Vacuum problem!

[Deagle44]

I only have air comming from the defrost. So I replaced the Vacuum pump, still nothing. Lines behind the glovebox seem fine and lines going to resevoir and from pump seem okay. lines to hubs seem fine. my Auto 4x4 has never worked since I bought the truck either, and I know my one hub is not in great shape which explains the no auto 4x4 BUT vents were all working fine before, 4x4 never did. Any ideas? I've read a little about some sort of solenoid broken somewhere that might be the cause of it? I'd like to exhuast every option myself before I take it to the dealer to get fixed. Kinda cold out here and sucks to have no heat on my feet!!!

[dhanna6powerstroke]

See the black cylindrical piece just barely sticking up by the engine oil cap? Check to make sure there is a small grey vavuum line hooked to that.

[Deagle44]

just checked that line, it is still hooked up but when I turn the key on to start the pump there is NO suction or anything AT ALL at that line, should there be? I have no idea where to go next, how do I go about tracing down a leak?

[simonl]

hi there.. had the same issue not too long ago, if you check near you're vacuum tank, you will notice 2 (if I remember correct) little black hoses coming out of the tank and going to the solenoid.. Unplug the line that is going to the solenoid and plug it with youre finger, if the pump stops after a few secs thant you know youre problem is probably there or a least on the 4x4 side...
If thats the case, and you dont care about the 4x4 not working on auto (wich seems to be the case) you can by-pass the 4x4 by finding the vacuum hose that goes to the solenoid and plug.
that should fix you're problem

Simon

[Deagle44]

THANK YOU THANK YOU THANK YOU!!!! You are a genius simonl!!!! I had the bypass the solenoid completely and block of the line going into it, I think the solenoid itself is shot if I block the 4x4 line it does not work so with a new solenoid maybe I can have my auto 4x4 back as well!!! Been having this problem since the fall so excited to have this fixed! Man I love this site, have solved so many problems just from guys on here and have been able to pass the knowledge on as well!

[simonl]

GOOD JOB, now youre next step shoul be to by-pass the solenoid by putting the 4x4 line in directly to the vacuum ''bottle'' see if it shuts down, if not, youre going to have to disconect the vacuum line at every connection point and plug it with youre finger to see where exactly is the vacuum loss... first connection is over the front passenger axle right behind the plastic wheel well... from there, there is a ''Y'' that redirects you to both weels indepently... just disconnect and plug with youre finger at each section.. you will know a least where youre issue is....
In my case, the driver side seal was busted so had to get everything off to change that.. took about 2-3 hours but now everything works except I think I now have a leak on the pass. side.... well hope this helps.. if you need anything else..
you can always p.m. me

Oh and my solenoid was also shot.... total fix was about 100-150$ on parts

Simon

[Deagle44]

sounds good! I'll check for leaks sometime when I feel like undertaking it that is! I think it may be just the solenoid, when I plugged the line at the first joint nothing, there is only a 12 inch section of hose from there to the solenoid so bypassing it completely should tell me.