Rad.caps

[wayne nesbitt]

I caught the tail end of a thread on 9# rad caps a while back. I had the
shop drop my rad last year. It had been weeping in the bottom corner since I
got it 7 years ago. I had driven it like that for over 25,000 miles. It
never leaked much just enough to mess up the asphalt drive way with a couple
of spots. I told the shop to put in new cores if there was any doubt but
they just resoldered it saying it was solid. I believe It was leaking on the
seam where it joins the reservoir.

It seems to me that the rad material is as strong or stronger than the new
rads they are putting into the cars today so I don't follow why we can not
operate them at 18 psi. It doesn't leak now under that pressure.

It seems to me that the extra pressure will give more boil over protection.

What is the thinking on the con side of this guys? Maybe I should spend the
big bucks on a new cap if one could find a nine pounder these days

TIA
Wayne

 

[gene]

some stuff up on my page about this.
gen

>I caught the tail end of a thread on 9# rad caps a while back. I had the
>shop drop my rad last year. It had been weeping in the bottom corner since I
>got it 7 years ago. I had driven it like that for over 25,000 miles. It
>never leaked much just enough to mess up the asphalt drive way with a couple
>of spots. I told the shop to put in new cores if there was any doubt but
>they just resoldered it saying it was solid. I believe It was leaking on the
>seam where it joins the reservoir.
>
>It seems to me that the rad material is as strong or stronger than the new
>rads they are putting into the cars today so I don't follow why we can not
>operate them at 18 psi. It doesn't leak now under that pressure.
>
>It seems to me that the extra pressure will give more boil over protection.
>
>What is the thinking on the con side of this guys? Maybe I should spend the
>big bucks on a new cap if one could find a nine pounder these days
>
>TIA
>Wayne
>
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/

 

[brent covey]

Hi Wayne-

I've got 15+ psi caps (and 195 thermostats) on all my old cars, and none
have required replacement of the factory installed 1960's radiators thus far-

I wouldnt see any problems generally with using a higher pressure cap. A
system in good condition will last about as long with higher pressures, one
with leaks will just leak a little sooner.

I might also add I've switched to the new DexCool type antifreeze across
the board, with good results thus far, I've read the pros and cons of it in
older vehicles, there is a question about the protection afforded to lead
solder joints, but my view is the remaining deposits from the original
green stuff should be more than adequate, and if nothing else, the new
stuff doesnt attack them, so the damage if any will not get worse. If
anyones interested in using it, I would think its perfectly safe. Probably
kinda a synthetic lubricant kinda overkill, and not worth the money, but
hey;-) GM claims the ginger pills sold in the Parts department are very
effective, also.

I'd also be interested in hearing what experiences people have with higher
pressure caps- seems a blown rad or heater core (if that happened, which
seems doubtful) is preferable to a boiled engine damaging its headgaskets.

Brent Covey
Vancouver BC

>What is the thinking on the con side of this guys? Maybe I should spend the
>big bucks on a new cap if one could find a nine pounder these days

 

[wayne newland]

Wayne

Stay with what the radiator was designed for, or you will blow the thing out on
the road, and that isn't very funny (to say nothing of the expense).
]
Wayne Newland ex-Wynn's cooling system instructor

> I caught the tail end of a thread on 9# rad caps a while back. I had the
> shop drop my rad last year. It had been weeping in the bottom corner since I
> got it 7 years ago. I had driven it like that for over 25,000 miles. It
> never leaked much just enough to mess up the asphalt drive way with a couple
> of spots. I told the shop to put in new cores if there was any doubt but
> they just resoldered it saying it was solid. I believe It was leaking on the
> seam where it joins the reservoir.
>
> It seems to me that the rad material is as strong or stronger than the new
> rads they are putting into the cars today so I don't follow why we can not
> operate them at 18 psi. It doesn't leak now under that pressure.
>
> It seems to me that the extra pressure will give more boil over protection.
>
> What is the thinking on the con side of this guys? Maybe I should spend the
> big bucks on a new cap if one could find a nine pounder these days
>
> TIA
> Wayne

 

[john wright]

Here the deal,
The factory recommended cap is 9 pounds. and most people run the 9,10
or sometimes a 12# cap if they can't find the lower pressure caps. The
radiator is so large that with the higher pressure caps the balloons
under pressure and then contracts when it cools down. This causes the
radiator to crack at the seams, which is appears what happened to you.
If you run the high pressure cap it is not if but when it will fail.
This isn't anything new with the GMC.

J.R. Wright
GMC GreatLakers
77 Eleganza II
Michigan

>
> Hi Wayne-
>
> I've got 15+ psi caps (and 195 thermostats) on all my old cars, and none
> have required replacement of the factory installed 1960's radiators thus far-
>
> I wouldnt see any problems generally with using a higher pressure cap. A
> system in good condition will last about as long with higher pressures, one
> with leaks will just leak a little sooner.
>
> I might also add I've switched to the new DexCool type antifreeze across
> the board, with good results thus far, I've read the pros and cons of it in
> older vehicles, there is a question about the protection afforded to lead
> solder joints, but my view is the remaining deposits from the original
> green stuff should be more than adequate, and if nothing else, the new
> stuff doesnt attack them, so the damage if any will not get worse. If
> anyones interested in using it, I would think its perfectly safe. Probably
> kinda a synthetic lubricant kinda overkill, and not worth the money, but
> hey;-) GM claims the ginger pills sold in the Parts department are very
> effective, also.
>
> I'd also be interested in hearing what experiences people have with higher
> pressure caps- seems a blown rad or heater core (if that happened, which
> seems doubtful) is preferable to a boiled engine damaging its headgaskets.
>
> Brent Covey
> Vancouver BC
>
> >What is the thinking on the con side of this guys? Maybe I should spend the
> >big bucks on a new cap if one could find a nine pounder these days

- --

 

[john wright]

Wayne,
The 9# cap is available at your local GM dealer. Ask for AC Delco type
RC32 part and a 10# cap is available at most autoparts store
under a Stant part number 10237, if they don't have it, have them order
it for you. The lower pressure rated caps are not carried by the store
much but they are available.

J.R. Wright
GMC GreatLakers
77 Eleganza II
Michigan

>
> I caught the tail end of a thread on 9# rad caps a while back. I had the
> shop drop my rad last year. It had been weeping in the bottom corner since I
> got it 7 years ago. I had driven it like that for over 25,000 miles. It
> never leaked much just enough to mess up the asphalt drive way with a couple
> of spots. I told the shop to put in new cores if there was any doubt but
> they just resoldered it saying it was solid. I believe It was leaking on the
> seam where it joins the reservoir.
>
> It seems to me that the rad material is as strong or stronger than the new
> rads they are putting into the cars today so I don't follow why we can not
> operate them at 18 psi. It doesn't leak now under that pressure.
>
> It seems to me that the extra pressure will give more boil over protection.
>
> What is the thinking on the con side of this guys? Maybe I should spend the
> big bucks on a new cap if one could find a nine pounder these days
>
> TIA
> Wayne

- --

 

[wayne newland]

J.R.

THANKS FOR THE BACK-UP.

wayne Newland F9300 75 Palm Beach Columbia (Rain), Md

> Here the deal,
> The factory recommended cap is 9 pounds. and most people run the 9,10
> or sometimes a 12# cap if they can't find the lower pressure caps. The
> radiator is so large that with the higher pressure caps the balloons
> under pressure and then contracts when it cools down. This causes the
> radiator to crack at the seams, which is appears what happened to you.
> If you run the high pressure cap it is not if but when it will fail.
> This isn't anything new with the GMC.
>
> J.R. Wright
> GMC GreatLakers
> 77 Eleganza II
> Michigan
>

> >
> > Hi Wayne-
> >
> > I've got 15+ psi caps (and 195 thermostats) on all my old cars, and none
> > have required replacement of the factory installed 1960's radiators thus far-
> >
> > I wouldnt see any problems generally with using a higher pressure cap. A
> > system in good condition will last about as long with higher pressures, one
> > with leaks will just leak a little sooner.
> >
> > I might also add I've switched to the new DexCool type antifreeze across
> > the board, with good results thus far, I've read the pros and cons of it in
> > older vehicles, there is a question about the protection afforded to lead
> > solder joints, but my view is the remaining deposits from the original
> > green stuff should be more than adequate, and if nothing else, the new
> > stuff doesnt attack them, so the damage if any will not get worse. If
> > anyones interested in using it, I would think its perfectly safe. Probably
> > kinda a synthetic lubricant kinda overkill, and not worth the money, but
> > hey;-) GM claims the ginger pills sold in the Parts department are very
> > effective, also.
> >
> > I'd also be interested in hearing what experiences people have with higher
> > pressure caps- seems a blown rad or heater core (if that happened, which
> > seems doubtful) is preferable to a boiled engine damaging its headgaskets.
> >
> > Brent Covey
> > Vancouver BC
> >
> > >What is the thinking on the con side of this guys? Maybe I should spend the
> > >big bucks on a new cap if one could find a nine pounder these days
>
> --