I’m trying to fix the water leak problem on the crossover at the top of the water pump. I was able to get a new O ring. It leaks when I’m filling the radiator without even having any pressure. I got a new seal from the local auto parts shop that is for this year and model. I’ve tried putting a washer that fits in the top of the water pump to put pressure.
The car is a 63 Coupe De Ville but it has a 64 429. If the previous owner used the crossover from the original motor, which from I’ve researched was a 390, would the crossover work. I have a machinist looking at it and trying figure it out.
Any info would be much appreciated.

Views: 73


You need to be a member of 63/64 Cadillac Website to add comments!

Join 63/64 Cadillac Website

Comment by Matt H on July 25, 2018 at 1:10am

Thanks Jason 

Comment by Jason Edge on July 24, 2018 at 5:20pm

The cylinder head water outlet pipe (cross over pipe, water intake, or whatever you like to call it, is the same 1963 to 1964 although there are two types - with ac and without. Either way, alignment into water pump cavity is the same. I have had 5 driver cars and installed them a half dozen time and never had one leak.
Two things I have done:
First: As previously noted make sure the male nipple is not corroded. If badly corroded it will leak... period.  I have coated them and built them up with JB Weld on a previous driver car before installing. Seemed to have worked as it did not leak.
Second: Put new O-ring into water pump cavity first. When you mount the cylinder head water outlet pipe to the heads, the male nipple will push down and seat inside the ring. The gut instinct is the slide the O-ring on the nipple first. It will just slide up the nipple when outlet pipe is installed.

I have never used more than one O-ring but do not see where it would hurt as long as they are pushed in to the cavity first. I have also never used Permatex or other sealants.  The job of the O-ring is to sell between the nipple on the outlet pipe and the top water pump cavity and if you have such a gap that they will not fill the void and need to use some type of sealant I would instead build the nipple up.

Comment by Matt H on July 24, 2018 at 5:13pm

Thanks Russ

Comment by Russ Austin on July 24, 2018 at 4:51pm

The step on top does not seat into the water pump.

Comment by Matt H on July 24, 2018 at 3:52pm

Thanks but we aren’t even to that point of it over heating. The water flows past the O ring when I’m just filling it without it being under pressure. 

Comment by Tony and Ginny 429 on July 24, 2018 at 12:53pm
The problem with bad WPs coming out of the box and the engine running hot was a problem that was happening about 8 months a year ago
You sB fine unless the WP is a fairly new installation due to that timing

The pumps impeller was in the wrong location and had to be moved for those WPs to work correctly ?

The info on the subject is in the library on this site (Use search engine )

Comment by Tony and Ginny 429 on July 24, 2018 at 12:43pm
Go to Old Air products --on line only
You should find the 20/80 valve you need there new

When i called and spoke to the OAP they told me they no longer had that valve but i did find it on line on there website
I had purchased one on ebay for 30 dollars more than OAP and returned it due to the large diff in price
My purchase was just two - three months ago

Comment by Matt H on July 23, 2018 at 11:29pm
Forget the first statement. Mid type.
Comment by Matt H on July 23, 2018 at 11:28pm
Thank you. It does have putting. I tried putting kB weld around it. A machinist has it now and will put a new nipple in it. I tried the permetex and did not work. The water pump was replaced before I bought the car but not sure where or what brand. The machinist was wondering if the step on top is to seat in the water pump since it’s .950 and the hole in the wearer pump is 1.000”
Comment by Tony and Ginny 429 on July 23, 2018 at 9:50pm
Did you recently replace the water pump ?
If so what brand did you use and when was it purchased and from who

In the recent past there have been issues with WP running hot out of the box after being installed

I use two washers on the cross over and Permatex on them
It never leaks again when done that way
Do use a sealer in the coolant per the manual --always



  • Add Photos
  • View All


Current 1963/64 Cadillac Listings on eBay

Started by Jason Edge in For Sale. Last reply by Jason Edge 4 hours ago. 0 Replies

To see all 1963/64 Cadillacs Listed on eBay in the USA…Continue

Tags: ebay

Interesting tale... at least, i think it is.

Started by Kevin Campbell in General Discussion. Last reply by Jason Edge 8 hours ago. 5 Replies

A good mate of mine mows the grass for an elderly couple a few miles away. The other day, while at the back door receiving his payment, he noticed the picture of a 1964 Cadillac on the wall.My mate…Continue

painting 1963 cadillac

Started by paul k in Restoration Discussion 18 hours ago. 0 Replies

How  much paint do I need to buy to paint 1963 cadillac sedan deville 4 door?Continue

Blog Posts

Brakes Went Out

Posted by Christopher Codd on August 8, 2018 at 8:25am 18 Comments

My '64 Cadillac DeVille had been sitting for awhile while I was travelling this summer and when I came home it had some issues starting. After replacing the plugs and the ignition coil, it was running better than it had in a long time but the brakes were sticking. I noticed the brake pedal was traveling a little farther than usual when slowing down. Soon after I noticed a hissing noise coming from around the brake pedal. Then I lost the brakes pretty much completely. I couldn't find any…


Tom and Dwight's excellent 64 Fleetwood tales

Posted by Norman Silverman on July 29, 2018 at 2:52pm 1 Comment

Wow, what a great recitation of events-and what a magnificent restoration. 

Thanks for providing a most pleasurable read.


Comfortron AC trouble shooting

Posted by Norman Silverman on July 23, 2018 at 8:54pm 5 Comments

OK, here we go.....

I got the book to troubleshoot the system. INDISPENSABLE to this effort. 

As I do a cursory exam, I see that the AC RECIRC SOLENOID is Cracked (the WHITE one in the engine compartment coming out of the HVAC body with two vacuum hoses on it). I tried to patch it up (cracked all around the base), but it does not look like it will hold. 



A/C Issue / Stumped !

Posted by Dana G Cooper on July 23, 2018 at 6:29pm 37 Comments

My 63 CDV factory A/C was trash so I replaced every part in the system and converted to R134 . I also installed a STV bypass kit which eliminated the STV all together and converted the system to a cycling system.  I vacumed and charged the system with 36oz of 134. The system is cycling as it should and the pressures are right at 250 high side, cycle off at 25lbs and cycle back on at about 35lbs. It is making plenty of water on the low side hoses and evaporator drain. There is very good air…



  • Add Videos
  • View All

© 2018   Created by Jason Edge.   Powered by

Badges  |  Report an Issue  |  Terms of Service