300tdi non abs spongey brakes.. fault finding.

Good afternoon all,

Well after replacing the boot floor and two core plugs, changing all the filters and oils my bargain 300tdi is almost ready for the road... But I still have the brakes to sort out.

They lack power and the pedal is spongey.. The first time you push it it drops a few inches before anything at all happens.. second time it's firmer but still not really up to much.

So.. whats the sequence for ID'ing the fault..

I've started already by checking the wheel bearings are all in adjustment (they are) and looking at the condition of the pads/disks and calipers... the disks and pads are probably due for replacement but although that might exaplain some of the lack of power it doesn't explain the pedal creep!

So.. how to go about finding the fault in the hydaulics?

1. vacume pump - is there a way to check it's working correctly?
2. And the servo?
3. Master cylinder - can you check this without stripping it down?
4. pipework - already looked it over and cant see any obvious leaks/weaps.

Any advice will be most appreciated.. (I hate hydaulics).. I'm going to do the disks/pads this week.. As it's the brakes if I cant easily find/fix the fault I'll hand it to a local 4x4 specialist... As I dont like the idea of a hippo (sorry disco) with crappy brakes!

Cheers,
J

Check the easy things first. Symptoms point exactly to air in the hydraulic system. Bleed the brakes from the bleed nipples at the calipers. 90% this will be the problem

Thanks.. Any tips on bleeding landy brakes? My experience of bleeding hydaulics is limited to motorcycle brake/clutch systems which dont have power assist etc..
I tend to go with putting a clear tube on the bleed nipple and into a clear container with enough fluid to cover the hose.. then undo the nipple and reservior cap and pump the lever until no more bubbles show in the clear tube (keeping the fluid in the res topped up).. do up the nipple and hey presto.

J

Cheers! thats much better than the haynes pages!

When i fitted new discs and pads to my Disco i also fitted new pistons and seals in the front calipers.
Then last week O/S/F caliper started leaking, turns out grit had got in a scratched one of the pistons. Gonna put new seals in tomorrow which will hopefully fix the problem.

Easy to see if its happening, after pumping the brake petal a few times the fluid will drip off the back of the caliper.

Chris.