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 Posted: 05-18-2020 05:27 pm
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kart54
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Haven't been on the forum in several years as the car has been sitting in the garage. Well, with Covid 19 I had time this weekend to get it going. I was actually very happy at the start; new battery, new fuel, and new fuel pump and it fired right up.
Went to move it and the brakes were locked. After pushing it back and forth a few times they let go and it was mobile again. I had left the handbrake up and I suspect the shoes were locked to the drums.
When I pushed on the brake pedal it was solid as a rock. After a few pushes it suddenly let go and went to the floor. I have absolutely no pedal pressure no matter how much I pump it. No leaks from any of the wheel cylinders.
My feeling is that something (probably a seal) let go in the master cylinder.
Before I order a new master cylinder any suggestions on what to check or how to check it.
There is almost another jensen healey on the road again once I get this sorted out.

Kart 54

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 Posted: 05-18-2020 08:17 pm
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discogodfather
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If you can't find a puddle of fluid somewhere then yes, it's most likely the master cylinder. The good news is it isn't hugely expensive.

To check the master make sure there is enough fluid in it and see if you can get a friend to sit in the car and apply a steady pressure while you look through the top (with the cap off). If you see enough fluid in there and the level remains steady but the pedal keeps falling to the floor, there is a busted seal in there.

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 Posted: 05-18-2020 08:51 pm
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kart54
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Thank you. I will give that a try when I get home tonight.

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 Posted: 05-19-2020 05:16 pm
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redracer
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The "cheap" version is the TR6 master cylinder which does not sit at the same cant as on the booster for the TR6. You will need to "CONSTANTLY" monitor the brake fluid as if it is not full, there is likely air getting in the front hole.
I used to get them brass sleeved in California, but they retired and used Apple Hydraulics for the last 3.

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 Posted: 05-19-2020 11:58 pm
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kart54
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well, with the reservoir full I get no movement of the brake fluid and still no puddles under the car. So I am ordering a new master. Been years since I've done that so I will have to look up the bench bleed procedure before I put it on.
I'll report the outcome once it's done.

Kart54

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 Posted: 05-20-2020 01:50 am
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redracer
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forgot nto mention that the fluid could be leaking INTO the brake booster, and may not show for a while.
When you pull the master off, you will see if there is fluid there

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 Posted: 05-20-2020 05:12 pm
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kart54
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I haven't pulled it yet but that is definitely a possibility I will check out.

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 Posted: 05-20-2020 05:22 pm
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pokeyjoe
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And down the rabbit hole you go.

I don't think there is any way to check for fluid in the booster without removing it. When I removed my MC, there was fluid between the MC and the booster (and a lack of paint underneath the area where it dripped). I decided to remove the booster (required pedal box removal). When I pulled the check valve out and rolled the booster around, fluid came out the hole.

Removing the pedal box isn't any fun, but does provide an opportunity to re-seal the pedal box to the firewall and help prohibit water ingress.

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 Posted: 05-21-2020 01:44 am
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kart54
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Yep, on the rabbit hole.
I also own a 77 Alfa Spider that is my regular daily driver. There is no such thing as an easy fix. Last time on that car a failed clutch slave led to a new clutch slave followed by a new clutch master that led to a new brake master that led to a new brake booster. That was all in a span of two weeks. Everything in that car sits side by side and everything failed within that two week period.
Sooooo, down the rabbit hole I go. The only good thing I can say is that last time I did a master on the Jensen it was $140.00 bucks or more. I just ordered the exact same master for $45.67.
Can't wait to get it and drive the Jensen again. It is actually a much better car and much more comfortable than the Alfa

Kart54

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 Posted: 05-21-2020 02:27 am
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discogodfather
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kart54 wrote:
It is actually a much better car and much more comfortable than the Alfa

Kart54


Guys complain about how the British girls are so temperamental, but the Italians are in another league.

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