Load sensing proportioning valve replacement

glebez

glebez

New Member
Hey smart folks,

so my 1995 L300 (P05W) had a leaky brake cylinder in the rear on the left and brakes only worked there for 17%.
I gave it to the workshop for repairs and now they are calling me, saying that they replaced the cylinder, but there's still not enough braking power.
They claim the load sensing proportioning valve is toast and needs replacement, but they can't source it from Mitsubishi (they're a dealer) or anywhere else.

I looked at the diagrams and the part number seems to be MB587252 and I also can't find it anywhere for sale online.

So, I'd appreciate any advice here, maybe you know some alternative part that can be fitted or any other way to source it.
Also, how likely it is that the valve really needs replacement, maybe those mechanics are just not very good at their job? I searched the forum a didn't seem to find other people having much trouble with it.

Thanks a ton in advance.
 
Just to be clear here: You have the load sensing valve that lives above the rear axle, connected to the axle via a spring. The valve limits the pressure to the rear brakes depending on how compressed the suspension is. I've pointed this out because most people on here are more familiar with the JDM Delica's G-force sensing valve, which is mounted near the middle of the van and limits rear brake pressure based on deceleration.

Your valve must be connected to the rear axle and adjusted using the procedure and specs in the workshop manual. If it's maladjusted it will prevent the rear brakes from operating properly. Your workshop sounds competent, so I expect they've tried with the valve adjusted to all sorts of positions.

MB587252 is out of production, was only fitted to the L300, and I don't know of any generic replacements (but I'm more familiar with the other G-force sensing valve).
It's a fairly robust part though, it's probably rebuildable. I would disassemble it, clean everything, and reassemble with new seals and see how it goes. Seals might need to be replaced with generic O-rings, and if it's corroded inside the bores might need sleeving.
An alternative would be to fit a generic adjustable proportioning valve. Once adjusted correctly it'll work fine if you normally carry the same load, but if you sometimes have the van empty and sometimes have it fully loaded you'll find the rear brakes are too strong when it's empty (rear tyres lock up well before the fronts) and too weak when fully loaded (rear tyres never lock up).
 
Thanks for the great insights @Growlerbearnz !
My L300 is a camper, so it always carries quite some load of the camper build.
I'll see if I can find somebody who can help me with rebuilding the valve, Im afraid it might be well corroded, my rear axle is rusty.

Lurking around the web, I also stumbled upon load sensing valve for mitsubishi L200, part number MB618321, for example, here: https://sinaparts.com/car-accessori...e-brake-compensator-mb618321-auto-parts-42730

And it seems quite similar to the picture I see in the manual. The car is still in the workshop, so I can't take a look at the actual one. Maybe worth a try to get it and see if it fits.
 

Attachments

  • Screenshot at Aug 25 11-00-32.png
    Screenshot at Aug 25 11-00-32.png
    18.8 KB · Views: 18
  • ila-42731-6.jpeg
    ila-42731-6.jpeg
    223.7 KB · Views: 17
That looks very similar! Can you send that photo to the workshop and see if they think it's the same?
Sometimes parts have a different part number when they're practically the same, but have one small part that's different. I wonder if the valve is the same, but the spring or lever are a different length? You might be able to swap your old spring or lever onto the new valve.

I would try it for sure! Let us know if it works. :)
 
Looks very similar to the valve found in Mitsubishi Mighty Max trucks sold in the US and globally. The proportioning rate might be similar, or off a little, but there is some adjustability to help compensate. Not a bad price at $39.

KIPA Load Sensing Valve Brake Compensator For Mitsubishi L200 L200 K22T K34T K72T K74T K76T K77T 4D56 Triton 1986-2007# MB618321

61a6Lu5GpFS._AC_SX466_.jpg
 
Hey all, digging out this one to give some details, maybe it'll help someone in the future.

I have managed to find a good mechanic finally and we got to the root cause: the rear axle was leaking oil on both sides ---> brake pads were soaked and that caused poor braking, nothing to do with the valve, as Mitsubishi claimed. Did a rear axle gaskets overhaul and now everything is back to normal. Now I have this spare valve from L200 laying around, let's see if I ever need it.
 
Thanks for the update!

glebez said:
...brake pads were soaked...
Click to expand...
To be fair, you can't expect a guide dog to recognise contaminated brake pads. You're a good man for letting a blind mechanic try to fix your brakes the forst time round, but I'm glad you found someone who could fix it in the end.
 
glebez said:
Hey all, digging out this one to give some details, maybe it'll help someone in the future.

I have managed to find a good mechanic finally and we got to the root cause: the rear axle was leaking oil on both sides ---> brake pads were soaked and that caused poor braking, nothing to do with the valve, as Mitsubishi claimed. Did a rear axle gaskets overhaul and now everything is back to normal. Now I have this spare valve from L200 laying around, let's see if I ever need it.
Click to expand...
Hey, Mine is going in for rebuild.. Leaking.. Can I buy this off you? Need it air bagged to Townsville QLD..
 
You must log in or register to reply here.
Top