.Anyway the guys here will sort it im sure.I see your in Poland,im in Ireland.There us a guy in Holland who got me parts for our Mack.Best of luck with it..

Paul

[Mark T]

Welcome. I'm guessing CL64 is correct about the governer. The other part ?? looks to be an accumulator of some type. Fire trucks tend to be a different animal than the typical on highway truck. There are several fire truck (Mack fire truck) enthusiasts on this site that I'm certain will be interested in this thread when they see it. I'm confident they'll also have much better input than our guesses so far too.  I would hope you do continue to post progress, we all love stuff like that. 

[steve s.]

Welcome! You have come to the right place for help. The first part in question is obviously a Pierce Governor, its purpose is to limit the maximum speed of the engine. The second part is a hydraulic brake booster, essentially a power assist.  A was mentioned, the Mack Trucks Historical Museum can provide you with all types of information pertaining to your truck, by all means contact them. Do I guess right that you are in Poland? Can you tell us how this old Mack found its way to you? What part of the country are you in?

[tjc transport]

21 minutes ago, steve s. said:

Welcome! You have come to the right place for help. The first part in question is obviously a Pierce Governor, its purpose is to limit the maximum speed of the engine. The second part is a hydraulic brake booster, essentially a power assist.  A was mentioned, the Mack Trucks Historical Museum can provide you with all types of information pertaining to your truck, by all means contact them. Do I guess right that you are in Poland? Can you tell us how this old Mack found its way to you? What part of the country are you in?

i agree with Steve. 

first part is the engine RPM regulator or governor.

second part is a hydraulic power brake booster.

[Geoff Weeks]

The "can" thing on the frame rail is a Bendix Hydrovac brake booster.  It has a little air cleaner (small vertical can) and a large vacuum line to the engine intake. There needs to be a check valve between the engine and the hydrovac, so no pressure from a back-fire in the engine.

 The Hydrovac are very reliable and it wouldn't surprise me in the least that is works just fine. I have 3 of them and haven't had to go inside on any of them.

[Brocky]

  You have a neat project!!! Welcome to BMT!!! Some of your questions have already been answered. Look for a hand operated valve on or under the edge of the dash which will lock the hydraulic brakes in applied position. Our 1947 GMC fire tanker had one.. When Vald from Moscow Russia checks in he can probably help you with European parts sourcing as he knows a Mack group in the Netherlands. Please keep the pictures and progress updates coming.

[yarnall]

What is the serial number on your truck. It has the old style fenders which make it pre 1950.  I have serial number 1101 which is a 1947.  Your is likely from the war years with the painted radiator shell.  Steve S gave you the answer you need.  Hopefully you documented the disassembly so you can put it back together. I would never have the guts to take a truck that far part.  Good luck with it. Mike 

[Joseph Cummings]

Yeah it's the Governor. Factory setting for truck engines was 2250RPM. Fire apparatus might have been higher. I had one in a late 40's LF wrecker, and I turned it up a bit. I got clocked doing a bit over 80 on I 95 towing an R model tandem tractor backwards one night. I got the speed up on the downhill heading to the Scudder Falls bridge, and it held it all the way to Woodhaven Rd where I got stopped. Oh how I miss the 1980's

[mowerman]

lol ya for one thing we were all a lot younger

[cruiseliner64]

14 hours ago, Joseph Cummings said:

Yeah it's the Governor. Factory setting for truck engines was 2250RPM. Fire apparatus might have been higher. I had one in a late 40's LF wrecker, and I turned it up a bit. I got clocked doing a bit over 80 on I 95 towing an R model tandem tractor backwards one night. I got the speed up on the downhill heading to the Scudder Falls bridge, and it held it all the way to Woodhaven Rd where I got stopped. Oh how I miss the 1980's

Oh how I miss the 80s too.Best trucks, plain good food ,great chics and cold beer was cheap!!!!!

Paul

[cruiseliner64]

Oh and the music was top notch too.. 

Paul

[Mack85LS]

It’s been a while since my last update, so I want to start by thanking everyone who took the time to share their thoughts and advice regarding my issues. I hope this discussion has been engaging for you and I wish to repay you (sooner than later) with final presentation of restoration.

Special thanks to brighter minds than me (@mowerman ; @70mackMB; @cruiseliner64; @steve s.; @tjc transport and @Joseph Cummings) for pointing out the 1st part which is RPM governor. Huge thanks for that!

Now, onto the second part, which turned out to be far trickier than I anticipated. I spent two hours searching for a component that looked like an air compressor for the brakes, only to discover(after 2 mental breakdowns and three coffee brakes) that there is none… Turns out, the brakes are vacuum-operated. I believe that’s the case here (correct me if I’m wrong), and I came across a related post that supported this conclusion. For my defence, the part in the photo (highlighted in blue) appears to be a vacuum cylinder connected to the rear tires.

For this revelation, I owe thanks to @Geoff Weeks, you nailed it. I hope this post will save someone in the future from the same two-hour rabbit hole I went down. Once again, I appreciate everyone’s help and can’t wait to share with you future progress!

(P.S since I want everyone to be listened so:

@steve s. This old baby came to us From Germany( probably someone bought it earlier and left it to rot in peace… that’s a no-no) and I’m located right in the middle of the Poland;

@yarnall well this Mack was listed to be built in 1953 but you might be right… the chassis number is 1057)

[yarnall]

With a serial number of 1057 it definitely is not a 1953.  Someone on here might have the serial number list and be able to tell you the delivery date and original fire company. 
The thing circled in blue is the master cylinder for the brakes. It will likely need to be rebuilt or replaced.  As will the wheel cylinders- 1 on each front wheel and two on the back. The brake fluid destroys them. By now you have figured out that it has hydraulic brakes. Get the brakes rebuilt and the master cylinder filled and bled before you put the body on.  Otherwise it is a terrible job to do on you back under the truck. 
keep us posted on your progress.  Mike

[Geoff Weeks]

I know the master cyl for my K-7 was still available new from Rock Auto a few years ago. Most of those single line big masters are still available new as they were often used well into the 70's on trucks and long after that on fork trucks.

 You need to be careful though. Most hydrovac's had the RPV in the outlet of the hydrovac and can't have one in the outlet of the master. You can remove them if all you can find is a master with one.

I also got a master rebuild kit at the same time, but haven't used it yet.

 Hyd brake cyl can be sleeved if badly pitted and new are not available. Masters can also but it is a much more difficult process to make the small drilled holes though the reservoir opening, requiring long twist drills that are easy to break. 

[Geoff Weeks]

Try and get a casting number off the master cyl, I used to have a book that would cross casting number and bore size to MC number.  I don't know if I can still find it.

[Geoff Weeks]

Closest thing I can come up with is a Wagner F2981. It would have a casting number of 1099FE and takes a F8450 rebiuld kit.

It has a 1 3/4" bore and not RCV.

 This is going just off pictures, You MUST verify that it is the same bore.

Nothing else I found used the three bolt side mount and didn't have an RCV and was for brake fluid.

https://www.brakeproducts.com/Products/Wagner/

 

Edited December 13 by Geoff Weeks

[Joseph Cummings]

13 hours ago, cruiseliner64 said:

Oh how I miss the 80s too.Best trucks, plain good food ,great chics and cold beer was cheap!!!!!

Paul

This music vid had a U Model flying NEMF colors. Little Miss NEMF, Nancy Shevell is now Mrs Paul McCartney

 

Edited December 13 by Joseph Cummings

[mowerman]

Hey thanks for the round of applause bud … vacuum brakes that’s it  . Haven’t heard that in years actually owned vehicles though the years with them … glad else could help… bob 

[mowerman]

and yes, Paul McCartney‘s wife the company also folded a while back. You’re probably knew that.

[Geoff Weeks]

12 hours ago, Mack85LS said:

 

 

Now, onto the second part, which turned out to be far trickier than I anticipated. I spent two hours searching for a component that looked like an air compressor for the brakes, only to discover(after 2 mental breakdowns and three coffee brakes) that there is none… Turns out, the brakes are vacuum-operated. I believe that’s the case here (correct me if I’m wrong), and I came across a related post that supported this conclusion. For my defence, the part in the photo (highlighted in blue) appears to be a vacuum cylinder connected to the rear tires.

For this revelation, I owe thanks to @Geoff Weeks, you nailed it. I hope this post will save someone in the future from the same two-hour rabbit hole I went down. Once again, I appreciate everyone’s help and can’t wait to share with you future progress!

It wasn't until I re-read what you wrote, that I saw a few misconceptions on your brake system.

 The brakes are hydraulic with vacuum assist (boost). The thing in blue is the master cylinder, just like a car has. It is bigger and only has a single line. Dual masters didn't come out until much later.

The master is connected to the foot pedal by a push rod. It make pressure in the hydraulic line which goes to the wheel cylinders in each brake.

Along the way it passes through the frame mounted "Hydrovac booster". If the engine is off and no vacuum, the pressure passes right through the unit and on to the brakes, un boosted.

 IF the engine is running and there is vacuum in the booster, the control valve closes off vacuum to one side (rear) of the big can and modulates how much atmospheric pressure is allowed to the back side, which moves the piston in the hydraulic portion, boosting the amount of foot pressure from the master. In this way it multiplies the pressure generated by the drivers foot but is always controlled by the drivers foot pressure. 

 So it is not true "vacuum brakes" which work like air brakes in reverse, but vacuum assisted hydraulic.

[Geoff Weeks]

This brings us to the little air cleaner on the hydrovac, it filters all air that gets drawn into the hydrovac to keep from gumming up and damaging the hydrovac, but just as important, any air entering the hydrovac eventually enters the engine as well.

 Repair the air cleaner and hose to prevent damage.

[mowerman]

now that I think it over, I guess we’re still pretty much on vacuum brake boosters, aren’t we?