Joe Reeves

[willxuout]

So, I heard you are the OMC Guru. I've got a question for you.<br /><br />I have a 1996 Evinrude 225 v6 carburated outboard. The top two cylinders burn and foul out brand new spark plugs after only 2-4 hours of 3/4 throttle cruising. the top two plugs have alot of carbon buildup on them and a little dry while the bottom four plugs look medium brown and oily with the same amount of runtime. i took it to the shop and they checked the voltage, spark, and carbs. they said that everything was o.k. add a little more oil to the mix. the vro is disconnected and i premix the oil at 40:1 to be on the safe side. i noticed that there was some real thick black oil residue leaking from the bottom of the air intake after they looked at the carbs. it had never done this before. anyway, about 7 hours on the motor the thing seized up. i took it back to a different mechanic and he said that the top bearing on the crank had worked its way to the top. before i took it to the shop i removed the heads and all cyliinder walls look perfect and smooth...however, the top two piston head have alot of carbon buildup on the top of the piston head only...no buildup on the cylinder walls. these are the cylinders that show alot of carbon buildup on the plugs. nay thoughts...was there something wrong with this?<br /><br />I have taken this motor to every boat dealer i know and i keep geeting the run around. <br /><br />please help if you can. <br /><br />thanks.

 

[Joe Reeves]

Re: Joe Reeves

Willxuout..... Unfortunately I retired a few years before that 1996 engine cam into existence and I'm not familiar with its design.<br /><br />The only cause that I'm aware of thet would burn out, destroy a spark plug within 2 to 4 hours of running time would be having a fine water spray entering the cylinder(s).... but it would be very unusual to have that occur to the top cylinder s/plug on opposite banks, both port & starboard. Even if a water spray was entering via a faulty cracked exhaust passageway (between the banks), that spray would completely eliminate any carbon build up.<br /><br />You didn't mention compression, check it. It should be approximately 100+ psi, possibly only 90 psi as the compression was lowered to compensate for the poor quality fuel, but the readings should be even on all cylinders. What is it?<br /><br />Spark, with the s/plugs out, should jump a 7/16" gap with a strong blue flame on all cylinders. Does it?<br /><br />The fuel feed system on that engine feeds in an "X" pattern... top port carburetor feeds the top starboard cylinder etc. This leads me to wonder if the jets in those two top carburetors are loose, possible the wrong jets, or if the jets might be installed in the wrong passageway.<br /><br />As mentioned, I retired before that engine was manufactured and I don't have a book on it but if the top main bearing head (c/c head) is anything similar to all other OMC 225hp outboards, it would be impossible for it to ride up and cause the engine to seize (I'll check into that).<br /><br />Is that engine a 60° or 90° V/6 ? Sorry not to be able to give you a solid answer and cure to your problem, but hopefully some of the above will steer you in the right direction. Let me know what you find.

 

[seahorse5]

Re: Joe Reeves

A lower crankshaft seal leak can cause water in #2 cylinder. Vacuum from the #2 intake manifold "sucks" residual oil from the lower crank bearing to the upper one. If water gets in through the bottom seal, it travels from the lower bearing, through a recirculation line to the top bearing, then on to #2 intake.<br /><br />There was a recall letter back in '96 for loose upper crankshaft bearing housing bolts. They were to be replaced with a new gold colored one. It only applied to a certain serial number range.<br /><br />The correct plug for your '06 225 is a Champion QL78YC gapped at .030".

 

[willxuout]

Re: Joe Reeves

Joe:<br /><br />Thanks for the advice. I've always leaned toward the spark (is it as strong on the bottom four cylinders as the top two?) and the carb issue. I had the first mechanic pull the carbs and he said that they had the right jets installed. I'll let the new mechanic tell me what he finds.<br /><br />The compression was just checked when I replaced the stator about 10 hours ago. It was 100 psi on all six cylinders.<br /><br />The motor is a 90 deg looper.<br /><br />Thanks for the advice. I'll let you know what they find out.<br /><br />Bill

 

[willxuout]

Re: Joe Reeves

Hey Joe,<br /><br />I found out what the problem was. The rubber fuel lines that feed the carbs were shot. The top two lines were actually kinked were they turn into the carbs causing a fuel restriction in the top two carbs. So, it's going to cost me $5000 to rebuild. The mech is going to setup the oil injection vro system, which was previously disconnected and removed because the guy before me premixed his fuel. I'm all for that because this wouldn't have happened had the vro been connected. He is also going to install all the warning lights and horns associated with the vro system. He said that as long as the system is maintained annually and the pump is replaced every 3-4 years there shouldn't be a problem. We'll see.