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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
Hey everybody, I'm back again with a question. Lately my '97 Evo has been making some valve noise. It almost sounds like the cars in the Jetsons if that makes sense. History: I had a vacuum leak at the intake manifold and ran the bike for a while until I figured out where it was. The valve noise kind of coincided with this event, so I figured I might've burn up an exhaust valve running lean. I checked the compression and it seems fine on both cylinders so I think I can rule that out. I also replaced the tappet filter and spring to see if the valve train was being starved for oil. Still have some noise from sounds like the front cylinder. Oil pressure (per my tappet spring mounted gauge) shows about 20psi at cruising RPM. I threw a little Sea Foam in the oil to see if maybe some crust was starving it, but it was still noisy after a 20 minute cruise. What should I be checking next?
Yep.
I'd get in the cam chest to examine.
There was a service bulletin that came down from the Motor Company in the Evo days, at 25,000 miles to "inspect and/or replace" the lifters.
Failure to do so,(without knowledge of that) has raised havoc for many folks over the years.
Scott
could be either a lifter roller or inner cam bearing.either way it should be looked into ASAP
Originally Posted by Hillsidecycle.com
Yep.
I'd get in the cam chest to examine.
There was a service bulletin that came down from the Motor Company in the Evo days, at 25,000 miles to "inspect and/or replace" the lifters.
Failure to do so,(without knowledge of that) has raised havoc for many folks over the years.
Scott
Oh man, really? This motor only has about 40k on it, so I was surprised when the valve train started making noise. Without a stethoscope it definitely sounds like it's coming from the front lifter area, kinda mid-motor. I guess that could be the cam bearing too, huh? Damn, guess I gotta crack her open. What am I looking for? Wear/scoring on one of the lifters or on the cam bearing?
There was a service bulletin that came down from the Motor Company in the Evo days, at 25,000 miles to "inspect and/or replace" the lifters.
I wish you could post a service bulletin number or date. I've looked and asked around and can't find any indication this exists.
When HD releases a service bulletin, the following model year factory service manual will contain said information that was relayed via the service bulletin. Do you know of any year HD factory service manual that indicated a service replacement interval for the lifters? I'm not suggesting that this isn't a good idea, it just seems like something that some people keep repeating and then becomes gospel without any proof.
I think the number of failed lifter rollers reported on various forums tells us it is good practice to replace the lifters at 25,000 miles...Don`t need to see a factory service bulletin at this point.
On a `97 with 40K on the clock, time for lifters and inner cam bearing (B-138).
Last edited by Dan89FLSTC; Jun 4, 2020 at 03:02 PM.
I think the number of failed lifter rollers reported on various forums tells us it is good practice to replace the lifters at 25,000 miles...Don`t need to see a factory service bulletin at this point.
Agree, but that is an opinion. That doesn't make it a reported/recommended procedure from the HD motor company based on a non-existent technical bulletin.
Had a similar noise coming from Reaper's engine, and it turned out to be a lifter roller. The surface was galled, and it had gone out of round!! Luckily for me, it still spun, and didn't destroy the cam lobe! Here are a couple of pics of what I found.
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Suddenly noisy valve train on 97 Evo
