Issue w/1999 Minivan Front Brakes

Issue is with a 1999 Chrysler Town & Country Limited Van w/90K miles. The
brakes worked perfectly before I had the master cylinder replaced. This was
done strictly as a preventative measure since the service place I used noted
a "slight leak". The brakes seemed to work fine for several hundred miles
and then after they were used , the brake pedal got really high and tight,
and then the front brakes seized. Driving became nearly impossible and we
needed to leave the van by the side of the road for 30 minutes ... once they
cooled down, they worked OK again. Between the time the master cylinder was
replaced and the brakes seized, we noted considerably worse gas mileage.

Took the van back to the garage where the work was done and after some time
the technician was able to repeat the problem. They replaced with a new
master cylinder and power bled the brakes again... that was several weeks
ago and the van seemed to be fine up till last night, but that was mostly
around town type suburban driving. Last night after a 60 mile 1-way trip on
a state highway (some stop and go from higher speeds), the brakes exhibited
similar symptoms (brake pedal got high and very tight, front wheels got
extremely hot even without much stopping, highway mileage dropped by ~25%).
But, in this case, the brakes never fully seized , but instead became
noticeably sluggish (poorer acceleration and did not "coast" - no gas - at
cruising speed very well).

I know the van needs to go back since we have only put on about 400 miles
since the second master cylinder was installed. I'd like to be able to
suggest the cause to them since they seem to have little idea of the
problem. When this happened the first time I specifically asked if they had
used the correct part and also the correct brake fluid and was told yes to
both. Does anyone else have any ideas on what could cause this behavior?
To be clear, the issue is not with a single caliper. When they replaced the
cylinder the second time, they checked and said both were operating normally
and there were no issues there. Also, both wheels get extremely hot to the
touch, not just one. When this happens the car seems to brake normally and
does not pull to either side when accelerating, driving at speed, or when
braking. I appreciate the great expertise on this newsgroup, does any one
have any thoughts or ideas? Thanks in advance.

Bob


To

 

Assuming an OEM part was installed I would lean towards a contaminated
system. Look at the seals on the master cylinder top and see if they are
swelled up to the point they protrude out. This would make the cap hard to
put on. If this is the case, it is contaminated.

Glenn Beasley
Chrysler Tech

 

As always, thanks for your advice Glenn. You are great about providing
advice and sharing your knowledge. I have never had an issue like this ever
before so appreciate the input all the more.

I removed the cap and the rubber seal in the cap appears to be fine. The
cap was easy to unscrew/remove and then reinstall. Fluid was still full and
looked clean through the translucent plastic reservoir. The master cylinder
appears to be slightly different in size and shape from what I recall. Not
sure whose part they used ... receipt does not indicate a name or part
number. The cylinder is stamped "7C E6K" on the front. A Google search on
E6K (7C possibly a date code?) and 7CE6K yielded nothing.

Just double checked the receipt and the vehicle has 1,200 miles since the
second MC replacement. So assuming they used the correct master cylinder
and the system is contaminated, what is the recommended remedy? An if not
the correct MC, what would cause it to build this pressure in the lines over
time?

Bob

 

I'd be curious, since there's no mention of the back brakes or wheels
getting hot, only fronts. did anyone check to see if the front calipers are
dragging or binding? is one brake pad in front wearing more than the other?
that might be a sign. like i say, i was just curious if that had been
looked into. I've had calipers drag due to a broken piston that would on
occasion tilt sideways a little bit and drag like hell.

 

I've seen this more than a few times on the LH platform, master cylinder
leaks fluid out the back, power booster is ruined by the brake fluid,
specifically the pushrod where it passes thru the booster diaphragm, it
gets corroded and won't allow full release of the master cylinder.

Do you hear a wooosh noise from under the dash when you press the brake
pedal?

 

If the problem was not there until they installed the master cyl, get your
money back or tell them to install a MOPAR part before going any further.

Glenn

 

Rob,

The calipers are functioning normally and do not bind. Both front brakes do
get very hot so both are dragging equally it would appear. The rears, which
are drum brakes are indeed cool.

Bob

 

Aarcuda,

Thanks for the additional thought. I'll report this to the mechanic and
will also report Glenn's instructions to only use the Mopar part too and see
what he says. That all said, the mechanic told me previously that the
leaking master cylinder was a pretty frequent occurrence on that vintage
minivan and said that they had replaced many of these over the years, but
never seen the problems they are having with my van now.

Bob

 

Glenn,

Thanks again for the thoughts. There were no other braking issues prior to
the preventive replacement of the leaking master cylinder.

As I just noted in my response to Aarcuda, the mechanic at this garage (who
I trust) told me they replace these fairly frequently and have never had any
previous issues like I am experiencing now. I'll ask them to look at the
brake booster for the damage/issue Aarcuda noted and if that does not pan
out, then ask that they replace the cylinder again with the Mopar part. I
am willing to pay the difference in the cost of the part, but will ask them
to eat the cost of the labor and re-bleeding the system since this is a
safety liability concern. I also have issues with my wasted fuel, wear and
tear on the transmission, and the worn out front pads and heated/warped
rotors, but this will also likely be at my expense.

They have been pretty good about this thus far, so I am hoping we can come
to terms on getting this fixed permanently.

BTW, Can you share any additional insight on why you feel that the Master
Cylinder for this particular vehicle (1999 T&C Limited) must be Mopar to
work properly?

Bob

 

The other suggestions are good but I wonder if the push rod is just adjusted
too tight. The lines are supposed to be open to the reservoir when the
pedal is released so that no pressure can build but if the push rod slack is
adjusted too tight the pistons in the master cylinder might not fully
retract and uncover the reservoir ports when the pedal is released. What
this does is since the brakes are dragging slightly they start to heat up
and the heat causes the brake fluid to expand but since the ports are closed
the expanding fluid has nowhere to go and the pressure starts increasing
which applies the brakes harder so they get even hotter and the pressure
goes up more in a positive feedback cycle until the pressure either forces
the master cylinder piston back far enough to uncover the port and bleed off
or until the brakes lock completely.

 

Because the first 2 aftermarket ones caused a problem!

 

Daniel,

Another good idea to pass on to the mechanic doing the work. Based on
Glenn's replies, it also could be that the newer (and after market) cylinder
requires adjustment when installed. Thanks for taking the time to reply.

Bob

 

I'll put my $1.50 on Daniel being right or the corrosion on the
plunger mentioned earlier being right. It sounds like the master
cylinder isn't being allowed to fully retract for some reason.

Steve B.

 

make dam sure that the the calipers slides and bushings are not seized not
allowing proper operation of the front brakes
also if the caliper slides on the steering knuckles are not cleaned and lubed
then the pad ends wear a groove in to the spindles and the pads get stuck in
that notch and the calipers can not retract properly
and there is stainless steel shimplates availble to repair that scenario
i have also seen pads punched out were the ends have burs that bind the pads
those burs need to be ground down flat so pads travel freely on slides

 

Thanks for the thoughts, but hits is NOT the issue. All calipers function
properly and the proper shims are in place and the guides and pins are lubed
and move freely. As I noted previously, BOTH front brakes seem to drag
slightly causing the heating ... but this only happens after extensive miles
are put on the vehicle. Driving around town for 5 miles and displayed fuel
mileage seems normal, the brake pedal is normal and the front wheels are
normal warm to touch. Drive 50 miles on stop and go highway (not
Interstate) and pedal gets high/tight, fuel mileage decreases noticeably,
and BOTH wheels are too hot to touch. Definitely some type of residual
pressure issue in the front brake lines ... probably related to heating. I
need to follow up ...others prior suggestions are the likely cause. Thanks
for the time to reply.

Bob

 

I wanted to post this message to close out my own post from several weeks
back regarding brake issues I had after the master cylinder was replaced on
my 1999 T&C Limited minivan.

I took the vehicle back to the garage where the previous work had been done
and gave them another chance to fix the issue. They told me that both of
the previous master cylinders had come from the local Chrysler parts counter
and that my VIN had been used to assure that they were indeed the correct
part.

Based on what Aarcuda and Daniel had suggested in this thread and with some
additional research from the Internet to support the diagnosis, I had them
go ahead and replace the brake booster too. We've now had the van back for
a week and a half and have noticed that the brake pedal feels better and we
have not noticed the back pressure that was occurring previously. We are
optimistic that this will fix the problem.

I speculate that the slightly leaking older master cylinder compensated
enough for the bad brake booster that this was not an issue prior to having
the master cylinder replaced. In any event, I just anted to close out this
post so that anyone experiencing this brake pedal back pressure and
dragging/locking front brakes in the future knows to look also at the brake
booster.

Thanks again to all for the valuable comments and ideas that helped steer to
this component.

Bob