Mercruiser 2.5 ticking sound

Scott06 · May 30, 2025

dirkg said:
I've got no tools to pull the crank pulley so can't look at the gears atm, but feels like that would be my next step(?).

you could probably get an idea of the back lash in the timing gears by turning the crank back and forth and seeing the delay in either rocker movement or the rotor in dizzy turning.

Also did you run it with the block circulating pump belt off. Possible if the bearing in it is bad it could make noise

Scott Danforth · May 30, 2025

you know that flat tappet cam lobes and lifter should not be mixed and matched (they mate for life)

Scott06 · May 30, 2025

Scott Danforth said:
you know that flat tappet cam lobes and lifter should not be mixed and matched (they mate for life)

trying to read that sign in the rear view mirror...

dirkg · Jun 6, 2025

So after going through the troubles of replacing the camshaft I'm basically back at a point where all lifters, rods, valves and lobes are married up again. The gears on the cam definitely had some beating (see image attached for the ones interested) so I guess I for sure hasn't hurt (at least I had fun and learned sth new

).

After putting it all back unfortunately the issue wasn't resolved and ironically the only thing left I didn't do was the distributor. Replaced that one and guess what, issue seems to he solved.

Happy times, except that I have a new sound and it makes me wonder whether my "learning" accidentally killed a bearing or sth. See the video:

.

Does this sound familiar to anyone?

dirkg · Jun 8, 2025

I guess some things in life are just simpler than they sound like. Turned out the above issue was my water pump touching the crank pulley (not a perfect mid circle alignment it seemed).

I'm still not 100 procent happy with the sounds produced by the engine, but maybe I should just start accepting given this beast is hitting the 50 year old mark

Grub54891 · Jun 8, 2025

Yeah, they sound like a tractor at idle.

Scott Danforth · Jun 8, 2025

More like a bag of hammers in the dryer.

dirkg · 2025-06-24T03:47:33-0600

With the engine back together and into the boat it just still feels wrong to me that it's making this sound. Perhaps I'm an idiot for trying to get this resolved in a 40+ year old block - but that's me

I made a new video with the sounds, which is only audible at around 1500/2000 RPM:

. There's different angles and you can clearly hear the sound coming from the left side, close to the distributor/pump/whatever else might be causing it.

So far what has been done:
- Valve adjustment
- Checked rods - they're straight
- Cleaned Lifters
- Replaced cam shaft and checked lobs - seem all alright (shaft, lifters, rods, and head all come from a different engine - which did not make this sound but was cracked on the inside)
- Fuel pump checked
- Distributor replaced for another one

Like what the heck is even left that could be making this noise?

Scott Danforth · 2025-06-24T06:25:20-0600

dirkg said:
Perhaps I'm an idiot for trying to get this resolved in a 40+ year old block - but that's me

- Replaced cam shaft and checked lobs - seem all alright (shaft, lifters, rods, and head all come from a different engine - which did not make this sound but was cracked on the inside)

did you make sure that each lifter was put back to the exact same lobe? flat tappet lifters mate for life. if you swap lobes and lifters, you usually take out the lobe and the lifters.

dirkg · 2025-06-24T12:56:24-0600

Scott Danforth said:
did you make sure that each lifter was put back to the exact same lobe? flat tappet lifters mate for life. if you swap lobes and lifters, you usually take out the lobe and the lifters.

Yup - 100%. Originally I moved the head from the cracked block onto the new one, leaving the old lobes and lifters. Then, given the sound (although didn't ran the engine before so not sure if it had the sound with the other head), replaced the cam and all other parts. So right now everything from the lobes up to the valves is mated again.

Scott Danforth · 2025-06-24T13:32:20-0600

dirkg said:
So right now everything from the lobes up to the valves is mated again.

Not according to post #3 and #12 where you ran the lifters on other lobes.

dirkg said:
and even replaced them for another set I had laying around.

dirkg said:
I've got another camshaft from the "donor" engine if which I also pulled the head. Feels like I'm getting to a point where I'm going to pull the pullet, check the gears and perhaps just swap the camshaft for the other one (which would also unite it again with the lifters).

dirkg · 2025-06-25T02:57:35-0600

Scott Danforth said:
Not according to post #3 and #12 where you ran the lifters on other lobes.

In the process there was a moment where they weren't mated indeed. Engine made a sound: started replacing some parts, eventually sound persisted, replaced all parts from lobes to head from same donor engine. So in the current state everything is mated.

Scott Danforth · 2025-06-25T03:32:21-0600

Good luck, pretty sure you roached all the lifters and lobes with that parts swapping

Mercruiser 2.5 ticking sound

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