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-   -   Merc 525 help??? (https://www.offshoreonly.com/forums/general-boating-discussion/207163-merc-525-help.html)

vinnysrt8 04-19-2009 08:28 AM

Yes i did a tune up when it started happening did no change

vinnysrt8 04-19-2009 08:29 AM

all the plugs look good and the coil all has power.

vinnysrt8 04-19-2009 08:30 AM

the compreesion on the motor is 160 on all 8 but i didnt do a leak down test ill do that today.

Wazzup Racing 04-19-2009 03:59 PM

Might sound too easy, but change the map sensor. we go through a ton of them. Check the small black ground wires attached at the bell housing stud.

bjablonski 04-19-2009 08:27 PM

I had the same problem with my 500 efi's after storing it all winter. I replaced the fuel regulator and all was good. It was a reasonably easy job...good luck

vinnysrt8 04-19-2009 08:42 PM

Well today i put the boat in the water to test it out after changing the wires it sounded good on land went for a quick ride it ran good for about 15 min it was at 5400 rpm then the oil pushed out of the dipstick so i am thinking there is some blow by and that why its running like crap any input thanks.

vinnysrt8 04-19-2009 09:28 PM

Another thing is the oil temp goes sky hight it is at 250+ as the other motor it is at 200..
the water pressure is good water temp good oil pressure good.

Boat Tech 04-19-2009 10:13 PM

Was the engine ever rebuilt ?

vinnysrt8 04-20-2009 11:34 AM


Originally Posted by THLWL (Post 2848238)
Good luck is all I can say. My popping sound was stuck valves in head. I've stuck the exhaust valves in the heads for the third year in a row and am still under 200 hours on engines. NO ONE can find the culprit. I've now had the heads rebuilt by the third diff shop. Merc Racing has been no help. I originally had capt call exhaust and they blamed it on that. The last 2 years, I've had Merc original exhaust and still sticking. We've done it all to the heads - enlarged tolerances, etc. Hope your prob is not with the valves sticking cause IT SUCKS! BTW, if the popping sounds like it's thru the intake (like mine), it can be an indication the exhaust valve not opening properly to let out fired exhaust. And 5400 on RPM's, my rev limiter alarm goes off at about 5100.

that must be the problem that exactly what it is doing.. ya my rev limiter is a little higher.

vinnysrt8 04-20-2009 11:34 AM


Originally Posted by boat teck (Post 2847941)
Was the engine ever rebuilt ?

nope it is a stock merc 525 built in 04


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