TC10284 113 #1 Posted September 7, 2019 (edited) So I have a 518H that I've been working on. This one has had so many bugs and frustrations... Hopefully...one of the last few issues that has plagued this thing is a persistent oil leak from behind the fuel pump. It is not the fuel pump. I have tried two new ones on it (just today I broke one of the cheap plastic outlets on the one that was on it trying to remove the hose). Put a new one on it, it did the same thing. The original pump also did this. I took the mounting screws off and it appears to be coming from the tiny hole in the back that are on the new pumps. I'm not sure what's causing this. Edited September 7, 2019 by TC10284 Share this post Link to post Share on other sites
JoeM 8,347 #2 Posted September 7, 2019 is the engine breather blocked? to much oil in crankcase? 1 Share this post Link to post Share on other sites
lynnmor 7,823 #3 Posted September 7, 2019 Did you replace the pulse hose on the back side of the fuel pump? If you remove the oil filter, then look in with a flashlight and mirror, you might be able to see if the oil filter bracket gasket is leaking, or some other problem. If the engine fins are getting sprayed with oil they will clog with dirt. Share this post Link to post Share on other sites
TC10284 113 #4 Posted September 7, 2019 (edited) 1 hour ago, lynnmor said: Did you replace the pulse hose on the back side of the fuel pump? If you remove the oil filter, then look in with a flashlight and mirror, you might be able to see if the oil filter bracket gasket is leaking, or some other problem. If the engine fins are getting sprayed with oil they will clog with dirt. Yes, it's a new hose. I'll check on that as soon as I am ready to drain the oil. There doesn't appear to be any oil being sprayed elsewhere. It is only coming from the back of the fuel pump and running down the outside of the shroud. I've had the fuel pump off and watched it spray out of the small hole on the back. Edited September 7, 2019 by TC10284 Share this post Link to post Share on other sites
TC10284 113 #5 Posted September 7, 2019 6 hours ago, OILUJ52 said: is the engine breather blocked? to much oil in crankcase? I am going to check on the engine breather today. The top of the oil level is maybe 1mm over the "Full" mark. No more. Share this post Link to post Share on other sites
TC10284 113 #6 Posted September 7, 2019 One problem I found just now when checking the reed valve in the crankcase breather is that the spring is missing. That would explain why I keep getting oil in the air filter... Share this post Link to post Share on other sites
TC10284 113 #7 Posted September 8, 2019 I replaced the spring for the Reed valve, and also swapped back to the original carb from a new aftermarket carb. So far it runs a lot better. Much less surging, very minor remains. Barely noticeable. Additionally, I test mowed for maybe 10min and I did not see any oil coming from the back or the fuel pump. I need to do a longer run, but so far, so good. 1 Share this post Link to post Share on other sites
