Early 850 antilock brake pump leaking

[hungryman54]

Advice or guidance for removing and repairing. bottom of pump and block saturated with brake fluid. appears to be coming from around circular pump base. O-ring? Gasket?

[nickm]

I guess you figured this out.

There are 2 small pistons with o rings that the motor actuates. Each side has a hex screw and spring retaining them. Remove the motor and hex screws replace the o-rings.

[hungryman54]

Appreciate it, boss! I have not removed the unit as of yet. Waiting to see if there might be another unit; just in case it’s damaged beyond o-rings. Is there a gasket of sorts around the motor housing? Still looking for an access route for removing. Appears master cylinder may have to come out 🤔

[nickm]

You need to remove the pump motor, module, and the aluminium block as a whole..
So you will need to bleed the system.
Use a container to drain from the master cylinder

So remove all the brake lines and wire harness. Then remove the unit as a whole.
There are 3 bolts down on the chassis rail. The bracket has slots to help removal.

When you get the unit out the motor cover lifts up and you can remove the motor with a 2 torx.

There are no gaskets. At the side of the block are 2 screws that hold the little pistons in.
The motor has an eccentric shaft that actuates the pistons.

Likely the motor wires will have degraded so you can fix that with some heatshrink.
And re-flow the module solder joints while you are there.

[hungryman54]

Appreciate the advice and support. Finally found a back unit that matches what I have (TRACS). Does the master cylinder need removed? Accessing the bolts from the bottom or top? I thought there was an “O”ring at the base of the motor
Okay, guys, great advice!! I will get back to you as to my progress

[nickm]

Originally Posted by hungryman54

Appreciate the advice and support. Finally found a back unit that matches what I have (TRACS). Does the master cylinder need removed? Accessing the bolts from the bottom or top? I thought there was an “O”ring at the base of the motor
Okay, guys, great advice!! I will get back to you as to my progress

Is this your unit?
No need to remove the master cylinder

[Luxobarge]

Originally Posted by nickm

No need to remove the master cylinder

That's what I thought, but there might be if it's a left-hand-drive model, which I assume it is.

[nickm]

Originally Posted by Luxobarge

That's what I thought, but there might be if it's a left-hand-drive model, which I assume it is.

Yes I would say that would be a LHD thing.

In the picture you can see the bracket that connects to the chassis rail/inner guard
The torx plug that hold the piston in are just above the security sticker. The other on the opposite side. My guess is they are your leak.

Also note the condition of the motor wires there

[hungryman54]

No, not my unit. Found one here in the states. Apparently, with TRACS, only 93-95 had this particular unit.

[nickm]

I have the 1995 Volvo service manual in a PDF. It works the same.
DM me I'll send it to you. There is a diag of your system