86overland

wrenchtech

How do you know that it's not letting fluid get get to the back brakes?

You could temporarily run the brake line directly to the back brakes and eliminate the LSPV. When mine went bad, I just got rid of it entirely and was totally happy with the results. You would have to block off the return line that runs back to the Tee, which is on the frame rail by the front passenger side wheel well. I eliminated the return line and put a plug in the Tee.

You can get the plug from one of the great Toyota enthusiasts and fabricators, Roger Brown, at his 4crawler.com website

86overland

akwheeler

Removing parts NEVER makes anything work the way it's supposed to. The LSPV is basically a totally mechanical ABS system, with no load it will limit the pressure to the rear brakes to help keep them from locking up, with a load more pressure can be applied without them locking, so Load Sensing Proportioning Valve.
If you really want to know if that is your problem start at your master cylinder and disconnect the rear brake line... have a buddy press the pedal... do you get fluid?
Reconnect it and move to the back of the truck and disconnect the line going into the LSPV... buddy presses pedal, do you get fluid?
reconnect and disconnect the line coming out of the LSPV with the sense arm all the way up... any fluid?
If you still get fluid, keep moving down the line until you determine where the blockage is. If you don't get any fluid on any one of the checks above you either have a bad master cylinder or a blocked line or it is indeed the LSPV.

86overland

wrenchtech

Definitely do your diagnostic work to determine the actual cause of the problem before making any changes to your brake system.

If the LSPV is bad, it looks like Toyota still sells the valves for the older trucks and 4runners for about $150.

One day my LSPV actually failed and left me rolling down the road without any brakes at all. Thankfully, I was able to coast it to a safe stop. Looking for a cheap fix, I eliminated the whole LSPV system. When I ran my '84 Xtra Cab without it the back brakes would lock up ahead of the fronts, but it was manageable for me, even on snow-packed roads. In fact my back brakes were almost useless before I eliminated the LSPV, so I was happy to finally be getting some braking force at the back wheels. That, said, for safety's sake, it would be best to have a functioning LSPV. It looks like Toyota still sells the valves for the older trucks and 4runners for about $150. Alternatively, you could eliminate the LSPV and plumb in an adjustable proportioning valve. It's not a perfect solution, but it is workable.

Here's a link to an online Toyota Dealer Parts seller with your part. link

akwheeler

did you try breaking the line at the rear brake hose? or at each wheel cylinder?
you mention getting fluid at the LSPV but is that from the bleeder screw or the line coming out? there is a difference.
I believe the bleeder is actually connected to the front brakes (pressure from there controls the bypass part inside the LSPV so if you lose the front brakes the rears will get full pressure, so bleeding there won't do anything for air in the rear brake lines.
Please help me help you! did you disconnect the line going into the LSPV and get fluid there?
Did you disconnect the line coming out and get fluid there?
Did you disconnect the flexible hose and get fluid there?

Tims86Toy

I ran into this problem about 10 years ago. The LSPV basically rusted away. I couldn't figure out how to bleed the rear brakes because like you, I wasn't getting any fluid even using my vacuum bleeder. At that time I couldn't find a replacement. So I wound up mounting a manual proportioning valve at the master cylinder, capping the tee and the return line.

The best way, and for this scenario, was to gravity bleed the brakes starting with the driver rear. It takes time but it will work. Grab a beer and a pint of brake fluid and stand guard over the MC.

Once you're done bleeding, set the MPV under normal load. You really don't need to adjust it after that unless you're hauling ridiculous loads. I've hauled my 600RR, ramp, and all my track gear many times and I hardly notice a difference.

Darcage1

I just deleted my lspv setup and now I have what feels like light dragging on the rear end while driving down the road off and on any advice? Thanks no I didn't install a manual proportioning valve.

Blueman

I replaced my LSPV with a factory part. It was pricey, but now the front/rear brake balance is much better and the pedal doesn't feel like it has notch in it.

Sure you can remove it, sure you can replace it with something aftermarket and tune it up, but think about the value of your time and risk of not getting it right. I'm not saying don't change the design from what some very detailed and thoughtful Toyota engineers worked on and tested to be safe, but if you're gonna walk that path just remember you're a test pilot. Some test pilots have awesome times and great successes. Some don't.

arlindsay1992

iTrader: (8)

I replaced the LSPV in both my Toyota trucks with new OEM. Works just like normal, there are no better options, only cheap compromises. Should be good for another 30 years and 300,000 miles.

I tried the LSPV delete, I was not pleased. Braking performance was not improved and of course it lost the load sensing function. It ended up being a waste of money for me since I eventually went back to stock.

There are certain cases where there are improvements over what the factory designed and engineered, but they are rare. Most of the time they knew what they were doing and people's "fixes" or "improvements" are really just cheap hackjobs.

Numbchux

Thank you very much for searching for the answers to your question. But this is very much a case where it would be better to start a new thread, with all your vehicle information, symptoms, and questions. Digging up several old threads just adds confusion.

Innocent Fool

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