Brake issues with my 1990 F250

[condor74]

Ok the truck has been running great. With an old truck of course you have a few issues from time to time.

Here is the issue. The pedal is hard. It takes both feet to bring it to a stop some times. If you are driving down the road and hit the brakes, you have power assist. If you lift off the brake and then lean on it again the pedal is rock hard. I have already replaced the brake booster. It did improve it a little but still has an issue.

It seems that the problem is the vacuum pump. It seems so obvious now, I dont know why I didnt catch it before. I was thinking of when this started and it was a couple of months ago. I had just pulled the truck out of the back yard and was getting it running again. It now has a new transmission, new radiator, and while I was in there, I noticed that there was metal bracket with a pulley on it that was not stock and was vibrating and rattling. It was attached to the alternator bracket and was putting just a little bit of tension on the belt that runs from the alternator to the vacuum pump. I removed the added on tensioner and tightened the belts up. That is when the problem started. I am thinking of loosening the belt to the vacuum pump to see if it can build vacuum again.

Anyway. For the long term it looks like I will be buying a new vacuum pump....

 

['94IDITurbo7.3]

I would check to see if you are getting vaccum. if you are then it is probly the booster.

 

[Blind Driver2]

Make sure the old vacuum hoses are not collapsing

 

[subway]

i vacume gage is actaully a really good idea on this trucks it can let you know the condition of the pump before it goes out while towing your 5th wheel. they can actaully run and work for a while at a lower capacity and the driver is none the wiser until it bombs.

anyway i agree check your lines over or attach a gage directly to the pump to test before you just throw parts at it. most pumps are in the $100 range so ne need to spend that if you can avoid it.

for future ref there is a bolt under the head of the pump that you can remove to change the oil on them. its basically just a cam and two bearings in there.

 

[condor74]

Change the oil on a vacuum pump? I was not aware this was possible. Is it possible that if I took it apart and inspected and cleaned that i could maybe get it to work again? Just a hope I guess.

 

[Fordsandguns]

I would think that if the internal assembly is still lubricated and functioning that if you could get a new diaphragm it would be possible. I have heard of the diaphragm being replaced on one before to make it work.
I don't know about repairing the internals though.

 

[subway]

if the bearings are ok and the cam is not worn down it is possible to just replace the diaphram at the top. i think the trouble comes in where they usually wear out together if it was never serviced.

 

[condor74]

Well the vacuum pump is not completely dead. Maybe later tonight I will remove it and see what I can do. currently at idle it pulls 9 to 10 inches of vacuum. Spec is 21 inches

 

[Kevin 007]

I would also like to know how to change the oil on the pump.