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Old 06-18-2007, 11:35 AM
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AZCACTUS AZCACTUS is offline
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Default 73' Fj40 Booster

Hi everyone! I found this site yesterday while surfing for info on fj40 brakes. I have an 40 that has been sitting for 5 yrs. and plan on giitn er going again. I had a fairly new master cylinder on it when I put it in storage. Resevoirs were full. I havent been driving it so there is no reason to think that the fairly new wheel cylinders are leaking. The crux of all this is the two master cylinder fluid levels are all the way down. In my way of thinking it can only be that the master is leaking into the booster.

The question is this: I know I have to deal with the master, but will I have to replace the booster as well? By the way, the brakes are stock drums. Thanks for any advise. Jeff
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Old 06-18-2007, 04:56 PM
SteveH SteveH is offline
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Look at the front of the booster below the master cylinder and see if there's fluid that ran down the booster and peeled the paint off. When MCs leak, the fluid often finds its way down the front of the booster.

If you're going to pull the master cylinder anyway (to replace it), then pull the booster, too and set it nose-down and see what leaks/runs out.

I've seen boosters survived inhaling quite a bit of brake fluid, so don't assume it ruined the booster. You might try running the engine to pull a vacuum and seeing if the booster will hold a vacuum. When you pull out the fitting, the booster should make a whoosh.

Denver Power Brake can rebuild 'cruiser boosters - I had them do one years ago and it has worked fine to this day.
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Old 06-19-2007, 08:11 AM
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Quote:
Originally Posted by SteveH View Post
Look at the front of the booster below the master cylinder and see if there's fluid that ran down the booster and peeled the paint off. When MCs leak, the fluid often finds its way down the front of the booster.

If you're going to pull the master cylinder anyway (to replace it), then pull the booster, too and set it nose-down and see what leaks/runs out.

I've seen boosters survived inhaling quite a bit of brake fluid, so don't assume it ruined the booster. You might try running the engine to pull a vacuum and seeing if the booster will hold a vacuum. When you pull out the fitting, the booster should make a whoosh.

Denver Power Brake can rebuild 'cruiser boosters - I had them do one years ago and it has worked fine to this day.
Thanks Steve! I suspect the booster may be shot. I am going to pull the mc and replace it. That may be why I am having trouble getting the engine to idle after I replaced plugs, plug wires and new rotor and rotor cap. When you said " holding a vacuum" a lightbulb went off in my head. I know that specter sells rebuilt booster's for $600.00 including the core charge. I don't know how much Denver Power Brake gets the rebuild kits for, but I called a Toyota parts dealer here locally and was told that the new booster's have been discontinued and a rebuild kit was available for $400.00! They do have the mc for around $257.00
I will isolate the booster hose away from the booster and plug it with a bolt to see if I can idle the engine sufficient enough to adjust the timing.
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Old 06-19-2007, 11:39 AM
SteveH SteveH is offline
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I had Denver Power Brake rebuild my booster and paint it all pretty (even masking off the original decal) for $150? years ago.

Often you can hear the vacuum leaking thru the booster and making a whistling sound. A leaking booster is bad news for your engine, so don't wait.

Since the booster has a check valve, start the engine, run it for a couple minutes, then shut it off. Gently remove the check valve from the booster, and see how much (if any) 'whoosh' you get. The booster should hold its vacuum for quite some time - several minutes at least. There are used brake boosters in the 'cruiser community, so don't pay SOR anything like $600. They also don't fail that often, so many used ones are good for many more years.

The spring in a booster is fairly strong, so if you do any sort of DIY stuff, be very careful.

Steve
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