# Bench bleeding of cylinders **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [February 4, 2014, 11:11pm UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541 "2014-02-04T23:11:05Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![JuniorMint](https://avatars.discourse-cdn.com/v4/letter/j/5fc32e/32.png) [@JuniorMint](https://community.cartalk.com/u/JuniorMint)\ **Post date:** [February 4, 2014, 11:11pm UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/1 "2014-02-04T23:11:05Z")
I need to know what to expect when bench bleeding clutch or brake cylinders. Obviously this could take a lot of space, but hopefully I can narrow it down: some details: The car is an '87 Porsche 944, and I have all new clutch/brake cylinders (FTE brand) to bench bleed. If you know about this car, then it had an original Girling brake master cylinder with Girling booster. I read the NAPA instruction sheet (see below), Haynes, as well as many other things. I can see how the cylinder should be held in a vise and positioned to let bubbles rise to the top and out the holes, but I am particularly wondering about what happens when the rod starts to be pushed. I have read that the rod should not be pushed in all the way. I also imagine (from testing my old one) that the fluid gets pushed out - with a lot of force - every hole on the cylinder. I see that NAPA makes some fittings and such to help bench bleeding, and it appears that there should be some sort of flow-through collection bin to catch this fluid. I guess when fluid flows without bubbles, the unit is transferred to the vehicle in a condition that prevents air from getting back in - or perhaps it is more forgiving? link to NAPA instructions: [http://s7d9.scene7.com/is/content/GenuinePartsCompany/1229488pdf?$PDF$](http://s7d9.scene7.com/is/content/GenuinePartsCompany/1229488pdf?%24PDF%24) NAPA tool: [http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Brake-Bleeder-Kit-Master-Cylinder-Only-For-Bench-Bleeding-Master-Cylinders-Before-Installing-On-Vehicle/\_/R-NDP7001795\_0375747757](http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Brake-Bleeder-Kit-Master-Cylinder-Only-For-Bench-Bleeding-Master-Cylinders-Before-Installing-On-Vehicle/_/R-NDP7001795_0375747757) ---
**Author:** ![knfenimore](https://avatars.discourse-cdn.com/v4/letter/k/9fc348/32.png) [@knfenimore](https://community.cartalk.com/u/knfenimore)\ **Post date:** [February 4, 2014, 11:23pm UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/2 "2014-02-04T23:23:10Z")
I bought a master cylinder bleed kit. It screws into the MC holes where the brake lines go and 2 rubber hoses feed the fluid back up into the reservoir. I just pushed on the cylinder rod and let off and pushed again until no more bubbles were going into the reservoir. ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [February 5, 2014, 1:25am UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/3 "2014-02-05T01:25:29Z")
I want to tell this person to have someone fix the brakes and move on to something he can actually do. But that would not be polite. ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [February 5, 2014, 1:36am UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/4 "2014-02-05T01:36:58Z")
Bench bleeding of the master cylinder only allows you to pump brake fluid in a circulating manner into the MC chambers, pumping the air out, such that when you install the MC its chambers are filled with fluid rather than air and you don’t pump all that air into the lines. If you didn’t bench bleed the MC before installing it you’d be pushing all the air that the chambers are filled with directly into the brake lines, and you’d then have to push it all the way through the lines and out the bleeders. But that does not mean you don’t need to bleed the lines after installing the unit. You will need to. Some air will get into the lines. There’s no way totally avoid it unless you submerge the entire vehicle in a pool full of brake fluid to install the MC. And that isn’t possible. ---
**Author:** ![pleasedodgevan2](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@pleasedodgevan2](https://community.cartalk.com/u/pleasedodgevan2)\ **Post date:** [February 5, 2014, 4:18am UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/5 "2014-02-05T04:18:31Z")
It’s a little sloppy but some people are quick. Don’t get brake fluid on the paint or the paint comes right off. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [February 5, 2014, 5:10am UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/6 "2014-02-05T05:10:35Z")
@JuniorMint I’m going to be blunt You bench bleed the brake master and the clutch master with a kit. This is what I use > **[Super price on Thexton 803X at ToolTopia.com](https://www.tooltopia.com/thexton-803x.aspx?utm_source=googlebase&utm_medium=cse&utm_term=thx803x&utm_campaign=googlebase_18u&gclid=co3mwcfys7wcfcq9qgodosaara)** > > Universal Master Cylinder Bleeder Kit Then you hook up the diaphragm brake bleeder and the proper adapters, and bleed the lines on the vehicle powerprobe has the adapters you need My method is efficient and you don’t need a second person Done No more to be said about this I’m glad we all agree that was easy Next ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [February 5, 2014, 5:30am UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/7 "2014-02-05T05:30:21Z")
I did this on my Ford truck a couples years ago, brake MC. The instructions how to do it came with the new MC. And it came with some special fittings as I recall, just for doing the bench bleeding. I don’t think it took longer than about 5-10 minutes, not a big job. I do think I recall running the expressed fluid right back into the top using some supplied rubber tubing. Did yours come with bench bleeding fittings, tubing, and instructions? A couple of cautions, one is to use a level to make sure the MC is absolutely level before you start. Second is to pay careful attention to where the instructions tell you to place the vice on the MC. Usually you clamp on a flange of some sort, definitely not the MC’s body. If you clamp the MC in the wrong place, e.g. clamping on the cylinder, you can easily damage it beyond repair. Also to avoid damage to the MC, I used a wooden dowel to press with. ---
**Author:** ![JuniorMint](https://avatars.discourse-cdn.com/v4/letter/j/5fc32e/32.png) [@JuniorMint](https://community.cartalk.com/u/JuniorMint)\ **Post date:** [February 17, 2014, 3:12am UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/8 "2014-02-17T03:12:25Z")
I finally got around to getting this kit from NAPA: [http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Brake-Bleeder-Kit-Master-Cylinder-Only-For-Bench-Bleeding-Master-Cylinders-Before-Installing-On-Vehicle/\_/R-NDP7001795\_0375747757](http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Brake-Bleeder-Kit-Master-Cylinder-Only-For-Bench-Bleeding-Master-Cylinders-Before-Installing-On-Vehicle/_/R-NDP7001795_0375747757) each fitting turns out to have different measurements - i.e. only one of them fits any of the same sized holes on this particular cylinder. Unless there’s a place that sells the single fittings, and I assume all those ports need to be connected - that means three of these kits are needed - yes I looked on tooltopia and powerprobe - thanks @db4690 - but no single fittings. ---
**Author:** ![NYBo](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nybo/32/17281_2.png) [@NYBo](https://community.cartalk.com/u/NYBo)\ **Post date:** [February 17, 2014, 5:38am UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/9 "2014-02-17T05:38:49Z")
The clutch M/C is connected to the brake M/C and doesn’t have its own reservoir, which makes it a bit trickier. ---
**Author:** ![meaneyedcatz](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/meaneyedcatz/32/692_2.png) [@meaneyedcatz](https://community.cartalk.com/u/meaneyedcatz)\ **Post date:** [February 17, 2014, 7:52am UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/10 "2014-02-17T07:52:56Z")
Master cylinders normally sit at an angle and if you don’t bench bleed you will not get all the air out. You can use a kit to pump the fluid back into the resv or blow the fluid all over the floor. Creates a huge mess. ---
**Author:** ![JuniorMint](https://avatars.discourse-cdn.com/v4/letter/j/5fc32e/32.png) [@JuniorMint](https://community.cartalk.com/u/JuniorMint)\ **Post date:** [February 17, 2014, 10:26pm UTC](https://community.cartalk.com/t/bench-bleeding-of-cylinders/83541/11 "2014-02-17T22:26:14Z")
I forgot to ask : how should the fittings be removed once the cylinder is installed, so no air gets in? just be careful and re-bleed the system after installation?