Vacuum line

[wayne newland]

While tracing vacuum lines (why no action on the heater/ac controls) I
discovered that the tiny vacuum line from the block to the vacuum tank
was broken at the block end. It seems to be a special made up item.
Other than Cinnabar, is there another source? Is it wise to try to
cobble-up a replacement or try to get a special part? If you are
having dash control problems, get out your vacuum pumb and vac gauge and
go to work, before it gets cold. What started this was reading an
article in GMC MH News.

Wayne Newland F9300 75 Plam Beach

 

[wayne newland]

Emery

What I wound up doing was buying some 1/4 inch vacuum hose, spraying the inside
with W-D 40 and forcing the stubb into a 2 inch length and putting the other end
back onto the fitting on the intake manifold. Then I checked the vacuum at the
tank up front and was pulling 20 steady and getting about 19 out of the tank.
The funny part of this is I have checked all of the vac lines that I can reach
and they all work except for the heater control in the hot water hoses. When I
run the engine up to normal temp, the control still does not operate, but the
water is circulating hot. If I put a vac pump on the control, it works (back &
forth), but thus far not on the system. I taught cooling system maint to
mechanics for 10 years for the Wynn Oil Co and there is still strange things to
be learned

Thanks for the reply....you are the first

Wayne

> In a message dated 7/18/99 3:38:16 PM Eastern Daylight Time, wayne

>
> discovered that the tiny vacuum line from the block to the vacuum tank
> was broken at the block end. It seems to be a special made up item.
> Other than Cinnabar, is there another source? >>
> Wayne -- you can find this small tubing at almost any auto parts store. Its
> the same as that used for windshield washer line. You can also get a rubber
> adapter line to join it to the larger vacuum port at the manifold. Try Pep
> Boys if you have one near you. I bought new plastic line there when mice
> chewed through mine.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

 

[wayne newland]

Emery

Thanks for the suggestion about cleaning out the vacuum tank. Could I blow it
out without removing it?

The end of the vac hose (tube) inside of the dash goes into a 3-way plug. I
haven't tried to remove that end yet. What's involved?

Wayne Newland F9300 75 Palm Beach

> In a message dated 7/23/99 1:46:14 AM Eastern Daylight Time, wayne

>
> reach
> and they all work except for the heater control in the hot water hoses.
> When I
> run the engine up to normal temp, the control still does not operate, but
> the
> water is circulating hot. >>
> Wayne -- trace that line from the heater valve back up to the back of the
> dash panel and to the heater/air conditioning controls. It must have a leak
> somewhere. The problem with not fixing it is that you'll have heat all the
> time even when running the air conditioner.
>
> Also, you might want to take off the little black vacuum tank sometime and
> shake the water out of it. It sometimes collects condensation especially if
> you've had a vacuum leak somewhere.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

 

[wayne newland]

Emery

What started all of this, was an article in Cinnebar's magazine (Dec 98) about
no dash heat. Having taught cooling system maint for Wynn's, I borrowed a vac
pump from the co I used to work for and pumped the valve. It works like a champ
- - that is it goes back and forth. It doesnot work with engine vac. So I looked
a long time at the diagram in the book and came to the conclusion that there is
a heat sensor tied into the controls behind the dash. Ran the engine to normal
and still no action on the valve. I do have hot water going thru the heater
lines and heat coming out the dash vents. I can't hear a vac leak and I do own
a vac gauge. I have not been able to get a vac reading on the line to the
heater valve.

One good thing to come out of all of this - I found a vac leak at the block and
repaired it. Things should work better now. Now if I can just figure out that
heater valve.......

Wayne

> In a message dated 7/24/99 1:08:02 AM Eastern Daylight Time,

>
>
> reach
> and they all work except for the heater control in the hot water hoses.
> When I
> run the engine up to normal temp, the control still does not operate, but
> the
> water is circulating hot. >> >>
>
> Wayne -- you might have a valve that is stuck in the open position. Take it
> off and manually move the lever or else used a vacuum tester and see if the
> valve opens and closes. If you can't blow through it, it is closed.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

 

[wayne newland]

Emery

No vac at heater control end of vac hose, either hot or cold in any
position on the dash . The control does respond to a vac pump.

Wayne Newland

> In a message dated 7/24/99 10:35:58 AM Eastern Daylight Time, wayne

>
> I
> haven't tried to remove that end yet. What's involved?
> >>
> Wayne - I wouldn't remove the tubes from the heater controls under the dash.
> Put the control at heat and see if you have a vacuum drawing on the hose at
> the end where it attaches to the heater hose valve. Then turn the control
> off and check the vacuum at the same place. If this appears to work
> correctly then you might have a faulty heater hose valve.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

 

[mark grady]

For what it's worth -- and I realize these coaches are all the same but
different -- our '77 Kingsley only turns off the heater coolant flow with
the dash control in the MAX A/C position.

Some of these heater controls also apply vacuum (thereby turning off the
coolant flow) when the temp control is completely to the left.

Just a FWIW.

Mark

| -----Original Message-----
| From: owner-gmcmotorhome
| [mailtowner-gmcmotorhome]On Behalf Of
| EMERYSTORA
| Sent: Saturday, July 24, 1999 4:33 PM
| To: gmcmotorhome
| Subject: Re: GMC: Vacuum line
|
|
| In a message dated 7/24/99 10:35:58 AM Eastern Daylight Time,
| wayne

|
|

 

[wayne newland]

Mark

You're right...they are different. I have not checked the vac with the
blower in different positions. Maybe the hot water flow is there to feed the
heat exchanger on the hot water tank...no one has come up with that idea
(that I have read).

Wayne

> For what it's worth -- and I realize these coaches are all the same but
> different -- our '77 Kingsley only turns off the heater coolant flow with
> the dash control in the MAX A/C position.
>
> Some of these heater controls also apply vacuum (thereby turning off the
> coolant flow) when the temp control is completely to the left.
>
> Just a FWIW.
>
> Mark
>
> | -----Original Message-----
> | From: owner-gmcmotorhome
> | [mailtowner-gmcmotorhome]On Behalf Of
> | EMERYSTORA
> | Sent: Saturday, July 24, 1999 4:33 PM
> | To: gmcmotorhome
> | Subject: Re: GMC: Vacuum line
> |
> |
> | In a message dated 7/24/99 10:35:58 AM Eastern Daylight Time,
> | wayne

> |
> | | 3-way plug.
> | I

 

[mark grady]

Actually, I've posted that idea a couple of times.... It works great.

Use vac operated valves from an early Cad, they require vacuum to open,
rather than the reverse operation of the GMC valve.

|Maybe the hot water flow is there
|to feed the
|heat exchanger on the hot water tank...no one has come up with that idea
|(that I have read).
|
|Wayne

 

[wayne newland]

Emery

Thanks for the lession. That 's what I get for thinking out loud instead of
checking the manuel.

Wayne

> In a message dated 7/25/99 4:26:34 AM Eastern Daylight Time, wayne

>
> heat exchanger on the hot water tank >>
> No -- the heat exchanger is fed by its own hoses that are teed into the
> heater hoses at the engine. The water flowing through the heat exchanger
> does not flow through the heater.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

 

[wayne newland]

Emery

Thanks to people like you, I did not use any sealer on the vac repair. I just
lubricated the inside of the new vac line with WD- 40 and forced the stub into it
and am getting good vac at the tank

wAYNE

> In a message dated 7/24/99 1:03:25 PM Eastern Daylight Time, wayne

>
> block and
> repaired it. Things should work better now. Now if I can just figure out
> that
> heater valve.......
>
> Wayne
> >>
>
> Wayne -- there is a good suggestion on
> http://www.web-access.net/~bmassey/air_conditing.html
>
> Separating
> Hot from Cold
>
> You might have to lubricate the rotary valve seal in the heater control valve
> using silicone grease. If anyone has gone yo throttle body fuel injection be
> careful about using any type of silicone including RTV. sealants because
> silicone compounds sucked into the intake manifold can quickly ruin an oxygen
> sensor. I found this out the hard way.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM