Water crossover at water pump, leak at O-Ring

[Scott Santora]

My head is about to explode!!!! I would like to reopen the discussion of the issue of getting the water pump to crossover connection to seal at the O-Ring.

 This all started because of a "gasket" leak at the water pump to front cover housing. The water pump was fine but since I had to remove the water pump to fix the leak anyway, thought I might as well replace the water pump. The original water pump to crossover connection was NOT leaking.

 To make everything go easy on myself, I removed the radiator, P/S pump and alternator. I had a nice clear path to the area to work on.

 When I removed the crossover, there was some very minimal corrosion at the male connection on the crossover to the water pump. I sanded the male connection with some 400 grit sandpaper, applied a skim coat of JB Weld to fill the small pits, then after the JB Weld dried, sanded that down smooth. Slick as snot on a door knob in January. 

 When I reassembled everything, I put the crossover and water pump together off the car. I put the O-Ring on the crossover male end first, put that into the water pump, then put that assembly back on the car, tightened and torqued everything to specs. Put the rest of the car back together and started adding antifreeze. As I was adding the AF, coolant started POURING out of the crossover to water connection. 

 Went to the repair manual where it stated to "coat the O-Ring with silicone". I had used assembly grease. It did also say to put the O-ring into the water pump first which Initially I put it on the crossover male end first. Then I read the 2021 discussion here about using 2 gaskets on the crossover to head connection to correct the angle due to gasket thickness. 

 So now I took just the crossover off, cleaned everything real good, used 2 gaskets on each side of the crossover to head, Put the O-Ring in the water pump housing FIRST, I did use assembly grease again because the shop manual did not say silicone sealant, it said silicone. Made sure that the male nipple seated good into the water pump, Tightened and torqued everything, crossed my fingers and then started to add antifreeze to the radiator. AGAIN, coolant started pouring out of the water pump to crossover connection. When I say pouring, I mean pouring. It might as well have been an open hole.

 If someone has an answer to this, I would really appreciate the advice! As best as I can tell, everything looks lined-up and installed correctly. Does the shop manual mean silicone sealant on the O-Ring???

[Matti Roth]

Hi,

you need to put 2 o-rings to waterpump. Some people use gasket sealer there as well.

[Scott Santora]

Thanks Matti. When I was reading a variety of older posts, some said use two O-rings, some said two gaskets on the crossover to head connection. Knowing that I put the O-Ring on the crossover first and only used the gaskets supplied with the water pump, I wrongly figured those were my issues. Do you think along with doubling up on the O-Ring, do I still double up the gaskets on the crossover/head connection? Does that really make a difference? I really don't want to take this apart a 4th time if I don't have to. The car is supposed to go in today to have the transmission that I had rebuilt installed. I was actually hoping to be driving this restoration this weekend.

[Dennis P. DiBari]

Hi Scott,

     This is the most frustrating part of the Cadillac 429 engine.  I have been working on my car many years, but this is the trickiest part.  The water pump, the crossover, O rings, and head connector.  Matti and Russ are right.  Better off with two O Rings and gasket maker.  Let it all set for a better seal.  Very frustrating.  Could have been designed better!!!

Dennis DiBari

[Russ Austin]

Defiantly use black RTV gasket maker with 2 O rings.  Do not gob it into to hole as it will clog the passage way.  Put a little bit on the O ring and push down to the bottom of the water pump hole. Put more RTV on the installed O ring. Lightly coat the second O ring and install.  Clean out any stray RTV that squeezed down the hole of the water pump. 

Install the cross over tube and let it set for 24 hours before adding coolant. This is probably the most important step, as it sets the RTV up. 

[Dennis P. DiBari]

Scott,

     I don't know if I would double up the gaskets on the crossover to head connection.  Try the one gasket per side and give it 24 hours to set before installing.  Two gaskets per side may be giving you too much space to leak.

Dennis DiBari

[Scott Santora]

So, unfortunately I had to leave and go work on the car before the last several replies came in. My car is not at my home, I am doing the restoration at another location. Anyway, here is what I ended up doing:

I used two O-rings and two gaskets on the crossover to head connection. I also used a small amount of silicone sealer (blue, to match the engine color) on the O-rings. I waited only about a half hour due to time constraints before I filled the radiator.  

That seems to have worked. Before, as soon as I added the coolant, it would start pouring out of the O-ring connection immediately. This time, no leaks. BUT... I still don't know for sure if this actually fixed the leak. I could not start the car and let it warm up to temperature to check the repair. The transmission is out of the car and my starter is wired off to the side. This is why I had the time constraints. The trans was pulled last week to get rebuilt. I had an appointment today to have the transmission reinstalled. I had to get this engine in operating condition so the tech that did the trans overhaul could test drive the car after the instiall. And now as I am writing this, it just occurred to me that  I could have done a pressure test on the system!!! What a mess!!!! Should not be working on a car with a head that had already exploded!!! I'll update either tomorrow or Monday. I was late for my appointment so the trans might not get installed until then.Thanks again everyone!

[Dennis P. DiBari]

Scott,

     You can only do so much on the Caddy.  The two O rings is better and let everything set a while before starting.  We all go through this; don't let it get you.  Give update when you start it and good luck with it.

Dennis DiBari, Cottekill, NY