37 Roadmaster cooling system question - bypass valve

[37_Roadmaster_C]

Hi All,

I am finally getting the 37 Roadmaster Phaeton on the road. I am in the process of cleaning up the cooling system and have a question about the thermostat bypass valve. It appears that the housing has rusted the bypass valve seat area to the point that the valve will not seat and seal compleatly. I have read about various fixes for this and would like some feedback from the members here. I would really like to keep the car as stock as possible, but modifications are not out of the question if they are really the best option. My thoughts... If the bypass valve should seat and seal compleatly I could machine the housing and a new seat and press in the seat (I have a well equipped hobby machine shop). The other option mentioned by other 37-38 Buick owners is to remove the bypass valve and install a fixed 1/4 inch oriface in its place. I am leaning towards the new seat to keep things as designed. While this would be much more work it would keep the car stockish. I really want to do the best thing for the car and only do the work once. Any thoughts and all feedback are greatly appreciated.

Robin

[JoelsBuicks]

Robin, I've seen several of these bypass valves but I have yet to see any that seated, even the ones not rusted. When I first seen this, I thought maybe there was rubber or leather missing but I've read somewhere, perhaps on this forum, that a complete seating was never intended. I now see it as being "self cleaning" because a completely seated bypass valve that actuated by pressure, would soon become plugged. The engineer in me wants to plug this bypass valve but I'm going to give it a chance work.

[37_Roadmaster_C]

Joel,

Thanks for the info. I am going only by what I see in the shop manual, which could easily not be as detailed as I would like. On my housing the valve cone bottoms out and leaves about 3/32 of an inch gap. This might be right. The 'seat' area is rough from rust, but it seems relatively even. I would think that it would be more uneven if rusting was the sole cause of the gap and that would be quite a lot of rust. Also, the car has been in dry storage and drained of coolant since 1953 so there could not be a lot of rusting going on.

Thanks,

Robin

[danhar1960]

G'day Robin.

It sounds like your bypass valve is normal. That valve does not "seat and seal" as such and there is supposed to be a gap between the valve and body. That 3/32" gap provides what would equate to about a 1/2" hole. They did away with the valve in '47 and just used a fixed hole but yours is correct for '37.

Danny

[Guest CAFoster]

Robin,

It sounds like it might be a good candidate for the molasses rust removal system. You can look at the youtube videos by desertrodder

I used this on my 36 Buick model 41 bypass assembly and it did the job, removing the rust and freeing up the valve. The fermenting solution is rather smelly, but it is amazing how it works.

Chris

[Guest Grant Magrath]

My concern with the molasses rust removal system is outlined in the link below.

FWIW, we use a solution of diluted phospheric acid to soak rusty parts in.

Cheers

Grant

[37_Roadmaster_C]

Thank you everyone for the insight. It sounds like I was making a mountain out of a mole hill. I will clean things up and put her back togeather. As for rust removal, I have a really neat trick that I learned from some other machinists. It is an electrolysis method for rust removal. Very simply you use a relatively low DC voltage to electrically remove rust, think battery charger. To do this you will need a plastic container large enough to hold your parts with enough room at the outer edge for a steel plate (use only steel, Not stainless, galvanized, copper etc). Make a solution of water and washing soda (baking soda will work just not as well), use about 1 table spoon soda to a gallon of water. Hook up your battery charger as follows... Positive lead to the steel plate, negative lead to your part (if several parts connect them togeather with clips, wire etc.), make sure the parts do NOT short to the plate. Place the parts in the solution with the plate and plug in the charger. Word of caution, this process releases hydrogen gas so do it in a well ventalated area or outside. If the current is to high for the charger make the solution weaker by adding water, 1-5 amps is plenty for medium parts (water pump size). You will see bubbles forming, this means it is working. Let it cook for as long as needed to remove rust, normally 24 hours or so will go a good job on moderately rusted parts. Turn off the charger and wash off the parts, a light scuff with steel wool helps a lot. If not good enough just put back in the soup and let it cook longer. Now for some insight...

1) this method works best with a straight path between the parts and the plate. I use a 12 inch steel pipe section in a 5 gallon plastic bucket for my plate.

2) the solution will rapidly get dirty and rusty - no problem as long as there is current being drawn from the charger.

3) the parts will come out with a black coating on them, this is normal and will not hurt anything.

4) this method is safe for all steel and cast iron parts, it will NOT remove any base metal only rust.

5) the solution is safe and nontoxic, only water, washing soda and rust. To dispose of it simply dump it down the drain or in the field. Remember, the rust will stain concrete so don't dump it in the driveway.

Give this method a try, you will be suprised at the results.

Robin

[Guest Grant Magrath]

Yeah, we used that to restore old tools. Works well! We didn't have any washing soda, so we used salt. Anything that acts as an electrolyte will suffice, but soda is the best.

Cheers

Grant

[Guest Straight eight]

Here is a direct quote from the Buick Manual of after manufacturing changes .