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Old 04-03-2019, 08:21 AM   #1
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Motive Bleeder/Coolant

My Motive bleeder arrives today... so I'm watching a vid on bleeding the brakes.

The guy screws the cap onto the reservoir... pumps it to ~25psi... and I start thinking...

Now... say you suspect you've a coolant leak. With the proper adapter... couldn't one screw the cap onto the coolant reservoir... pump it up to whichever pressure... and watch the gauge to see if there's any pressure loss/leak?

Thank you.
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Old 04-03-2019, 08:40 AM   #2
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If the threading is the same, I would imagine so as long as it's clean. But I'm probably wrong, so take that with a grain of salt.
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Old 04-03-2019, 08:52 AM   #3
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Originally Posted by Starter986 View Post
My Motive bleeder arrives today... so I'm watching a vid on bleeding the brakes.

The guy screws the cap onto the reservoir... pumps it to ~25psi... and I start thinking...

Now... say you suspect you've a coolant leak. With the proper adapter... couldn't one screw the cap onto the coolant reservoir... pump it up to whichever pressure... and watch the gauge to see if there's any pressure loss/leak?

Thank you.
First of all, you should NEVER pressurize your braking system to 25 PSIG with the Motive tool, 12-15 PSIG is plenty. The plastic brake reservoir tank and seals were never designed to hold that kind of pressure.

Second, Stant makes an excellent coolant pressure testing system with all of the necessary adaptors to fit just about anything on the street.
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Old 04-03-2019, 09:07 AM   #4
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Originally Posted by JFP in PA View Post
First of all, you should NEVER pressurize your braking system to 25 PSIG with the Motive tool, 12-15 PSIG is plenty. The plastic brake reservoir tank and seals were never designed to hold that kind of pressure.

Second, Stant makes an excellent coolant pressure testing system with all of the necessary adaptors to fit just about anything on the street.
Yeah... I saw the guy pump the tank to 25... and I was thinking, "Haven't seen that number on the forums".

Thanks!
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Old 04-03-2019, 01:09 PM   #5
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Quote:
Originally Posted by JFP in PA View Post
First of all, you should NEVER pressurize your braking system to 25 PSIG with the Motive tool, 12-15 PSIG is plenty. The plastic brake reservoir tank and seals were never designed to hold that kind of pressure.

Second, Stant makes an excellent coolant pressure testing system with all of the necessary adaptors to fit just about anything on the street.
This is one of those tasks that you're better off taking it to an indy shop. They have the proper tools and can put it up on a lift for inspection . The Stant kit is expensive and you won't work off the cost in a home garage. Euro shops will touch this task, other shops won't. They're afraid of elfen magic, I guess.
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Old 04-03-2019, 01:51 PM   #6
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The Stant kit is expensive and you won't work off the cost in a home garage.
It is less than $70 on Amazon, and often shows up for less than that on sale, and it works on any liquid cooled system. I really don't see that as expensive.
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Old 04-03-2019, 08:18 PM   #7
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Porsche shop manual on page 47-7 says bleed brakes at 1.5 bar or about 22 PSI.
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Old 04-03-2019, 10:44 PM   #8
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In general i'm using around 1 to 1,5 bar in older cars. The plastic reservoirs can brake or start to leak if you use too much pressure.
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Old 04-04-2019, 02:22 AM   #9
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Porsche shop manual on page 47-7 says bleed brakes at 1.5 bar or about 22 PSI.
Which is too high and will cause the reservoir seals to fail. We have had more than one car in the shop for exactly this reason.
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Old 04-04-2019, 07:01 AM   #10
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Someone should tell Pelican to revise their tech article if 25 psi is too high.

This is right out of the article and 101 Projects book.

https://www.pelicanparts.com/techarticles/Boxster_Tech/48-BRAKES-Bleeding_Brakes/48-BRAKES-Bleeding_Brakes.htm

"The procedure is to add fluid, attach the bleeder to the top of the reservoir cap, and pump up the bleeder bottle to about 25 psi using the hand pump."

I did a bleed last summer using the Motive bleeder exactly as the tech article calls for and did not have an issue. I know I am only one guy and maybe got lucky but I'd hate to see anyone else have issue simply because they followed some flawed instructions.
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Old 04-04-2019, 07:20 AM   #11
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my new master cylinder seals started leaking at about 20psi, and there is no reason to even get that high. 15 psi is all you need.
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Old 04-04-2019, 09:16 AM   #12
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Thanks Guys,

Good advice, I'll dial it down for now on....

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Last edited by Paul; 04-04-2019 at 09:21 AM.
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