The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new cap
allows the system to vent through the overflow when it's hot. There are no
external leaks and there is no coolant in the oil. The cap makes faint venting
sounds when the upper radiator hose is squeezed.

I've tried two new caps and I believe the problem is the filler neck height.
The radiator codes show it's original (Blackstone, left factory in June '72).
The NAPA parts book shows the same cap is used for CJ '72 - '86 but Quadratec
shows the std one is only '74 - '86. Can someone measure the height of the
inner seal to the outer neck on a vehicle in this timeframe and send me the
measurement? Mine is 3/4" and shows no signs of modifications.

Thanks.

Lee

 

3/4" it is, on my 86.

Maybe your cores are plugged so the top tank has too much pressure on
it?

I just flushed mine and it will flow the garden hose on full in the top
hose hole out the bottom with no backing up. You might want to remove
the hoses and try yours.

Do you have a clutch fan on it? If so maybe it has worn out. When the
engine is hot and shut down a good clutch will stop the fan
instantaneously almost.

I have also seen and had a couple years back, head gaskets blow so that
exhaust goes into the rad pressurizing the crap out of it. That I could
see because of smoke and tiny bubbles, many many tiny bubbles once the
t-stat opened. Some t-stats have a bypass hole that makes bubbles when
the engine is just warming up, but once open these head gasket bubbles
turned to foam. I got photos of my 258 doing that....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

LeeB103926 wrote:
>
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new cap
> allows the system to vent through the overflow when it's hot. There are no
> external leaks and there is no coolant in the oil. The cap makes faint venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck height.
> The radiator codes show it's original (Blackstone, left factory in June '72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of the
> inner seal to the outer neck on a vehicle in this timeframe and send me the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee

 

3/4" it is, on my 86.

Maybe your cores are plugged so the top tank has too much pressure on
it?

I just flushed mine and it will flow the garden hose on full in the top
hose hole out the bottom with no backing up. You might want to remove
the hoses and try yours.

Do you have a clutch fan on it? If so maybe it has worn out. When the
engine is hot and shut down a good clutch will stop the fan
instantaneously almost.

I have also seen and had a couple years back, head gaskets blow so that
exhaust goes into the rad pressurizing the crap out of it. That I could
see because of smoke and tiny bubbles, many many tiny bubbles once the
t-stat opened. Some t-stats have a bypass hole that makes bubbles when
the engine is just warming up, but once open these head gasket bubbles
turned to foam. I got photos of my 258 doing that....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

LeeB103926 wrote:
>
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new cap
> allows the system to vent through the overflow when it's hot. There are no
> external leaks and there is no coolant in the oil. The cap makes faint venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck height.
> The radiator codes show it's original (Blackstone, left factory in June '72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of the
> inner seal to the outer neck on a vehicle in this timeframe and send me the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee

 

3/4" it is, on my 86.

Maybe your cores are plugged so the top tank has too much pressure on
it?

I just flushed mine and it will flow the garden hose on full in the top
hose hole out the bottom with no backing up. You might want to remove
the hoses and try yours.

Do you have a clutch fan on it? If so maybe it has worn out. When the
engine is hot and shut down a good clutch will stop the fan
instantaneously almost.

I have also seen and had a couple years back, head gaskets blow so that
exhaust goes into the rad pressurizing the crap out of it. That I could
see because of smoke and tiny bubbles, many many tiny bubbles once the
t-stat opened. Some t-stats have a bypass hole that makes bubbles when
the engine is just warming up, but once open these head gasket bubbles
turned to foam. I got photos of my 258 doing that....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

LeeB103926 wrote:
>
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new cap
> allows the system to vent through the overflow when it's hot. There are no
> external leaks and there is no coolant in the oil. The cap makes faint venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck height.
> The radiator codes show it's original (Blackstone, left factory in June '72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of the
> inner seal to the outer neck on a vehicle in this timeframe and send me the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee

 

3/4" on my 81 CJ7

"LeeB103926" <leeb103926@aol.com> wrote in message
news:20040918145610.25923.00000928@mb-m03.aol.com...
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new
cap
> allows the system to vent through the overflow when it's hot. There are
no
> external leaks and there is no coolant in the oil. The cap makes faint
venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck
height.
> The radiator codes show it's original (Blackstone, left factory in June
'72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but
Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of
the
> inner seal to the outer neck on a vehicle in this timeframe and send me
the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee
>

 

3/4" on my 81 CJ7

"LeeB103926" <leeb103926@aol.com> wrote in message
news:20040918145610.25923.00000928@mb-m03.aol.com...
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new
cap
> allows the system to vent through the overflow when it's hot. There are
no
> external leaks and there is no coolant in the oil. The cap makes faint
venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck
height.
> The radiator codes show it's original (Blackstone, left factory in June
'72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but
Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of
the
> inner seal to the outer neck on a vehicle in this timeframe and send me
the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee
>

 

3/4" on my 81 CJ7

"LeeB103926" <leeb103926@aol.com> wrote in message
news:20040918145610.25923.00000928@mb-m03.aol.com...
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new
cap
> allows the system to vent through the overflow when it's hot. There are
no
> external leaks and there is no coolant in the oil. The cap makes faint
venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck
height.
> The radiator codes show it's original (Blackstone, left factory in June
'72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but
Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of
the
> inner seal to the outer neck on a vehicle in this timeframe and send me
the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee
>

 

The cap may be new, but is it the right pressure rating. I recently had the
same problem with an "82 258. Bought a new cap and trusted the counter
person. The cap was rated lower than manufactures spec. Kragen wouldn't
exchange it when I brought it to there attention. Lesson learned, don't
trust a counter girl that is younger than the vehicle.

"LeeB103926" <leeb103926@aol.com> wrote in message
news:20040918145610.25923.00000928@mb-m03.aol.com...
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new
> cap
> allows the system to vent through the overflow when it's hot. There are
> no
> external leaks and there is no coolant in the oil. The cap makes faint
> venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck
> height.
> The radiator codes show it's original (Blackstone, left factory in June
> '72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but
> Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of
> the
> inner seal to the outer neck on a vehicle in this timeframe and send me
> the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee
>

 

The cap may be new, but is it the right pressure rating. I recently had the
same problem with an "82 258. Bought a new cap and trusted the counter
person. The cap was rated lower than manufactures spec. Kragen wouldn't
exchange it when I brought it to there attention. Lesson learned, don't
trust a counter girl that is younger than the vehicle.

"LeeB103926" <leeb103926@aol.com> wrote in message
news:20040918145610.25923.00000928@mb-m03.aol.com...
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new
> cap
> allows the system to vent through the overflow when it's hot. There are
> no
> external leaks and there is no coolant in the oil. The cap makes faint
> venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck
> height.
> The radiator codes show it's original (Blackstone, left factory in June
> '72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but
> Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of
> the
> inner seal to the outer neck on a vehicle in this timeframe and send me
> the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee
>

 

The cap may be new, but is it the right pressure rating. I recently had the
same problem with an "82 258. Bought a new cap and trusted the counter
person. The cap was rated lower than manufactures spec. Kragen wouldn't
exchange it when I brought it to there attention. Lesson learned, don't
trust a counter girl that is younger than the vehicle.

"LeeB103926" <leeb103926@aol.com> wrote in message
news:20040918145610.25923.00000928@mb-m03.aol.com...
> The cooling system in my '73 CJ5 with a 258 does not hold pressure. A new
> cap
> allows the system to vent through the overflow when it's hot. There are
> no
> external leaks and there is no coolant in the oil. The cap makes faint
> venting
> sounds when the upper radiator hose is squeezed.
>
> I've tried two new caps and I believe the problem is the filler neck
> height.
> The radiator codes show it's original (Blackstone, left factory in June
> '72).
> The NAPA parts book shows the same cap is used for CJ '72 - '86 but
> Quadratec
> shows the std one is only '74 - '86. Can someone measure the height of
> the
> inner seal to the outer neck on a vehicle in this timeframe and send me
> the
> measurement? Mine is 3/4" and shows no signs of modifications.
>
> Thanks.
>
> Lee
>