Question-------------------------
Followup To
Question -
Dear Mr McInnis,
I have started to experience an intermitent problem with the brakes on my Range Rover. Occasionally they apply themselves while I am driving along on straight flat roads. This has the effect of the engine appearing to lose power so that sometimes it is difficult to get the car to go faster than 35mph. Other times when experiencing the problem I can get the car up to 70mph, but no more. After such an event, when the car is stationary, you can smell the brakes and, in the dark, see part of the hub glow red hot. I initially thought that the cause of the problem was that the brakes were sticking and I had the caliper pistons striped down and checked and new brake pads fitted. However, I still have the problem and I am wondering if the traction control or hill decent electronics are kicking in to apply the brakes. Do you have any experience of this and, if so, what do you think is causing it? I look forward to receiving your reply.
Answer -
Hi Rob,
that is a serious problem. Over heated rotors can warp and cause all sorts of safety related problems. Usually, seized calipers are the cause and I have yet to hear that the HDC, TC or even ABS system causing such problems.
I would consider having the bearing inspected to see if there is any trouble found in there. My father had the bearings fail on the rear wheel of his Cadillac and it gave the trouble that you mentioned. In the dark, you could see the hub glowing red and you'd dare not touch the area for at least 2 hours afterwards.
IF it is due to the calipers seizing, there may be a problem with the Master Cylinder. Could be air in the MC or some other internal malfunction.
To bleed the system, you'll need an assistant to pump the brake pedal, one to maintain the fluid reservoir while you loosen or tighten the brake bleeding nipple. Before you start, spray lubricant (WD-40, Liquid Wrench, ...) around the nipple. Make sure no lubricant can be sprayed onto your pads or rotors ... use an old rag to catch the overspray.
Begin the bleeding process with the furthest caliper away from the the master cylinder. That would be the rear caliper, N/S/R then the O/S/R. When the rear is done, move to the front calipers, N/S/F then O/S/F.
For the rear calipers:
Carefully wrench open the nipple using a brake nipple wrench (most auto parts stores carry them). Once the nipple is 'Cracked' open (no longer tightly sealed), have your assistant turn the ignition ON and press the pedal. The ABS pump should be running and pump the fluid through the loose nipple. Immediately close the nipple and repeat this process on the other side. Make sure to top the fluid up at all times.
For the front calipers:
The front brakes have to have the pedal pumped to getting the fluid through. Keep an eye on the brake fluid level when you are bleeding or you will have to start again all over again.
I hope this is helpful. If this does not help, you'll have to consider the dealership or an experienced LR mechanic. I know there are problems with the ABS systems on most LandRovers...usually the ABS modulator is replaced but sometimes the wheel sensors are at fault. Let's hope its not either of these as they are expensive to replace.
Best of luck,
JohnMc
John,
Many thanks for your analysis of the problem. We have now found out that if you press the brake pedal hard it clears the problem for a while so we are thinking that it may be the brake servo pump that is causing the problem. Do you have any thoughts on that?
Best regards
Rob Whiston
Answer********************* follow up ***************
Hi Rob,
I've been told that sometimes the servo loses vacuum and can cause problems. I've read that several RRC owners have swapped in Defender servo's because they felt that they were more reliable and provided better stopping capability.
Check for vacuum leadksand see if that helps.
Regards,
JohnMc
