1970s 1978 Seville & high flow thermostats

[Seville Life]

I've always bought Stant thermostats? I think they've been bought out and are now known as

I see what are called High-Flow thermostats available by firms like FlowKooler and Mr Gasket?

The originals have worked fine over my 40+ years with Cadillac.

Does anyone know if these high-flow are worth buying? Thanks...Paul

[TJ Hopland]

Quick search and looking at the pictures they look like what I remember being called a balanced design.  The different design of the actual valve is supposed to resist being pushed shut by the flow.  I'm assuming that if you do things like change to a high flow pump and start messing with pulley sizes and other mods maybe that becomes a problem?   I don't know if that's an additional feature of these stats or the easiest way to make the hole bigger?

I would say if everything else is stock just go with a stock style stat.  If its been working why upset things. 

[Seville Life]

Yes I'm tempted to agree.

It is odd that in our Cadillac world I can't find anybody that's had anything to do with them?

Maybe it's a racing/high performance thing? Thanks.

[James Landi]

Many old car enthusiasts (my self included), peek into the original radiator, see what appears to be clean-green, and believe the cooling system is fine.  Won't bore you with details-- the original radiators WERE great HOWEVER, most of these decades' old radiators are heavily scaled and work fine for around town driving but entirely fail for extended driving.  What happens: the pressure and heat in the cooling system builds to the point that the water pump is not pumping and in many cases the radiator blows out.  On Cadillacs built in the 80's on forward, internal damage to the engine is likely.  All this is to day, have your radiator expertly cleaned, have your engine's cooling system aggressively flushed.   Hope this helps,   James

[Chopper1942]

As a side note, you should replace the coolant every several years. One way to determine if it is time to change the coolant is to use a DMM. Set the meter on the DC mV scale. Insert 1 probe in the coolant and the other probe on a cleaned spot on the radiator tank. If the DMM reads close to or greater than 500 mV, you need to drain, flush, and refill your cooling system. The coolant is breaking down and the electrolysis in the cooling system will damage the radiator, heater core, and other dissimilar metals (such as aluminum components).

[Seville Life]

Thanks guys. Pleased others have noted the two-year coolant replacement.

I do indeed flush and back flush my system and replace with a 50/50 mix using ethylene glycol.

Twice in 14 months have I headed to the French Riviera, driving due-south, traffic stopping for no reason (bad driving) and once sitting there for an hour, sun blasting at me, Climate on, no problem.

[bcroe]

This genertion has the cooling system pretty well
set up.  But they are old, and radiators lose
efficiency ith use.  When I get a car, I put in
a brand new radiator with 4 rows of tubes, and a
temp gauge.  That brings it up to my extreme
expectations for many years.  The temp gauge
essentially is tied to the thermostat opening
temp. 

When I see the temp gauge starting to rise a
bit, I know it is time to recore or replace
the radiator.  I often need to tone them down
some in severe cold, by blocking half the air
flow with cardboard.  First thing to check for
rising temp in summer, is if I left it in. 
Bruce Roe

[James Landi]

Paul, 

Having been stuck in traffic last night on the way down from Maine to NJ, I can only imagine how much improved my life would be if I were stuck in traffic on my way to the FRENCH RIVIERA-- the comparison causes me to smile and celebrate your good fortune!   Happy Holidays, James

[Seville Life]

Thanks guys. Yes my radiator is four rows and 42 rows deep, new core, crazy money, $600.

Chopper - not heard of that test before, thanks.

James - indeed, the trip to the Riviera is wonderful and the French love our Cadillacs. I was in Saint-Raphael and stopped to let a group of older, rather elegant French matrons across. They stopped half way across and applauded, one taking her hands off her walking frame? I had visions of having to get out and stand her upright again. Young girl ran down the street once to get a better picture? Wild.

Best wishes to you all for 2024.