The Stovebolt Site Forums The Parking Lot Big Bolts hydrovac help needed

I put a rebuilt hydrovac on my 55 (6400). I read
in the technical manual "Fill vacuum power cylinder with Bendix Vacuum Cylinder Oil to the level of the lubrication plug." Well I went to the part store and ask for some of the oil and they never head of it and said to use hydraulic oil. I got a gallon and proceeded to fill her up.
Of course it ran out the vacuum line hole pretty quickly! Where exactly is the level of the lubrication plug and is hydraulic oil the correct
thing to use?

Hy hope4u, the old hydrovac has a felt backing up the seal proper, I was told that the lube served two purposes, one to keep the inner surface from rusting, the other to keep a line of lube at the edge of the seal. As you probably realize standard lubricants do not perform well in a vacuum, that is why the vacuum cylinder oil was developed. I would not use hydraulic oil myself, I know that others on this forum have tried to find the correct lube with little success, I would suggest using an oil recommended for a vacuum pump, the type of pump that diesel powered vehicles use to generate vacuum for their power brake boosters. As you known " brake fluid " is not an oil at all, and any " oils " that enter the brake system cause no end of problems, hope that helps

If memory serves me right you only need to add an ounce or two. I've heard of guys using sewing machine oil, but I don't know if there are any side effects from using it.

Mike B

How about oil for a air conditioning compressor? R 12 systems use a mineral oil, and newer R 134 A systems use a pag oil. one of these may close to the right oil. I would imagine that the mineral oil used in the R12 auto ac sysetm would be close to what they had back then. can be bought at any auto parts store in sm bottle. I'm pretty shure that's what we used in the old vacume pumps.

I think hydraulic oil will be too thick.

I'm gonna look up the original recomended oil & see what I can dig up, but I had thought about using Marvel Mystery Oil.
I found a reference on the Auto Boardz site that mentioned something called Neats Foot Oil for leather products,... Odd, but ya never know.

But seeing as these items are still being made & installed in things like forklifts, you might contact the Bendix Tech Support Team at TBS.TechTeam@bendix.com. I doubt they are still using leather for the seals, but ya never know what they have in thier books.

I used 3-in-1 oil . Might not be right but seems pretty safe. Just my 2 cents...

I would think if they are not using leather seals as Freq2002 mentioned then any air tool oil otta be good.
If seals are leather then maybe the neats foot oil. However I would check and make sure that it doesn’t have any corrosive effects on the metal. I think neats foot oil is a little acidic.

I just sent an email to ABS Power Brake. I wanted to know the answer to this myself. I know they rebuild these units there. I'll let you know how they answer.

http://www.abspowerbrake.com/contact.html

Is this similar to your unit????
http://picasaweb.google.com/orchidskip/HYDROVAC?authkey=57r0_h37YH0

Yes, that looks a lot like the one I have.

They haven't answered back yet. Some time back, I was there asking about brakes when I saw a Hydrovac unit sitting on the shelf that had been rebuilt. So I know they are familiar with those things. If they don't email back I will call them or go by there and ask in person- let you know.

okay, He finally answered back. Here's what he said:
"It's a special assembly oil. It's $25.00 a bottle. Call Doug at (714) 775-6549."

That is ABS Brake. Just to set the record straight, I have no connection to them other than having gone there and discussed brakes for my truck. I will be going there next week on my lunch break to pick up some of that stuff myself. Good luck with your projects!!!!

I went with a lil 2oz. bottle of Marvel Mystery Oil for air tools. Half of it filled the housing to specified point. Guess I'll see how well it works out, if I ever get this engine back together that is. :p

I got my master cylinder and hydro-booster from ABS I like those guys. I let them know what I had and what I wanted from it and they where the only ones who would work with a two ton. You know there is a lot of aftermarket for the little ones but not much for the Big Bolts.

First of all, thanks for asking this question to Hope4U. Okay. I went over to ABS Brake today at lunch and talked to Doug. He said to just use mineral oil. (I won't tell you what I put in mine because I was so far off, it's embarrassing.) So, all you guys who made that suggestion were right. He said they use an assemble oil but that it's a non petroleum mineral oil and to just use that. To his credit, he could have sold me an expensive bottle of assembly oil. BTW, there was another Hydrovac unit like mine sitting on the cart of rebuilt brake masters so I can assure you, they know that unit.

Someone pointed out to me that non-petroleum mineral oil is like dehydrated water. I looked up mineral oil to find that it IS petroleum based. Duh! So I looked up neatsfoot oil. Turns out that the stuff is rendered from steer shins and has some special qualities that make it a uniquely good oil for leather. Other rendered animal oils are used for cutting oils and certain types of bearing grease because of their affinity for metal. Apparently, whale oil had previously been a high quality oil used for the manufacture of such products but has now been replaced by these cow products. Just though I'd try to redeem myself a little here...