1997 F150 brake problems
08-17-2008, 01:30 AM
#1
Junior Member
Thread Starter
Join Date: Aug 2008
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
1997 F150 brake problems
I'm having problems with a soft spongy pedal on my 1997 F150 extended cab. I've replaced the pads, shoes, master cylinder, brake lines, changed the brake fluid, etc. Just can't seem to get the spongy out of the brakes. It feels like air in the lines but I've bled them several times and it hasn't changed the way they feel.
Took it to a dealer recently because the brake light was on and wouldn't go off. They changed the ABS electronic controller and the light went off but still having the same problem with the brakes. The dealership said they had done all they could do and didn't have any more suggestions.
Anyone have any ideas?
Took it to a dealer recently because the brake light was on and wouldn't go off. They changed the ABS electronic controller and the light went off but still having the same problem with the brakes. The dealership said they had done all they could do and didn't have any more suggestions.
Anyone have any ideas?
08-17-2008, 03:55 AM
#2
I Voted For Bill and Opus
So your dealer didn't want to mess with an old truck, well a bogey hex on them. 
With everything you have done I think you will find the master cylinder (MC) is bad. First check to see if there is a track of Brake Fluid running down from the bottom of the MC. Just because you don't see anything does not mean it is not leaking there is a rubber boot the push rod passes through which will collect and hold most of the brake fluid that gets past the MC's seal, and you won't see it on the outside at all. I would not suggest rebuilding the MC yourself, not that it is difficult in fact it is very easy. the problem is the cost of the kit is almost as much as a rebuilt unit from the parts store, add the necessary cylinder hone and it will cost as much as a rebuild unit.
There is one more thing that can cause a spongy pedal, this isn't very common but a bad flex brake line can cause it. When a flex line is in failure mode it will make like a balloon when you hit the pedal. Inspect them to see if there is any sign this is happening, it isn't always easy to tell. If you find it is a flex line do your self a favor and replace them with braided metal flex line.
With everything you have done I think you will find the master cylinder (MC) is bad. First check to see if there is a track of Brake Fluid running down from the bottom of the MC. Just because you don't see anything does not mean it is not leaking there is a rubber boot the push rod passes through which will collect and hold most of the brake fluid that gets past the MC's seal, and you won't see it on the outside at all. I would not suggest rebuilding the MC yourself, not that it is difficult in fact it is very easy. the problem is the cost of the kit is almost as much as a rebuilt unit from the parts store, add the necessary cylinder hone and it will cost as much as a rebuild unit.
There is one more thing that can cause a spongy pedal, this isn't very common but a bad flex brake line can cause it. When a flex line is in failure mode it will make like a balloon when you hit the pedal. Inspect them to see if there is any sign this is happening, it isn't always easy to tell. If you find it is a flex line do your self a favor and replace them with braided metal flex line.
The picture below shows the boot and push rod mentioned above. you can see how the leaking brake fluid is eating up the boot.
Last edited by transmaster; 08-17-2008 at 11:02 AM.
08-17-2008, 04:41 AM
#4
I Voted For Bill and Opus
You would normally think if the pedal is spongy it is air in the system so you bleed, and bleed, and bleed ,
trying to find the air bubble. But what is happeing is the Master Cylinder is leaking fluid under pressure and this is what is causing the spongy pedal.
trying to find the air bubble. But what is happeing is the Master Cylinder is leaking fluid under pressure and this is what is causing the spongy pedal.
Last edited by transmaster; 08-17-2008 at 04:47 AM.