Stuck or collapsed lifter? 350 Mercruise

[markbabb]

I have a 350 mercruise which is approx. four years old since it was installed as a newly rebuilt longblock. Three weeks ago what started out as a ticking sound now sound like a loud clanging. I have isolated it to the #8, last cylinder on the starboard side.It gets much louder after it gets warmed up. The oil has been change regularly although may have been overfilled by about a half a quart or more about the same time the noise started. I have been told this could be from a collapsed or stuck lifter and although the engine is running the same as it has always has performance wise, I know the noise can't be a good sign. Anyone care to enlighten me on a probable cause? If I tear the engine down to get to the offending lifter how much else should be replaced at the same time or what other damage should I look for? Thanks in advance for any helpful advise!

 

[bobbyc]

Suck out the excess oil first and then pull the valve cover...it may just be a rocker arm or pushrod

 

[barrylee66]

I would pull the valve cover. also it could be a worn cam lobe this is common with wydraulic flat tappet cams if thats whats in it.

 

[markbabb]

I have already changed the oil and added some marvelous mystery oil thinking if it was a stuck lifter that might free it. The last trip out it is making the same loud noise after it warms up. Bobby C -When you say it may be a pushrod or rocker arm -can you be more specific-?
Thanks

 

[chiefalen]

You did a compression test ?

On a warm motor, all the plugs out and the throttle down.

Keep the plugs in order so you know what plug came out of what hole.

Lets start with that.

 

[Bob & Sue]

Usually if it's a flat cam lobe, bent push rod or loose rocker the noise would be there right from start up but not always it's an engine never simple. It may be a collapsed lifter usually that would also make the engine backfire not always. If your engine has flat lifters I wouldn't run the engine a lot you'll be running metal shavings thru the engine. A good starting place would be to pull the valve cover and all the plugs first and turn the engine over using a breaker bar and socket to see what's going on with that cylinder then do all the above check for loose rocker arm, bent push rod (remove rocker arm pull out push rod roll on flat surface to see if it's bent) , compression check, maybe weak valve spring. Good luck hope it's a simple one.

 

[markbabb]

Thanks for the advice, I guess this weekend I will be turning some bolts. Thanks to Bondo for the manuals!!!