Bob Whitley 3 #1 Posted January 12, 2020 Hello group! New to the group today, purchased my 520H new in 1995. My tractor has developed an oil leak at the bottom of the engine where the drain pipe screws into the bottom pan. Apparently the threads in the pan have worn because the pipe cannot be tightened. Looking for any ideas as to how to fix my leak. Helicoil kit? Thank you. Bob W Share this post Link to post Share on other sites
wallfish 15,771 #2 Posted January 12, 2020 You may want to take a closer look for a crack in the engine block right around where the pipe goes into it. Probably on the bottom if that's the thinnest part of the pan. If that thread gets tightened to much into the aluminum block, it will crack the block. Clean that area well and look for the oil weeping out and or the thin dark line of a crack. If you install a new pipe and or thread sealant and it still doesn't seal, there's probably a crack. The threads could also get distorted I guess so thread sealant might fix that. Share this post Link to post Share on other sites
Bob Whitley 3 #3 Posted January 12, 2020 Thank you for the reply. When I changed the oil I unscrewed the pipe from the pan and some of the alum threads came out with the pipe. So, I'm thinking that the threads have been damaged. Would you suggest teflon tape as the best thread seal? Or something else? Thanks again for the reply. Bob W Share this post Link to post Share on other sites
JCM 8,568 #4 Posted January 12, 2020 As @wallfish mentioned if after you have determined that the block is not cracked by checking the area around the block using a telescoping inspection mirror and a good small flashlight, you may want to replace the black iron threaded nipple which should be 3/8 x 3'' coming out of the block and while your at it the 3/8 x 4'' nipple and 3/8'' black elbow, use the blue teflon tape on the male threads , usually 2 or 3 wraps and then some pipe dope over that and then tighten everything and see if that works. You may be able to find a small tube in the home centers and not have to buy a can of it. Remember to apply the teflon tape in a clockwise direction so the tape will not unravel and do not overtighten the nipple into the block. Hope this helps and good luck. 1 Share this post Link to post Share on other sites
wallfish 15,771 #5 Posted January 12, 2020 Here's some thread sealant. https://www.amazon.com/Genuine-Henkel-Loctite-542-Hydraulic/dp/B072JTXNP5 1 Share this post Link to post Share on other sites
WHX?? 46,404 #6 Posted January 12, 2020 Bob All of my 520's leaked ther but fortunately the fix as JCM mentioned fixed it. Jim & I are in trades where we can get our hands on the good stuff thread sealers tho. Worse part was having to lift the motor abit to be able to turn the elbow. On one the threads were somewhat questionable but not cracked and a quality thread sealer as 'Fish mentioned fixed that one. If you have to go that route make sure the threads are clean using Q-tips. and tip the motor up abit till the sealer cures. Yes use new pipe nipples & fittings. 1 Share this post Link to post Share on other sites
Bob Whitley 3 #7 Posted January 12, 2020 Wow! I never expected this amount of a responses! I can tell that you all appreciate these great machines. I was fortunate to have a father that installed in me the value of owning and operating a Wheel Horse tractor. I truly appreciate this forum and will do what I can to give back to the group. Once I verify the no-crack situation, I will order the thread seal. (Loctite) And then there was mention of blue thread tape. I have white teflon thread tape, is that not the same thing? 1 Share this post Link to post Share on other sites
JCM 8,568 #8 Posted January 12, 2020 Blue teflon tape is a bit heavier duty and doesn't need as many wraps as the white and will not tear as the white frequently does. To many wraps of either kind is not a good idea and could possibly cause the aluminum to crack from expansion if that is not already a problem. Share this post Link to post Share on other sites
Bob Whitley 3 #9 Posted January 12, 2020 Thanks again, Headed out to lift an engine and do some looking! Have a great day! Bob Share this post Link to post Share on other sites
lynnmor 6,707 #10 Posted January 12, 2020 (edited) I run a tap in to get the threads back to new condition, then I thoroughly clean all oil and debris from the threads. Using Teflon tape reduces friction considerably and will help crack the aluminum with normal tightening, I use a new nipple and red high strength threadlocker on this joint only so that it will stay in place without overtightening, if removal is ever needed, heat the pipe to free it. Helicoil is not an option for these pipe threads, the fix is replacement or welding and cutting new threads. Edited January 12, 2020 by lynnmor Share this post Link to post Share on other sites
WHX?? 46,404 #11 Posted January 12, 2020 I'll 2nd use the the red loc tite. I have had good luck with this stuff too. https://www.amazon.com/Highside-Chemicals-10004-Brush-Top-Plastic/dp/B00009W5HX Share this post Link to post Share on other sites
WildmanC120 613 #12 Posted January 13, 2020 Yellow Teflon tape for oil and gas. Just did it on my 416-h. The oil drain was loose. Had to take the engine mount bolts out so you can raise the engine a little. 1 Share this post Link to post Share on other sites
Bob Whitley 3 #13 Posted January 19, 2020 Thanks to all that responded. The deed is done, new pipes, red loctite 542 and no more loose or leaking pipe on my tractor! Have a great Sunday! 2 Share this post Link to post Share on other sites
Rich16 32 #14 Posted November 3, 2020 I've had this problem with every Onan WH (currently 3) I've had and I'm going to try a new tact - aluminum pipe instead of iron. The weight of the 4" long iron pipe and cap hanging off the elbow in the 'unscrew' direction of where it all inserts into the engine seems too much. Or risk the dreaded overtightening and screwing up engine threads or breaking the block. I'm buying all new aluminum plumbing (standard 3/8 pipe NPT threads) from McMaster-Carr for $25 and trying that. Anyone think this is a bad idea? Share this post Link to post Share on other sites
lynnmor 6,707 #15 Posted November 4, 2020 15 hours ago, Rich16 said: I've had this problem with every Onan WH (currently 3) I've had and I'm going to try a new tact - aluminum pipe instead of iron. The weight of the 4" long iron pipe and cap hanging off the elbow in the 'unscrew' direction of where it all inserts into the engine seems too much. Or risk the dreaded overtightening and screwing up engine threads or breaking the block. I'm buying all new aluminum plumbing (standard 3/8 pipe NPT threads) from McMaster-Carr for $25 and trying that. Anyone think this is a bad idea? You do run the risk of the aluminum in aluminum galling or seizing unlike using steel in aluminum. If I ever make a significant change it will be to use a drain valve like this. Share this post Link to post Share on other sites