Proportioning Valve leak. What option do I have? (1 Viewer)

Joined
Feb 27, 2011
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249
Hello all,
I just found that my 80's Proportioning Valve is leaking. I kind of noticed my brake fluid got low 1/4 inch in this 3 month, I decide to look for potential problem or leak on brake line. What I found is the rubber seal is full of brake fluid inside.

Do I have any other option other than replace it? Eliminate entire valve, or repair the valve?

Thanks.
 

NLXTACY

Wits' End
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West Hills, CA
 
 
There is a rebuilt kit from Toyota. I have one that is sitting on my shelf. But I think I'd rather just replace with new OEM to make my life easier. It's pretty easy.

Edit: I don't have rust so :meh:
 
Joined
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Twin Ports of Superior, WI and Duluth, MN
I live in North Rust Town and I just deleted the LSPV and the ABS while I was at it. My brakes have never been better. My personal opinion is that if the goal is to have good, functioning brakes, deleting is the way to go if you are having trouble with either, especially if you live in a rusty area.

You can dink around trying to rebuild or replace the valve and you may find that it wasn't a big deal, but you'll also spend a bunch of money trying to fix it. In the end, all you will have is a truck with working brakes, which is also what I have and it didn't cost me a dime.

Of course if you live in an area that does inspections, you might run into trouble. I would be curious to know whether they would even know the LSPV was supposed to be there if you just removed it all though.
 
Joined
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Charlotte, NC & Alexandria, VA
I just replaced mine, after initially intending to rebuild it. Internally the valve was so degraded I would have had to machine it to use the rebuild kit (my son has the piston on his desk; he loves it). The replacement valve isn't a wallet breaker. DO NOT adjust the adjuster (on the passenger side attached to the axle). They come set from the vendor at the correct dimension.

Per the FSM, I had my brake balance checked at the dealership afterwards (because I am OCD and do not have that many gauges), and it was OEM. The tech I talked to said I was the first person who asked for that check in his ten years of LC repairs (doesn't say much for the attention to detail at dealerships). He also told me that he's never moved the adjuster from its delivered condition and every truck road tested well.

As for deleting the valve, I know there are many, many adherents, but I'm almost sure none of them work for insurance companies. Something to consider; it is your truck, but it's their money.
 
Joined
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Twin Ports of Superior, WI and Duluth, MN
I just replaced mine, after initially intending to rebuild it. Internally the valve was so degraded I would have had to machine it to use the rebuild kit (my son has the piston on his desk; he loves it). The replacement valve isn't a wallet breaker. DO NOT adjust the adjuster (on the passenger side attached to the axle). They come set from the vendor at the correct dimension.

Per the FSM, I had my brake balance checked at the dealership afterwards (because I am OCD and do not have that many gauges), and it was OEM. The tech I talked to said I was the first person who asked for that check in his ten years of LC repairs (doesn't say much for the attention to detail at dealerships). He also told me that he's never moved the adjuster from its delivered condition and every truck road tested well.

As for deleting the valve, I know there are many, many adherents, but I'm almost sure none of them work for insurance companies. Something to consider; it is your truck, but it's their money.

I actually told my insurance broker that I deleted my ABS and my LSPV because I was concerned about possible liability. He said it was better to have told him. He just took that out of the options that I said the truck initially had and my premium actually went down by $6 per month when I did that and there is no reduction of coverage because of it. He told me that they actually consider some of the early ABS systems more dangerous than not having it all and according to what he told me, they consider the 80 to be one of those cars, at least for my '94.

I just carry liability, but I have a top tier policy because I don't ever want to need to cover a gap between what my insurer will pay and what I am legally bound to if something happens and a jury awards a big settlement. I use AllState FWIW.
 
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Bend, OR
 
I actually told my insurance broker that I deleted my ABS and my LSPV because I was concerned about possible liability. He said it was better to have told him. He just took that out of the options that I said the truck initially had and my premium actually went down by $6 per month when I did that and there is no reduction of coverage because of it. He told me that they actually consider some of the early ABS systems more dangerous than not having it all and according to what he told me, they consider the 80 to be one of those cars, at least for my '94.

I just carry liability, but I have a top tier policy because I don't ever want to need to cover a gap between what my insurer will pay and what I am legally bound to if something happens and a jury awards a big settlement. I use AllState FWIW.
This is great information for the folks on the fence in regard to deleting ABS and or LPSV, thanks! In my case my wife drives the truck on snowy roads a lot so I plan to leave the ABS intact but if the LPSV ever acts up I'd be more apt to remove it.
 

NLXTACY

Wits' End
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Not in CA folks. Talk to your agent. Negligence is a muther f'er in CA litigation. I was warned by my agent who builds hot rods.
 
Joined
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Messages
249
This is great information thank you guys.
I took a picture of it, it's very slow leak I don't even notice for brake performance, at least for now.

Red Merle : Yes I'm in rust area, not too far from WI, I'm in SK Canada. The cost for the parts is about $200.
I probably more liking for remove it for good.
When you remove it, how did you complete 2 brake line connection?

 
Joined
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Twin Ports of Superior, WI and Duluth, MN
This is great information thank you guys.
I took a picture of it, it's very slow leak I don't even notice for brake performance, at least for now.

Red Merle : Yes I'm in rust area, not too far from WI, I'm in SK Canada. The cost for the parts is about $200.
I probably more liking for remove it for good.
When you remove it, how did you complete 2 brake line connection?

You don't need to buy anything to delete the LSPV and the ABS if you decide to go that route. All of the parts are already mounted on your truck, you just have to reconfigure them if you go that route. I used Brake Booster & Vacuum Tube for 1994 Toyota Land Cruiser thread, but Jose's (@jcardona1 's write-up was really useful too. He takes better photos and he has a natural way of explaining things that makes sense to me. It's linked somewher in that thread. I used his build thread for my HG job too and it was invaluable and he's just a good guy).

It's pretty simple. I just left my LSPV under there and mine looks ten times worse than yours does. I figure it will either just rust off eventually or I will get irritated by it and saw it off when I go to sandblast my undercarriage this summer. As with everything on this truck, I slather bar chain oil on everything that looks rusty or I may want to remove at some point or looks like a candidate to be more rusty. What is a PITA today will be easy as pie to remove after 6 months of having the oil soak into everything.

Frankly, if you are at all worried about losing what the LSPV did for you, you can do what Jose did and jam a proportioning valve in the way he did. I would be curious to see if he had ever adjusted that after his first attempt. The brakes on this truck really don't need all of that stuff unless you are running a metric ton(literally) of other stuff added on and always have a full house. I am sure there may be some measurable improvement if that is the case, but for a stocker or lightly built rig, just having the MC, booster and other components other than the ABS doodad and the LSPV working properly will do wonders for your braking performance, especially if you have already replaced everything else.

I would swap out those soft lines too, just because it makes sense and your junk is pretty old if they have never been replaced before.
 
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Twin Ports of Superior, WI and Duluth, MN
I heard that if you remove the LSPV, the brakes will lock easily. Is this true? I would like to get rid of that valve...
It's a Load Sensing Proportioning Valve. It's supposed to sense how much pressure that you are putting on the rear brakes and to account for more weight.

It works, to a point. If you disconnect it and you don't have a proportioning valve, you are feeding whatever boost into your master and then to the calipers. I have new everything and I can stomp on the brakes at 65 MPH, come to a controlled stop and not skid on dry pavement in a hurry. The brakes are responsive and the truck feels nimble, it doesn't lurch, drift, or ghost on me; at all
 

jvazquez53

El Tractor
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May 6, 2007
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San Juan Puerto Rico
 
 
It's a Load Sensing Proportioning Valve. It's supposed to sense how much pressure that you are putting on the rear brakes and to account for more weight.

It works, to a point. If you disconnect it and you don't have a proportioning valve, you are feeding whatever boost into your master and then to the calipers. I have new everything and I can stomp on the brakes at 65 MPH, come to a controlled stop and not skid on dry pavement in a hurry. The brakes are responsive and the truck feels nimble, it doesn't lurch, drift, or ghost on me; at all

I have drums in the rear, that was my concern...
 

lumbee1

Native American
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Holly Springs, NC
 
I cut the rod to the LSPV and then carefully disconnected the hardlines and removed the LSPV. I disassembled the LSPV and replaced the proportioning valve with a bolt, washer, and nitrile washer. This turns the LSPV into an overbuilt T. I bleed the system and had the wife pump the brakes. The LSPV sprayed fluid all over the ground. I carefully disconnected the hardlines and removed the LSPV again and promptly threw it in the trash.

Go to Autozone, Advanced Auto, Pep Boys. Get a M10x1.0 inverted union. Connect the union to the top hardline and the rear axle hardline. Remove the sense line (the lower hardline that comes from the front of the truck). The sense line connects to the T under the master cylinder to the LSPV. Once the line is removed, cut the hardline and remove one of the brake line fittings. Weld up the hole and reinstall the fitting as a plug on the T under the master cylinder. M10x1.0 plugs are impossible to find.

Bleed the system and enjoy ABS with powerful braking.
 

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