: 500 Cad engine overheats in my Malibu,low speed

05-12-12, 08:34 PM
I am looking to overdrive my waterpump by useing a smaller water pump pulley.Mine is a single grove 6 1/2" pulley.I would like to find a Cadillac smaller diameter to use but have no part numbers or ways to reference Cadillac numbers.Any help is appreciated.

05-13-12, 05:58 PM
Make sure you have the fan shroud and big A/C fan setup. I would expect the biggest
4 row radiator that fits the space is needed. If the "off the shelf" types (probably cheap
imports) don't do it, you can have an extra duty radiator built for the car, not cheap.

Bruce Roe

05-14-12, 09:29 AM
Thanks for the reply.
Have large (1")3 tube rad,fully enclosed with custom shroud,1200 cfm pusher fan,6 blade mechanical fan moved forward to within an inch of rad..Really need to overdrive water pump at low speed.Moroso recommends a 6" pulley instead of the stock 6 5/8".Was hoping some Chevy or other GM application might work?

05-14-12, 03:09 PM
Sorry I can't help with the pulley. Be sure the overflow tank is in order. The
electric fans help a lot on cool down after shut off, but can't move nearly as
much air as an engine driven fan. Some engine fans are deeper than others,
check it out.

I was fustrated with off the shelf radiators. Put down some $500 to get a top
quality 4 row from usradiator.com Before I was done, the paperwork
said COOL CRAFT COMPONENTS. They sold me a quality radiator, after I waited
a couple weeks for building & shipping UPS ground. Their standard 4 row fit my
77 Delta 3 row brackets, same tank. But the core was thicker, so I had to trim
my plastic fan bezel about 5/16" for that. From then on, my temp gauge needle
was anchored at 185.
Expect a couple extra smaller water connections that might have to be plugged,
on their "universal" tank. Low coolant, some Cads ran the heater from the
They offer a premium HIGH EFFICIENCY version of the radiator for another $100 or so.
good luck,
Bruce Roe

07-04-12, 11:21 PM
Are you sure you have the proper Cadillac 195 thermostat and not a regular GM type?

07-06-12, 03:57 PM
Here is the answer to your overheating... 94354 Get a waterpump with a solid disc.. Years back NAPA sold them , now your only going to get them from vendors that specialize in these motors.. MTS is one of them.. I think the brand they sell is FLOWCOOLER. I had all the things Bruce talks about and still would over heat.. Now with type of waterpump and a 180 degree thermostat it almost never goes over 190 degrees and stays at 180 while its moving...

07-07-12, 09:38 PM
A smaller pulley could speed up the flow thru the radiator and because it doesn't stay in the radiator long enough, the coolant never gets to transfer the heat. So a smaller pulley might cause it to run even hotter! One of the functions of a thermostat is to restrict coolant flow to have it remain in the radiator long enough to expel the heat to the exterior. The general rule of thumb for a shroud is to have half the fan blade in the shroud and the back half of the blade out of the shroud. My definition of "overheats" means it boils over and the temperature never stabilizes. Running too warm is not overheating. Tell us what the cooling system does as driven at low speed? Does this car have a recovery, overflow tank?

08-17-12, 05:05 PM
My Elco project has a 7 blade fan with a clutch, and the stock '77 Chevy shroud, on my 507 engine. Seems like the fan pulls best when located at the rear of the shroud, instead of being close to the radiator core. I have a cheapie aluminum 3-row radiator. During cam break-in, temp indicated 175 degrees with a 180* Cadillac thermostat. It needs to be a Caddy type, or the opening under the thermostat has to be plugged, if using a Chevy type etc.

08-17-12, 06:32 PM
This guy either died or is one of those that takes the info given and never posts back with the fix!

08-18-12, 04:20 PM
He was last on this site on 5-17-12 ... So we are waisting our breath..

08-21-12, 11:55 PM
I should have looked closer at the date !!

01-07-13, 08:24 PM
its not a waste... other people read this too and appreciate the info...
i have a 500 on a model t so i am limited on radiator options,, the water pump and thermostat info is helpful...