I had my car fixed at a body shop due to some fender damage on a hit and run. They had it from December 29th through January 12th. The shop claimed they didn't have to remove the wheel to replace the fender, but I haven't been able to remove the wheel yet to check for damage.

In my car I have the Z1 rotors, Hawk HPS Street pads, Z1 stainless premium lines, and Motul 5.1 Synthetic fluid. I've had this setup since October 16th, 2021. I do drive the car pretty hard and brake a lot on twisties.

I last checked the brake lines (all 4, during alignment) in August and they were perfectly normal -- no damage at all.

When I picked up the car and drove it home, the pedal felt like there was no braking power until the pedal was depressed almost ALL THE WAY... and when it did finally brake, the brake power was WEAK.

So I suspect air in the lines but I'm having trouble finding information on what causes this besides water accumulation or a leak. Is there any possible way this could have been the resullt of something the shop did? There are various other problems with their work, which they said they will be fixing when I return at a later date -- so it's not like they're fully competent. There IS a possibility this is due to something they did, but I would like to find proof so they can reimburse a flush of the fluid. What should I be checking to find out what the cause of the air is?

I have my dinky trunk lift and I was going to just lift the car with that tommorow when there's space in the garage, remove the wheel where the replaced fender is, and inspect for damage or signs of problems. I just really hope that my Harbor Freight torque wrench doesn't fall apart on me like it did the last time I was trying to torque the wheels back on (80 ft lbs) with the one I exchanged.

I also wanted to go on a cruise Sunday (plus I've been without my car way too long), so I'll most likely be buying some fluid nearby somewhere and having a JiffyLube flush it on Saturday. I'm open to suggestions for 5.1 fluid I can buy in places like O'Reilly, Advanced Auto, or Walmart. I don't want to wait to receive Motul 5.1 (shipped) and I don't want to drive the car in this state to the nearest location which sells Motul 5.1, because it's about 30-35 miles away.

Finally, is Motul 5.1 something that has a con of degrading really quickly because it's too "performance-focused"? Maybe this is why my issue is happening? Would things last longer if I went with something else?

Thanks

UPDATE: As I've inspected my car some more and checked the fluid apperance.. tried as best I can to find any leaks near the reservoir and around/on calipers/rotors/tires (car is pretty low), I've so far come to the conclusion that my original instinct is correct -- there is air in the lines. I tried depressing the brake pedal a bit and after the 2nd press I felt the pressure. The only thing I don't get is how it's already this bad after only 14 months. I'm thinking I should try DOT4 and I have seen mixed information online but it's possible 5.1 just absorbs water faster.

Here's how the fluid looks:

 

That brake fluid looks too dark for being only 15 months old. I recommend a good DOT 4 fluid like ATE Gold 200 (which is widely available) to do a full four-wheel bleed. As for establishing whether the body shop was responsible, that's debatable. Not sure how you'd ever prove it, unless you could show how and why they'd pull a brake line doing bodywork.

 

I am limited on time and already setup plans to get it flushed and replaced with DOT 4 tomorrow, but have no choice on the fluid. They have it setup in the system used to flush the system. I can't have them add my own.

They weren't sure exactly which brand it is so I called the other 2 stores in the area and they both use penray. I figure it's the regular, not the plus one.. because I don't see why they would spend on plus as most consumers probably don't care what they get.

https://penray.com/product/synthetic-dot-4-brake-fluid/

It looks like the standards aren't as stringent as it says "Wet Boiling Point 311ºF minimum" and "Dry Boiling Point Exceeds 465ºF" rather than a specific claim.

Yeah, I was in the same situation about proving it was something they did, which is what I was trying to rule out so I could determine if it's just a really bad coincidence. I ended up concluding that it was and in the meantime I've also pulled the only wheel they would need to pull off and there's no damage to the brake lines. Additionally, I believe their claim they didn't remove the wheel because of the feeling/sound of breaking the lugs free. I don't think they would have been that way if they were recently put back on.

Anyways I am going to have JiffyLube flush the system and take a look at it tomorrow. I know the staff there a bi, they aren't braindead, and I live nearby. Should be operating fine tomorrow and I'll see if we can find if there's a leak/problem anywhere.

 

flushed.

They said there's a leak in the rear left brake line. I'm going to talk with a fren IRL and have him look at it too. I was suggesting it just be tightened but they seemed to not be interested in that at JiffyLube (and it's not like they tend to do that. They let me go underneath and do extra things for me and call me into the bay and talk to me. They're very cool with me at this location).

I didn't have time today to check that myself and was fixing other things for a cruise tomorrow.

I'll have to put back on a stock line or see what I can get from Z1. I emailed them asking some questions. I don't really want mismatched brake lines for many reasons (don't need to hear about 'it will work fine' -- that isn't the point). The leak is slow, so if I have to wait to get a replacement stainless premium Z1 line that's fine with me.

 

If you've got a slow leak, it's introducing air into the system. Everytime you step on the brakes, hydraulic pressure pushes more brake fluid through the entire system, where fluid will escape through the weakest area (like a leaky brake line) as you introduce more air into the entire system. I don't know what kind of time restraints you have, but this is not the time to be risking brake failure because of it!

 

The brake fluid you are using is good, it's considered a "long life" fluid 12-24 months per Motul.

You do have fluid contamination and with your issue it could point to a bad master cylinder.

 

update.. my fren wasn't able to see a leak either.. and I have monitored the levels and it hasn't lowered at all.

meanwhile, brake feel hasn't been like it should. better than when I picked it up from the body shop, but nowhere near how it should feel.

I took it back today and told them I want them to do it the way I was saying.. the bleed order and also actually bleeding the inner bleeders.

Now it feels right. Now it's braking well.