Ford Super Duty (1999-2016) :: Vacuum Leak Under Dash Under Acceleration
Dec 4, 2015
I have recently developed a vacuum leak on my 2002 F-350 V-10 under the passenger side of the dash. It is only audible when I am accelerating moderately to heavily or when the truck downshifts going up a hill. None of the vehicles HVAC or ESOF functions seem to be affected by this leak from what I can tell, but it's rather annoying to listen to this loud sucking noise every time I hit the gas moderately hard such as climbing a hill or merging onto the freeway. I don't know how I could search for this leak since it only happens when I'm driving and accelerating and not at a stop. What might be going on or where I should begin my search?
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How to diagnose a vacuum leak without a vacuum leak diagnostic tool.
My ESOF won't engage, AC/heat blowers default to defrost - classic symptoms. And while we can leave without AC/heat, we really need the ability to engage 4x4 low, especially as we get higher into the Andes and the roads unsmooth.
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When I put my 06 f350 in 4x4 my ac defaults to defrost. I assume this means a vacuum leak. My question is, is the white tube supposed to be open for air intake or plugged off with something?
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So I have an 05 f350 5.4 with the shift on the fly and the auto/manual locking hubs.. I already know I have a leak with the vacuum and I just use the hubs manually, then shift on the fly to activate the transfer case.
I went to use the 4wd the other night in a snow storm and I have no 4wd, light on the dash comes on and i can hear the transfer case clicking in when i hit the switch between 2wd and 4wd.
So I got under the truck while it was on the ground and manually locked the passenger side, Then tried spinning the axle and it wont spin freely, so obviously its locked.
Tried the same thing on the driver side and the axle spins freely while the hub is locked, So obviously the locking part of the hub is no good... So i guess my question is, even with just 1 wheel locking in the front, shouldn't I pretty much get 3wd? or am i missing something...will it not engage at all because both sides arent locked?
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I noticed that my 4WD is only working now when I manually lock the hubs in (they have that options!), and the air blows out the defroster when I shift, so it looks like I have a vacuum leak. Where are the typical leak points on a 2006 F250? What's the best way to confirm a leak (other than just replacing all of the hose)?
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2002 F250 SD 4X4 5.4L. 4.5 inch pro comp lift tire size 305/75/R16. K&N cold air set up. 208,000kms
I know the truck does horrible on gas but lately is been getting worse, maybe I am getting 350km to a tank. Mixed highway city driving. Sounds like I might have a vacuum leak somewhere but I have no engine light. I've had the truck since last year and put about 10,000km. on it done regular oil changes .. brake maintenance no motor work so far.
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I have 2 issues and wonder if they are related. I don't have a CEL but I'm getting a P0442 DTC with my code reader - EVAP system leak detected
Also, my ESOF doesn't work. The hubs will lock manually. Can this be related?
I've already cleared the code and it came back. My ESOF hasn't been working for a while but I just haven't had the time or motivation to look into it until now.
I tried the HVAC Test and there may be a slow leak in the system. I can get the vents to switch from defrost to face vents but it switches halfway back to defrost, both are on at the same time for 20 seconds, then it recovers and goes back to the face vents.
My 4wd relays seem to work as well.
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My 1999 F 250 5.4 liter. I know I have a vacuum leak because whenever I accelerate the air conditioning coming from the vents switches to the defroster. So my question is how do I go about finding the leak? My hubs in the front are manual so I know I don't have lines going up there. I do have some mechanical capabilities I've changed water pumps alternators brakes etc. But never anything with vacuum lines or a/c.
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I'm from SC where we are currently getting our rainfall for the next 3 years, so it's an occasion to find leaks. My 2001 F250 has developed one right in the middle of the passenger side dash, I saw it running down a white vacuum tube and dripping off to the floor mat. Is there a place in the cowl that will hold water and leak?
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My heater vents have been acting up. I have read that there may be a vacuum leak that causes the blend doors to default to defrost...
Where the vacuum line fails? I have ESOF 4x4 and that is still working. I think there may be a correlation between engine vacuum and my vents: at cruising or idle the vents work ok (not perfect) and under acceleration (less vacuum) the dash vents stop blowing.
I thought that the blend doors had their own vacuum pump, so I do not know why things change at different amount of throttle?
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I recently purchased this truck and have towed a couple of times with it. It has 98,000 miles and I do not know if the automatic transmission fluid has been changed. Should I have it flushed or drop the pan and change it? I have a lift so doing the change is no problem, although it might be worth it to pay a transmission shop to do it.
Also, I hear what appears to be like a heat shield rattle or something that sounds kinda like an exhaust leak during loaded acceleration. What to look for to locate the noise? One last question, the air bag light is on sometimes then off sometimes. Any known air bag light issues? I love the truck, hate the gas mileage!
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I have a 2001 f250 last night we had a good rain and this morning as i was backing down the driveway water came running down the passenger side floor board from under the dash i cant seem to find where it came from on the inside and can not find any standing water under the cowl where could it be coming from?
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How and where to check? This probably has been covered a million times.
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I have manual hubs on my truck. Can I pull those vacuum lines and plug the holes?
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I have a V-10 in my Y2K F-250. Under the throttle body there is an elbow on a vacuum line that is badly cracked. I went to parts store and bought a heater line that fit both ends (different sizes) but isnt the exact angle of the original. It fixed the hissing vacuum leak but now it is running pretty rough. Doesnt seem to be pinched but it's definitely different. The poor performance during acceleration wasnt a problem before but is very noticeable now. Could the line being different effect the performance?
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2002 F-250 SD XLT V10
While rummaging in my garage a couple of days ago I stumbled upon a vintage Stewart Warner mechanical vacuum gauge. I would like to install it on my truck.
My question is: Where is a a good connection point for the vacuum line? Detailed direction/photo preferred as I am both Ford and V10 engine challenged.
Same question with respect to following gauges:
Volt
Oil Press
Water Temp....
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Truck has been neglected for a while so this upgrade/repair I installed Powerstop brake rotor, caliper, bracket and pads. New Timkin wheel bearing, Moog U-Joints, and new inner/outer axle seals. Also replaced all the brake hoses and the remaining original rusty brake lines. About a month before I replaced the failed Auto/Manual vacuum operated locking hubs with Mile Marker units, which do not need the vacuum line, the drivers side was missing. and was letting water into the wheel bearing. So I decided to plug them and remove the vacuum lines from under the hood as well.
If there is interest I can get pictures of the vacuum lines, and what I changed under the hood. That was pretty self explanatory.
Could not find a google search for the thread size of the vacuum nipple in the knuckle. It is a 3/8"-24 fine thread.
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I don't have any leaks at the moment, but after inspecting my vacuum lines they're starting to look brittle and I want to replace them proactively. Is there a kit to do this or should I just cut a section off and take it in to an auto parts store to match the size, and buy it by the foot?
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So my auto locking hubs have not been working for a couple years and I have just been locking them manually as needed. But now I have a boat and I like putting the truck in 4x4 at the landings just for added safety. It's difficult to manually put the truck in and out of 4x4 for just a few minutes when I know I have auto hubs. Plus I recently got aftermarket rims and they cover the manual locks, which can be accessed with a screw driver, but again, tough.
So today I bought the vacuum solenoid valve, whatever its called, and installed it, and they work! But the vacuum pump will not shut off while the 4x4 is engaged. The auto hubs work, my a/c controls work, everything works fine, the only symptom is the pump not shutting off. My a/c stays right where I put it, it doesn't go into defrost or anything, not even for a second, like it used to when my solenoid first started failing. Is the pump running normal? Or is there a leak on the other side of that solenoid? Should I even worry about it if everything else is working?
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Having trouble with vacuum on my '06 CCLB V10. I only lose vacuum while towing, not sure why. Lines all seem like they're fine. I have no issues while unloaded. What could be causing this?
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I have a 2004 F-350 diesel. My vent selector is always on defrost so I suspected a broken hose but traced all out and all seem to be fine. I disconnected the line coming from the pump to the tank and no vacuum. The pump doesn't seem to be running but it's hard to tell with the engine noise and vibration. What tells the pump to run and how can I bench check it?
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