Mercruiser 3.0 no compression on cylinder 1

[Carpediem27]

Last weekend I was out and my motor died. I was able to get it to fire back up and make it 8 miles back to the landing. It sounded rough but I was able to get up on a plain. The temp got higher than normal but would drop right down when the thermostat opened. It still runs, but it sounds like a Harley. Upon further troubleshooting I discovered that cylinder 1 has zero compression but the other three have 185. I tried to look through the spark plug hole to see the piston but was unable to see.

The oil looks good, no noticeable water. It needs a little throttle to idle and it shakes(definitely only running on 3)

I don't know what to look for next, any suggestions are most welcome.

.

 

[scoflaw]

Take the valve cover off and see what's going on

 

[Carpediem27]

Will do, do I run it with the cover off if nothing appears off. Sorry, I'm not sure what I should be looking for

 

[scoflaw]

See if both valves are going up and down . If that looks normal then the head comes off next.

 

[Carpediem27]

See if both valves are going up and down . If that looks normal then the head comes off next.

Thanks, I'll update as soon as I have time to take a look

 

[Scott215]

Following

 

[Carpediem27]

Thanks, I'll update as soon as I have time to take a look

I got the valve cover off yesterday. The keepers on one of the valves is missing, and the push rod has a slight bend.

 

[Nater Potater]

I got the valve cover off yesterday. The keepers on one of the valves is missing, and the push rod has a slight bend.

Ouchy! With the keepers missing, the valve has most likely had an intimate meeting with the piston. 'Hard to say what might have caused this. Possibly an over-rev excursion at some point?

 

[Scott215]

At least there is only 1 head to pull. Hope the piston and cylinder are ok.