[12Voltlife]

OK, I just replaced the power steering pump, the high pressure lines and the soft low pressure lines. What I have now is a leak out the bottom of the hydraulic unit up on the firewall. None of the lines seem to be leaking and the seam between the master cylinder and the hydraulic unit is dry. The leak is under the unit and I can't see what is leaking. Has anyone been down this road before? I don't know what to look for here. Thanks
2000, 2500,5.9 261000mi.

 

[Junkman]

You will be getting a mirror and a light. The hydroboost wouldn't start leaking just because you replaced lines. Either a line isn't sealing or the baster cylinder has been leaking and you didn't notice or, or, or. Fluid blows all over the place and is difficult to find the leak. You have to go through the trouble of getting everything clean and figuring out how to view the hard to reach places.

It could be something as simple as a rubber hose end cracked and needing to be cut off back to good rubber. It could also be the tappet cover gasket mixing oil with something else. Lights, brake cleaner, rags and mirrors.

 

[12Voltlife]

Thanks junkman, I just cleaned all the mess from the high pressure lines leaking and was feeling good not leaving a mess everywhare I parked. So, there is nothing under the unit to leak, this is dead center under the unit and only while turning the wheel. Must be one of the pressure lines leaking. I'll take a little mirror and check around tomorrow. I love hydraulic systems, fix one leak only to find the next.
Thanks.

 

[Junkman]

It took a long time to determine that the return line ends were cracked and not sealing correctly. I eventually bought some constant pressure clamps and cut the ends off. Fuel injection clamps would also work better than regular worm gear hose clamps.

 

[12Voltlife]

I just noticed this today and did a quick inspection to be sure nothing was leaking on the work I did with the PS pump and lines. The leak only leaks with pressure applied by turning the wheel. The hard line from the hydro unit to the gear box has a short piece of flex line, I'll take a close look at that in the morning. All the other lines from and to the pump/gear were replaced. Or I could have a bad hard line. I'll get back and let you know. Thanks

 

[12Voltlife]

OK, A good inspection has shown me that all the lines are solid, and all connections are not leaking. The issue is a small weep hole on the very bottom center of the hydro unit is leaking very well. This is similar to our 5.9 water pumps which leak out the weep hole when the seals fail. This tells me that the hydro unit internal seals have gone bad yet the system still works, it just leaks a lot. Now I need to track down a hydro unit, anyone have a good lead ? I don't think I want to try and rebuild something like this, but I don't actually know if it can be rebuilt. Thanks in advance....

 

[12Voltlife]

This video answered many of my questions.,. https://youtu.be/6Fe61PdRZ0U

I searched this forum and found threads but many of the links are old a don't work.
So this job seemed to be less terrifying than I thought at first. There are several good new videos on YouTube. I'll keep posting the job as it goes...

Parts, parts

 

[krrz350]

I just 2 rebuilds back to back last month. It is a lot easier than you think. The only reservation I still have is that on my personal unit, the 2 pedal shaft seals were leaking and the only way to replace them is to cut and re-weld the pedal shaft. I am confident with my welding, it's just that is such a crucial shaft...

 

[Junkman]

I bought one from the parts house and got lucky. It's been working for a few years. Just buy one if you can't weld the shaft.

It seems that there are 2 versions of hydroboost available and only 1 needs welding. I think the specifics are in the directions for the seal kit. So, find the kit on line, read the instructions then decide. Mopar1973man posted some links before he decided to work only on his site. You might check there too.

 

[NIsaacs]

I just did mine, here are some pictures and a little info.

https://www.turbodieselregister.com/threads/weekend-maintenance-on-the-01.259915/#post-2558205

 

[12Voltlife]

The link shows the the unit pulled apart while still mounted to the firewall. I thought this might be possible, saves a lot of work pulling the entire assembly out then replacing the brake light switch. Something to think about.
I ordered the round seal and the figure 8 seal online from Boost Auto Parts $19.99 includes shipping (mail). I won't have time until next Saturday anyway.

 

[12Voltlife]

So I pulled the hydroboost out to replace the seals inside, it's a job, not too difficult but it takes some time. Pulled the unit apart cleaned everything up all pretty and replaced the seals, the round and figure 8.
Put the unit together and installed in the truck. Fired the truck up and the brake peddal went to the floor and stayed there.
I thought, I _____ __ in a big way. Packed up and went in the house.
Next day, pulled it out again and opened the unit and found that I didn't attach the spool shaft to the spool lever, the spool controls the fluid flow in and out and how much pressure. In my post above the video pic shows the spool shaft, it has a cone shaped top on it. Watch the video, the guy points this important step out..
I believe I missed this detail because 1. I thought I had it on the shaft, 2. I was distracted by the push rod spring staying aligned in the unit and the figure 8 seal staying in place.
Anyway, everything worked out well, all is functioning fine and there are no leaks, the round seal was the bad one, it goes bad and the fluid pumps out the weep hole in the bottom.
The job was much easier to do the second time around, I had experience !
Total cost. Seals $19.95, fluid $5.99