rays87turbo

I recently picked up an 88 SE for $200, I was told the motor was good, but at the time it didn't run.
I got it running. On startup it revs to 3000 for about 30 seconds then falls to 1500 and finally to around 750, where its pretty steady. When I drove it it felt like it had power, like an N/A 4-cyl would feel....I've never driven a good rotary before so I'm not sure if this is right. Once I got it running following thesteps I found on this forum, I was pretty pleased. I also had to replace the master and slave clutch cylinders, but that was no problem.
It also needed a brake job, so I replaced everything and after bleeding the system twice it still will not brake properly. When braking above 25mph, it starts to brake, then the pedal gets hard and it acts like theres no more pressure available.
Next I decided to check the vacuum, my autometer boost gauge read between 10 and 12inHg.
After looking on the forum I found that that was prety low, and I should check compression. I did. I got 30-30-30, on the front rotor and didn't check the rear.
I didn't do that with the pedal to the floor however, how much difference will that make?
Is 10-12inHg low enough to make the brakes not work? Or is there something else wrong there?

jimmyv13

30-30-30 is considered very low. You might try some ATF to break up some of the carbon....that may increase your compression. I did this to my old 12A FB, and it made it feel like a new car again. How many miles on the clock? Running Marvels Mystery oil with the fuel has been thrown around here to help with lubrication and carbon breakdown.


When you say you replaced everything with the brakes, how far did you go...pads, rotors, calipers, lines, master cylinder, fluid?

rays87turbo

I first ran it with ATF to get it running.

Pads, hardware kit, resurfaced rotors, fluid. Everything else seemed OK from what I could tell. My greater concern is the low vacuum, and the low compression. I noticed I was supposed to do the comp test with the gas pedal to the floor? Is this true, and will it show me vastly different results? It just seems to be idleing and driving too well to have that low compression.

JamesBong

You probably got the low compression because the throttle was shut. Try the compression test at Wide Open Throttle (WOT) to be able to suck the maximum amount of air in there, and get the maximum amount of compression.

You should also replace all of the vacuum lines with silicone lines. If you still have the origional black rubber lines, they're going to be hard and brittle, and leaking like they aren't even connected. This may fix your brake problem, but that may be something else.

If you're slowly losing braking power, you either have a leak in the line, or the master cylinder needs to be rebuilt/replaced. I had similar symptomes with my brakes, and it turned out to be a leak in the master cylinder plunger. Once pressure was built up, it would slowly leak past the plunger back in to the resivoir. A couple of pumps on the pedal, and I had pressure again. Not too safe to drive like that though.

Good luck.

jhammons01

I am having the same issues that James Bong is describing. Be aware that all the usual places quote $150 for the master Cylnder. Kragen has one for $44 with exchange. That is the way to go. my.02

MidnightOwl

I have a braking issue as well, except I have had no pressure for about 6 months. The pedal will just go all the way to the floor and id have to stomp on it rather hard to stop. I bled the brakes and it had pressure for about a day, then when I was headed to a gas station, the pedal just went to the floor and it was back to normal. There aren't any leaks of any kind at the calipers. I'm slapping a new master cylinder in it tomorrow actually, but does anyone know what else would cause this?

JamesBong

MidinghtOwl, if you can't find any leaks anywhere, and the brake fluid level isn't changing, I would suspect the master cyllinder. When you change it, bleeding it out can take quite a while. Just be patient, and follow the FSM procedure.