Where to check for vacuum leaks

[sparks57]

I have a very strong feeling I have a vacuum leak. While sitting at a stop light, when I am holding the brake pedal, the brake lights come on and the brake pedal gets really stiff.



Are there any other signs? I know if there is no vacuum, the vents won't switch over (although it does take a couple second for mine to switch), and the wipers won't work... so it can't be that bad.



It takes about 2-3 seconds for the brake lights to come on.



First of all, does this sound like a vacuum leak, and second of all, where are the vacuum hoses so I can check them?



What else might be the culprit if I can't find any leaky hoses?



BTW: This problem seems to get worse in the winter, it's happened ever since I got the truck.

 

[Grey Wolf]

Chris follow the hoses up from the Vacuum pump to the brake booster, they are fairly large lines. Pay close attension to the "T" that goes into the booster they are plastic and I had one crack on me. The crack was on the bottom so I missed until I took it off to check it! The rest of the lines branch off and go to the A/C doors, Anti Lock and cruise control... if you have one.

 

[sparks57]

Ok... I'm not sure what any of that is... but I'm sure I can figure it out when I go under there to look.



I can only learn how to fix things as fast as I can break them!

 

[Grey Wolf]

Well the power steering and vacuum pump are a unit, located under the injection pump. The brake booster is what your master cyl is connected to, it's a large reserve container. As soon as you see the large line that goes to booster the rest will come to you, just like you said !

 

[sparks57]

Cool! I know what you're talking about now...



Thanks!

 

["Mad Max"]

Chris - I had similar problems, traced it to the end of a vacuum hose that goes to a solenoid-looking thing about the size of a hockey puck that sits right up under the d-side hood hinge/spring location. Turns out the plastic nipple busted off and was not allowing the vacuum to build. I plugged the line temporarly and it fixed the problem, re-epoxy'd the nipple, and stuck the tube back on. Few months later I busted the nipple again fitting gauges and so I just plugged it again and haven't looked back. Not sure what the solenoid thing does but it doesn't seem to care... .

- Sam

 

[dpuckett]

CHris, I think the wipers are electric, thus vacuum has no effect on them.



Check the lines for rotting, cracks, etc. With 11 years, and God-knows-how-many miles, it is possible they need replaced.



Daniel

 

[prototech]

Hey Chris,

I've been fighting the same problem and it's driving me nuts!!!

I'm wondering if that hockey puck isn't a vaccum sensor for the brake system? it doesn't apear to do anything else. If this cold will ever let up, I need a day to go through the whole system and test everything with a vaccum gauge, hopefully this Saturday. good luck!! I'll let you know if I find anything!

Proto

 

["Mad Max"]

I'm not certain but with the hose disconnected from the 'puck' my brake light has not come on, so at least there's that. But it does make me wonder about what the puck think does... . I dunno, so long as the light stays off.

- S

 

[Grey Wolf]

The "Hockey Puck" monitors low vacuum you will notice an electrical connector on it. The connector will signal your red warning light to come on at low vacuum



This will happen if booster vacuum falls below a set point (8. 5 In of vacuum) for 10 seconds. I found this out working on my sons '90.