1959 Cadillac (6267) Thermostat Housing Leak

[Coupe Deville]

Hello everyone. I atempted to flush my radiator and replace upper and lower hoses and the thermostat today. Had a little issue with the lower hose fit but got it sorted. My problem is with the thermostat/water outlet housing. When i removed the housing there was almost nothing left off a gasket. So i scraped the surface flat, put in the new thermostat and a new gasket. Water poured out of there when filled. I have been told that if you put the mating surface of the housing on a grinder and make it perfectly smooth it should fix the leak. Does this sound like a good idea? Should i apply and silicone/sealnt on the gasket? Also how tight should the 4 bolts be? And one more question. how many pounds should the radiator cap be. the one that came off the car was 7 and the new is 13. sorry for asking so many questions. the fourm is great.Any help is appricated.

Thanks

-Gavin

[76eldo]

The mating surfaces have to be pretty flat.  If you cannot locate another thermostat housing I would take it apart, let it dry out and reinstall using some Permatex form-a gasket on the surfaces.

Brian

[Ken Perry]

It needs to be flat,you can use a file or try a flat piece of cement ,like a walk way. After it is flat with no pits take a new piece of 100 grit sand paper and lay that on a flat surface and make it purfect! Don't laugh till you try it!!! Ken Perry

[Dan LeBlanc]

Silicone has always worked well for me.  Put on your bead, go around the bolt holes, and attach finger tight.  Allow to cure for 24 hours, tighten to final torque spec.  If you tighten while the silicone is still wet, it just oozes out and defeats the purpose.

[Coupe Deville]

Should I include the gasket with the silicone?

[Dan LeBlanc]

Silicone will become your gasket.  I prefer the black RTV stuff.

[Coupe Deville]

Thanks for the advice everyone. I went to the auto parts store and bought some silicone gasket maker. Would it hurt to include the original gasket and then just run a bead of silicone on ethier side of it?

Thanks

-Gavin

[n2caddies]

That's what I do.
Randy

[MY 59]

everyone is correct in saying both surfaces need to be flat.
I used a small 100mm x 100mm piece of glass, wrapped it with wet and dry sandpaper and both surfaces came up perfect.
used a new gasket with a tiny smear of sealant, tightened it down to about 15 - 20 Ft Pds (I think) and it is sweet!

[Coupe Deville]

Hello everyone. Thanks for all of the ideas and help. I did make the surfaces flat and used some sealant and tighten the nuts down just over hand tight. Yesterday the gasket front side was just a little damp in one spot and there was two little weeps of coolant. I tighten the bolts down a little bit more and have not had problems yet. So it may just be i dint tighten them down enough. Its kinda strange because before i changed the thermostat the original gasket was in there for 10 years+ and there was not much left of it and the bolts were practicly hand tight when i removed them.

I have a two more questions about the cooling system and thought i will just ask them here then putting a new topic. When we go on drives with the new coolant/thermostat/and hoses the radiator seems to be hotter to the touch then before. Also when the water comes out of the bottom of the radiator hose it is cold, but when it goes into the water pump again the hose feels hot. Is this normal? Or am i just paranoid now.

Sorry for all of the questions. Thanks

-Gavin

[35-709]

To my mind these are invaluable source of information, especially when doing something you have not done very often, or at all before, including torque values.  Cheap at thrice the price.  I find the book form most useful and convenient but some like the CD.

http://www.ebay.com/sch/6000/i.html?_nkw=1959+Cadillac+shop+manual&_rdc=2

[Jeff Wilk]

With a well functioning thermo and radiator what you describe is correct. Hot water from engine flows out of thermo gooseneck into top hose and then into radiator where it is cooled. It then flows out the bottom hose into waterpump then back into engine.  Thus the lower hose is cooler than the upper hose.   Get the shop manual asap.  It is THE MOST important part for any restoration or basic repair.

[cwcinps]

I would note what Jeff said, lower is Warmer - you mention Cold.  It is possible to have air trapped and have a vapor lock going on.  It should result in the car eventually overheating.  You may want to check the radiator that water freely flows thru it as well, taking hoses off and pouring water thru it and make sure it flows free.  Then drain and refill making sure it takes near capacity as listed is in the shop manual.
If it was just a choice of word, cold vs cooler then just check levels and make sure it is not overheating and ENJOY