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  #11  
Old 08-24-2010, 01:50 PM
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I've read that for some, bleeding the brakes is one of the few things the OCD crowd will let a dealership do

Matt, did you bench bleed the MC after you ran it dry or bleed it on the truck? Never done that and hope to never have to but the procedure in the FSM makes it look pretty benign.

I've been lucky so far on both the 80 and the LX. I had never bled brakes before until a couple years ago. I've finally gotten decent as using the Motive power bleeder (key is a REAL tight seal) and decided that everytime I bleed the brakes I'll do a flush at the same time because trying to judge how much fluid to put into the Motive is a useless exercise in futility.

That said, I'm with John that even a well bled 80's brakes aren't something you'll write home about

I've contemplated getting those Speed Bleeders to make the pump and let up method a one person operation. But I'm not sure how you monitor whether air is coming out or not sitting in the truck push the brake

I might have to try Corey's technique next time of "aiding" the Motive with an extra push of the pedal...
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Old 08-24-2010, 07:09 PM
Bikeman Bikeman is offline
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The one thing I don't touch on my 80's are the brakes. I let someone else do it with a power bleeder and have firm pedals on both.
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  #13  
Old 08-27-2010, 10:48 AM
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This story is my experience verbatim:

http://www.expeditionportal.com/foru...ead.php?t=4575

80 brakes seem to be frustrating to a lot of people.

I had it power flushed this morning, and they were unable to get the "mush" out as well. Seems like the Master Cylinder is the next likely part to be replaced. Does it make sense that the design of the 80 brakes would cause the LSPV to be the circuit most affected by a MC leak? I haven't read about a lot of 80 series MC problems, but maybe by letting it run dry during this process I dislodged a "fluid seal" and introduced a small air leak in the O-ring?

Has anyone else had to replace their 80 MC? Looks like I have a few choices: Marlin sells a big bore MC for the 80's, MAF has AISIN brand units, and of course there's OEM.
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Old 08-27-2010, 12:52 PM
Bikeman Bikeman is offline
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Wow. Bummer, Matt. When the shop power bled mine, after getting it back, there was no evidence the LSPV was even cracked open.
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  #15  
Old 08-27-2010, 01:14 PM
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Man, I just don't get it. The only time I have had issues similar to what you are having was when I made the mistake of letting air into a system that had an ABS pump. It took me an eternity to get that thing bled until I found the right bleed screw.

after reading that other guy's post I feel like it's not the MC...

how much air is still coming from the LSPV? a lot?
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  #16  
Old 08-27-2010, 01:15 PM
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Bummer Matt...

The longer you have the 80 the more you read about the little "nuances" of the rig...I never know what sort of credence to lend things you read about on here, MUD, etc. That said, little things like the problems people have encountered after running the MC dry, or folks that have busted off the vent line on the top of the radiator when replacing the spark plugs, or folks that have busted off the knock sensor when replacing the PHH, make me not temp fate when doing certain stuff and make me take extra precautions....

I haven't been where you are right now luckily for me because my skills wouldn't be good enough to get me out of the hole
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Jeff Z. (the "not quite as skinny" one)
TLCA #17037
'97 LX450 - aka "The Whale"
'97 FZJ80 Antique Sage AE #267, stock
12/74 FJ40, 2F, SM420, 4" Lift, ARBs, 33" MTRs

:

"...anything else i can do for you guys, how about i wash your car or mow your lawn while you figure out your firewall system? I am now boarderline insane/unibomber." Kipper

"That assumes I'm even capable of pulling and stabbing..." Jacket

"I really like having a detachable unit." Beater
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Old 08-27-2010, 01:32 PM
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Wonder if running it dry could let a piece of debris flow down, scoring the piston bore wall or nicking a seal.

BTW, the Marlin 'Big Bore' MC is the stock Aisin FJ80 Non-ABS part, it's 'big' relative to the standard size Hilux. The FJ80 came with a 1" piston, which would upgrade a '79-'85 mini truck that came with a 13/16" piston. The potential upgrade for you would be to a 1-1/16" unit from a HD T100. But doing this with no other changes (primarily using the matching booster) might make the pedal even more mushy. BTW, I don't know if the FZJ80 has a different MC and I'm not sure how ABS affects your swap options.

I once went through trying to figure all that out. My truck was delivered with the 'big' bore master cylinder (what some people call the 'V6' brakes). The engine in the Hilux does not seemed to have been the determiner of what brakes you got, but rather if you have 8" or 10" rear drums (1986-1988 IFS I think had 8" but all trucks from 1989-1995 have 10" rear drums) and the caliper piston size. In any case with a FZJ80 you would already have at least a 1" bore master cylinder and maybe a 1-1/6" since some 4Runners (V6 from 1992-1995) and many T100 had them.

http://risingsun4x4club.org/forum2/s...41&postcount=4
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  #18  
Old 08-27-2010, 01:41 PM
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Matt, quick question.

Did you replace all of the soft lines? I ask because I have it in my memory bank that someone in the club had issues with brakes and it turned out that one or more of their soft lines was loosing its integrity and what would happen is when you hit the brakes the pressure would cause the line to "balloon" and reduce the pedal effectiveness.

Granted, as I recall this was on a FJ40 with really old lines...
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Jeff Z. (the "not quite as skinny" one)
TLCA #17037
'97 LX450 - aka "The Whale"
'97 FZJ80 Antique Sage AE #267, stock
12/74 FJ40, 2F, SM420, 4" Lift, ARBs, 33" MTRs

:

"...anything else i can do for you guys, how about i wash your car or mow your lawn while you figure out your firewall system? I am now boarderline insane/unibomber." Kipper

"That assumes I'm even capable of pulling and stabbing..." Jacket

"I really like having a detachable unit." Beater
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  #19  
Old 08-27-2010, 02:41 PM
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Quote:
Originally Posted by rover67 View Post
Man, I just don't get it. The only time I have had issues similar to what you are having was when I made the mistake of letting air into a system that had an ABS pump. It took me an eternity to get that thing bled until I found the right bleed screw.

after reading that other guy's post I feel like it's not the MC...

how much air is still coming from the LSPV? a lot?
Last time I did it, it was just a few bubbles. Becky said the pedal felt good resistance so I cranked it closed. Felt pretty good going around the block, but the next day the pedal went to the floor a couple of times.

Honestly - it seems like it goes in intervals. Like it'll be just fluid and maybe a few bubbles, but if I keep allowing my pedal pumper to push more fluid, it eventually "finds" another pocket of air - so much so that you hear it crackle when it enters the tube outside the bleeder. That behavior might lend itself to a leak in the MC.

Quote:
Originally Posted by corsair23 View Post
Bummer Matt...

The longer you have the 80 the more you read about the little "nuances" of the rig...I never know what sort of credence to lend things you read about on here, MUD, etc. That said, little things like the problems people have encountered after running the MC dry, or folks that have busted off the vent line on the top of the radiator when replacing the spark plugs, or folks that have busted off the knock sensor when replacing the PHH, make me not temp fate when doing certain stuff and make me take extra precautions....

I haven't been where you are right now luckily for me because my skills wouldn't be good enough to get me out of the hole
I'm barely qualified to be a shade tree mechanic, but I've bled enough brake systems successfully to know that this is a serious anomaly.

Quote:
Originally Posted by DaveInDenver View Post
Wonder if running it dry could let a piece of debris flow down, scoring the piston bore wall or nicking a seal.

BTW, the Marlin 'Big Bore' MC is the stock Aisin FJ80 Non-ABS part, it's 'big' relative to the standard size Hilux. The FJ80 came with a 1" piston, which would upgrade a '79-'85 mini truck that came with a 13/16" piston. The potential upgrade for you would be to a 1-1/16" unit from a HD T100. But doing this with no other changes (primarily using the matching booster) might make the pedal even more mushy. BTW, I don't know if the FZJ80 has a different MC and I'm not sure how ABS affects your swap options.
Good to know Dave - thanks. The Marlin MC is probably the same Aisin unit that MAF sells for 80's. And I wonder the same thing about debris or something affecting the MC when it ran dry. I'm going to try and do a pedal test on the MC this weekend and see if I can detect a leak.

Quote:
Originally Posted by corsair23 View Post
Matt, quick question.

Did you replace all of the soft lines? I ask because I have it in my memory bank that someone in the club had issues with brakes and it turned out that one or more of their soft lines was loosing its integrity and what would happen is when you hit the brakes the pressure would cause the line to "balloon" and reduce the pedal effectiveness.

Granted, as I recall this was on a FJ40 with really old lines...
Not all the soft lines, just the ones that extend from the frame to the axle housing. So I suppose your theory is possible, although I keep coming back to the fact that its just the LSPV circuit that seems to be packed full of air. The four corners push out fluid and nothing more.
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  #20  
Old 08-27-2010, 02:51 PM
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Yes : letting the master cylinder "can" (but not always) damage the seal. Rendering the master cylinder defective.

- you don't need to bleed the lspv thingy unless you opened the lines to it directly. Or drained the system. The fluid pass threw it.

- I've found that the best way to bleed a troublesome system such as yours is a "one man brake bleeder" which is assentally just a tight fitting hose on the bleeder then submerged into a bottle filled about 1" with brake fluid. Because when you pump, the air comes out. But when you relese, it sucks fluid In, not air. Do this about 1/2 - 3-4 of the resivior. And you should be golden. If that dosent work un-bolt the rod to the diff and force it all the way up to take out all the slack in the piston essentially "top dead center " =( less volume to fill)

-Do not use pressure bleeders on vehicles with ABS ! You can distroy the motor. This is why tool manufacture stoped producing them. And you can only find vacume bleeders Now.

- I use vacume bleeders, the one man bleeder and the 3 pumps methods of bleeding. And the most affective method is the 3 pumps but you have to close the bleeder while the stream is still flowing solidly. And not after the flow stops. And open the bleader slowly. If you open it fast. Even with NO air, it will look like there is air Because of how it's shooting out.
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