Question for the day.

[Ken B]

1978 GMC

On the one I am recovering after 19 years of inactivity, I have no brakes. The master cylinder REAR reservoir is almost FULL and the FRONT reservoir
is bone DRY. There is a leak somewhere. My question is on the earlier GMCs the rear most reservoir if for the front brakes and the front reservoir
is for the rear brakes.

I remember something about the 1978 reservoir being was different (maybe reversed) from previous years.

Is the front master cylinder reservoir for the rear brakes on a 1978 GMC?
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[john phillips]

If you think the problem is the front calipers, start there, it is much
easier to check them than to check the 4 cylinders in the back.

> 1978 GMC
>
> On the one I am recovering after 19 years of inactivity, I have no
> brakes. The master cylinder REAR reservoir is almost FULL and the FRONT
> reservoir
> is bone DRY. There is a leak somewhere. My question is on the earlier
> GMCs the rear most reservoir if for the front brakes and the front reservoir
> is for the rear brakes.
>
> I remember something about the 1978 reservoir being was different (maybe
> reversed) from previous years.
>
> Is the front master cylinder reservoir for the rear brakes on a 1978 GMC?
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*

 

[Jim Hupy]

Bob, UNLESS SOMEONE HAS CHANGED IT, the forward most reservoir is for the
rear drum brakes. If it is empty, you have a leak. Most likely the wheel
cylinders, but it could be a line as well.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

If you think the problem is the front calipers, start there, it is much
easier to check them than to check the 4 cylinders in the back.

> 1978 GMC
>
> On the one I am recovering after 19 years of inactivity, I have no
> brakes. The master cylinder REAR reservoir is almost FULL and the FRONT
> reservoir
> is bone DRY. There is a leak somewhere. My question is on the earlier
> GMCs the rear most reservoir if for the front brakes and the front
reservoir
> is for the rear brakes.
>
> I remember something about the 1978 reservoir being was different (maybe
> reversed) from previous years.
>
> Is the front master cylinder reservoir for the rear brakes on a 1978 GMC?
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--

*John Phillips*
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[Ken B]

You have confirmed exactly what I thought. It was just that I remembered that there was something different on a 1978. I sucked dry the rear
reservoir and filled both before I left last night. I have not bleed the fronts yet. I will start looking at lines and wheel cylinders for the
rears. I'm guessing that I will find a rusted through line somewhere.

Thanks Jim.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[thomas phipps]

Ken, Think about the combination valve. My steel one rusted the sliding valve in one position. This resulted in one empty compartment in the MC
because the seals eventually failed.
If you do not have the brass combination valve, get one and change it out. You will be much happier.
Tom, sent from Perry GA FMCA rally.
See you in Tucson
--
2012 Phoenix Cruiser model 2552
KA4CSG

 

[Ken B]

I'll keep that in mind. I do have a solid brake light on which I assume was caused by me stepping on the brake with no fluid in one of the two
reservoirs. I'm hoping that light resets when I get both sides up to pressure.

I will look around the valve for leaks.

I did not make it out there today. I'm busy with a collapsed driveway culvert. I'll probably look for the leak tomorrow.

Thanks Tom
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Jim Hupy]

Ken, the brake warning light is a sign that your distribution valve is
functional. If it were full of crud, the valve would not move, and the
light would probaby not come on. You are right about when you bleed the
brakes, the light should go out.
Jim Hupy

> I'll keep that in mind. I do have a solid brake light on which I assume
> was caused by me stepping on the brake with no fluid in one of the two
> reservoirs. I'm hoping that light resets when I get both sides up to
> pressure.
>
> I will look around the valve for leaks.
>
> I did not make it out there today. I'm busy with a collapsed driveway
> culvert. I'll probably look for the leak tomorrow.
>
> Thanks Tom
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>