Mercruiser 3.0 with noisy valves

[brewern]

Re: Mercruiser 3.0 with noisy valves

I just chased a bunch of noises from my 3.0. At the end, the clatter wasn't rhythmic enough to be lifter related. The only thing I could come up with was loose flywheel bolts. Wow. I was right and I replaced the bolts and torqued them down to 65lb/ft[SUP]2[/SUP]. It's been quiet ever since.

Unlike yourself, I am gearing up for a season of diving and hunting. The heat is breaking and the seas are flat calm today. It should be fun.

I don't believe that's the case with mine. Mine seems very rythmic. My plan is to replace the lifters and take it to the KY river, which is only a few miles away.
Question.... I know once I replace the lifters I'm suppose to run the engine at 1500-2000 RPM for 20 minutes, but can I do that in my driveway using muffs? Or would it be better to do it under load?

 

[NetDoc]

Re: Mercruiser 3.0 with noisy valves

I don't believe that's the case with mine. Mine seems very rythmic. My plan is to replace the lifters and take it to the KY river, which is only a few miles away.
Question.... I know once I replace the lifters I'm suppose to run the engine at 1500-2000 RPM for 20 minutes, but can I do that in my driveway using muffs? Or would it be better to do it under load?

It doesn't matter. You're just getting the lifters to seat on the cam and they don't "strain" under a load like bearings do.

Loose flywheel bolts are pretty uncommon as it's a function of incompetence. The guy who gave me the boat bragged about the engine being recently rebuilt by a certified OMC mechanic. I have been less than impressed with his work so far and may be pulling the engine to go through it myself.

 

[RogersJetboat454]

Re: Mercruiser 3.0 with noisy valves

When you pull your old lifters out, thoroughly check them out, especially the tappet that contacts the cam lobe. Any mushrooming, pitting, grind marks, or dishing is a sign that the lobe the lifter was sitting on is in rough shape.

 

[fishrdan]

Re: Mercruiser 3.0 with noisy valves

When you pull your old lifters out, thoroughly check them out, especially the tappet that contacts the cam lobe. Any mushrooming, pitting, grind marks, or dishing is a sign that the lobe the lifter was sitting on is in rough shape.

^^^ Yup...

You can rig up a dial indicator and check each each rocker arm at the push rod, to see if all the exhaust lobes are lifting the same amount, do the same with the intakes. Slight variations are not to be worried about, but if lobes are wiped out, you'll find out quick with a dial indicator.

The cam in my 72 140HP was trashed, several lobes 1/2 worn, the engine still ran 1/2 way decent with the wiped lobes Lifters on the wiped lobes looked like what RJ said.

You can break in new lifters running off the muffs, just make sure to keep an eye on water flow, don't walk away from it.

 

[brewern]

Re: Mercruiser 3.0 with noisy valves

I'll make sure I check the lifters thoroughly and take pictures, and video, and share them right here on iBoats.

Dial indicator... check! I learn something new everyday on this forum!

Thanks everyone for your help. I've started a renovation thread which I think will be a little more appropriate for where I'm headed with this boat. So, please come over to:

http://forums.iboats.com/showthread.php?t=579407

to follow the continuation of this post. Thanks for your help so far, you are all a huge asset to me.