The thermostat housing leaks despite best efforts to retighten. It is a nice aluminum piece with an O ring. No other gasket or sealant was used. I am inclined to dispense with the O ring and use a conventional paper gasket with a bit of sealant. Any reason not to?
Sealing thermostat housing with O Ring
- Thread starter CESLAW
- Start date
Chuck
Just my two cents, but I'd probably first try keeping the o-ring, but using RTV in the metal-to-metal contact area, keeping it off the o-ring and out of the ring groove. Also, I'm sure you already thought of this, but make certain the o-ring is not twisted or pinched when you install it in the groove. Double-check that the o-ring is not cut or torn anywhere, too. Oh, and you can easily overtighten the bolts in most o-ring applications, causing the o-ring to squish out of the ring groove.
O-ring seals are ususally pretty foolproof. None the less, it is a pain to chase down these little gremlins. Good luck.
Eric
Just my two cents, but I'd probably first try keeping the o-ring, but using RTV in the metal-to-metal contact area, keeping it off the o-ring and out of the ring groove. Also, I'm sure you already thought of this, but make certain the o-ring is not twisted or pinched when you install it in the groove. Double-check that the o-ring is not cut or torn anywhere, too. Oh, and you can easily overtighten the bolts in most o-ring applications, causing the o-ring to squish out of the ring groove.
O-ring seals are ususally pretty foolproof. None the less, it is a pain to chase down these little gremlins. Good luck.
Eric
Also make sure that the o-ring is the correct size for the groove. The o-ring should sit proud of the surface before it is installed. They may have machined the groove too deep for the o-ring provided, or the o-ring diameter is too small. Otherwise it should seal without any issues.
Regards,
Andy
Regards,
Andy
Ron Earp
Admin
Is that one of the swivel housings? It looks like it.
If so, IMHO, they are huge pieces of sh*! and don't seal. Mine didn't. Tried to get it to work but failed. Numerous times. Took it down to my local circle track welding guy and his response was:
"Is that one of those swivel necks? That is a huge piece of sh*!. throw it away."
And I did. Found a correct cast piece that was at the right angle and all is well. Reinforced the old saying that "Chrome won't get you home."
Chuck:
As mentioned o rings are a pretty good seal.
A problem I have seen is the groove is just too deep for the o ring, and once the bolts are brought down no amount of tightening will make a difference. If you have access to a lathe you can simply face off a bit of the housing, and a good quality o ring such as Viton or other compatible material will insure a failure free seal.
I do agree with the other guys on the swivel necks being total crap, but you may get away with a good sealer until you can finalize the angle with a welded neck.
Good luck
Phil
As mentioned o rings are a pretty good seal.
A problem I have seen is the groove is just too deep for the o ring, and once the bolts are brought down no amount of tightening will make a difference. If you have access to a lathe you can simply face off a bit of the housing, and a good quality o ring such as Viton or other compatible material will insure a failure free seal.
I do agree with the other guys on the swivel necks being total crap, but you may get away with a good sealer until you can finalize the angle with a welded neck.
Good luck
Phil
Thanks for the tips. The only reason I used this swivel neck housing was to get the right angle. Things are really tight in that location. This was not my first choice.
There are two O rings. Actually it is a large O ring and a small O ring for the bypass connected to gether. So replacing the O ring(s) might be a challenge. I like the idea of some sealant. The leak is little more than a bit of seepage, so a bit of sealant should do the job.
There are two O rings. Actually it is a large O ring and a small O ring for the bypass connected to gether. So replacing the O ring(s) might be a challenge. I like the idea of some sealant. The leak is little more than a bit of seepage, so a bit of sealant should do the job.
Chuck - I toss the O-Ring and use The Right Stuff. let it tack up for about 10 minutes and install with just snug bolts - wait 6-8 hours and then torque the bolts.. No leaks when I've done it this way.
Now the swivel part may be another story altogether.. I've not used one of those..
Now the swivel part may be another story altogether.. I've not used one of those..
Ron Earp
Admin
Boy I went does this exact same road round about December of 2010. O-ring tore. Tried to get the o-rings, then tried sealant, then welding it up....then ended up using a slightly different water hose and a new neck, problem solved.
Good luck with it.
FWIW Permatex makes a dedicated thermostat housing/water pump RTV, which is different from their normal RTV. It comes in a suitably smaller tube, and is cheap. I guess the normal stuff is optimized to combat oil seepage while the gray stuff is oriented towards sealing against water leaks.
I've used it for years, and it works fantastic!
I like this response, looks like Permatex has a dedicated sealer for this problem area. The aluminum housing on my Cobra also suffered from seeping so I went back to the OEM thick cast iron unit and problem went away. I have the same housing as Chuck so will focus extra attention when I install it. Thanks for the heads up!
FWIW, Mazda racers use Hylomar on the rotary engine water jacket o-rings to augment this large sealing area and remain flexible to the expansion/contraction between the aluminum and steel housings.
Good Tip. Actually have a small tube that we used on Ryan's GT 350 thermostat. I had forgotten about it. Thanks for the reminder !
Drove the GT yesterday between snow showers and the thermostat housing was dry after a 25 mile cruise. This is clearly an intermittent, small leak. But a big repair job, since we have to remove lots of stuff to get to it.
Jim Rosenthal
Supporter
Chuck, I had one of these on the Kirkham and it worked fine. Is yours warped, maybe? I had mine in the Garage Sale section; if you want to try another one, I'll just give it to you. PM me if you want it. This one did not leak on the Cobra.
Something else to consider, since I found out the hard way, keep the thermostat body in place even if you knock out the middle to make it free flow. Most housings and manifolds have a recess machined in to allow for the thermostat stamping and a gasket to complete the seal.
I suspect with no thermostat the hot, pressurized coolant decides to leave the premises via the gap, even if walled in with a paper gasket. O ring might do it, certainly would if your manifold or outlet had an o-ring groove machined in. If both have o-ring grooves you may be back to leaving the tin in... Cheers
I suspect with no thermostat the hot, pressurized coolant decides to leave the premises via the gap, even if walled in with a paper gasket. O ring might do it, certainly would if your manifold or outlet had an o-ring groove machined in. If both have o-ring grooves you may be back to leaving the tin in... Cheers
Just give the housing a quick touch on the bench sander - that'll take off any high spots.
If the O ring groove maintain on the right tolerance according to O ring supply it should not be leaking.
Just like to share information .
Please notice the two diagram
Different directions of the pressure and contact area of the O ring
Only have metric chart, you may find some inches information on the website.
LIM
Just like to share information .
Please notice the two diagram
Different directions of the pressure and contact area of the O ring
Only have metric chart, you may find some inches information on the website.
LIM
Seymour Snerd
Lifetime Supporter
