vacuum problem
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
luthrebediesel,
Welcome to FTE and the IDI forum.
I am going to stay silent, I know very little about automatics.
We have several users here that are good with them though, they should be along shortly.
Welcome to FTE and the IDI forum.
I am going to stay silent, I know very little about automatics.
We have several users here that are good with them though, they should be along shortly.
Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
How does a VRV work. I know that the modulator valve has to have vacuum on it at all times unless ur getting on it. So if one side of the VRV has supply and one goes to the mv, even when ur getting on it its still gonna have vacuum when u open her up cause theres no where for the vacuum to go. If the VRV is completely at rest should vacuum be able to flow through it? Im working on a truck with the same problem. If i floor it it changes like ur just tooling around but when i too; around it winds up. WTF?
Senior User
Joined: May 2008
Posts: 198
Likes: 0
From: I live in Tennessee
I completely rebuilt the engine. I removed the engine and had the block sleved. After examining the vrv closely i saw that it was labeled trans and vac and i did have it right. When i tore it down to rebuild it i just took the ip off and laid it in the back and never adjusted anything. Why does the diesel c6 also have that rod on the kickdown i thought if you lost enough vacuum it would kickdown anyways. Its a retired uhaul if that helps. U haul does some weird stuff.
Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
The kickdown rod and the VRV operate independently, no connection except through the throttle linkage. Vacuum failure has no effect on the operation of the kickdown rod. I never used the kickdown rod with my driving style, and have heard of some simply disabling it altogether. Normally the VRV is quite effective at timing the shifting.
From what you are saying, the truck has done this since you got it, correct?
Have you inspected the inside of the vacuum line from the transmission to see if there is ATF in there?
Have you checked the vacuum system to make sure you have enough vacuum? lack of power brakes, for example, could indicate low vacuum.
From what you are saying, the truck has done this since you got it, correct?
Have you inspected the inside of the vacuum line from the transmission to see if there is ATF in there?
Have you checked the vacuum system to make sure you have enough vacuum? lack of power brakes, for example, could indicate low vacuum.
Senior User
Joined: May 2008
Posts: 198
Likes: 0
From: I live in Tennessee
im going to test it tomorrow according to james and see whats going on. Ill be testing the vacuum pump output and the vrv output. I got a pump and a gauge from oreillys today maybe their cheap crap will work right. oh and now it hasnt done this all along just after the rebuild
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