Brake Problem with Ford Mondeo

JohnnyBananas

Hi All,

I have failed my NCT due to my rear driver side brake not working properly. For some reason, it appears the brake fluid pressure reaching the brake cylinder is considerably lower than that of the other 3 brakes.

It appears something is going wrong between the brake fluid resoviour (underneath the bonnet) and the brake cylinder. I have checked for leaks along the way and have replaced the rear brake pipe regulator valve, but to no avail.

Has anyone any ideas (and suggested solutions) to what may be the problem.

All help will be greatly appreciated. Thanks in advance for all responses.

(1996 Ford Mondeo LX 1597cc Chassis No: GBBFTB40999)

JohnnyBananas

Anyone?

AzureAuto

What s the condition of the brake lines themselves like. A 196 factory spec Mondeo would have had steel lines and the likelihood is that they would be quite corroded by now? Potentially the line to the rear wheel in question could have collapsed internally, restricting the flow of brake fluid?
Alternatively a decent brake fluid change would flush out any air pockets that might be reducing braking pressure in the system, especially if it hasn't been changed within the last decade, as many cars on Irish roads seem not to have. As a rule, brake fluid should be changed every 2 years.
Something to be getting on with anyway...

nct tester

discs or drums brakes?? what were the handbrake readings??

JohnnyBananas

nct tester wrote: »

discs or drums brakes?? what were the handbrake readings??

Brake drums. Forgot to mention the handbrake has an imbalance of 48%. (1.090 kN on Driver Side, 2.110 kN on Passenger side). When I leave the handbrake on for a period of time, the brake inside the rear driver side wheel stiffens and I have to bang it with a hammer to get moving.

Now that I think of it, this imbalance is similar to the brake test for the rear axle (0.940 kN on Driver Side, 2.420 kN on Passenger side). I have already replaced the brake shoes on both sides, which didn’t solve the problem.

Again, all suggestions welcome and thanks in advance.

CJhaughey

Have you checked the handbrake cable is free? If it seizes even slightly it will make the brake lever sit forward reducing the effect of the hydraulic cylinder.
I would order a new cable and fit it.
I think this is likely to be the problem especially if you have to bang the wheel to get it to release.
Cables are only around 20 euro and are easily fitted.

nct tester

are you sure they are adjusted evenly both sides?? what i mean is , after the new shoes were fitted, is there the same resistance both side when you pull the handbrake up 1 or 2 notches? if there is and there is still a high imbalance, i would say you possibly have a problem with both a wheel cylinder and a handbrake cable. i would replace as a pair if thats the route you go down. but start with the cheapest option , adjustment.

AzureAuto

JohnnyBananas wrote: »

Brake drums. Forgot to mention the handbrake has an imbalance of 48%. (1.090 kN on Driver Side, 2.110 kN on.

That information is key to the source of the problem, so there is reduced braking effort on the driver's side. The drum brakes should be adjusted equally, ensuring all parts are moving and sliding freely, i.e. no binding. With the drum off, get an assistant to slowly raise the handbrake and observe the motion of the cable and its lever, if there is little or no movement, then the cable is likely seized and will need replacing. Remember its the imbalance that constitutes the failure, so ensuring both drums are adjusted correctly is crucial to passing the test.

JohnnyBananas

I have adjusted the brakes and now the handbrake is evenly balanced. (1.620 kN on driver side, 1.600 kN on passenger side).

I have again failed the brake test. (1.260 kN on driver side, 2.190 kN on passenger side).

Any suggestions on what else to try before I consider scrapping the vehicle. (I might try changing the brake fluid)

As always, thanks in advance for all assistance.

(Recap, I have changed the brake shoes, the brake cylinder, the rear pipe regulator valve and adjusted the brakes to get rid of the handbrake imbalance)

CJhaughey

JohnnyBananas wrote: »

(Recap, I have changed the brake shoes, the brake cylinder, the rear pipe regulator valve and adjusted the brakes to get rid of the handbrake imbalance)

What is the pipe regulator valve? is the LSPV?
Is the flexible hose working and not collapsed internally, I have seen this and the hose looks fine but the inside has collapsed resulting in poor braking.
Is it bled properly no air in the line? That would also reduce braking effort.

martyc5674

Sounds like you've covered your bases so it's pointing at a collapsed line or crud in a line.
I'm not familiar with mondeo but make sure your auto adjusters are operating properly esp if you still have sticking drums after replacing cable and wheel cylinder???

How's your front left??...
Your master cylinder is split into two... And each side provides braking to a front and back wheel diagonally opposite each other so in the case of master cylinder failure you'll have some kind of proportional braking to hopefully pull you up!!

When bleeding, bleed the wheel furthest from master cylinder first(back left typically) then the front right... Then back left then front right ..
You'd be surprised what flushing out the brake fluid can do for brake performance.
Marty.

Esel

martyc5674 wrote: »

When bleeding, bleed the wheel furthest from master cylinder first(back left typically) then the front right... Then back right then front left ..

FYP - I hope?

martyc5674

Esel wrote: »

FYP - I hope?

Sorry...I blame the mobile phone!!

JohnnyBananas

Thanks for all responses.

I have bled the blake fluid and I have rebooked the test. If anyone has any further recommendations before doing the test I am all ears.

BrensBenz

Pinched / kinked pipework????

JohnnyBananas

CJhaughey wrote: »

Is the flexible hose working and not collapsed internally, I have seen this and the hose looks fine but the inside has collapsed resulting in poor braking.
Is it bled properly no air in the line? That would also reduce braking effort.

I replaced flexible hose.

martyc5674 wrote: »

How's your front left??...

Front brakes read Drivers side 2.850kN, Passenger side 2.890kN.

HellFireClub

JohnnyBananas wrote: »

I have adjusted the brakes and now the handbrake is evenly balanced. (1.620 kN on driver side, 1.600 kN on passenger side).

I have again failed the brake test. (1.260 kN on driver side, 2.190 kN on passenger side).

Any suggestions on what else to try before I consider scrapping the vehicle. (I might try changing the brake fluid)

As always, thanks in advance for all assistance.

(Recap, I have changed the brake shoes, the brake cylinder, the rear pipe regulator valve and adjusted the brakes to get rid of the handbrake imbalance)

Is there any chance that someone jacked up the car from the underside and accidentally pinched the brake pipe that runs down the length of the car while doing so? This would cause a service brake imbalance problem on the rear axle.

dieselbug

Check that you have an equal flow of fluid from both rear cylinders when you are bleeding. Also bleed with the full weight of the car on the rear wheels, axle.

I bleed new wheel cylinders with the drum removed, place a thumb and forefinger on each piston, open the bleeder and squeeze the pistons together forcing the fluid and air out, close bleeder, release pistons and allow to expand under the weight of the internal spring. Repeat until you are satisfied all air is removed, handy, quick and effective.
Also carefully check the drums for wear, have they been skimmed anytime? place a shoe inside the drum and check how the shoe and drum surface mate together. hth

HellFireClub

dieselbug wrote: »

Also carefully check the drums for wear, have they been skimmed anytime? place a shoe inside the drum and check how the shoe and drum surface mate together. hth

The balance on the parking brake being near perfect eliminates any issue with the brake shoe & drum surfaces being a problem, either down to brake shoe lining wear or possibly oil contamination. If there was any issue here with the brake drum working surface or the brake shoe lining material working together, the near identical braking force results for the parking brake on the rear axle wouldn't be there.

OP this is a hydraulic problem. At this stage, I think you'd be better off bringing the car to a mechanic who has a test lane/brake tester, with a list of the work you have done, because it is pointless just trying one adjustment and then going back to probably fail again. You need to have the problem sorted and verified as sorted before you go back for another retest I think...

If this came into my garage when I had a test lane, this is how I'd be dealing with it:

(1) Satisfy myself that the whole system has been properly bled by bleeding it all again.

(2) Checking that the brake hose on the rear axle isn't twisted & therefore causing an obstruction to the flow of oil going through it. You may laugh, but it's easily done & something I've seen before that caused an NCT fail. Also, I'd check that the steel brake pipe that runs down the side of the car hasn't been pinched by a lifting or a jacking operation.

(3) Also, I'd be checking the wheel cylinder you fitted. As a matter of best practice, I'd have replaced both for a start. Also, is there any possibility at all that you were supplied with & then fitted the wrong wheel cylinder, with respect to the old one that came off? Again, you may laugh, but easily done. If the piston diameter was a different (smaller) diameter to the one that came off, you could easily end up in this situation.

(4) I'd check the brake balancing valve you replaced, is there any chance you got the ports mixed up & have it connected up wrong?

If you have cleared all of the hurdles above, can you take a pic of your brake master cylinder and post it up here?