mechanics-wheel cylinder brief leak

[LX89]

I was looking at the rear drum brakes on my 89-5.0 Mustang.

I decided to check the wheel cylinders to see if the pistons were not sticking.
A mechanic once told me to push the pistons back in with a screwdriver to see if they are free and if they go back in they are ok.

Tried the drivers side and both pistons went back in,then the rear piston started leaking some brake fluid,not a lot but enough to make some drops on the ground.
I cleaned the brake fluid off with brake cleaner,put the drum back on and pumped the brakes to get the pistons back where they were and it hasn't leaked a drop with the brake pedal under pressure.

No signs of any leakage before doing this and the master cylinder is right up.I didn't try it on the passenger side after this happened,lol.
Wheel cylinders are original and never showed any signs of leakage.

Any recommendations or cause for concern or did I just maybe push the piston in to far on the rear piston?

[Ponyryd]

Probably leaking a bit, often it will stay dry for a few months or years when this happens, depends how much the car is driven.

[ZR]

Yes possible it won't leak again but in the same breath, if cyls, rear flex hose and front flex hoses are original, in the interest of safety, long overdue all are replaced n brake fluid fully flushed.

[LX89]

Talked to the mechanic a week and a half ago.
Said I probably pushed the piston in too far and if it's not leaking now it's basically fine.

Because of the age of the parts I decided to have the wheel cylinders,all brake hoses and brake fluid replaced.
Parking brake cables were replaced last fall.

One thing that hasn't changed after that work is the drivers side drum still gets a lot hotter than the passenger side drum.

I had a different mechanic check out the rear brakes in 2014 and he said they were working fine but he couldn't give me an answer why one side was hotter than the other.
Anyone have an answer,this is pissing me off a bit.

[Ponyryd]

I would swap the drums from side-to-side, that will help narrow it down since it could be a drum with a different steel makeup causing the shoes to bite harder.

[ZR]

Hotter side to side, wheel cyl hanging a bit, brake adjustment is out, park brake cable hanging up or adjusted too tight or return springs sacked out.

[LX89]

Parking brake has no manual adjustment on this car.
You set the spring tension in the parking brake handle,hook up the cables at the equalizer,pull out a nail holding the tension and it's set.

When I would check the drums in the past before the work the drivers side would leave a ring of brake dust on the ground when laying the drum on the ground and the passenger side would leave pretty much no brake dust on the ground.

Don't know if that will change after the work.
I checked them before the work and they would apply/release on both sides no problem.

I have a set of new brake springs lying around at home,but I don't know if that would make any difference as both sides apply/release.

[ZR]

What they do static vs when under actual braking could yield entirely different results. Replacing hold down and return springs is prudent plus cost is minimal.

[LX89]

Do you think weak return springs would cause only one side to get hotter?
Wouldn't the springs be equally worn/weak on both sides.

[ZR]

Even grooves where shoe contacts the backing plate can affect

[LX89]

Two weeks ago I replaced the return,hold down and self adjuster springs with a spring kit from NAPA.
Said made in USA on the box.

Backing plate contact points look good and are greased.
I have a brake shoe adjustment gauge so I don't think the adjustment is way off.
Did a bunch of reverse then forward stops to fine tune it.

No difference,the drivers side drum still gets a lot hotter.
Last week I swapped the drums side to side and the drivers side drum still gets a lot hotter.

Now wtf?
Any chance it could be the drums or wheel bearing?
Drums are original with 206 km.
I measured the ID of each drum with the gauge and both are exactly 9 inches which is what a new drum would measure.No wear ridge on either drum.

Mechanic who installed the new parking brake cables last fall and recently the wheel cylinders and hoses mentioned nothing unusual.

Any ideas and if anyone has had a foxbody or other car with this issue chime in.

[ZR]

Sure you have clearance on bar that energizes parking brake?

[LX89]

Going by memory I'm pretty sure there was clearance.
With the parking brake not applied you could move that bar a bit back and forth I think.

I made sure it was positioned right.
I did check the parking brake and the drums would lock and release.

[ZR]

Odd time, return springs on the cables themselves is too long and can actually push the shoe backwards a hard n push shoe ever so slightly outward n cause drag. Most common if aftermarket cables used but can happen with OEM replacements.

[LX89]

Drivers side drum still got hotter with the original parking brake cables that were shot.
New cables were from NAPA and made in China but looked to be decent quality and the cable was coated.

Back in 2014 when I first noticed the hotter drum I raised the back wheels off the ground and ran the wheels at speed for awhile and the drums did not get hot or warm so there was no drag.
I haven't done that since then.

Somethings up,there's only one brake line going back to the rear brakes so both sides should be even or close in temp.
I can't figure this crap out.

Those return springs on the cables don't look very strong.

[hammerhead]

before you spend anymore money I would re-bleed the brakes - if there is air in the line feeding the right rear the left side will be doing all the work - air in the line could still apply the brakes but with not with much force and with the wheel off the ground everything may appear to be ok - I would re-bleed the rear brakes starting with the furthest one away from the master cylinder first (right rear) - if this doesn't work branch out from there - keep in mind when trouble shooting always start with the least expensive area and branch out

[LX89]

Local mechanic who installed the hoses and wheel cylinders bled the brakes.
Must have used a pressure bleeder.

Brake pedal feels as firm as it was before bleeding.

I'm not going to touch that as I can't do a better job than a pressure bleeder at home.
With my luck I'd probably screw things up more.

I'll stop by the garage soon and see what he says.
Hopefully he has an answer unlike the last mechanic.
This guy is reputable/honest and has been around a long time.