Hydraulic Thread Sealant - Printable Version

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+--- Thread: Hydraulic Thread Sealant (/showthread.php?tid=5540)

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Hydraulic Thread Sealant - Richard - 06-26-2020

Both times (another story) I have replaced my radiator the bottom connection for the transmission cooler has been a source of leaks. The leak occurs where the 3/4NPT pipe screws into the transmission cooler on the radiator. This joint is further complicated by the fact that a TEE is on the other end of pipe nipple, and the TEE is where the transmission temp is taken for the gauge on the dash. You can’t just spin the nipple to make it tighter without the TEE hitting the fan shroud. And I added a longer nipple so that I could spin it completely around. 

Needless to say, ATF oozing into the engine bay, dispersed by the fan, makes a pretty good mess. I was motivated to stop this leak. All kinds of thread sealant were tried, teflon tape was tried, cleaning up the threads with a tap was tried. All my attempts would drip just a bit when the engine got hot. 

I found Loctite 545. It’s made specifically for hydraulic fittings. It does set once cured, so some force will be required to break it loose. So far, the fitting is dry as a bone. You won’t find it at Lowes/HD or any local parts place. You can get it on Amazon or McMaster Carr. 

I think it would also work for a pesky air fitting, but I haven’t used it in that application.

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RE: Hydraulic Thread Sealant - HoosierDaddy - 06-27-2020

Thx Richard. I will add that to my Repairers Guild of America tool box!

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