Home » Public Forums » GMCnet » JC-4 Vacuum Pump?? (maybe you don't want to bet your life on it!)
| Re: [GMCnet] JC-4 Vacuum Pump?? [message #323861 is a reply to message #323860] |
Wed, 13 September 2017 22:24   |
Jerry Wheeler
Messages: 246
Registered: January 2013
Karma:
|
Senior Member |
|
|
Why not do the test with the ignition left on?? Perhaps our coach will
stop with the pump running. If my motor dies, I would not turn off the
ignition switch; I would want to be able to steer the coach when rolling,
even if I did not have brakes. By the way, I have the Delco vacuum pump
that is not longer available, but I have not tested my brakes; I have my
vacuum pump wired to a separate source for 12v, not the ignition switch. I
probably should do the same test you did Richard.
JR Wheeler 78 Royale NC/OR
On Wed, Sep 13, 2017 at 10:36 PM, D C _Mac_ Macdonald
wrote:
> I wonder if anyone has done a similar test using the European Ford (Azure
> ?) vacuum port?
>
>
> ~~ ~ D C "Mac" Macdonald ~ ~~
> ~ ~ Amateur Radio - K2GKK ~ ~
> ~ ~ Since 30 November '53 ~ ~
> ~ ~ USAF and FAA, Retired ~ ~
> ~ Member GMCMI and Classics ~
> ~ ~ ~ Oklahoma City, OK ~ ~ ~
> ~~ ~ ~ "The Money Pit" ~ ~ ~~
> ~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
> ~ ~ ~ '76 ex-Palm Beach ~ ~ ~
> ~~ k2gkk + hotmail dot com ~~
> ~ www.gmcmhphotos.com/okclb ~
> ~~ Cellphone: 405-642-7337 ~~
> ______________
> |[ ]~~~[][ ][]\
> "--OO--[]---O-"
>
> ________________________________
> From: Gmclist on behalf of RJW mygmc@palmbeachgmc.com>
> Sent: Wednesday, September 13, 2017 21:08
> To: gmclist@list.gmcnet.org
> Subject: [GMCnet] JC-4 Vacuum Pump??
>
> While getting ready to leave for the Elkhart rally, I had a conversation
> with a well respected and reliable GMCer about vacuum pumps.
>
> I had mentioned that I have installed in my coach the often recommended
> "JC-4 Vacuum Pump". He remarked that most of them were not very good at
> providing an adequate backup vacuum (for braking) in the event of an engine
> failure. But, that's why we have them, for an adequate vacuum source to
> give us brakes if the motor goes south and stops producing vacuum.
>
> I decided to do a test to see how my brakes work without engine vacuum and
> how the JC-4 does as a backup. I have a 1/2 mile stretch of road near my
> house with little traffic. I drove there in my GMC and started out going
> 30 MPH, put it in neutral and shut down the motor. I pressed the brake
> pedal a few times to dump vacuum and then tried to stop. The result was
> not good and it was a good thing I didn't have to stop because I could not
> stop.
>
> I did it again, except this time after shutting the motor off I turned the
> ignition back on (to power the JC-4 pump). I did the same thing, dumped the
> vacuum, but now I could hear the pump running when I pressed the brake
> pedal. I waited until it stopped and then I tried to stop the coach. The
> result was there was a slight improvement over no vacuum, but not what I
> had expected. I was able to stop, but it seemed not much better than with
> no vacuum. I repeated these tests several times with the same results.
>
> I would not want to be going down a mountain road with a toad and try to
> stop with the engine not running and relying on the JC-4.
>
> My conclusion is that I am going to get rid of my JC-4 and go to something
> more robust.
>
> Apparently, the problem with the JC-4 is that it shuts off before adequate
> (for our needs) vacuum is achieved. It might be possible to by pass the
> internal pressure switch to something that would allow it to pump down to
> the vacuum that we need to stop. Then maybe it would be OK.
>
> My advice for those that have JC-4 Vacuum Pumps is to try my test and see
> how comfortable you are with it as your emergency vacuum backup.
> --
> Richard
> 76 Palm Beach
> SE Michigan
> www.PalmBeachGMC.com
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
Current Time: Tue May 07 08:00:30 CDT 2024
Total time taken to generate the page: 0.00659 seconds
|
GMCforum
Search
Help
Register
Login
Home
