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Discussion Starter #1
Hi all,
I have a slow oil leak from my left side intake valve adjuster. See attached pic. The oil appears to be seeping out around the slotted adjustment screw... not sure if it's seeping around the locknut also, but that locknut is nice and tight. I've made sure the washer behind the locknut is flat and free of burrs.

Is there an O-ring or any other type of seal inside this assembly that could have failed and caused this oil leak? If so, does anyone know the part number?

Any other suggestions?

Thanks so much!
Max

(not sure why this picture uploaded sideways - sorry - the right side is towards the ground... you can see the oil dribbling from around the slotted screw and down the cover.)

IMG_1322.jpg
 

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First, phone uploads often come out sideways or upside down. If you transfer them to a computer before uploading, things usually come out right. As for your leak - there is an o-ring on the eccentric shaft that is the valve adjuster, but to replace it requires the cam bearing cap to be pulled... not that big a deal if done correctly, but if you decide to do it and haven't ever, ask questions before just yanking it off the camshaft. It can be done in the frame is done properly
 

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I keep o-ring assortments in my shop. It saves a trip to the dealer or a wait if I order it, and probably saves money in the long run. I have 4 boxes of standard and metric o-rings handy. Unless it's unusually large or small, I usually have it. Also, I'm kind of anal about this stuff. I'd have to replace all 4, especially since you have to remove the bearing cap anyway. You'll have it halfway apart. Just do all 4 while you have your hands dirty, and you won't have to worry about which one you did next time.

Sent from my SAMSUNG-SM-G890A using Tapatalk
 

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Discussion Starter #6 (Edited)
Thanks everyone! Super helpful.

Ancientdad (or others), my assumption on how to replace this o-ring is: remove the locknut, remove the cover, hopefully the o-ring is visible and replaceable here, then replace cover and lucknut and re-set valve adjustment. Am I correct or way off? I’ve adjusted my valves before but have never pulled off one of these 4 cam covers.
 

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These covers are the cam bearing housings, ie they support the camshafts, if you just pull one off while the cam chain is under tension and the valves are open you're asking for trouble. I believe Tom (ancientdad) has a method to do this safely, something along the lines of pulling the cam chain tensioner and rotating the cams until the valves are almost all closed, might even need to break the cam chain. I'd wait for Tom to describe his method before doing anything just to be safe.
 

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^^^yes, the key to removing a cam bearing cap without causing damage to the aluminum bearing surface is to remove the tension on the cam from the cam chain and any valves that might be open before pulling the bearing cap off.

-Start with removing the valve covers as if to adjust the valves, and remove the alternator cover to be able to turn the crankshaft.

-Loosen the lock nut and lock bolt on the cam chain tensioner. With your finger on the end of the cam chain tensioner body, slowly turn the engine backwards to where you see an intake valve being opened and feel for the cam chain tensioner rod moving backwards (essentially loosening the chain) - you might need to insert a small bolt or punch in the open end of the tensioner body to feel the movement. When you feel the tensioner move backwards, stop and lock the tensioner lock bolt.

-Then, slowly and carefully turn the engine until you see no intake valves are open. At this point you've removed any tension on the intake cam from the tensioner and valves, and it's safe to remove the cam bearing cap.

-Pull the screws, valve adjuster lock nut and washer and tap around the outside of the bearing cap until it breaks the gasket loose and you can remove the bearing cap. Watch for thin shims that might be stuck to the cam bearing journal to reduce end play in the cam (sometimes oil film causes a shim to stick to the end of the bearing cap, and you want to put the shim, if there is one, back on the cam bearing journal). Also, watch for the cam follower (essentially the rocker arm) shaft movement out of the head as you pull the bearing cap, you want to keep the shaft in place so the follower doesn't come off... not the end of the world if it does, they can just be tricky to get back under the cam and on the shaft sometimes when the head is assembled. The o-ring you want to replace is on the valve adjuster shaft.

-Replace the o-ring and clean the gasket surface on the head and cam bearing cap, and be careful to avoid any gasket scrapings getting into the head in any way - there is a small oil return hole at the lower area of the bearing cap opening and you don't want to clog it or allow gasket material to get into the oil galleries.

-The key in this whole operation is to be sure not to force the cam bearing cap off, or back on, the camshaft to avoid doing damage to the bearing surface inside the cap.

-Once all that is done, you can re-assemble with a new gasket and tighten the screws on the cap (if you've replace the JIS screws with allen heads, be careful not to overtighten). At this point, be sure the mark on the valve adjuster shaft (the notch that is 90° to the screwdriver slot) is pointing outward from the engine - toward the rear of the bike for the intake valves, toward the front for the exhaust.

-Then loosen the lock bolt on the cam chain tensioner and turn the crankshaft in the direction of rotation until one of the exhaust valves is being opened (which tensions the front of the chain) and then tighten the lock bolt and lock nut. Then adjust your valves, button it up and you're good.
 

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Discussion Starter #9
Ancientdad, you are a wealth of information. Thank you so much for taking the time to explain this. It all makes sense. I’ll let you know if I run into any problems!

Thanks again,
Max
 

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Use the proper o-ring - which, to the eye, will look too small and thin, but it's correct. Old ones will appear to be much larger than new ones when you take them off (squashed for 40+ years).
Use of a thicker o-ring will cause the adjuster shaft to bind and not be turn-able once the cam cover is tightened down.

Don't ask how I know this..........
 

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Discussion Starter #11
As I'm thinking about this more, I'm wondering if I should just go ahead and replace the cam chain and do all 4 seals while I'm at it. This bike has 26k miles on it and I have no idea when the cam chain was last replaced, if ever.

Is there a similarly-clever way to replace the cam chain without pulling the engine and ripping everything all apart? Ancientdad, any advice or links?

Thanks!

PS: Bill... thanks for the tip! I'll definitely get the Honda OEM parts for those O-rings.
 

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As I'm thinking about this more, I'm wondering if I should just go ahead and replace the cam chain and do all 4 seals while I'm at it. This bike has 26k miles on it and I have no idea when the cam chain was last replaced, if ever.

Is there a similarly-clever way to replace the cam chain without pulling the engine and ripping everything all apart? Ancientdad, any advice or links?

Thanks!

PS: Bill... thanks for the tip! I'll definitely get the Honda OEM parts for those O-rings.
Actually, one of the aftermarket gasket sets I bought came with the o-rings - they came from 4into1.com, I used them on mine with no issues (I want to say it was NE brand but can't be sure). Though I'd usually agree with changing the cam chain at that many miles, and you absolutely can work on the cams and followers with the engine still in the frame (but it's a lot more challenging), I'd recommend you just replace the leaking o-ring and see how things go after that. I've never personally seen a cam chain break on a 450 (though I'm sure some have), but the replacement of it under those situational circumstances is a lot harder and I really wouldn't recommend it for the first time digging into an engine like this. Too many things about re-assembly have to be adjusted for the inability to access the proper areas to do it - I did it, but you can see at the link below it was a bigger challenge, and this is only some of what you have to do to accomplish it in the frame

http://www.hondatwins.net/forums/1-project-logs/65305-cl450-project-reboot-street-legal-time-5.html#post632449
 

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Discussion Starter #13
Good advice Tom, thank you. The method you described before is for the Intake side. I'm assuming for the Exhaust, after the cam chain tensioner is disengaged, I would rotate the engine until neither exhaust valve is opening and do the O-ring replacement then. Is that correct? Or are there any additional tricks for the exhaust side?

Thanks!
Max
 

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Yeah, pretty much the same. The cam chain tensioner doesn't actually disengage, it's just the spring-loaded tensioner rod that pushes the roller that contacts the chain that gets pushed backwards to allow some slack. You could remove the tensioner assembly from the back of the cylinders, but the gasket usually shreds and it's in a tough spot to remove and replace and clean the gasket surface - and you don't actually need that much slack, just enough to remove tension on either of the cams. The difference in doing the o-rings on the exhaust adjusters is the points and advancer assembly on the left side and the tach drive on the right, other than that they are pretty much the same. If no others are leaking, I'd leave well enough alone for now... it's possible, with that mileage, that you'll end up going into the top end in a year or so anyway for other reasons (not wishing anything bad on you, just the reality of a 40+ year old engine eventually needing something else). BTW, if you aren't aware of it by now you need to understand - these engines have no pool of oil under the cams and followers to provide lube on cold starts and those parts, along with the cam bearing surfaces (aluminum on steel cam journals) rely on oil flow, which goes up the 2 right-hand cylinder studs to get into the cams themselves and flow across to the bearings and out the orifices in the lobes to lube the followers, lobes and bearing surfaces. That oil flow takes a full minute or two to get to the top end, so plan to run the engine as slowly and gently as possible during warm-up and don't just fire it and ride off under power - or you'll be going into the top end a lot sooner than you'd expect to replace severely worn parts.
 

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Discussion Starter #15
Thanks for the tip, Tom. I definitely noticed how much the valvetrain quiets down after 60sec, and I've made sure to never rev the engine or take off until it's idled for a good few minutes past the "quiet-down" point. Glad to know the technical reason behind it! My BMW 3-series made similar noises until its hydraulic lifters received oil flow after startup...
 

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Thanks for the tip, Tom. I definitely noticed how much the valvetrain quiets down after 60sec, and I've made sure to never rev the engine or take off until it's idled for a good few minutes past the "quiet-down" point. Glad to know the technical reason behind it! My BMW 3-series made similar noises until its hydraulic lifters received oil flow after startup...
Good - BTW, I meant to post this in case you haven't seen something similar about your engine. They're my favorite of all the vintage Honda twins (although the 72/77 series - 250s and 305s are pretty cool too), very unique and advanced for their time and still makes people scratch their heads when not familiar (sorry, replaced with jpegs for better zoom)

cam drive.jpg DOHC450 head.jpg
 

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Discussion Starter #17
Hey Tom, or others, I believe I have a new problem.
While doing the method you described for the intake side, I'm pretty darn sure that I've skipped 2 cam teeth on the intake. I felt the cam chain tensioner push backwards (had to use a screwdriver, it was wayyy in there), then continued to turn the engine backwards a few more degrees to see if it would push further, and then "CLICK" - the chain skipped a tooth on the intake cam. I gingerly tried again and got another CLICK - a 2nd skipped tooth. If I turn the engine forwards now, the left intake valve contacts the rising left piston and obviously the motor won't turn forward any more than that. I certainly didn't force it.

So - am I screwed? Is there any way to roll that intake cam back 2 teeth without breaking the cam chain?

Another thought - if this cam chain is 40k miles old, probably worn and stretched... at this point am I just better off breaking the cam chain and replacing it? I think that's probably the right answer. Would I have to remove the motor from the frame, or can the cam chain be replaced without pulling the motor?

I should also mention, that a few hundred miles ago when i checked my cam timing, the marks on the cam chains didn't quite line up with the marks on the cylinder head. They were just a few degrees off. Is that another sign of a worn/stretched cam chain, I'm guessing?

Thanks!!
 

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I'm a bit puzzled by this: "had to use a screwdriver, it was wayyy in there". The tensioner rod moves backward toward the end of the housing when you turn the engine backwards a bit to create some slack, so the end of the rod should be really close to, or right at, the end of the housing where you could almost feel the end of it with your finger... it wouldn't be deep in the housing. that would be when the chain was tensioned - rod extended inward, moving the tensioner roller further into the chain to take up slack.

There must be a lot of wear on both your cam chain and maybe the center roller if it actually jumped teeth. I've personally never had it happen. No, the timing marks don't always line up perfectly, often they are off a degree or two and sometimes both are a bit. If you're sure that's really what happened, the timing can be reset in the frame but it's a real PITA... and if the chain did slip, you're not in the position to rotate the engine to find the original master link to break the chain there. With that many miles on the engine, your best move at this point would be to pull it and just do the top end, new chain, check cams and followers, leak test the valves, check pistons and cylinders and if they're still in specs, put a set of rings in it
 

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Discussion Starter #19
Thanks Tom. As I think more about it, it may have actually been the crankshaft that skipped on the chain, not the intake cam.

And regarding the cam chain tensioner - even when the rod moved rearward, it was still pretty deep within the cam chain tensioner housing. No way I could have felt it with a finger. I guess that means it's a pretty worn chain.

Tomorrow I'll call a local shop to see how much they'll charge to do this work (too many projects and not enough time!), otherwise it looks like I'll have a few more weeks of non-riding garage time :)

Thanks for your help!
Cheers,
Max
 

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Yeah, I didn't clarify but it had to be the crankshaft sprocket that slipped if that's what happened. I understand what you meant about the tensioner now and you're right, if it's that deep in the housing the chain and/or other components must be pretty worn... 40k is a lot of miles, particularly if the maintenance along the way wasn't that good. Hate to see you take it to a shop - so few today even know anything about this engine and it's not the simplest vintage twin to overhaul a top end on when not familiar, plus the labor rate for them "learning" will be just like the labor rate they charge for something they're totally familiar with. If that's what you have to do... is the guy you're going to take it to the same "shadetree mechanic" who did the work you mentioned back in June?
 
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