1985 150HP-Cylinder damage! (see pictures)

[BJBUSYBOY]

Hey guys,

My motor recently overheated while idling back to the dock, I pulled the plugs and found a little water in the bottom cylinder on the PORT/left bank. I then did a compression test, I found that cylinder to be 10 PSI less than the other 5 cylinders ***********Blown Head Gasket*********. I pulled the head to replace the head gasket and this is what I found. The 1st picture is a good cylinder wall (cylinder # 1) for comparison. The rest are the damaged pictures. The weird thing is????the motor runs perfect with no problems??????? But not for long i guess!!!!

Note: See the gap between the piston and cylinder wall *****YOU CAN CLEARLY SEE THE RINGS****** and there's about 1/16? of play on either end. Also see the transfer of Aluminum from the piston to the wall of the cylinder, this is where the pitting is! The pitting is very very smooth and not rough at all!

What do ya'll think? Is it good for 1 more season?

 

[Chris1956]

Re: 1985 150HP-Cylinder damage! (see pictures)

I guess I am surprized that the compression is so close, considering the damage. It is within specs.

You could use some muriatic acid to remove the aluminum from the cylinder walls, and maybe hone it a bit.

 

[iwombat]

Re: 1985 150HP-Cylinder damage! (see pictures)

Hard to tell from the pictures, but it really doesn't look all that bad. Looks like a good honing would clean all that scoring up. The bigger question is whether the cylinder is still in spec to the size of the piston. With the compression numbers, I'm guessing it probably is. If it were mine, I'd remove the powerhead, hone up that cylinder, measure for spec, and replace the rings.

I don't think I'd be too scared to put a new head gasket on it and closely monitor the compression over time either. As added insurance I'd rebuild the carb that feeds the cylinder to make sure it's getting proper lube.

Of course, this is all off of what I'm seeing in the pictures -- very mild score marks with no deep scratches.

 

[emdsapmgr]

Re: 1985 150HP-Cylinder damage! (see pictures)

I'm with Wombat on this. A small amount of streaking on cylinder walls is normal. Yours is somewhat worse, but I don't see any actual aluiminum transfer-where the piston aluminum delaminates and sticks to the cylinder walls. I'd pull the intake transfer covers off on the bad cylinders and look at the sides of the pistons. Look for stuck rings (carbon) and check to see if the piston skirts have not started to delaminate. Check it out and then make your decision.

 

[iwombat]

Re: 1985 150HP-Cylinder damage! (see pictures)

emdsapmgr brings up a good point.

Pull the side inspection cover and see how much wear is on the side of the piston as well as the condition of the rings. I'm guessing it'll look pretty good.

 

[BJBUSYBOY]

Re: 1985 150HP-Cylinder damage! (see pictures)

Great, if I were a Crayola....I would be tickled pink!!!! A very masculine pink!!!! lol....I'll have a look at the side of the piston and the rings and hope for the best!!! I've had it for 5 years and run the motor like a scalded *** cat, pulled a thousand tubers and hammer that throttle down and made it scream. I just ordered 2 seals from iboats for my exhaust housing and just installed a whole new water pump. Then i'll be ready for some po boy bass tournaments. Thank ya'll sooo much for the reply and all the info...i'm new to this forum and lookin' forward to the next time i need some advice!!!

Thanks again, Jason