200 Mariner

[Bigshrimpin]

Well, ran it yesterday and it is still spitting intermittantly...but not overheating. But when I ran it up it was rough early then would get over 4800 rpm. Changed fuel filter and water seperator and still topped at 48-4900 rpm not 5600 as it usually does. I talked to the mechanic and he seemed to think it might have a blown head gasket or O ring. He thinks its blowing air exhaust into the water jackets which is causing the pulse. There was also alot of water coming out of the upper exhaust below the upper tell tale. It looks like something I could handle myself so I will give it a shot on tuesday or at least open it up and see. I remember the last day I had it out last year...I was wailing on it with a three man tube and it wasn't running all that good then. He happened to have a similer motor apart and the heads look somewhat accessable.
Does any of this sound like it might make sense?
I have literally gone through the entire cooling system at this point and it all looks normal. Starting to really lose patience.
Joe

Joe - Focus on what's changed since the motor last hit 5600 rpm. How much water is coming out the oval exhaust ports? If it's just spitting a little water out . . . that is totally normal behavior. O-ring heads came out on the 2.5L in 2001/2002 after mercury stopped producing Mariner. if you are worried about blown headgasket or water coming in . . . check the plugs and see if any look steam cleaned (like brand new). That's one of the signs of a blown headgasket . . . also check for low compression (on one or more cylinders same side).

Personally I think problem without knowing anything about the motor could be a lose plug wire, bad coil, etc. causing one cylinder not to fire (or fire intermittently). Get a spark tester and figure out if one cylinder isn't firing.



No offense but that mechanic seems to be overlooking some obvious details and jumping into some pricey "unrelated" repairs. For a good referral you can ask on www.screamandfly.com for someone in the area that knows your motor.