Vacuum Leak??

[Crazy Cowboy]

I'm thinking my 7.3 has a vacuum leak SOMEWHERE.... My automatic 4WD is not locking in and my A/C blows cold BUT it only works on defrost no matter what position the knob is (Max, A/C, Vent, etc..) which makes me think there's a leak somewhere. Also, isn't the wastegate controlled by vacuum? If there's a leak somewhere wouldn't it affect that in negative way?

I know very little, barely anything, about diesels or turbo engines as I deal with Vettes - but I'm learning!! And I love it!

 

[99250]

The a/c selector switch and 4wd are run by a electric vaccum pump on your passenger side fender in the engine bay. the wastegate is run off the intake horn. pop the hood look at the red line comming from the wastegate and that will explain that it wont hurt anything there. but the vaccum pump may not be working or maybe something came unplugged? let us know

 

[Crazy Cowboy]

Cool!! I will check out that electric pump.... is there a fuse for it somewhere if it's not working or is it common for them to burn out? Thanks a million!

 

[99250]

Im not sure if there is a fuse or not if you have your owners manual look in there if not i will search mine and try to see.

 

[Tbar]

Turn the key on and listen for the vacuum pump buzzing on the passenger side fender well.

Be sure to check the vacuum hose on the hubs. It is very common for these to dry rot.(hose on rt in pic)

Finally, inspect the orings on the 4x hub.


Tbar

 

[drmjf]

I'm thinking my 7.3 has a vacuum leak SOMEWHERE.... My automatic 4WD is not locking in and my A/C blows cold BUT it only works on defrost no matter what position the knob is (Max, A/C, Vent, etc..) which makes me think there's a leak somewhere. Also, isn't the wastegate controlled by vacuum? If there's a leak somewhere wouldn't it affect that in negative way?

I know very little, barely anything, about diesels or turbo engines as I deal with Vettes - but I'm learning!! And I love it!

Cowboy, check under the glove box. I had the same thing happen this summer. My sons size 13 shoes kicked the vacuum connector off. Plugged it back in everything fixed.

 

[Crazy Cowboy]

Going out to check those things right now. You guys are the best!

 

[Crazy Cowboy]

OK, well.... the pump is running. I unplugged the hose from the vacuum side and put my finger on it (the one that goes to what I believe is a vacuum canister??) and the pump stopped until I removed it. It runs constantly when it's connected to the hose though. There's a white/yellowish nipple right next to that which I believe is the exhaust port??

Checked the hoses on the hubs and they are connected and can't hear or feel any leaks. I checked behind the glovebox and the clear plug with a black and a white vaccum hose are connected. Didn't see any other ones. Unplugged them and there was no vacuum on them though. I'm lost! Must be a leak or unplugged end somewhere that I'm missing! I see there's a gray line going from the pump to the firewall which is probably for the A/C but all I found inside was a white and a black line behind the glovebox. There's also a line going to right above the passenger side valve cover, connecting to something that sits on a rubber hose about the size of a heater hose.

Any ideas or methods for tracking down the culprit? I may have to isolate them one at a time and see which one causes them to stop working.

 

[Tbar]

I couldn't see my cracked hose at the hub until I pulled it loose and inspected it..............


Tbar

 

[Crazy Cowboy]

OK, good idea! I noticed on the highway today that the dash vents came on for a little while.... guessing a cracked rubber line would be a possible problem. Think I'll just replace all 4 hub lines for a few bucks, until I get the Warn hubs. Then I'll just block them off up top.

Will keep ya posted on the outcome