# d21 brakes



## nissassin (Nov 18, 2018)

after replacing a rear wheel brake cylinder (right rear) on my 1989 d21 hardbody (4cyl;auto;rwd), i tried bleeding my brakes several times but the pedal still goes to the floor initially. the pedal gets fairly firm after one pump, and will stay firm as long as it's pressed down but after the pedal comes back up, it goes back to the floor again when pressed. the engine also sputters and shakes when i apply the brake, and usually dies, but the idle is fairly low and the trucks been sitting for several months with only periodic starts. i'm considering the master cylinder now, and would welcome any thoughts. only about 85,000 miles on it so far.


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## rogoman (Dec 16, 2004)

If the engine dies when you apply the brakes, that indicates a major vacuum leak somewhere in the brake booster system. The vacuum draw on the booster diaphragm is what gives you power brakes. If the booster, rubber diaphragm or system check valve are damaged, this will provide an unwanted path for the engine vacuum to leak out. Thus causing the same thing as an intake manifold leak. Before replacing the master cylinder, check the booster hoses for any cracks and make sure they are tight. If that's OK, then replace the brake booster.


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## smj999smj (Jan 1, 2006)

A booster issue still won't cause a low pedal. First, make sure both rear brakes are properly adjusted. Then, make sure you bleed in the proper order: left-rear, right-rear, left-front, right-front. If you have a load sensing valve on the rear axle, bleed that first.


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## nissassin (Nov 18, 2018)

*brake bleed order question*



smj999smj said:


> A booster issue still won't cause a low pedal. First, make sure both rear brakes are properly adjusted. Then, make sure you bleed in the proper order: left-rear, right-rear, left-front, right-front. If you have a load sensing valve on the rear axle, bleed that first.


is this order of bleeding you outline correct? i went rear passenger wheel (right side), rear drivers side(left), front passenger side(right), front drivers side (left). i have always followed the order of farthest distance first from the master cylinder (in front of steering wheel) when bleeding brakes in the past and it has worked for me on many cars. i have always thought that the designations right side, left side (steering wheel side in u.s.) on cars was as you would be sitting in the drivers seat, not standing in front of the car. the replacement passenger side rear brake cylinder(shoes) was installed due to a broken bleed valve after replacing a frozen caliper on the passenger side front (disc). when i replaced the rear cylinder, i spread the shoes apart and held them apart with a small wrench while i replaced the cylinder (not oem)...i did not disassemble all pieces. i tried gravity bleeding for the first time twice before trying the traditional pump and hold which i tried 3 times. how could a (slightly?) maladjusted rear brake cylinder cause this bleeding issue? thanks for your reply.


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## smj999smj (Jan 1, 2006)

Yes, the method I described is the proper bleeding sequence for your truck...and left side is driver's side in the US. Different vehicles have different bleeding procedures, especially when they have an ABS actuator plumbed into the hydraulic circuit. The procedure you did is correct for some vehicles and "furthest back, first" was the way it was done back in the days before ABS. The procedure I gave you came right from the factory service manual for your vehicle. If you want to double-check, NICO Club has free access to online Nissan service manuals:

https://********.com/nissan-service-manuals

Non-oem wheel cylinders is usually not an issue, assuming they are the correct size. Slipping the old one out and slipping the new one in, without total disassembly of the shoes, is okay, as well. However, you still need to make sure the rear brake adjustment is correct before you start bleeding the system.

Put "n i c o c l u b" in place of the "*****" in the link address above, but without the spaces!


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## nuttinwrongwitnissinbits (Nov 11, 2019)

Yea your advice must have been golden *smj999smj. There has been no further response. *I will add you cannot assess the vacuum booster when the pedal is going to the floor. It can displace enough volume to cause a no vacuum condition in the manifold . So you get a stall. That can also happen to a lesser amount still causing a stutter in the engine running at idle , when the brakes are properly bled.. Also if you have bled one side of the rear, and then the other to still find some sponginess ? REbleed the first cylinder in case an air bubble has sat in the 'T' on the diff while the second was being done. I've been into D21's for ten years now and still am finding forums and advice that has missed my radar for so long. All you want to find out is mostly online but finding it can be surprisingly difficult or illusive.


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