stegs 327 #1 Posted February 9, 2022 There is a small 1/4"? line coming out the bottom side of the air filter housing. It appears to be some sort of vac line? I have the one hooked to the guage on the dash, and its works properly (although the needle bounces really fast) But this one is slightly smaller, connects to the underside of the air filter housing Its attach at the housing, and is run towards the dash. Does anybody know what it attaches to or where it goes? Im sorry, still very new to the 520 and onan engines. 1 Share this post Link to post Share on other sites
Snoopy11 5,718 #2 Posted February 9, 2022 May we have some Don Share this post Link to post Share on other sites
WHX?? 51,733 #3 Posted February 9, 2022 (edited) Yes it should go to a small square sensor mounted just below the dash. Left side of battery I think. It is for the dirty filter light on the dash. It senses pressure/vacuum You might find the nipple where the hose attaches is broke off. I would be surprised if it's not.... It's very common to have them bust off. I seldom agree with Snoopy and would never insult or consult him but in this case, or any other thread, we do like our . But you knew that by now didn't you! Edited February 9, 2022 by WHX?? 1 Share this post Link to post Share on other sites
stegs 327 #4 Posted February 9, 2022 Thanks guys LOL i knew yall wanted pictures, but i thought its just because you admire my latest purchase so much I actually know exactly what your talking about. Its just to the left of the battery (sitting on tractor) Its about the size of a box of matches give/take. And yes that nipple is still there on my tractor. Ill plug it back in I noticed it when messing with my 9 pin connector, seen it hanging down....must have fallen off or got pulled off when i was working in that area and never noticed!!! 3 Share this post Link to post Share on other sites
Snoopy11 5,718 #5 Posted February 9, 2022 (edited) 10 minutes ago, WHX?? said: we do like our . Oh... are you talking about... ??? Not only does it help diagnose... but... future thread-viewers will thank-you! Don Edited February 9, 2022 by Snoopy11 1 Share this post Link to post Share on other sites
Snoopy11 5,718 #6 Posted February 9, 2022 2 minutes ago, stegs said: i knew yall wanted pictures 3 minutes ago, stegs said: i thought its just because you admire my latest purchase so much Also: Don Share this post Link to post Share on other sites
Handy Don 14,061 #7 Posted February 10, 2022 6 hours ago, stegs said: Thanks guys LOL i knew yall wanted pictures, but i thought its just because you admire my latest purchase so much I actually know exactly what your talking about. Its just to the left of the battery (sitting on tractor) Its about the size of a box of matches give/take. And yes that nipple is still there on my tractor. Ill plug it back in I noticed it when messing with my 9 pin connector, seen it hanging down....must have fallen off or got pulled off when i was working in that area and never noticed!!! Treat the plastic nipple on the sensor with care. As @WHX?? noted, finding an unbroken one is pretty rare! Also, realize that with that tube not connected, the engine is drawing in unfiltered air through it--so if it can't be connected properly, plug it. 1 Share this post Link to post Share on other sites
lynnmor 7,815 #8 Posted February 10, 2022 11 minutes ago, Handy Don said: Treat the plastic nipple on the sensor with care. As @WHX?? noted, finding an unbroken one is pretty rare! Also, realize that with that tube not connected, the engine is drawing in unfiltered air through it--so if it can't be connected properly, plug it. Also, find tubing that is very flexible and route or support it so that there is no load on that nipple. At one time I was able to purchase the switches for a reasonable price here:https://howlandtechnology.com/products/pressure-vacuum-differential-switches/ 1 Share this post Link to post Share on other sites
WHX?? 51,733 #9 Posted February 10, 2022 I didn't see prices on them Don @Handy Don er I'm sorry @lynnmor but we were looking for them awhile back for the purists. If I recollect the thread right Toro still had them, was quite proud of them and wanted our firstborn. The concensus was to plug it and check/change your filters regularly as a good tractor person should. All four of my 520's are busted off. Good advice above on supporting the hose Stegs. Share this post Link to post Share on other sites
lynnmor 7,815 #10 Posted February 10, 2022 I made cover plates from aluminum to bolt over the broken nipple side of the switches. The cover plates have nipples standing where needed, and a tiny o-ring on the opposite side to seal the parts. Four very small screws hold it together. 1 Share this post Link to post Share on other sites
Handy Don 14,061 #11 Posted February 10, 2022 12 hours ago, lynnmor said: I made cover plates from aluminum to bolt over the broken nipple side of the switches. The cover plates have nipples standing where needed, and a tiny o-ring on the opposite side to seal the parts. Four very small screws hold it together. I've temporarily supported the tube and hooked it to the pressure side of the switch (yeah, no value for sensing--just keeps dirty air out!) and just follow @WHX??'s plan of regular checking until I stumble on a better idea! 1 Share this post Link to post Share on other sites