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when the brake pedal goes right to the floor

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SteveSt View Drop Down
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    Posted: 13 Sep 19 at 16:34
And you cannot stop...
You thank your lucky stars you were ACTUALLY in the MOT station on the brake tester and NOT on the motorway heading for the back of an artic at 50!
Couldn't get the rear brakes to give any sort of reading -probably the compensator- so I stamped REALLY hard on the pedal only for the pressure to disappear and the pedal to go to the floor!
Got the LT off the tester and found a puddle of fluid underneath the back where one of the line pipes had burst.
I am just about to go underneath and start taking things apart with the intention of replacing some of the pipe runs. I am expecting corrosion to be the culprit. It's at the rear of the LT near the back axle.
I will follow this post up with some pics and reports on the curves I encounter as the job progresses.
BUT to start with - a couple of questions.
1/. Has any else had this happen to their LT (hopefully NOT resulting in an accident)? and if so what issues did they encounter when repairing; Any recommendations - please.
2/. Does anyone have a favourite brake bleeding tool? I have seen this one:
https://www.amazon.co.uk/gp/product/B000ROARTI/ref=ox_sc_act_title_1?smid=A3P5ROKL5A1OLE&psc=1
Gets mixed reviews - but most of the bugs seem 'fixable'
3/. Is there a method of testing the efficiency of the compensator? It was replaced about 5 years ago, so I am hoping it's seized up.
Thanks in advance
LT31 1991 2.4 TD Florida Westphalia • Honda ST1100 • Ford Tourneo Connect
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Buss Marius Quote  Post ReplyReply Direct Link To This Post Posted: 14 Sep 19 at 19:05
I use this tool. https://www.youtube.com/watch?v=HPK5Q13A9_k&t=378s
I think it is OK, butt the compensator was wrong adjusted, so not wery much came throug on my T4. When i tried to test if the brakes moved at all, the T4 rolled Down on me and sent med in an ambulance to the university Hospital in Oslo, where i stayed for 5 days. The first night in intensive care unit. So be careful when working under the LT, it is even more Heavy.
I dont know a metod to test the compensator, my Karmann is around 1550kg emepty and 1660kg on the rear, when we are using it, so the compensator doeen move very much.
87 Karmann LT L 2,4D. 89 T3 Syncro Reimo 1,9TD. 2000 T4 Caravelle TDI
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveSt Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 19 at 10:14
Hey BM, I trust you are fully recovered from that terrible event. I had a Lotus Cortina come down on me many years ago. I felt the car coming down and move my head out of the way of the diff just in time. We were making some checks underneath during a rally and the jack (hydraulic) sank into the soft tarmac which had been laid on the earth at the side of the road. Fortunately there were many other crews about who heard me shouting; they physically lifted the car off me so I could crawl out uninjured!.
As for the bleeder - I have gone for the pressure one. I have tried a vacuum one before and did not get on with it.

LT31 1991 2.4 TD Florida Westphalia • Honda ST1100 • Ford Tourneo Connect
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monster LT Quote  Post ReplyReply Direct Link To This Post Posted: 18 Sep 19 at 15:17
You don't need anything special to bleed the brake system. Just an 8mm hose of about 50cm to place over the nipples, a plastic bottle containing some brake fluid (about 50ml to submerge the hose end in) with a 8mm hole cut into the top of the screw lid, an 11mm and an 8mm spanner (going from memory). It helps to have someone pump the brakes (only half way down) while you deal with the nipples. I've read in various manuals differing order of bleeding the system. I use: , rear drivers side, regulator, rear passenger, front passenger, front drivers side, then regulator again. Works for me. I've also read to start on the regulator and end on the regulator. Some start furthest others start closest to the master cylinder. I've tried both ways. Both work fine. The idea behind starting closest to the master cylinder will avoid taking the old fluid throughout the entire system before it's bled out.

Not the same situation as you but I had brake fade after some heavy breaking on long steep decents down mountains recently - twice! "OH MY GOD! NO BRAKES!" just as we enter a small village about to go under a narrow train bridge. 1st time I bled the brakes. 2nd time a week or so later I changed out the pads and fluid altogether. I used ATE typ 200 with ATE pads. Next time on even longer steeper mountains - no brake fade. Strongly recommend the typ 200. Regular dot 4's have a low wet boiling point at around 160degreesC if your lucky. Typ 200 is closer to 200degreesC. Also make sure not to overfill the resevoir - easily done ending up with fluid coming out of the relief valve if volume increases when fluid gets too hot.

When you say "compensator" do you mean the brake pressure regulator above the rear axle? If so did you have it replaced with a "new" one? These are obsolete since 2010, so you'd have been lucky to get one. If it's siezed you may be able to get it moving but if you've blown a seal nd it's leaking maybe you'll need to overhaul. There are many posts about this part, one of which is on vwlt.co.uk.



Edited by Monster LT - 18 Sep 19 at 21:25
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LTCamper89 Quote  Post ReplyReply Direct Link To This Post Posted: 19 Sep 19 at 12:17
Unfortunately, and fortunately, I have been there; no brakes heading down the sliproad onto a large roundabout. In one side and out the other.

While you are on check the two pipes behind the grille. They cannot be seen easily.
1989 LT28 2.4D    Saviour of 6Music, well one of them. Now playing http://www.bbc.co.uk/radio/player/bbc_6music

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monster LT Quote  Post ReplyReply Direct Link To This Post Posted: 19 Sep 19 at 23:46
As you'll may be replacing some corroded brake lines you may want to consider Cupro Nickle Kunifer brake lines. Not used them but I plan to if needed. They don't rust, easy to bend / flare. Don't get this confused with Copper electroplated steel ones that are more easily available.
Also worth having a flare nut wrench (set) for bleeder valves and brake unions.
From experience it's worth getting some spare bleed valves as they tend to be corroded and will round off easy - hence using flare nut wrench. If they are too far rounded tap a hex socket on a size smaller and get if off being careful not to snap it.
Also to correct my earlier comment:
Originally posted by Monster LT Monster LT wrote:

If it's siezed you may be able to get it moving but if you've blown a seal nd it's leaking maybe you'll need to overhaul.

There is no "seal" as such to "blow". Meant the o-rings - they tend to perish not blow. The piston can gum up and stick inernally as you probably know since you've already replaced one.


Edited by Monster LT - 19 Sep 19 at 23:55
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Monster LT Quote  Post ReplyReply Direct Link To This Post Posted: 19 Sep 19 at 23:57
Originally posted by LTCamper89 LTCamper89 wrote:

Unfortunately, and fortunately, I have been there; no brakes heading down the sliproad onto a large roundabout. In one side and out the other.

While you are on check the two pipes behind the grille. They cannot be seen easily.

So what was the cause of your brake failure LTCamper89?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LTCamper89 Quote  Post ReplyReply Direct Link To This Post Posted: 20 Sep 19 at 12:03
Corrosion, and yes, not an enjoyable experience.Thumbs Down
1989 LT28 2.4D    Saviour of 6Music, well one of them. Now playing http://www.bbc.co.uk/radio/player/bbc_6music

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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveSt Quote  Post ReplyReply Direct Link To This Post Posted: 23 Sep 19 at 22:58
I have replaced both runs of pipe running to the compensator from the unions which are half-way back near the gear box with KuNi line to BSEN 12449. As Monster LT says "reasonably easy to bend / flare." Although I've added the reasonably as the result I came up with from my bending efforts wasn't pretty but it did the job.
Took LT back to the MOT station today for a check on the back brakes and I now have a pass - at least on the brakes  - full test is tomorrow.

The offending corroded section of pipe was hidden behind the section of L shaped 'plastic' support/protection(see pic below) and would not have been discovered by the "up on the ramp" MOT examination, the fluid had spurted out when burst the line by stamping VERY HARD on the brake pedal whilst on the tester.
Brake line hidden

The corrosion can just be seen on the line in the pic below.
corroded brake line
Only one of the two lines was corroded but both have been renewed.

The Sealey pressure bleeder was, in my view, very handy; although I did make the dumb-arse mistake of disconnecting it form the reservoir and putting the input cap with pipe connected and fluid still in pressure bleeder tank into a plastic pot below the level of the fluid - Syphon - doh! I found Isopropanol very good at cleaning up the overflow on the rubber matting!
I also bought one of these:

https://ebay.us/MhdG5N
Very handy for my nipples - although I do have a seized lower nipple on one of the front calipers. As I reckoned any air would be at the top, I left it sleeping for another day.
LT31 1991 2.4 TD Florida Westphalia • Honda ST1100 • Ford Tourneo Connect
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BeJay Quote  Post ReplyReply Direct Link To This Post Posted: 24 Sep 19 at 08:33
Originally posted by SteveSt SteveSt wrote:

the fluid had spurted out when burst the line by stamping VERY HARD on the brake pedal whilst on the tester.

I've always found you usually get a better result on the brake tester by using a pretty firm but progressive pressure on the brake pedal rather than 'stamping VERY HARD' on it, might be worth a try while it's on the tester.
NIL ILLIGITIMUS CARBORUNDUM
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveSt Quote  Post ReplyReply Direct Link To This Post Posted: 24 Sep 19 at 09:33
BeJay
It was only after using the F b P approach a number of times with a virtually non-existent reading did I resort to the HEAVY FOOTED approach that burst the pipe. I am rather glad it all happened the way it did. To have the brake line burst whilst on the tester is for more "enjoyable" than having it happen going into a round-a-about a la LTCamper89
In this context my definition of enjoy' covers something that can be experienced in negative amounts!



er g
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BeJay Quote  Post ReplyReply Direct Link To This Post Posted: 24 Sep 19 at 11:11
  Fair enough, and you're definitely right about it happening on the test rollers rather than in an emergency on the road. 

NIL ILLIGITIMUS CARBORUNDUM
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