Mercruiser 3.0lx tapping or knocking sound

[MikeDobbs]

Hey everyone-

So I'm trying to figure out this tapping/knocking sound that my Merc 3.0lx is making. I'll attach a video so you can hear it- seems to be coming from towards the back of the engine- closer to no4 cyll than no 1.

Engine serial #0K277779

I'm planning on pulling the rocker arm cover tomorrow, but I can't figure out which procedure to follow in the manual. On page 3A-10 of the merc manual (Service manual #13, section 3) it says to just torque the rocker arm nuts to 20ftlb and no further adjustment is necessary. But on the very next page it describes a procedure for setting the valve lash. The second page makes mention of hydraulic lifters, which I thought my engine did not have- so my question is: Do I just need to pop the cover and torque everything to 20? Or do I need to go through the whole procedure outlined on pg 3A-11 of the manual?

Screen shots of those two pages attached.

 

[flipbro]

Go through the procedure to set the valve lash.. Did you check the exhaust flappers like Bondo suggested in one of your othsr posts. As it sure sounds like it

 

[MikeDobbs]

Thanks filipbro- Haven't gotten to that yet- not sure how to do it. Do I just need to unbolt the riser? Where would/should the flapper be- in the riser or the tube it connects to?

 

[MikeDobbs]

Just realized I never put up the video...

 

[flipbro]

Im not real familiar with the 3.0 but it should in the exhaust pipe that runs to your riser.. After listening to the video again I would definily be pulling the valve cover and checking things out. Bent push rod or collapsed lifter

 

[Eric 3.7LX Alpha 1]

In your other thread you have going you put the camera near the prop/drive... you can hear it misfire...

Mercruiser 3.0 Valve Adjustment Video

 

[Eric 3.7LX Alpha 1]

If you do have a loose one, check the push rod by removing it and rolling it against something flat like a piece of glass.

 

[MikeDobbs]

Happy memorial day everyone

So, this morning I pulled the value/rocker arm cover and went through the valve adjustment as per the merc manual. Everything went fine except that I noticed a fair amount of lateral play in most of the rocker arms. I don't know if this is normal, or means I have more work to do. I took a video so you could see the play I am referring to as well as the degree of movement. If you can, please take a look and let me know if I should be reassembling and starting the engine- or ordering more parts

Thanks in advance- I'm off to get the exhaust elbow off, to inspect the flapper thing as per Bondo and filipbro

Also- for reference, the engine is in TDC with no4 cyllinder in the firing position as per the manual for the second round of adjustments.

 

[MikeDobbs]

No Title

Follow up question about the exhaust flapper. I pulled the exhaust all the way down to the lower tube that connects to the transom. The flapper is in there (photo attached). And I can reach in an pull each side up- so it seems to be working. Does that eliminate that? Or is it a replace when you're looking at it kind of part?

Follow up question about the exhaust riser. My riser is certainly showing signs of corrosion along the inside and inner tubes. I bought a new gasket set, and the metal seems solid (I've hit it with a wrench and screwdriver in a number of different positions). What would you do in my shoes. Should I soak it in some sort of rust remover and then clean it up and reinstall- or is it new exhaust riser time?

Thanks!

 

[flipbro]

The side to side is normal on the rockers.. Did you check for bent push rods? Or calapsed lifters .Also does the exhaust flapper still have the rubber around the edge?

 

[MikeDobbs]

The side to side is normal on the rockers.. Did you check for bent push rods? Or calapsed lifters .Also does the exhaust flapper still have the rubber around the edge?

Bent push rods- not sure. I didn't pull them out, but I spun them round and round while checking for lash. I figured if the spun freely then they should be straight. Do I need to pull them all out? No big deal if yes, the valve cover is still off- I can do it tomorrow. I don't know what a collapsed lifter it- what does that mean, and how would I check for it?

Exhaust flapper- not sure- I can go back and take a closer look. Never seen one before so I'm not sure what it should be like. You're saying there should be rubber around the edges of the flaps? Is it a big deal to remove the thing or does it just slide out if I remove the last rubber piece- if easy to get out I can just pull it and post a pic online...

Also- I hate to ask, but how's this exhaust manifold look?