Brake Load Sensing Valve

[garethpaul]

Hi Guys,

Bit of a long shot, but does anyone have one of the above hanging about for a 92-97 corolla? Usually mounted just behind the left of the rear bumper.

I've had a strange issue with my brakes whereby the footbrake on the rear sometimes works on the offside and sometimes doesn't.

I believe I have pinpointed it to be this load sensor valve. It has two pushrods under the rubber boot, one for each side, and one is currently seized.

Thanks in advance.

[alan333]

Try working the seized one with some wd40. I had this on a van a while ago, if it wasn't carrying much weight it wasn't getting operated so it seized up now and then.

[garethpaul]

Cheers for the reply.

I get where you are coming from, but the arm and associated linkages are all free and working "normally". I was quite surprised when I removed the rubber boot how clean it was underneath - almost brand new looking.

The issue is there are two pushrods/pistons under this boot that are operated by the arm. These disappear into the valve body through associated seals. One still has some red coloured grease around its base and moves freely. The other side the grease has gone crusty, and the pushrod appears to be stuck in the out (closed) position.

There is no rust (that I can see), and the pushrods appear to be anodised a lovely bright blue colour, so I guess there is hope yet.

I have cleaned out as much of the hard grease as I can with wooden toothpick and applied some penetrating fluid around the base of the pushrod to see if I can soften it up a bit. It's going "uphill" so to speak as the pushrods point to the floor so it may take some time to creep up. I will keep applying every few days in the hope that it will free up, but still looking for a spare valve just in case.

[oldcodger]

Not familiar with that unit and not sure what, if any rubber parts it contains, but it probably does as the red stuff, is likey to be Red Rubber Grease which is safe on rubber, most other greases are not.

You can buy small sachets at some motor shops or plenty on eBay. Big tins about £12

Never seen such valves on sale at any of the specialist brake places, expect its a new part from Toyota only; have you check their price ?

[garethpaul]

It does seem pretty unique - all the ones I have seen on the net are single pushrod design. I very much doubt it is available from third partys. See photo below.

I have the part number, but I am too scared to phone toyota. I know it is going to be at least £200-£300 pounds going by the prices I have seen on various Eastern European websites that are the ones I can only find that list this part.

I've had a closer look this afternoon, and it turns out I was mistaken and the valve is actually stuck in the open position. Tracing the brake lines, it would appear that the wheel with the low reading on the roller brake tester is actually on the good side of this valve, and the stuck side of the valve is the one giving a high reading. It was assumed the the high reading was the good "benchmark", and the comparative low reading was therefore classed as low efficiency.

I think the arm is also out of adjusment, as no matter how much weight I put in the back - i.e 3 adults, the arm moves, but doesn't move enough to actually press on the good pushrod to open it up.

I've temporarily cable tied the arm up and tested again and the readings are both "high" and pretty evenly matched. I will get the arm adjusted so that it is fully applied when the back is loaded, and hopefully get the stuck rod freed over time.