Master Cylinder going bad?

[WES1977]

I've owned the 84 mini truck for about a year, and have been battling almost overheating at hwy speeds. It's not the fan clutch cause the PO put screws in it. I can get stuck in the mud for half an hour and still not over heat. but if i'm on the interstate my needle climbs high. I changed the rear brakes and test them out after the job and I still had the same problem, but i had a smoking gun per say. Both front disc where smoking, so i jacked up the front end and there was a lot of resistance. So I changed out the calipers and pads, changed out the lower radiator hose at the same time. So far I'm not getting hot but my lug nuts in the front our still pretty hot. And i can smell my brakes.

How much heat is acceptable or is my master cylinder bad?

 

[johnny4ever]

Wheel bearings? brake caliper components all good?

 

[WES1977]

calipers were replaced and i'm pretty sure they are still sticking. Is that the signs of a bad master or is there something i can do?

 

[x factor]

You might try changing the flex hoses to the calipers. If they are partially collapsed the could be holding residual pressure on the calipers.

 

[WES1977]

You might try changing the flex hoses to the calipers. If they are partially collapsed the could be holding residual pressure on the calipers.

Yeah, that's what my next step will be. I think it's the most likely.

 

[Vicm]

You could also check the brake boaster push rod , if it is not properly adjusted,it can cause the brakes to drag which seems to be your inherited problem.

 

[hankcamp]

Yeah your lugnuts shouldn't be getting hot what so ever. If you do end up doing a master cylinder look into a T100 swap. I hear there supposed to be great. Although I have no idea what your trucks specs are or what you use it for

 

[KLF]

You might try changing the flex hoses to the calipers. If they are partially collapsed the could be holding residual pressure on the calipers.

I have a pile of brake lines I'm gonna be tossing out, if you want them. Pay shipping and they're yours.

 

[WES1977]

Now to update the weirdness. Finally got the hoses from Napa and installed them today and the problem was still there. It got so bad I couldn't even drive in 3rd. When i got home the disk were smoking and I noticed the brake were real tight. So as i was getting a closer look at the smoking disk the truck just released and did a small roll fwd. So i jumped back in the truck and took it for a ride and could drive normal and no dragging noticed while driving. Drove down the hwy like 15mins and no problems except i need to bleed again cause it is now looser than when i bled. The lug nuts were only warm when i stopped the second time.

I'm wondering if i loosened up some blockage or something. not sure what is going on.

 

[flash02]

Think I've herd of line blockage were the hard lines were so gummed up the brakes would drag. Not sure if its worth it or not but you may want to remove the hard lines from the front and check to see if there is a ton of junk in them. Most people don't think that the brake system needs to be flushed every few years, dark brake fluid is just as bad as dark engine oil.

 

[WES1977]

Think I've herd of line blockage were the hard lines were so gummed up the brakes would drag. Not sure if its worth it or not but you may want to remove the hard lines from the front and check to see if there is a ton of junk in them. Most people don't think that the brake system needs to be flushed every few years, dark brake fluid is just as bad as dark engine oil.

Yeah, i've acually had that happen on z-28 before the line was too close to the header and made a blockage so bad it had to be replaced. The mechanic tried compressed air and still couldn't get through.

I'm not sure if the problem is going to return or not i'm going to flush out the lines with the current master cylinder and replace the master cylinder this weekend just to be safe. The repair manual says for sticking brakes to replace or clean the master cylinder in part of the troubleshooting section.