Am I pushing this engine too hard?

[adruid]

1984 Mercruiser 3.0 S#6821548 on a 22' Marathon 2200 Starfish. 2500 lbs. Got up to 3500RPM yesterday in L.A. Harbor with light wind and calm conditions. Engine seemed a little rough and would not go past 22mph. After about a half hour of slowing and then bringing it back up we looked at the engine. Creamy oil water mess sprayed inside compartment and on head just behind carb. and in front of exhaust, on port side only at valve cover, not head and block. Oil pressure at 40psi. Water temp. at 125-130F. We turned around to slowly motor back and everything seemed happy below 2000RPM. From what I have read, this is not really excessive RPM. I am going to chance oil and all filters, but figure the head gasket is leaking as well. It has not leaked before, but the engine has been run at an average of 2500RPM in my time with her. Is there a history of these engines having trouble at higher RPMs or was it just my time to change the head gasket? Thanks.

 

[flipbro]

Re: Am I pushing this engine too hard?

Possible cracked block! Compression test cylinders and pressure test the cooling system

 

[thumpar]

Re: Am I pushing this engine too hard?

You should be able to get to mid 4k RPM with no issues. Something is not right.

 

[UncleWillie]

Re: Am I pushing this engine too hard?

If 3500rpm and 22mph was at full throttle, you have a problem.
4500-5000 would be expected and well into the mid to upper 30mph range or more.

130 degrees is a cold engine. 160-180 is more common. Is the Thermostat still installed?

 

[alldodge]

Re: Am I pushing this engine too hard?

1984 Mercruiser 3.0 S#6821548 on a 22' Marathon 2200 Starfish. 2500 lbs. Got up to 3500RPM yesterday in L.A. Harbor with light wind and calm conditions. Engine seemed a little rough and would not go past 22mph. After about a half hour of slowing and then bringing it back up we looked at the engine. Creamy oil water mess sprayed inside compartment and on head just behind carb. and in front of exhaust, on port side only at valve cover, not head and block. Oil pressure at 40psi. Water temp. at 125-130F. We turned around to slowly motor back and everything seemed happy below 2000RPM. From what I have read, this is not really excessive RPM. I am going to chance oil and all filters, but figure the head gasket is leaking as well. It has not leaked before, but the engine has been run at an average of 2500RPM in my time with her. Is there a history of these engines having trouble at higher RPMs or was it just my time to change the head gasket? Thanks.

flipbro has it right, something is cracked

 

[adruid]

Re: Am I pushing this engine too hard?

It seems like this could run from "not good" all the way to "catastrophic." I'm looking for a mechanic who will check into the problem without insisting on "fixing it" without my being able to run the numbers and figure out what is the most reasonable course to take. I was ready for a head gasket, but definitely NOT a re-power! I've only had this boat since last summer, and just finished a lot of clean-up and added trim tabs. Sure hope I can find an honest mechanic to assist with the testing. Maybe the PO knew something was on the way when he told me to keep her down below 3500RPM. Thanks. Craig

 

[stonyloam]

Re: Am I pushing this engine too hard?

I'm leaning toward catastrophic:facepalm:

 

[dubs283]

Re: Am I pushing this engine too hard?

figure out what is the most reasonable course to take. I was ready for a head gasket, but definitely NOT a re-power!

get ready for a re-power

you could save a mechanic some time by changing the oil til its clean, then run the engine hard again - if you get the same mess its time for a new engine

 

[MarkSee]

Re: Am I pushing this engine too hard?

Maybe the PO knew something was on the way when he told me to keep her down below 3500RPM....

If he told you that, that was a remark of some type of looming trouble which would have signaled "pass on this boat"...

Mark

 

[adruid]

Just a follow up for those with a similar issue. I live in So. California, so "winterization" was not a factor. The problem ended up being the erosion of the exhaust elbow due to salt and low maintenance. Yes, there were worn valves and old/worn components galore, but no cracks or blown head. The MerCarb is now next on the list as it decided to stop a perfectly decent running engine in the middle of Los Angeles Harbor the second time we took it out to play. As with everything in life, this is another opportunity to learn, We all love our fun, but it must be accepted that maintenance follows fun. Salt neutralizers must be a part of the maintenance/fun cycle in salt water boating. Washing decks and cleaning carburetors are part of that cycle too. Thanks for the feedback. Happy Boating!
​Craig