sdcott40 0 #1 Posted May 21, 2016 Engine help with onan blows O ring out of oil filter soon as I start it Share this post Link to post Share on other sites
N3PUY 1,031 #2 Posted May 21, 2016 (edited) Is there an old O-ring stuck on the motor? Look for the o-ring that was on the filter removed. And the seal is too thick to escape between the filter and the motor surface. Edited May 21, 2016 by N3PUY pictures Share this post Link to post Share on other sites
onanparts.com 185 #3 Posted May 21, 2016 Couple things. If the filter is really old it could be clogged but that is very rare. If the bypass valve is sticking that will cause extremely high oil pressure. Below is from a rebuild article I did a few years ago. Applies to removing and replacing the bypass valve and spring. The oil bypass valve and spring are what regulates the oil pressure. The bolt in the first pic is removed and the spring will typically fall out after you turn the block upside down. Sometimes the bypass valve will come out with it, sometimes not. Not practical with engine still installed in machine. See next part.If not use a small magnetic pickup tool or spray some carb cleaner down the hole to breakup the oil that is holding it in place. If using compressed air to launch it out of the block, oil filter adapter must be removed, and you don't put a rag over the opening to catch it and hours later it's still hiding someplace you will never find it.....Part number is 120-0398.The valves hold up well but it's always a good idea to replace the spring, part number 120-0140 when rebuilding.When putting it back in, the "flat" end goes in first. The smaller rounded end on the top is what keeps the spring centered. Oil up the valve before installing it, drop it in the hole and then put the spring in. The copper washer can be reused if annealed. Heat it up cherry red and drop it into some water. What? You lost the bolt too? It's a 3/8-24 X 7/8. The length is what sets the oil pressure. Torque it to 10 foot pounds. Don't over tighten or you risk cracking the block! 4 Share this post Link to post Share on other sites