Brakes Nissan 88 2WD

Tiny
FORNELS
  • MEMBER
  • 1988 NISSAN HARDBODY
  • 4 CYL
  • 2WD
  • MANUAL
  • 200,000 MILES
I have problems with the brakes in a nissan 88 2wd. I bench bled the master cylinder, bled the wheels in the correct sequence and still the pedal hits the floor. I tried to locate the load sensing valve but there is none in this truck. I do no see any external leaks either. I already tried 3 master cylinders and am running out of ideas. Am I missing something? I have a good car knowledge and I have done this job before many times.
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Sunday, January 16th, 2011 AT 2:16 AM

9 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Check to make sure the pushrod that goes from the brake pedal to the MC isn't adjustable. Also, make sure the rubber brake lines to the calipers are not expanding when you hit the brakes. As far as the proportioning valve, it has one. Actually it can be one of two types. You need to bleed it too. I have attached pictures for you to review.
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Sunday, January 16th, 2011 AT 2:33 AM
Tiny
FORNELS
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I have these pictures. The first one is actually where the bleeding for the clutch master cylinder is. The second one seems more like it however I did not see anything along the frame. I thought it would be near the tank but nothing. I will check once more tomorrow. Someone at a nissan forum mentioned that his 88 truck 2wd did not have a sensing valve. I replaced both calipers and put new rubber hoses at the front. I had a problem like this before and solved by replacing the sensing valve. What is throwing me off is the fact that I do not see it.
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Sunday, January 16th, 2011 AT 3:34 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
I think I found the problem. After reading and reading. I found there are two different systems. One is equipped with a split hydraulic system (no proportioning valve) the other has a load sensing proportioning valve (its been awhile, but I remember working on these and seeing them). Based on that, I will assume you have the split hyraulic system. When bleeding the brakes with this system, you DON'T do it in the same order as usual (RR, LR, RF, LF). But rather you need to do this. Bleed either rear wheel first. Next, move to the opposite side front and bleed it. Repeat the procedure on the opposite side. That is righ out of Mitchel. See if that takes care of it for you. Let me know.
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Sunday, January 16th, 2011 AT 4:13 AM
Tiny
FORNELS
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I am going to try the bleeding as you suggested today and let you know. I will verify this by checking Mitchell. I am also going to try this other trick. Pinching the rubber hoses at the front to see if that makes the system maintain the pressure, if it those then the calipers would be suspect.

Thanks
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Sunday, January 16th, 2011 AT 12:55 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Let me know what you find. I'm anxious to see if that does the trick.
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Sunday, January 16th, 2011 AT 6:39 PM
Tiny
FORNELS
  • MEMBER
I am lost with this problem. I tried that bleeding method and brakes are still bad. It seems the problem is at the front. I plugged the master cylinder ports for the front lines and pedal is steady and solid but as soon as I connected the front lines went back to spongy again.
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Sunday, January 16th, 2011 AT 8:01 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Was there any change?
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Sunday, January 16th, 2011 AT 8:08 PM
Tiny
FORNELS
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Well, here is what I have done. I checked in the library and tried the bleeding as follows: rear left, rear right, front left and front right. I also became suspicious of my rebuilt calipers from Autozone (bought them in Palominas, AZ and drove with bad brakes to Phoenix). Thus, I picked another set at the junk yard and bled once more in the mentioned sequence. The bleeding was done with engine off. Before I would start the truck and the pedal would hit the floor no matter how many times I pumped. This time however, once I started the truck and pumped the pedal at least twice the pedal tended to hold. Since it was getting dark I left it at that. I will bleed once more but this time with the engine running. I usually do that the second time I bleed brakes. Also what I did this time was to fill the calipers with fresh fluid before assembling the front brakes. I think I will get them better with the engine running. I have never experienced this problem before. It seems very difficult to get the air out. I am also thinking about cracking the lines somewhere in between the master cylinder and the rear brakes. However, one thing I noticed is that the brakes deteriorated after bleeding the front. I still do not understand why. I thought since the lines are short and direct from the MC, there should not be any air in them. But it must have something to do with the fact that this MC design is both a MC and a load sensing valve at the same time. I remember checking this set up on a visit with some relatives but I did not pay much attention to it and since the parts were chinese (NISSA) I just shrugged off and blamed the MC and left. Now I have tried 3 MC and have spend almost 3 bottles of brake fluid in the last couple of days. I almost felt like switching to the other system. I will let you know the final outcome of this, I will nail it. Nothing gets by me. BTW I am also working on a LC and a 4runner with bad head gasket
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Tuesday, January 18th, 2011 AT 5:18 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
You have your hands full. Now that you have a pedal, you may want to try the sequence I mentioned if your way doesn't work.

Let me know.
Joe
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Tuesday, January 18th, 2011 AT 5:39 AM

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