Explain This???/
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Senior User
Joined: Dec 2003
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From: fl
Explain This???/
For the past 18,000 mi my truck has been making a roaring sound under hard acceleration. First I thought is was the fan staying engaged(bad clutch). It wasn't that. ,,,Next I thought it was the turbo going.............it wasn't that.
also along with the roaring sound, idle was rough and there was hesitation along with HARD shifting. I mean BAM every time it changed gears when I got on it. ........It started running crappier and crappier. Figured the Banks Chip was going bad so I pulled it. No change. Also was ready to take truck to the tranny shop.
Today I noticed the vacum line was dry rotted to the passenger hub. Since I have manual hubs I decided to just cap off the lines on both sides along with the hubs.
Since I did that the truck runs like a NEW truck. All of the above problems DISAPPEARED.
How could a bad vacum line cause all of those problems??? Or affect the ECM
Could it be a coincidence??????????
also along with the roaring sound, idle was rough and there was hesitation along with HARD shifting. I mean BAM every time it changed gears when I got on it. ........It started running crappier and crappier. Figured the Banks Chip was going bad so I pulled it. No change. Also was ready to take truck to the tranny shop.
Today I noticed the vacum line was dry rotted to the passenger hub. Since I have manual hubs I decided to just cap off the lines on both sides along with the hubs.
Since I did that the truck runs like a NEW truck. All of the above problems DISAPPEARED.
How could a bad vacum line cause all of those problems??? Or affect the ECM
Could it be a coincidence??????????
Laughing Gas
Joined: May 2007
Posts: 1,100
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From: Davis, Ca.
You would be surprised how much a bad vacuum line could affect the engine. I left one off one time on a little car and it ran like crap. Finally found the line put it on and everything ran great.
Posting Guru
Joined: Jul 2004
Posts: 1,777
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From: Buckingham, IA
That's a strange one. I'm trying to think of any way that the vacuum leak would affect the operation of the engine and can't come up with any. The vacuum system is totally separate from the engine. We'll see if someone can come up with something.
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Senior User
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From: fl
Reminds me of the time when I swapped out the alternator. Later that nite when I turned on the headlights, they both blew at the same time, Thats never happened since.
The only other thing I can think of is the build date on motor is the same as my Ex-wife's birthday 2/19
Elder User
Joined: Nov 2008
Posts: 668
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From: Northfield, MI
No mass air on the 7.3
As stated, the vacuum system is only for the HVAC and hubs.
With a very large vacuum leak, your HVAC would not switch doors correctly and would keep the recirc door open, which would make the blower motor sound loud. Are you sure it wasn't just the blower motor?
As stated, the vacuum system is only for the HVAC and hubs.
With a very large vacuum leak, your HVAC would not switch doors correctly and would keep the recirc door open, which would make the blower motor sound loud. Are you sure it wasn't just the blower motor?
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Hotshot
Joined: Jan 2008
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From: Rochdale MA
No mass air on the 7.3
As stated, the vacuum system is only for the HVAC and hubs.
With a very large vacuum leak, your HVAC would not switch doors correctly and would keep the recirc door open, which would make the blower motor sound loud. Are you sure it wasn't just the blower motor?
As stated, the vacuum system is only for the HVAC and hubs.
With a very large vacuum leak, your HVAC would not switch doors correctly and would keep the recirc door open, which would make the blower motor sound loud. Are you sure it wasn't just the blower motor?
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
These are diesels and have no manifold vacuum, or any other kind for that matter.
A bad vacuum line will have NO effect on a 7.3 engine's performance.
As others have said, it might affect your air conditioning or ability to auto-lock the front hubs, but nothing to do with the engine.
Different fuel, different ignition, different performance, different thinking.....
Pop
Laughing Gas
Joined: May 2007
Posts: 1,100
Likes: 0
From: Davis, Ca.
vacuum
But that was on a gasoline engine.
These are diesels and have no manifold vacuum, or any other kind for that matter.
A bad vacuum line will have NO effect on a 7.3 engine's performance.
As others have said, it might affect your air conditioning or ability to auto-lock the front hubs, but nothing to do with the engine.
Different fuel, different ignition, different performance, different thinking.....
Pop
These are diesels and have no manifold vacuum, or any other kind for that matter.
A bad vacuum line will have NO effect on a 7.3 engine's performance.
As others have said, it might affect your air conditioning or ability to auto-lock the front hubs, but nothing to do with the engine.
Different fuel, different ignition, different performance, different thinking.....
Pop
Posting Guru
Joined: Sep 2004
Posts: 1,616
Likes: 3
From: Sapulpa OK
I am a manual transmission guy but is the automatic trans controled by vacuum? If you have a vac. leak it will not shift properly. I remember my old '86 F350 with a 6.9 and C6. It had a vacuum modulator on the throttle linkage and if it wasn't adjusted right it would do all kinds of things.
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Nope. Nothing on the tranny is controlled by vacuum, either.
All electronic, with sensors to determine load, throttle position, RPM, etc.
Microprocessor determines when you should be shifting, but there's some really smart programmers at Ford behind the scenes writing lookup tables.
Pop
All electronic, with sensors to determine load, throttle position, RPM, etc.
Microprocessor determines when you should be shifting, but there's some really smart programmers at Ford behind the scenes writing lookup tables.
Pop
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Senior User
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From: fl
Opinions ???????
Thread Starter
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Senior User
Joined: Dec 2003
Posts: 331
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From: fl
After 2 days of perfect running the symptoms are BACK. Could the EBV be causing them???? (read 1st post please)
I do have a brand new Flex Fan to install to see if the fan clutch is causing the problem. Question: Is the nut on shaft clock wise to losen. (opposite of what you normaly would do)
I do have a brand new Flex Fan to install to see if the fan clutch is causing the problem. Question: Is the nut on shaft clock wise to losen. (opposite of what you normaly would do)