Bleeding Brakes

[tcrawfo]

I've got a few questions today.

First, I think I've got a failing/failed oil pressure switct....again! Can someone give me some instructions on how to wire my lift pump to bypass the oil pressure switch circuit...or whatever that fix is that I've read about here.

Second, what is the benefit of bleeding my brake lines and replacing the fluid with synthetic?

Third, I've changed my own oil in this truck since I bought it back in 1999 but I'm not sure I've done some of the "regular" lube maintenance that I should be. Can someone help me understand what under-chasis lubrication I should be doing and at what interval? Are there zirks I should be greasing? What type of grease should I use?

Thanks much to all of you who frequently help answer questions from one of the least mechanically-inclined member of the diesel page.

-Troy

[trbankii]

Cannot help you with the lift pump question, just learning the specifics of these diesels myself.

The issue with brake fluid is that it is hydroscopic - that is that it absorbs moisture. The first problem with this is that it leads to corrosion of the brake lines and cylinders. The second problem is more serious in that the moisture will vaporize when heated. This causes bubbles in the brake fluid, which can be compressed. Fluid cannot be compressed (relatively speaking) so when you step on the pedal the force is transferred to the calipers. Water vapor or air bubbles in the lines compress rather than transferring the force - leading to mushy brakes and problems stopping. Synthetic brake fluid is not hydroscopic, so it does not have this problem. However, most times you just flush the brake fluid every couple years rather than going to synthetic.

For the final question, the owner's manual should give you an idea of the various grease points as well as the grease to use. I just bought my '93 and it did not come with an owner's manual so I have to find out about those things as well.

[MTTwister]

Troy -
Front- end greasing - Almost any point that pivots will have a grease zerk fitting - Upper/lower ball joints - and steering knuckles, tie rods, pitman arm, idler arm, and some are a really PITA to get to - could be easier to drop the front splash shield to get to some ( on mine at least. )
Lithium based white grease should be good. Any grease is better than none - which could be the case.

Synthetic brake fluid - system would need a good flush, and it might not be compatible with all seals. Also, potentially overkill, 'cept in a race application. but it sounds cool.

edit - OPS Relay - Do a search - I know I posted about my expoloits on this. It releaves the current on the OPS contacts, but if your's are fried, you may need to replace the OPS too. But do the relay thing, too.

2nd edit - OK - Hot wiring the lift pump - need another search - basically there's a 'test' wire connector somewhere around the driver's side, hinge/fuse box area. Could be made hot in run I suppose, just don't roll your truck and leave the key on. smile.gif

[ 09-06-2005, 11:57 AM: Message edited by: MTTwister ]