ArdWrknTrk Posted February 26 Share Posted February 26 Air doesn't give more pressure than water. It is just that I THINK water molecules are bigger than air molecules, but I don't know that for sure. Jim will know. "Air" is mostly molecules of nitrogen, with about 20% oxygen, 2% argon and the rest mixed gases like CO²... 💡 Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 26 Share Posted February 26 "Air" is mostly molecules of nitrogen, with about 20% oxygen, 2% argon and the rest mixed gases like CO²... 💡 Ok, but how do the sizes of those molecules compare to water? Will some of the components in air leak more through the same orifice than water? Link to comment Share on other sites More sharing options...
viven44 Posted February 26 Author Share Posted February 26 "Air" is mostly molecules of nitrogen, with about 20% oxygen, 2% argon and the rest mixed gases like CO²... 💡 Ok now I’ve got pressure stable but still a pesky nano leak at the thermostat housing. I’m impatient and didn’t allow the gasket maker to set the full 24 hours. It’s the one time I wish I had “the right stuff lol”. The PSI is still mostly steady after about 15 mins though. May have dropped 0.2 PSI. No leaks under the block or in the cylinders. Think I’m ok to proceed ? Not in a rush but just don’t have the time during the week. I don’t think it will pass the air test as the thermostat housing would leak down a lot faster. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 26 Share Posted February 26 Ok, but how do the sizes of those molecules compare to water? Will some of the components in air leak more through the same orifice than water? Well, there's trace amounts of everything, right down to hydrogen, so definitely will migrate through seals far more easily than water. But all this is a fools errand because the engine hasn't been heat cycled, and everything is going to move, and need retorquing. 💡 When it comes down to it, the only thing that matters is how it performs in service. 🧐 Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 26 Share Posted February 26 Ok now I’ve got pressure stable but still a pesky nano leak at the thermostat housing. I’m impatient and didn’t allow the gasket maker to set the full 24 hours. It’s the one time I wish I had “the right stuff lol”. The PSI is still mostly steady after about 15 mins though. May have dropped 0.2 PSI. No leaks under the block or in the cylinders. Think I’m ok to proceed ? Not in a rush but just don’t have the time during the week. I don’t think it will pass the air test as the thermostat housing would leak down a lot faster. You are probably ok. But if you don't have time during the week to do much more then why not pull the thermostat housing, RTV it, and let it sit for 24 hours? To RTV it I would tighten the housing down finger tight, let it sit, and then torque it down to spec. That will get you an RTV gasket and not squeeze it all out. Link to comment Share on other sites More sharing options...
viven44 Posted February 26 Author Share Posted February 26 You are probably ok. But if you don't have time during the week to do much more then why not pull the thermostat housing, RTV it, and let it sit for 24 hours? To RTV it I would tighten the housing down finger tight, let it sit, and then torque it down to spec. That will get you an RTV gasket and not squeeze it all out. That’s the micro leak In about 30 mins that’s what I saw. It started right before the 1 in 15. It seems to have stabilized there for now. Pics under the block. No coolant leaks. Also scope showed nothing in the cylinders. My take is that if it’s a leak that’s smaller than even this, it probably wouldn’t hurt the engine ? Is that a fair thing to say ? Plus as I said before it’s only a gross test to make sure I didn’t screw up anything Link to comment Share on other sites More sharing options...
viven44 Posted February 26 Author Share Posted February 26 You are probably ok. But if you don't have time during the week to do much more then why not pull the thermostat housing, RTV it, and let it sit for 24 hours? To RTV it I would tighten the housing down finger tight, let it sit, and then torque it down to spec. That will get you an RTV gasket and not squeeze it all out. Yes I’ll do a better job with the RTV next time. As you suggested Link to comment Share on other sites More sharing options...
viven44 Posted February 26 Author Share Posted February 26 Well, there's trace amounts of everything, right down to hydrogen, so definitely will migrate through seals far more easily than water. But all this is a fools errand because the engine hasn't been heat cycled, and everything is going to move, and need retorquing. 💡 When it comes down to it, the only thing that matters is how it performs in service. 🧐 Yes agreed. The thermostat housing may not leak when warm and that is would be jelly side up… Update: the thermostat housing doesn't leak anymore. Just needed a bit extra time and the moisture from the coolant helped it get to a 100% maybe? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 27 Share Posted February 27 Yes agreed. The thermostat housing may not leak when warm and that is would be jelly side up… Update: the thermostat housing doesn't leak anymore. Just needed a bit extra time and the moisture from the coolant helped it get to a 100% maybe? Possibly.?!.?! I tend to use anerobics, except where indicated like my diff cover or the china walls. I like RTV, it's great all around, but a lot of times id rather something more specific. Link to comment Share on other sites More sharing options...
viven44 Posted February 27 Author Share Posted February 27 Possibly.?!.?! I tend to use anerobics, except where indicated like my diff cover or the china walls. I like RTV, it's great all around, but a lot of times id rather something more specific. I gave permatex 2 only 2 hours to set on either side of a felpro gasket, so I wasn't being fair to it. But i'm still impressed it set well after the customary 4 hours. I like permatex 2 overall the best because it has resistance to just about everything including fuel since its solvent based. Has better working time than RTV. I avoid RTVs for anything vertical like timing cover, water pump in proximity to fuel as they are not very fuel resistant per the datasheet. A couple of fuel leaks on the intake may possibly weaken RTV as it flows down the engine.. those are at least my thoughts/beliefs. I have no data to prove/disprove any of this. I do use RTV for oil seals like oil pan, differential covers. Link to comment Share on other sites More sharing options...
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