Mitsubishi Delica Owners Club UK™

[Andy W]

Hi,
With the van sitting parked up on the flat for a few hours or overnight if you press on the brake pedal it is good and solid; start the engine and drive away slowly, the pedal goes virtually to the floor though there is still braking and it isn't pulling to one side.  Pump the brakes like mad and generally it sorts itself out or driving for ten or fifteen seconds will do it.  After that they are all good and I can drive for hours and they remain good. Next time I start up after leaving it for a few hours they may or may not play up!

It's done this a few times over the years but it's over almost before I noticed, and I've never been able to see anything.  All the brake hoses were replaced a few months ago by a local garage and I rebuilt the calipers four years ago.  I replaced the load adjusting valve at about the time this first happened but also had the rear axle off as well which all might be coincidental. Last week I replaced one upper front wishbone and had to disconnect the caliper and then bleed it through after; now the pedal going to the floor seems worse but again it might be a coincidence.

Any thoughts would be much appreciated as I can't get my head around this one!

It's going for its MOT on Monday so no pressure!

Cheers Andy
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1994 LWB Super Exceed L400, Black & Silver

[Google]

[Andy W]

By the way, I replaced the hoses because the pedal never was solid, it always felt like there was air in the system or a hose that was old and expanding when pressurised. I got the garage to do it as I knew they would pump new fluid through rather than pump the pedal and they would get all the air out. After all that, the brakes were no different and I was a rediculous amount of money worse off!
It passed its MOT each year with nothing ever noted about the brakes.
Cheer Andy
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1994 LWB Super Exceed L400, Black & Silver

[andyman]

Is the drum handbrake purely cable/ mechanical on the L400? Were it a L300, with only drums on the rear, I'd suspect the shoes needed adjusting. I also had a long pedal travel on my L300, but also uneven braking. Turned out the caliper wasn't moving, basically the disc was bending with piston pressure, under braking, but pushing the piston back when foot pressure was removed, so leaving a big gap between one pad and the disc, hence the pedal travel. The  unevenness was only obvious when braking hard on a wet surface, which caused me a heartstopping moment when a motorcyclist cut in front of me, then had to brake sharply himself on seeing the right-turning vehicle that I had eased off for! My van slewed to the left, and nearly side-swiped him.
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Andy C L300 Super Exceed - over 100 smiles per gallon!

[Lewis]

The rear 'service brake is a caliper.
The Parking (Hand) brake is a mechanical shoe type brake unit.
Adjustments to either system does not have an affect on the other.

For more info and photos see:- http://www.MDOCUK.co.uk/forums/viewtopic.php?t=36472
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Copyright is retained for all my photos. Please don't copy them without asking permission
Do not blindly go where the path may lead you. Go where there is no path and leave a trail that others may follow!
ルイス

[andyman]

As I suspected. Any insight into o/p's problem, Lewis?
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Andy C L300 Super Exceed - over 100 smiles per gallon!

[Lewis]

Assuming that when the hoses were replaced, they also flushed and fully replaced the brake fluid, so that there is no water contamination.

First job would be to check all the new hose unions for leaks, then I would do a full bleed, as per the Mitsu manual diagram. Note that the order of doing the wheels depends on if or not ABS is fitted.

Then check the Brake Bias valve spring is correctly set.

If it still happened after that I would be taking a closer look at the Master cylinder, for potential air leaks or replacement.

HTH
_________________


Copyright is retained for all my photos. Please don't copy them without asking permission
Do not blindly go where the path may lead you. Go where there is no path and leave a trail that others may follow!
ルイス

[Andy W]

Thanks for the input so far, I drove it round the car park this morning and the following happened:-
Brake pedal solid before engine start
Started and drove slowly round the car park and all was good, gently braking as I went
Put the brakes on to slow down and reverse into a parking space and the pedal went to the floor.
By the time I had reversed into the parking space and stopped, the pedal was solid again! No pumping the brakes or anything.
So I'm guessing that should rule out the brake bias valve?
Cheers Andy
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1994 LWB Super Exceed L400, Black & Silver

[Deker]

Andy.

I read your description, me puzzled. But it suggests to me that there may be a problem with the Master Cylinder.

Brake pedal will be hard before engine is started, this is due to the brake servo having no vacuum.

You do not say how far brake pedal travels, after starting engine. Try that test.
You only say that pedal sinks low after driving a distance.

Brake bleeding - There is a recommended/suggested method for brake bleeding on these cars.

Before someone SHOUTS at me, I have my method which works every time I have to bleed brakes.
IT IS my opinion, but I do have tools to do it.

Next time "pedal goes to floor" Try this, to help diagnose Master Cylinder fault.

L400 Brake Bleed. My method. For RHD models. Jack up car, if possible both axles off ground.

Clamp all Flexi hoses, try brake pedal, if it sinks too low, there is air in the first part of the system.
Release a bleed nipple on the closest brake to the Master cylinder (Front Right wheel) bleed that brake.
If no difference, clamp that hose. Then move on to the Front Left wheel, do same as previous.

Again, if no difference, clamp BOTH front hoses.
Now move onto the rear axle. Repeat the above method/s. Each time, after bleeding, clamp a hose.

If none of this works, get to back me personally, PM me for phone call.

Mr D

[Deker]

RE: My above post.

Using the above method. I have succeeded with Bleeding brakes where others have failed.

You "wanna" a laugh      This applies to FX4 taxis, with Drum brakes.
Long time ago, I worked in a taxi garage. A taxi came in, needing a replacement Master cylinder. Old vehicles = common failure.

So the "mechanics"    set about replacing the cylinder, its an easy job.
Then came the Brake bleeding, I had trouble hiding my mirth, about the way they went about it.

ONLY needed three guys, one to pump the brake pedal, one to top up the master cylinder, one to bleed each brake.

A short while later, same job, another taxi. The job was given to me, the fella in charge, sez
"When you need to bleed the brakes, give us a shout"

A short while later, I said to fella in charge "Cylinder fitted, ready to go"   He sez "What about brake bleed" I said "Done"

I did NOT bleed any brakes. Never did tell him how I did it.

Mr D

[Andy W]

Thanks Deker, I will try this next w/e but what is bothering me most is that this is so random, drive for months with out an issue then it plays up now, but much worse this time 😔
I intermittent faults like this, so hard to get to the bottom of!
Andy
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1994 LWB Super Exceed L400, Black & Silver

[Deker]

Sounds like it could be Master Cylinder.

WARNING, sorry in advance, see below.

If so - Try this:  Undo the pipes from the MC, make sure to have brake fluid and water handy,
you need water to wash away excess brake fluid.

Pump the brake pedal rapidly a few times, to flush out debris that may have got into the cylinder.

Re-connect the pipes, do NOT tighten fully, make sure the cylinder is "topped up"  Now press the pedal to exclude air,
do this as required. Tighten the pipes.

Test the pedal. The WARNING bit = If the MC is faulty this test may/will show the MC is faulty, and may NO longer be serviceable.

At least you will have a "starting point" to work from.

Mr D

[Andy W]

Presumably, if I do that Deker, when I reconnect the brake lines, I will have to bleed the whole system?
Andy
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1994 LWB Super Exceed L400, Black & Silver

[andyman]

WARNING: The last time my brake pedal went to the floor while driving, I rear-ended and wrote off a Rav 4 with my Deli. (No one hurt, fortunately, but it didn't do much for my insurance!) The only damage to my Deli (L300) was a cracked plastic shroud over the bull-bar. The M/C had had a leak for a while, on that day it had just got a lot worse when I braked hard because the bloke in the Rav just sat at the junction instead of pulling out into the obvious gap. Totally my fault, but with a new M/C, I could almost stand the Deli on its nose!
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Andy C L300 Super Exceed - over 100 smiles per gallon!

[Andy W]

Well, up at 4am to head into work and get the van MOT’d; the brakes were fine on it for the three minutes to the petrol station, I left it running when I filled up and then off again along the waterfront for about five mins at 30mph (average speed camara’s).  I didn’t touch the brakes at all during this time but did go up a small hill for a minute or two.  I braked for the roundabout and there was no braking on the LHS (where I changed the wishbone and had to bleed the brakes) and very limited braking all round but obviously pulling a lot to the right.

I pumped it and it came right and for the next 45min's was fine – I was checking them every five mins or so, this was pretty much all country roads. Got to work did a lot of stopping and starting to hook up a trailer and move it around – it never faulted again.

I can see the correlation that the front LHS needs a lot more bleeding as there appears to be air there but I don’t understand it.  Having bled dozens of brakes, if there is air in the system it is spongy; pump the brakes and generally it will lose the sponginess for a very short while and then become spongy very quickly again – mine don’t do that.  The sponginess may not return for days – how can this happen, is there a part of the system that is not releasing the pressure sufficiently that I don’t know about?

I would add that at 4am on roads that are very quiet even during the busy periods and me driving much more slowly and checking the brakes regularly and well before any junctions I felt it was okay to drive – during the day is a different kettle of fish.

Andy
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1994 LWB Super Exceed L400, Black & Silver

[andyman]

Pulling to one side, is an indication of a sticky caliper (see my note above re- slewing sharply when braking hard to miss a m/cycle.) Not sure if the L400 has twin opposing pistons and no sliders, or twin pistons on one side of the caliper, + sliders to compensate.
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Andy C L300 Super Exceed - over 100 smiles per gallon!

[Lewis]

Twin Pistons on one side of the caliper.

As per the info and photos and diagrams shown in the link I put in my earlier post, above.
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Copyright is retained for all my photos. Please don't copy them without asking permission
Do not blindly go where the path may lead you. Go where there is no path and leave a trail that others may follow!
ルイス

[Andy W]

Pulling to one side can also be air in that side can't it? That would tie in with me removing the hose on that side to change the wishbone.
Andy
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1994 LWB Super Exceed L400, Black & Silver

[Green Grouch]

Since having freed up loads of Deli calipers due to sticking , I now carry 1 of the laser type heat thermometer temp sensor things.
Cost less than a tenner, and you can immediately find out if a caliper is sticking by the temperature difference between your calipers, and quickly rule out, if that is a problem.
I always bleed with the 1 way valve device, and don't open the bleed screw too much, just enough.

When I'm finished, I also keep the pedal held down before I tighten the bleed screw.

Call me ocd, but gives a quick reliable job.
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A Little Knowledge is Dangerous and expensive! especially if your me Mending anything!!

[Green Grouch]

Probably should have explained myself more there.


The 1 way valve, for those not aware, allows you to keep pumping the pedal, without you keeping having to tighten the bleed screw every pump.
But having the bleed screw to loose can allow air in through the threads, and the valve won't stop that.

I've learnt many hard ways before.

As said earlier, the sequence does seem to matter also as I found out the hard way there.

I also keep the engine running, but I believe some don't bother.

It's made the process quicker when I've done it anyway.

Don't ask me to explain how it all works!

Someone will soon. 👍
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A Little Knowledge is Dangerous and expensive! especially if your me Mending anything!!

[Deker]

M/C/s when worn, can draw air in from the back seal. Tho, I don't remember any that eliminated the air by "Pumping" the pedal.