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Matt
Matt, Engineer
Category: Car
Satisfied Customers: 16601
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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Wolseley 24/80 mk 2: I have trouble getting a pedal with the

Customer Question

I have trouble getting a pedal with the engine off but as soon as the engine is running my pedal comes right to the top and is rock hard even keeping the brakes engaged. The moment I switch off the engine the pedal can go down again. I have a new master cylinder and a recon brake booster. The car is a Wolseley 24/80 mk 2.
What can be my problem? There is no air in the system.
Paul
Submitted: 1 year ago.
Category: Car
Expert:  Matt replied 1 year ago.
Hello

its possible that the preload onto the master cylinder is set incorrectly

if you remove the master cylinder, and push the brake pedal down you should see that the pushrod has a little threaded adjuster on its end

try screwing this in a couple of turns and see if the situation improves
Customer: replied 1 year ago.

Mat,


the pushrod does not screw in and out .


It has a half ball on the end that is loose from the master cylinder piston.


Just pushes on the piston when applying the brakes.

Customer: replied 1 year ago.
Relist: Inaccurate answer.
still waiting for a reply to my reply
Customer: replied 1 year ago.

I feel the problem must be with the booster as without the engine running the brake pedal behaves normal, except for the initial low pedal.


The booster seems to put the whole system under pressure.


Why?


 


Paul

Expert:  Matt replied 1 year ago.
Hello Paul


OK if there's no adjustment on the pushrod do you have the old master cylinder and booster to compare the installed height of the pushrod between the new and the old?

as this really does sound like the booster is being actuated when it shouldn't be
Customer: replied 1 year ago.

My old master cylinder is identical to the new one fitted now. The booster


has been fully reconditioned. Bear in mind that the booster and master cylinder are not one unit. The booster sits on the opposite side of the engine and has got its own (sort off) master cylinder that feeds the brakes.


It is fed by the master cylinder that is operated by the brake pedal.


Paul

Expert:  Matt replied 1 year ago.
Hello Paul

thanks for the extra information

OK if its a remote servo then what controls the point of actuation is the spring on the air control valve on the side of the booster

see this document

http://gentry.zxq.net/Remote_Servo_Installation.pdf

if you look at fig 1 its the strength of the compression spring that is adjusted to provide different actuation points

so if you strip the valve down to reveal the spring I'd suggest fitting a spacer in line with it to increase the spring load and so move the actuation point
Matt, Engineer
Category: Car
Satisfied Customers: 16601
Experience: Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
Matt and 20 other Car Specialists are ready to help you
Customer: replied 1 year ago.

Matt, it has been some time. The problem with my booster was a cracked


rubber elbow between the air valve underneath the booster and the pipe that runs to the back of the booster. This was letting air in and activating the boosters slave cylinder.Simple and now fixed.


Do I have another free question?


Paul Ruys

Expert:  Matt replied 1 year ago.
Ask away Paul and I'll do my best to help
Customer: replied 1 year ago.

Hi Matt,


My Wolseley has a fully recon engine. rebore etc.


It runs fine but blows a lot of blue smoke after it has driven slowly or has been idling for a while.I though it was valve stems but these are also new,


guides and seats.


Any idea?


Paul

Expert:  Matt replied 1 year ago.
Hello Paul

how has the engine been run-in after its rebuild?

has its done over a 1000 miles yet? and what oil are you using
Customer: replied 1 year ago.

It has only done a couple of hundred miles.I am using Penrite HPR 30,


20 w 60, a mineral oil with zinc. I did not think that you had to specificaly run it in nowadays. One difference with the original pistons is that the new ones only have one oil ring (cast iron) as the old ones have another oil ring at the base of the pistons.I have never had this trouble with other early type engines that the same people reconditioned for me.


( MG TD, Jaguar MK 5, Alfa guilia 105,Hillman Minx)


Paul

Expert:  Matt replied 1 year ago.
Hello Paul

OK modern engines are broken in at the factory but when you rebuild any engine it needs running in

the best way of doing this is to adopt a 2/3rds the load and 2/3rds the revs approach and use a cheap mineral oil as high quality oils don't allow much wear so the rings never bed in

after 500 miles start using full load but not full revs and over 1000 miles use fully

So I suspect it will use oil whilst its still bedding in but this should come good over time
Customer: replied 1 year ago.

I thought I could have a few more questions for my initial $35.


Now they want more money when I rate you. Is that correct?


Paul

Expert:  Matt replied 1 year ago.
Hello Paul

as you've already rated me I get paid so don't worry

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