Mariner 75hp 4 stroke 2004 tight valve clearance

[Scouse g]

Hello guys
I recently bought a Bombard rib with a Mariner 75hp 4 stroke motor 2004 carb model
I ran it up last month and it had a rattle from no1 cylinder
Upon removing the cam cover and checking valve clearances, one of the inlet valves is tight against the cam.
Question is has anyone had this problem and can the head be removed without the powerhead being removed from the outboard?

[Limecc]

Sounds like valve seat recession

[Scouse g]

Thanks for the quick reply
Is it a common fault with these motors ?

[beamishken]

Originally Posted by Scouse g

Thanks for the quick reply
Is it a common fault with these motors ?

Valves receding into the head is relatively common on diesel engines , not so common on petrols due to the reduced compression. If its rattling too I suspect you have a bigger issue than valve recession. It may be but I'd be surprised, can you reset the valve clearance & retry & possibly compression test? No point in compression testing with a tight valve clearance.
Or have you just decided theres something sinister going on inside & thats why you want to open it up?

Sent from my SM-G950F using RIB Net mobile app

[Scouse g]

I will pull the cams out next week and see I'd there is a difference in height on the valves

[Davie]

Cylinder head will come off without removing powerhead. Had this twice on this type of block. 1 Mariner, 1 Yamaha both 5000+ Hours. Head had come off the valve and stuck in top of piston. If it’s an inlet valve remove the inlet manifold you will see the valves. What ever the issue is it’s a head off job if you have lost clearance.

[Scouse g]

Cheers for the info

[Scouse g]

I got myself a donor engine that's had a lecky fire
Powerhead is fine

[Davie]

Originally Posted by Scouse g

I got myself a donor engine that's had a lecky fire
Powerhead is fine

What was the reason for losing the clearance?

[Scouse g]

I’ve only just removed the cylinder head, inlet valve clearance should be 0.007- 0.009 inch
Upon inspection it was 0.005 on no1 cylinder
The head is a reworked version of a Ford ztec !

[beamishken]

Originally Posted by Scouse g

I’ve only just removed the cylinder head, inlet valve clearance should be 0.007- 0.009 inch

Upon inspection it was 0.005 on no1 cylinder

The head is a reworked version of a Ford ztec !

Thats not your problem then, need to look further, a couple of thou tight valve clearance will make little or no difference to the running & wont cause a rattle

Sent from my SM-G950F using RIB Net mobile app

[Scouse g]

I took the valves out of no1 cylinder last night, the inlet was leaking as it wasn't seating correctly, took the head to the machine shop to get the valve lapped in and the surface of the head cleaned, should start reassembly next week