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Old 08-27-2010, 02:41 PM
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Jacket Jacket is offline
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Join Date: Feb 2007
Location: Lafayette
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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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1976 FJ40 - green and mostly stock
1996 FZJ80 - not so stock
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