Mercruiser 3.0 losses power

[Oldpos]

I have had bad luck with the 3.0, rebuilt my engine and it flattened two cams on same lobe, a lot of you helped me trouble shoot that thank you. I have up on that engine and bought another boat for the motor.

i pulled the motor out of the donor boat swapped everything external from my motor onto it, ran it out of the boat and in my boat before taking it to the lake. I took it out today and it did great for the first half hour then when I was running at about 4000 rpm for about 10 minutes it last power and went down to 3400 rpm but kept running, and a ticking noise from the top of the motor. I pulled back the throttle and ran at 3200 rpm with no noise. I shut it off and looked it over with nothing obvious found. Started it up and repeated with same results, so again shut it down for about 30 minutes and ran it for the next few hours at 3200 rpm with no noise and no loss of power. Then took a break for an hour and went back out and ran it for an hour at 3800 rpm all good,let it sit for an hour while I fished then agin ran it for an hour at 3800 rpm and still no issues. Long winded I know sorry.

do you think a lifter just needed pumped up? The tag on the motor said I can run 4000 rpm but is that realistic? Any other thoughts or ideas?

 

[alldodge]

Not knowing which 3.0 it is your WOT can be 4200-4600 or 4400-4800
Running a 4K should not be an issue, but also don't know how long the donor motor sat before it was running again. Being just a tick and not a knock then it probably is just a lifter. You should be fine but take it easy on it for 10 hours or so

 

[Rick Stephens]

I would do two things. Get it warm and do a compression check. And then do a valve adjustment. Repeat the compression check.

New to you motor. Need to know the numbers. Always seems to be a few posting on how their valves were too tight.

 

[Oldpos]

Sorry it’s a 1989 3.0 lx non thunderbolt. I ran a compression check cold and dry when o first got it. Nbrs 1,2,4 were between 120-140. Nbr 3 was 90. Oiled the cylinders and ran multiple checks and all were between 140-160. I will try it warm this week. Thanks