M8 Harley Oil Pressure Relief Valve

Hey, it's Mike Roen with another Fix My Hog tech tip. Now with the Milwaukee-Eight, it's been out for almost three years now, and some bikes are actually starting to get a little more miles on them, or more importantly, if they've had some sort of a catastrophic failure, whether a lifter deteriorated or something and it's run debris through the engine. A lot of times, what a lot of people overlook is the bypass valve. Now, on the Twin Cam, it used to be in the cam plate, and you'd take that roll pin, drive it out, take the plunger out and the spring, clean the whole system out real good, because you didn't want any debris getting in that plunger. And, you know, if it did stick, you would have no oil pressure. So now what they did on the Milwaukee-Eight, is they actually have it built into the oil pump here. So anytime you're in there in the oil pump area and you wanna inspect this just to see if there is any debris or to make sure that that bypass valve is floating freely. So what you can do is you can maybe choose to make your own little tool. What this does is that depresses the spring. And what that does is that allows you to knock this roll pin outta here, a spring and a plunger is gonna come up. I ended up just getting a aftermarket tool and then I modified it a little bit so it works on both the Twin Cam and the M-Eight. So basically what we're gonna do is, we'll just take this pump part here. We're just using it for a display anyway. And... What I have, is I got an 1/8 inch punch and it's actually for a roll pin. If you zoom in on this, you can see it's got a little dimple on the end. That kinda helps it keep in guide on the roll pin, so. I got a little block of wood here, and what I'm gonna do is I'm just gonna take this roll pin and I'm gonna drive it out. The spring will come out and the plunger will come out. So what you wanna do is basically give it a tap here. It's starting to move, and then you take your little tool, now you can depress the spring. You gotta drive it out the rest of the way. It's kind of... You need another hand. What you're trying to avoid is driving that pin on, having that spring go shooting across the room. Okay. So here's your bypass spring. Some aftermarket companies do sell higher pressure ones. Typically, you know, the stock one works fine but you could always raise your oil pressure, add higher RPMs with that. Now more importantly, you got your roll pin here. I'll just put that there so I don't lose it. Take your magnet. And now you can fish out the little piston here. And really what you're looking for is any galling or scoring or any debris that's, you know, possibly, maybe in the oil pump here. So what you'll wanna do is take contact spray, little compressed air, clean it all up nice, and then reassemble it. So this is basically just a, it's an old oil pump that we're not gonna use anymore, so I'm gonna go ahead and put it back together to show you how, what the process is there. Take your magnet. Like I said before, you can kind of clean it up, look it over, put a little lube on it if you want. But really what you want to verify is that this is going up and down smoothly in that bore. And I can feel it, there's no burrs, it's no binding. We've taken motorcycles apart before, you know, especially on the Twin Cam, where that plungers just seized in there and we can't even get it out. You end up buying a new cam plate. In this configuration, you'd just be buying a new oil pump, so. Let's go ahead and stick the spring in. No top or bottom on it. Now we're gonna turn the pump around like this, lay it down. What I'm gonna do is I'm just gonna, just start that roll pin. Just a little bit. Okay. Now you depress your spring in. It's got a little built-in stop there. All right. Looks like I can go a little more. Looks good to me. Okay, that's a nice, little tech tip. Like I said, it's, it could be a really big difference, you know, if that thing was hanging up and you had no oil pressure, you'd can your motor all back together, you'd be cranking it over at the spark plugs out, trying to get oil pressure, maybe it'd start the bike, no oil pressure, your plungers hung up. All you gotta do is take it all apart again, replace the pump or clean this out, so. It's pretty important. All right, thanks for tuning in.