Cadillac: 1970 Cadillac Eldorado coolant overflow again

The Derfer wrote:
 

How long since a tune-up by someone who knew what they were doing?

The first thing I would check is the vacuum advance in the distributor.
If the advance diaphragm is still good (unlikely if it is original) then
check the thermostat.
Also check the lower radiator.

-jim

On May 5, 6:51*pm, The Derfer <com> wrote: 

are you sure you don't have any air in the system?

You can always try a new thermostat, or maybe put a lower temp one in.

m6onz5a <net> wrote in news:1b2f6637-eebc-4d40-8f15-
googlegroups.com:
 


how old is the water pump. some of those old beasts would eat the
impellers us so they wouldnt move enough water. KB

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On Wed, 5 May 2010 15:51:40 -0700 (PDT), The Derfer
<com> wrote:
 


Sounds like you don't have a high enough concentration of antifreeze.
Do you have an infrared temp gun you can aim at the thermostat housing
to see what temp the coolant is at? The last vehicle I had that did
what yours is doing was cured with a new radiator cap but you say
you've already put one on it. Are you sure you put on the right
pressure rating cap, it probably is supposed to be a 15 pound cap,
maybe you put on a lower pressure cap then that. See if there's a gas
station that has the gizmo that can check your coolant concentration
to see if the ratio of water to antifreeze is at least 50/50.

"The Derfer" <com> wrote in message
news:googlegroups.com... 

I seem to remember this topic from a long time ago.. I think we talked
about
hot spots in the engine, especially when cooling was marginal anyhow. When
the engine was shut off, there was still enough heat in these areas to cause
local boiling.

Now, what to do about it?

Troubleshoot systematically...
Make sure you dont miss anything small...
Correct (double check) thermostat?
Water pump impeller?
Lower hose collapsing leading to overheating?
Mineral scale (includes silicates) in the block or radiator?
Debris between the air conditioning condenser and the radiator?
Air bubble in the engine?
Cracked head, block, or blown head gasket?

I will try to search this symptom a little, because I remember it
well, but dont necessarily remember the normal cause of it.