1967 Cadillac Convertible

[ZOO]

If I had the space I’d own a Cadillac from the 1960s . . . So cool.

Bags and a turbo LS would be on my list .

[1990C4S]

Originally Posted by BK911

How can I verify where I'm loosing water?

If I have to pull the heads, how do I decide full rebuild or just heads?

If I just pull the heads, dual quads?

Start by pressurizing the coolant system with a test kit. Then listen carefully...

[jcwade]

In 1970, my mother and 2yo sister were driving in a '66 Sedan Deville when they were t-boned by a drunk at high speed. The car did not survive but they did, albeit with some broken bones.

With all the tinfoil cars on the road today, the only thing safer would be an Abrams.
But the Abrams gets better mileage.

[Scott Douglas]

Check your oil, make sure you don't have a milk shake goin' on.
Coolant is going somewhere. If not out the exhaust and no leaks apparent on the ground it MIGHT be inside the crankcase.

[speeder]

Originally Posted by 1990C4S

Start by pressurizing the coolant system with a test kit. Then listen carefully...

This is where you start. Bring it to a radiator shop or just a good general auto repair shop and have the cooling system checked. You’ll probably have to leave it overnight since the test is done cold.

If it’s any type of external leak, they will find it. If it’s not, you go from there. Cooling is important, you want to diagnose it correctly. Good luck.

[Nostril Cheese]

Regarding the coolant loss, How does the oil look?

What engine/pic of engine bay? Check compression? Pulling heads shouldnt be too hard on that.

Beautiful car.

[dafischer]

It could very well be something as simple as requiring a new radiator cap.

[911boost]

You need one of these:

https://www.pelicanparts.com/catalog/ShopCart/tool/POR_TOOL_MT0254_pg1.htm

Good point on the cap, I have had them cause issues in the past. The tool I show above can also be rented I bet from your local FLAPS.

[Nostril Cheese]

+1 on the cap

[speeder]

It's amazing how many older vehicles have either the incorrect coolant/radiator cap or a bad one. Or both. If it's even in doubt, replace it. Make sure it's the correct psi rating for the car.

[livi]

The K-Man rides again. Excellent!

[BK911]

The original cap was the one way cap used without a reservoir.
She would loose coolant out of the cap.
I replaced with a new cap from a newer caddy that was a 2-way cap used with a reservoir, and added a reservoir.
That system seems to be working properly; when she is hot there is water in the res, and when she cools off the water level goes down in the res.
After a couple of rides, and subsequent cool downs, the res was empty.
I checked the coolant level and it was a couple of inches below full.
No apparent leaks out the res, cap or rad.
I will go to the FLAPS today and get one of those pressure testers.
I will also do a leakdown.
And check the oil again.

Thanks for all the compliments and suggestions!