Brake rear drums overheating on My LC 80 series '90 GX model has been having reoccurring left side rear overheating after driving for 2-3 hours in traffic. It has been worked on many times since the lastest attempt both sides heated to about 100-110+F on the rim with the right one the hotter. The wheel cylinders have been replaced, the brake shoes, bearings and seals on the left side in the hub with the springs, self adjuster and cable in the drum, the front disc pads also. There has been some engineering: welding on the lh rear axle diff tube which was done. The problem stressed out the last mechanic any help is greatly needed. He wants to replace the master cylinder next. Remove self-adjuster mechanisms is it a possible fix? Stumped on what to do next ? Does anyone know a car exorcist with long distance abilities?
How about the flexible hoses? They can develop internal blockages that keep the brake engaged with your foot off the pedal.
As for the self-adjusters, do they over-adjust? That’s easy to check.
I’m puzzled. 100-110F, even on the rim, after 2-3 hours driving doesn’t strike me as all that hot.
Thanks for the input. I think the flexible hoses could be checked but they go to the disc brakes on front wheels. Not the rear ones with the brake shoes where the heating is or am I not knowing how those would be connected.
The self-adjusters do that probably over-adjusting, so how do I check that? That last mechanic changed the adjuster star assembly with most the parts in the LH inside parts were not new already.
You DO have flexible hoses in the back. They’re just not located directly at the wheel cylinders. Follow the steel lines back and you’ll come to them.
Sorry to puzzle you; the drive was broken in two parts with an hour or two in between that would of cooled them off. That was like probably only 45-60 min. return trip.
I’ve felt the wheels on my cars many times over the years. Even after only driving a few miles they feel warm. 100-110 F is only a few degrees over human body temperature. Brakes work by friction which generates heat. These temps seem normal.
How do I know if the hoses are messed up internally. I’ll check to see them when it gets light in the morning. Thanks are those hoses on front of the rear diff? I only remember the metal lines when trying to remove the left brake drum and adjusting them off so they would not drag or bind the wheel.
The temps could be off some since I took the thermometer out of the freezer to test them. They were uncomfortable to almost burning my fingers to make contact through on the rim or to get to the brake drum.
No good way to check the hoses, I’d just replace them. Are you is the US?
There’s only one brake hose to the rear brakes.
It connects from the solid brake line under the vehicle to the tee-fitting on the rear differential. Then the two solid brake lines go from the tee-fitting to the wheel cylinders.
That’s the hose you want to replace.
Tester
Brake shoes normally have a slight drag on the drums and would produce some negligible heat and if the rear wheels can be spun by hand immediately after repeatedly stomping the brake pedal with the rear axle raised it is unlikely that there is any problem.
Thanks tomorrow a friend and I will try to replace the rear one and maybe do the front two also. Oh texases I am in Nairobi Kenya but am from the US.
I would do one do them all. That way you only have to bleed it once and you have peace of mind.
Tester, as usual, is correct…Old brake hoses can swell up inside, blocking return fluid flow… When you apply the brakes there is enough pressure to force open the degraded hose but then the hose collapses inside, blocking the return flow of fluid and holding the brakes engaged…
An easy test. With car supported on a lift or jack-stands, remove both rear drums and CAREFULLY have someone apply the brakes while observers watch the brake shoe movement. Don’t overdo this…Then release the brakes and see if the shoes return to their proper resting points, tight on the centering pin. If they do not return, open a bleeder and see if they then return properly. If so, replace that flex-line… On a 25 year old vehicle, I would replace ALL the flex lines…
With all due respect to @Caddyman…as he said…“An easy test. With car supported on a lift or jack-stands, remove both rear drums and CAREFULLY have someone apply the brakes while observers watch the brake shoe movement. Don’t overdo this.”
If you press too far on the peddle, you will push the pistons right out of the wheel cylinders.
This will cause you to need to remove both cylinders and rebuild them. You can still use the old parts, because as you said they were replaced recently. But it’s time wasted to remove them…clean everything up, reassemble, and mount them back on.
Yosemite
Point taken…
I’ve done that a few times myself.
You go press on the peddle, and forget that you took off one of the drums for some reason.
As a matter of fact…I’ll admit…I did that about two months ago.
I forget the circumstances now, but I had to remove everything to get the wheel cylinder out and get everything cleaned up and back together.
Another 45 minutes that I could have been napping!!!
Once time I was waiting on brake drums to be delivered. Had everything else together and I could slap on the new drums, put the wheels on and I’d be done.
While waiting I remembered that the owner wanted me to check the serpentine belt because it squealed on a rare occasion. I hopped in and instinctively stepped on the brake to start the engine.
Brake fluid was gushing out and everything had to be redone and cleaned up.
Yep…I’ll admit it, I’ve done that!!!
Yosemite
I recommend pumping the brakes with the drum on so that a significant pressure is put on the hose to increase the likelihood of causing the hose liner to collapse and block the return flow. And when the pedal is pumped hard several strokes and released the wheel should be free to turn immediately.
And as for replacing all the hoses front and rear I would rarely do that as hose failure is a somewhat rare problem for me to find. Of course contaminated brake fluid would cause me to replace every rubber component but the greatest cause for brake hose failure is letting the caliper hang on the hose and flipping the caliper hose over into a kinked position, both mistakes by DIYers who don’t know better and Pros who don’t give a ----. I have cut collapsed brake hoses and found the liner to be soft, stretched and easliy wadded up even with light finger pressure.
And, believe it or not I was at a McParts store nearby and the middle aged man ahead of me asked for bulk 1/4" brake hose and hose clamps and when the clerk said they didn’t stock the hose and had no listing for it the man asked for transmission cooler hose. I was curious and asked what he was using it for and unbelievably he said his ultralight airplane had disc brakes and the hoses were leaking and none were available so he was replacing the failed rubber section himself. He blew me off when I insisted that the hose wouldn’t hold the pressure or survive the brake fluid.
In addition to replacing the rear flexible hose, here’s another possibility-
Is it possible that the rear brakes are doing ALL of the work? Perhaps the proportioning mechanism is stuck and only the rears are functioning?