First off thanks to all for this great site. I've already learned quite a bit on my 64 sdv for my own repairs. I've got a problem with my engine overheating. It started suddenly and it has a new water pump installed with about 75 miles on it. My question is has anyone ever lost an impeller off of a new water pump? I've already ordered another one as I've eliminated everything I can think of. Just wondering if this is possible and happened to anyone else. Thanks for help guys, Clovis

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Be sure to check that your thermostat is working correctly
It sB open when placed in a pot of boiling water
Not possible to loss an impeller ,only the bearing goes bad ( so watch you fan belt tension )
If the pump is new ,I do not think it is your problem
Check to see if your exhaust damper ,located in the exhaust pipe just below the exhaust header. , is in the open position when the car is at operating temp
Do not burn yourself
You can wire it open if it is not working as it should
If it stays closed. ,after the car warms. , it will cause high engine temps in our year cars
Rad cap needs to be in good order. , change out your antifreeze if it is old ,you may need a rad , but try a good flush of the system and new antifreeze
They now make a 5year replacement antifreeze

I'm wondering on the quality of the water pumps that are being produced. I have turned back a few so far, due to the impeller not being pressed on all the way. There is a large gap on the other ones I have seen too.  I'm looking for info on the water pump specs to see if its correct.

This isn't my first rodeo with old or new cars. When I buy something to keep I change everything rubber and all fluids not only changed bet flushed out. Brakes are brought back to new so any travel is dependable. Lot of work to change a water pump so getting down to last resorts I ordered one and will have a spare if it's not bad. Everything else has been changed and tested. I'll will post my findings when the new pump comes in. I also removed the exhaust damper to rid that restriction when I put in the new system and the fact it will never be driven in cold weather again.

I would think a damaged impeller would throw the unit out of balance along with gouging or breaking the timing cover and or pump housing. Do you have good coolant flow when the engine is at operating temperature? Have you pressure tested the system? Russ may be on to the cause, with the clearance of the impeller to pump body not being correct. 

You might check to be sure the carburetor is properly torqued to the manifold, there are no vacuum leaks, the static timing is correct and advance weights at the top of the distributor are free. Be sure the vacuum advance unit is working with the point plate advancing freely. It wouldn't hurt to put a few drops of motor oil on the point plate wick and some oil down the shaft up by the advance weights. Lightly lube the advance weights so they pivot freely. Retarded timing from a damaged vacuum advance or stuck centrifugal advance could cause overheating. Good luck, let us know what you find.

Hi David, I'm not seeing any flow in the rad but I can't remember if I saw any with the old pump or when I flushed the system 4 times. (Not that it really needed it that bad but I'm just anal that way). The plugs could not be any better for a carb setup. They look like they come out of an EFI engine. It is rebuilt and has 71000 on car in total. I have not checked timing yet but I've got at least a couple hundred miles on the car so far with no issues that way. (Other then when I put regular gas in it LOL) timing will be checked if the water pump is not the issue for sure. I'm very fortunate to have found a car this age in Canada that us RUST free with a rebuilt engine and Trans. I have no history on it so I don't even know for sure it's an original Canadian car or if the engine was rebuilt. Just have to go with the previous owners wife who stated it was a rebuild. No leaks from the engine or oil in the coolant. I also cut open the oil filer to check for metal and found none.
Dave brought up a good reminder
Retarded ignition timing or a lack of a vacuum advance will cause the engine to run hotter than it should
So should a vacuum leak
This might seem odd ,but it did happen to me
My 64 ran great around town ,but out on the highway at a constant 55 miles per hour ,the car would run a good deal hotter than it should
My fuel filter was dirty. ,and had the engine running lean at speed ,and took a while to trouble shoot ,due to those conditions
What year is your Cadillac ?
I can be more helpful with a 64
Looks like you have covered a lot of the basics already
Never can know the skill level of those we post with is ,until we get into the subject a bit
Russ , is one of the great source of info here ,so his consern about the pumps needs to be given the attention it deserves ,if he thinks there is a problem
let us know what you find
I see you have a 64
They are very prone to vacuum leaks due to the comfort control heat and AC design
A very complex system that all works by vacuum off the engine
You can isolate the engine vacuum from the cabin --by plugging the vacuum lines --coming out of the engine at the back of the intake maniflod
Be sure the dist vacuum advance is in good working order
The brake booster vacuum line is also in the same location so do not plug or disconnect that
You intake manifold is now isolated from any vacuum problems that you may have in the cabin an your intake is sealed from out side air ,other than that coming thru you carb
Hi Tony, thanks for the suggestions. I'm not thinking I have vacuum leaks as I have replaced a few of the vacuum hoses and it would show up on the plugs. Also the vacuum advance seems OK (though not tested with a pump) as driving conditions would show so. As a side note I bought a 1970 country squire a few years back and when I picked it up I had to ask the guy for a bunch of screws to plug vacuum leaks. The engine was bouncing all over and running like crap. After all was plugged off it was running smooth as a baby. Poor guy had been paying a Ford dealership to fix his wagon and still could not find a vacuum leak. I guess they had no computer to plug into LOL
Also the fuel filter has been changed along with the rest of the the systems. I do wonder how many of these cars burnt to the ground as a result of those filters. They are very prone to leaking after a filter change if not exactly centered when reinstalling the bowl. I did end up with a fire myself. Lost a little sleep over that LOL.
One last thing I haven't mentioned, it's overheating after 10 to 20 min in the driveway. It starts to sound like it has no oil kind of overheating. And it's not just hot it's REALLY hot! Top rad hose can't be touched lower just hot.

I would check thermostat, make sure it is right side up, and is opening up and you are getting good radiator flow per shop manual test procedures. Also, make sure heat riser on bottom of left/driver side exhaust manifold is not frozen shut and is opening up. You can visually see one working in this video:

As far as overheating, how are you determining this?  Temp gauge, IR heat gun? The temp sending units go bad and the new replacements are often miscalibrated. I keep an infrared heat gauge handy. My 64 CDV runs about 195 degrees at top of intake when fully heated up.

Before dismantling your engine and replacing a lot of parts check the basics first.



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