blown head gasket, 1994 225 Mariner......

[btravlin]

The 22 Aquasport that I was going to buy has a blown head gasket on the motor, but as yet I don't know the extent of the repair. I understand what this means to a car engine, but I'm not familiar with the inner workings of outboards.<br /><br />I'm assuming the owner didn't have sufficient water pressure, (didn't change the impeller?), got it hot, and the gasket started leaking water into the cylinder(s). Am I correct in thinking that the damage could be minimal or total rebuild material.....depending on whether he shut it down quickly or he warped the pistons, warped the head, or worse? <br /><br />I might still have a mechanic check it out and compress it. Can he do a pressure test on it to verify that the gasket is blown? <br /><br />How costly can this get? Would it be worth rebuilding at the right price for the rig? <br /><br />Let me know what you think. I hate throwing money away. I did that enough with my sailboat. Thanks......

 

[KCLOST]

Re: blown head gasket, 1994 225 Mariner......

You need to first remove the head(s), probably both of them.... Check the condition of the heads, pistons and cylinder walls. If there are any scuff marks on the cylinders you have a problem... If the top of the pistons are ate up, you have a problem... If the heads are warped, which you can check on a level plate, that is a problem also...<br />The heads slightly warped are the least of your problems and the easiest to fix.... If everything else looks ok, you can have the heads machined to make flat again... Then replace the head gaskets, and let her rip and check compression...<br /><br />I wouldn't buy it until you know for sure all the cylinders and pistons are ok, by confirming with a compression test and trial run.<br /><br />Let us know...

 

[andrewkafp]

Re: blown head gasket, 1994 225 Mariner......

Absolutely do a compression test and make sure you have no more than 10% variation between cyls.<br />Unless it's real cheap, I would give it a miss. OB's are expensive to repair and overheating is an outboard's biggest foe.

 

[fishhawk16]

Re: blown head gasket, 1994 225 Mariner......

Guys, other than showing conditions of rings and seating of the rings, would a compression test show - scuff marks on the cylinders, scoring, pitting etc?

 

[KCLOST]

Re: blown head gasket, 1994 225 Mariner......

It won't show them.....<br /><br />But a compression test will indicate if the cylinder is able to hold compression... Which is a good sign....<br /><br />I guess, I'm being redundant.... A bad compression test will indicate, either a bad piston, cylinder wall, piston ring(s), head gasket....<br />That is why I suggested that you pull the heads to investigate visually.. Then, replace the head gasket after to eliminate that as the cause of a bad compression test (assuming everything else looks ok). <br /><br />A compression test will tell you something is wrong, but not exactly what! Since you know a head gasket is blown, remove the head and inspect everything and then replace if all looks ok...

 

[gss036]

Re: blown head gasket, 1994 225 Mariner......

I have my head gaskets changed every 3 years or 100 hrs of saltwater running. The last time they looked good and could have made another year w/o problems, time before, the metal seals were pretty rusted and not far from starting to leak. Preventive maintence is the best meedicine you can do.<br />I would not pay more for the boat than what the hull is worth w/o the motor. I would think the seller would settle for that unless they agree to have it fixed.