Brakes not working?

Tiny
GONZALESAMY129
  • MEMBER
  • 1990 CHRYSLER FIFTH AVENUE
  • 3.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 169 MILES
I have a 1990 Chrysler new Yorker fifth avenue. I made a mistake and put engine oil in the brake fluid. I flushed out the brake lines, cleaned the master cylinder, put it back together and started bleeding the brakes. My front driver side did have brakes but not the passenger. The more I bleed the brakes it seems to be getting worse. No I have no pressure on either side. When I cap off one side of the master cylinder and bleed the brake I get fluid just fine. Once I connect everything together all of a sudden I don't get any fluid from either side. And still no brakes, When I push down the brake pedal when bleeding the brakes it sounds like there is more air sound coming from the pedal? No leaks I have seen yet, when bleeding the brakes the pedal stays squishy, and I can push it all the way to the floor and it seems like it tries to gain pressure but never does. None of the warning dash lights have came on. I do have a scan tool but with it being an older car I am not able to find the spot I would plug it into for it to read the system. Since the contamination I have not replaced any parts, only flushed the lines and cleaned the master cylinder.
what am I doing wrong or missing?
Tuesday, July 22nd, 2025 AT 7:46 AM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
OOF The petroleum products will do a number on every rubber seal in the system. It makes it soften and swell and will never return to normal. It is also almost impossible to flush it out of the flex lines and those will likely need to be replaced. I've used alcohol pumped through the steel lines and that seemed to work. For the master cylinder and the calipers and wheel cylinders, they can either be replaced or get kits and clean and rebuild them.
That is the only way you will remove all the contamination and the damaged rubber parts.
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Tuesday, July 22nd, 2025 AT 12:32 PM
Tiny
GONZALESAMY129
  • MEMBER
  • 2 POSTS
Thank you for this information it is very helpful. Out of your experience what would be the cheaper way to go buying all new master cylinder and the calipers and wheel cylinders, or the repair kits? Who Do you recommend to buy the parts from? Can I just purchase the rubber parts alone? Or do they come in the rebuild kits? Thank you for all your advice, I'm new to this and learning a lot along the way.
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Tuesday, July 22nd, 2025 AT 1:12 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,233 POSTS
I used to say just buy the kits and rebuild, these days though it's almost cheaper to just buy the complete part and you generally don't end up with poorly made parts. I tend to recommend Rock Auto online if you don't need the parts tomorrow, if you need to get the car on the road ASAP then I generally use Fisher or Advance.
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Tuesday, July 22nd, 2025 AT 3:16 PM

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