If I was going to sand the housing, I would use a piece of glass and no finer than 180 grit.  120 would be best, and do it with water.

Wisconny Steve, thanks for the help! lol

Mustang Steve, I will be doing another round of sanding with 120 grit. 

Raymond, I like your thinking.  If it doesn't seal this time I am going to try a cast iron housing and see if I have the same problem, maybe it is the intake but I did run the motor on a dyno and it didn't leak.

I just have a hard time believing that 15 ft.lbs is enough to flex this housing and a gasket wasn't making up the difference.  Flat surface, helicoil, gasket, the RIGHT STUFF, 8-10 ft lbs of torque.  The easiest part on the entire engine and it's kicking my tail!  LOL

Kristang wrote:

Wisconny Steve, thanks for the help! lol

Mustang Steve, I will be doing another round of sanding with 120 grit. 

Raymond, I like your thinking.  If it doesn't seal this time I am going to try a cast iron housing and see if I have the same problem, maybe it is the intake but I did run the motor on a dyno and it didn't leak.

I just have a hard time believing that 15 ft.lbs is enough to flex this housing and a gasket wasn't making up the difference.  Flat surface, helicoil, gasket, the RIGHT STUFF, 8-10 ft lbs of torque.  The easiest part on the entire engine and it's kicking my tail!  LOL

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just how much pressure are you putting in the system? . . if it is like 90 psi then it will certainly leak . . it shouldnt be more than around 25.

the 120 may or may not cause it to leak . . it "shouldnt" but this is why i suggested 280 . . even 220 is ok . . on housings that are heavily warped, i start with 80 then go to 180 then finish with 220 or 280.

a granite counter top or polished marble floor is every bit as flat as a piece of glass and wont flex under pressure like glass can.

actually, this is not necessarily the easiest part on the engine which is why you are having this problem . . even the cast iron intake and housing can be difficult to seal at times . . i have repaired well over 100 of these so i know what a pita they can occasionally be and the pos repo parts obviously dont help the situation which is why i mentioned that i often use factory ford aluminum housings.

it is possible that they did not surface your housing properly which is why you saw it was warped aftert you did my sanding/warp test.

the factory torque spec on an aluminum t stat housing is 13.5 ft lbs, not 15.

one of my points is that none of this is operator error providing the bolts are not too long as was suggested . . it is pos parts error.


 

Last edited by barnett468 (3/20/2015 1:59 PM)

I just cannot imagine that type of housing being warped bad enough to not seal when bolted down tight, with a single gasket (CORRECT gasket) and the tstat in the groove properly.  Are you sure there is not a crack in it somewhere that only opens up after it is bolted down and/or gets hot?  I have been messing with these old rides for a whole bunch of years and have just never seen one leak!  And from seeing the rest of your work, I really doubt you are so inexperienced that you cannot properly install a thermostat housing!

RTV is fine for sealing up stuff that does not have pressure on it, like valve covers and oil pans.  My opinion is you need a gasket when there is pressure being applied to any fluid the gasket is trying to seal.

Kristang wrote:

Well, I went through the entire process. Straightened the housing, helicoils, made my own gasket, used THE RIGHT STUFF, put pressure on the system-still leaks next to the bypass. I'm trying a different housing. I may have to go back to rubber hose.

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ok, something just isn't adding up . . it simply can't leak at the gasket if done as i described.

how much pressure are you using?

what do you mean go back to rubber hose?

did you let it dry for 2 hours or more?

did you check the intake surface for flatness?

if you are suggesting your metal bypass might be leaking, i told you how you can check it . . you can also put a small make up mirror underneath it and see exactly what is happening.

an exterior o ring seal should have at least .006" interference fit to hold much pressure . . how much interference fit do yours have?

heres an nos housing which has the raised lip on the sealing surface.

http://www.ebay.com/itm/NOS-mustang-ford-C4OZ-8592-A-1964-1965-289-thermostat-housing-/291321454840?pt=Motors_Car_Truck_Parts_Accessories&hash=item43d41ca0f8&vxp=mtr

Last edited by barnett468 (3/20/2015 6:12 PM)

I just looked closely at your T-stat housing and the lip where the bolts go thru looks a little thin.  Mine is 1/2" thick.  If yours is much thinner than that, it may be warping when it's tightened.  If so, I suggest you try another one.

Kristang wrote:

14-16 lbs on the gauge

I am using an aluminum line for my bypass.

I may have to go back to the rubber bypass hose.

Intake surface looked fine after checking it.

I did not give it 2 hours. Maybe 1/2 hour. I didn't fill the system with coolant, only air. It held pressure for about 15 minutes, then it started leaking air. Found the leak with soapy water.

The bypass line does not leak, the leak occurred between the housing and the intake outside where the bypass is located.

I do not have an oring seal

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14 - 16 psi is low . . it should hold at least 25 psi at that gasket.

it likely leaked after 30 minutes because you did not let it dry long enough . . there is a reason i said to let it dry for 12 hours . . even "the right stuff" needs way more than 30 minutes to completely dry . . like i said . . if you do it exactly how i said, it can not leak.

i think a t stat housing like this might be a good option for you . . purportedly made from billet 6061 aluminum . . torque it to 16 - 18 ft lbs . . dont use the grade 5 bolts it comes with.

http://www.ebay.com/itm/AEROFLOW-AF64-2033S-Billet-Thermostat-Housing-Silver-Suit-Ford-289-351W-/291391168326?pt=Race_Car_Parts&hash=item43d8445f46&vxp=mtr

[img]http://i.ebayimg.com/00/s/NTE4WDgwMA==/z/83YAAOxy63FS81GY/$_57.JPG[/img]


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this is the only other really good sealer i can think of.

[img]http://i.ebayimg.com/00/s/NjQwWDQ3OA==/z/MH8AAMXQHO9RbtaO/$T2eC16ZHJGsFFMn%29lzGrBRbt,OFJ4w~~60_12.JPG[/img]

 

Last edited by barnett468 (3/20/2015 8:29 PM)

Here is the housing I currently have:

http://www.cjponyparts.com/thermostat-housing-260-289-302-351w-1965-1970/p/TH3/

Compared to the housing Barnett has suggested along with other aftermarket housings I have looked at, it appears the base of the Drake housing is significantly thinner, plus I removed additional material from the surface to get it flat.

Kristang wrote:

I believe I just found the issue! I bolted the housing to the intake, tighten the AN nut to the water pump fitting. I grabbed my feeler gauge. I can get a .002 guage between the housing and the intake out board edge of the bypass tube. Backed the nut off the water pump and the gap closes! This housing is flexing for sure!

if you did this without a gasket then i suspect the intake is not flat.
 

When you are sanding, are you putting the sandpaper on a perfectly flat surface and moving the outlet across the surface. It would be impossibly to hand sand or file it flat otherwise.
I have sold a bunch of those outlets and have one on my car without an issue. I wonder if the modifications done to yours could cause it to bend. Or if the threaded fitting is jacking it away from the intake when tightened.

Steve, that is what I am thinking.  When I tighten the AN fitting to the water pump it creates a gap between the housing and intake.  When I loosen the nut, the gap goes away.  There's isnt much surface area around that bypass hole to seal against.  Less than 1/8" at its narrowest point, which is where the leaking occurs. 

I used a flat piece of glass to flatten the surface.  The thermostat DOES move when I tighten that nut.  I never would have thought it could!

Ray, I was just looking at that housing.  Now I'm looking at the intake.  I'm wondering if there's even enough surface around the bypass hole.  I looked at pics of the same manifold and it appears I have much less surface area.