URGENT: TE449 Camshaft spacer/bushing migration

Greetings:

I hope I may impose upon someone for advice. I took my valve cover off to check clearances, and the left end of the intake cam has a spacer/bushing inside it, which had migrated out. I can't see if there was any retainer, and the parts PDF shows nothing. Neither does the other end of the cam. The valve cover clearance isn't such that it will prevent it from coming out. Please see accompanying pictures. Is there actually a problem? How do I get the spacer to stay in the cam?

Sorry, don't know why it posted duplicate images.

Should I just tap it back in, so that it jams in? There doesn't appear to be a side load that is trying to displace it. Maybe I should use some Loctite.

Thanks, everyone.

There are no grooves in the insert, and it is loose until the flange is pushed back into the cam.

It can't come all the way out, as it hits the inside of the valve cover and head flange that meets the valve cover.

There is a drift pin in the exhaust cam, perhaps for a decompression valve mechanism for starting, but nothing in the parts PDF (page 13) for the intake.

The thing is, it was running fine, then I shut it down, and several hours later, I took the valve cover off to check the clearances, and there it was.

it is probably an interference fit and will take a minor force to re-insert it. blast it with dust-off (upside down so the liquid refrigerant comes out) and push it into a mildly pre-heated cam (maybe tap it with a copper or soft mallet). it looks like it should fit flush.

what's it "spacing"? or is it an oil block? and if so: I wonder if oil pressure pushed it out.

No idea about the oil block possibility. When it is protruding, it wobbles in the cam. I can see right through the cam from one end to the other, which is the same as in the manual where it shows the cam timing gear dots. There isn't a groove or hole in it, as I could shine a flashlight in and past it, and I spun it to check, but nothing's there.

The cam in the parts PDF comes as a unit, with this insert already installed.

After looking at the whole set-up, and trying to trace the lubrication pathway, I think you're right about it being an oil block. After reading more comments, and thinking about it, I decided to clean the mating surfaces as well as I could, then applied Loctite 243 around the perimeter of the insert, pushed it back in, and tapped it in somewhat. I have been waiting for the Loctite to cure, while simultaneously waiting for any more input. After some more thought, and if nothing better comes along, I am going to put a 1/4" bolt with fender washers all the way through the cam, use Loctite, then tighten it down enough to cause the washers to buckle/deform, so they become slightly conical/concave, to act as a self-centring mechanism. There's no significant load trying to pop out the insert(s), and the bolt will be balanced, plus at the center of rotation, so I don't think it will throw things out of balance. I never thought about it before, but camshafts aren't balanced like crankshafts, probably because the lobes aren't so pronouneed that they cause them to be sufficiently lopsided that they need balancing. Anyway, it would be more like adding a slightly heavier flywheel.

sounds okay. but a couple of minor points (I know you'll start fretting, but you're good- really):

• I assumed (hah.) that you'd be doing this with the cam out. No? it would be easier to get the "oil block" (?) flush this way- which also insures that the block that the block is parallel too. (and you could inspect the "pillow block" surface that the cam rides on for excess wear if the oil pressure was too low at this point; but don't worry about it now.)
• it's aluminum, right? cam is steel. locktite bearing and stud (723??) is made for this situation
• how easy was it to push in (flush)? if you could do it by hand, I might be worried. (...and would use epoxy or 723)
• you're not thinking of leaving the 1/4 bolt in the cam are you? I would not recommend that. using the bolt to install the block? yes.
• the rotational forces would be minimal closer to the axis... but I guess you get that.
• it probably was a minor manufacturing defect (oil block was not installed flush) from the factory. If it's a good, firm interference fit you should be good to go. the aluminum will grow with heat faster than the steel cam and should remain snug. the oil pressure differential should only be a pound or three, i would guess.
• all this is predicated on the GUESS that it is used to block the oil passage, to give the non-roller bearing surface some oil and pressure. If this is not the case, all the above points are bs.

good luck.

Cam would stay in. The right side has the semi-circular cut-outs, so a bolt would clear.

It goes in straight and flush now. When it's all the way in, I can't remove it with my fingers. I had to insert something in the hole to jam and pull it back out. Here I am trying to get it to stay in, then having to force it out. Kind of like, "Wake up! It's time for your sleeping pill!"

Don't know if it's aluminum. Never thought about Loctite Stud. That's the best idea so far.

I was thinking of leaving the bolt in. Why do you think not?

You may be familiar with Mazda rotary engines that were made of alternating aluminum and steel plates. If the engines got too hot, the aluminum would expand more, and be deformed when it hit the steel. When it cooled down, gaps opened up, and they would leak. My point is, if the insert is aluminum, and the cam is steel, might not the insert expand too much, then get deformed, and loosen when cool?

After considering your latest comments, here's what I'm going to do: I have used Loctite 243 to re-insert it. It was obviously out before, yet not hurting anything (aside from low oil supply to the cam lobe(s). I will run it for a while, then loosen the valve cover to peek inside later, to see if it's come out again. If it has, I will try Loctite Stud. I've thought about installing an inspection hole in the valve cover, and sealing it with a rubber plug. One thing at a time.

After I read your last post, I investigated Loctite Stud, found its current version, then happened upon a related product called Sleeve Retainer (640), which appears to be ideal for this situation.

after thinking about it a bit, I'm guessing (GUESSING) the oil comes IN from the journal bearing (the big middle hole) and leaves out the 2 cam lobe holes (and mostly your hollow camshaft). Since the plain non-roller bearing surface has already been lubricated (and also supported by oil pressure), about the only negative is that your valve area would be slightly more flooded with oil. And the cam lobes probably get enough oil by splashing in either case. maybe.

did that thing go in by hand?? or did you hafta press it in with a tool (hopefully)?

there is just about zero chance of deformation when your talking about circles within circles. The aluminum should be slightly bigger then the ID of the camshaft when cold (interference fit); slightly more so when hot. that's why I was hoping that you had to use a little force to get it in. Normally you would not need epoxy or anything else of course.

and insert it flush with the camshaft.

It went in by hand. Upon reflection, it appears that the inside end of the insert may fit into a mating hole, because, as I was fiddling with it, I found that if I pushed it in, it would be guided home (for want of a better descriptor) before the outside/end flange entered the cam. I would then use a tool to wedge into the inner diameter of the insert to pull it out, but the tool would bring it out about 5/16", then, having discarded the tool, I couldn't pull it out directly with my fingers. I'd have to spin/rock/wiggle it out. I applied the Loctite 243 (all I had) to the end/outer flange, as I couldn't get to the inner part. It did go in flush by hand, but I tapped it in with a tool to fully seat it. I will monitor the Loctite's effectiveness.

Trenchcoat85:

You previously said you didn't recommend leaving a makeshift retaining bolt in. Why? What do you think would happen? If I can get relatively concentric with the cam's centreline, and use Loctite with a lock washer/fender washers that have been deformed to become conical, plus, the whole bolt assembly may be weighing 100 grams (?), my observation is that it would vibrate minimally, hopefully not loosen, and just result in a bit more mass/inertia for the cam chain to move. The other cam is not hollow, as it has the decompressor, and it appears to me that the hollowing is a weight-saving measure.

well, if the right end of the "thing" has a guiding hole, then that means all of the oil entering the camshaft has to leave via the 2 cam lobe holes, right?

your description of putting it in flush by hand and THEN seating it is both confusing and reassuring. confusing because I thought/assumed it was supposed to be flush (but maybe now: recessed?) and reassuring because if you had to seat it, it should stay.

you're done, I'd say.

Assuming a 2" diameter fender washer, that's 6.28 inches travelled in one rev at the outer edge, and 1,675 feet per minute at 3,200 cam RPM (6,400 engine speed at 100 kph bike speed), which equates to about 19 mph for the washer's outer edge. I don't think there would be enough kinetic energy or momentum for it to self-destruct.

I bloody hope so.

I don't know about you, but I'm going to get some sleep. Thanks for all your help, and talk to you later. Good night (morning).

To clarify, although I tapped it with a tool to seat it, it didn't go any farther in. It remains flush.