2005 Caravan or Town and Country 300,000 Miles. My son worked on this as I watched. This was previously my vehicle. Ended up giving it to a widow. She brang it to my son cause it was driving funny for a week and front brake squeaked. Didn’t find any obvious signs of brake problems, but pads were 80% down so we put some new front pads on that I had kicking around in the garage (correct pads). Did not change rotors. I checked the oil and it only had 1.5 quarts in it. I lectured her about checking oil. My son seated pads. When he got back the right rotor was 250 degrees F, left 120 F. He probably got too aggressive seating pads. Checked that wheels released when brake pedal was released, no problem. I drove it to try and cool rotors And no symptoms. The rotor temperatures were still different, so I told her to go home so rotors can cool and come back tomorrow and I’ll check rotor temps. She came back and temps were equal and normal. Sent her on her way. Next day the right side rotor overheated. Brakes still released when pedal is released. So my son replaced pads and rotors. Next day left side overheated. So son is going to change out hoses. My question is what am I missing? Everything seems to be functioning properly and I’m still chasing diagnosis and getting frustrated. This should be simple. At this rate we are going to replace everything from rotors to master cylinder before we find the problem. The master cylinder would affect both sides at once, right? Any advice on what we missed is appreciated.
P.S. as I was typing this I realized that I didn’t inspect the hubs for Michigan contaminates when my son worked on it. This used to be my van, and I always put a light film of anti seize between hub and rotors, but there still might be hub corrosion. I’ll check run out today. Any other thoughts?
+1
And, when the master cylinder is replaced, be sure to flush the system and refill it with the correct-spec brake fluid. The overheating brakes almost surely “cooked” the brake fluid.
I’ll be sure to check the hoses first. Thanks. I didn’t know the master was split left to right. Thanks for the education. Time to teach son bench bleading.
When dual master cylinder systems were first introduced, one circuit was for the front brakes and the other was for the rear brakes. However, this can lead to handling instability if you have to brake very hard when one brake circuit is cut, and if one has to rely on just the rear brakes, the braking distance will be loooooong.
IIRC, Saab (or maybe it was Volvo??) was the first to introduce the diagonally-split layout for brake hydraulic systems, and–eventually–other manufacturers followed suit.
Ok, even though the master splits left to right, could the fault switch sides? I would think if one side looses or doesn’t get pressure, it would remain on the same side all the time.
Years ago I owned a 1988 Olds Ciera. I had a front brake that was overheating. At my local NAPA the trusted parts guy suggested it might be the hose collapsing on the inside, trapping fluid. The hose can look perfectly good on the outside but damaged inside. Long story short that’s exactly what it was.
I remember talking to a mechanic and he swore up and down that couldn’t happen. In my opinion he just hadn’t run across it before. So when I hear of dragging calipers or hot brakes that’s the first thing I think of.
With this sort of problem I’d be inclinded to just bite the bullet & replace the easily replaceable brake components with new , MC, calipers, rotors, flexible hoses. If you feel the problem is limited to the front brakes, start there, maybe that’s all you need. If problem remains, next up is the booster and the front/back pressure regulator. Before going down the entire road, a simple vacuum hold test on the booster makes sense.
Note that on some newer vehicles a special bleeding procedure is required to get all the air out, often requires a pro scan tool.
I think everyone is missing the part that this started after the sone replaced the pads and then the right rotor got hot, then the sone replaced them again and this time it was the left rotor getting hot…
That is a classic twisting the caliper and kinking the brake hose…
George, it is much easier and cheaper to CHECK for a twisted hose then to just start throwing parts and money at it hoping you find the problem… Heck you don’t even have to raise the vehicle or pull a wheel to do it…
She just got here a little while ago. Hoses are not twisted. Rotor temps are good and equal. There is .0005" to .001" run out on left. .007" run out on right. Son is now changing left hose. When he’s done with that, he’ll take the right caliper\bracket off and we will find the run out problem. Then replace hose. I guess I’m just going to chase this with parts until the master cylinder. I’m also beginning to wonder about the info from the widow. But I need to be sure about the brakes before I give a green light.
I suspect the left brake rotor is cold because the rotors were not resurfaced. The rotor surface is not flat, and the pad does not have full contact with the rotor surface. It could take more than 100 miles for the pads to match the rotor surface.
How hot? 800 degrees? 1000 degrees? Rotor turned blue? Pads show signs of heat damage?
Seems like you have been told to replace the whole brake system before we know what the problem is.
Just make to to replace both hoses if replacing one… The flow rate can be different from an old hose to a new one… I learned that when doing hydraulics on really big forklifts (Lulls)…lol
Thank you. The right rotor got presumably so hot, the rotor warped enough to cause vibration while braking. This may have not been the case. Just now I told him to clean hub. He did and runout went to .003 - .004. So I cleaned the hub properly and got the run out under .001. As far as how much they overheated, I’ve never seen it get above 300 degrees. She said they got smoking hot. I’m beginning to think with pads and rotors properly installed and 2 new hoses. The problem may be resolved. We’ll see.
Without reading, best practice is to clean and lube the caliper bolts. The inner pad can rub on the rotor even though you think it is releasing. But yeah, sum ting Wong.
All back together. Test drove 7 miles, braking occasionally. No air in system. LF 350 degrees, RF 300, both rears 200. I like it. Son overfilled the PS fluid the other day. I noticed it sprayed out and got on engine and smoke exited right rear well which explains why she thought the right front was smoking hot. So I can safely assume that the problem didn’t switch from side to side. I think my son learned that although brakes are simple, you need to be meticulous on whatever you do, especially in salt country . Thanks for all your input. I learned a thing or 2.
