Overheated Suzuki Outboard

I got some grass stuck over the water intakes on my 1980's Suzuki 85. I did not hear the alarm going off over the noise from the motor until the motor stopped making noise...

I cleaned off the junk, let it cools for five minutes and cranked it. It started peeing right away and ran a little rough. The powed was down about 25% from normal. I made it accross the lake and shut it down. it would not re start. It turns over fine and has good spark.

The compression in 1996 was #1-145lbs, #2- 155lbs, #3-150lbs

The compression in April 2007 was #1- 153lbs, #2-170 Lbs, #3- 157Lbs

The compression after the overheat is #1-125lbs, #2-100lbs, #3- 125lbs

I am thinking a head gasket and or warped head. What else would be a problem in this situation?

If I have the head shaved back flat and instal a new gasket what else should I look for?

The motor has a new impeller and thermastat as of a few months ago.

Thanks in advance for any help. I will have to fix it my self as I have very limited funds and want to do it right.

JIM

 

The serial number is 8501-717098 and is the VH model if that helps.

JIM

 

My long-ago experience with overheating on outboards would suggest cylinders, rings and pistons.

The motors I had experience with were Johnson and they were rebored and fitted with larger pistons. Power actually improved after ward. Obviously it was not a low cost exercise.

So I would be prepared for more than just the head gastket.

Rick W.

 

I just pulled the head. The cylinders show normal wear for a mid 1980's motor. it spins over freely. The #2 head gasked was blown in two places. i oiled up the cylinders and left the head on for now so they won't rust. I will sand blast the water jackets in the head (not the block side) to clean up a little corrosion and improve cooling then I will true up the head on my surface plate. I will re instal it with a new gasket and see how it runs. I can't afford a true rebuild at this time. Hopefully I can get another five or ten years out of it.

I will continue to look for suggestions as I repair it from the many people on this site who know what they are doing. I have only rebuilt lawn mowers and old chevy motors. This is very similar but I am sure there are little things that I will overlook without proper guidiance.

JIM

 

Hi TW aka Jim,
My old '94 Suzuki 15 did something very similar a few years ago. I don't know what caused the initial failure (although we suspect oil injector failure might have been involved) but halfway across the lake, we lost power and pisser-hole water flow (but still had flow out the exhaust bypass as is normal on these motors), and stalled a minute later. We were able to restart it, sort-of, and limped to the dock with engine output about 15% of normal. Upon teardown we discovered that the head gasket had blown out into one of the cooling channels, where the pieces of gasket blocked off the pisser hole. The cooling water had started flowing into the damaged cylinder and out its exhaust port, and from there out the exhaust. That cylinder was scored to shreds while we had been limping home on one working cylinder.
Turns out when we tried to have it rebuilt that the cylinder liners were some kind of fluropolymer-impregnated nicasil (or something like that, I can't recall exactly) and couldn't be re-honed without risking a block explosion on startup. Had to write off the motor. Needless to say the replacement Johnson has a solid iron block with no funky sleeves.
My point as it relates to you is, Suzuki has long been known for high-tech metallurgy and somewhat unusual engineering. Don't even think about taking a hone to one or doing piston/ring work without doing your research. I think you're on the right track to clean up the head and replace the head gasket. While you're at it, the cooling system should get a complete backflush and the water pump should be rebuilt with a new impeller, or else you might get the same problem again sooner than you'd like.

 

Thanks for the tip on honing. I sand blasted the head and put it on my surface plate. It is high in the middle (pulling away from the block). It is a little more warped than I can sand true on the plate and I don't have a fly cutter for my mill so I will have it machined. The high spot is where the gasket blew so everything looks as I expected so far. The motor still looks good inside. My biggest concern is that the rings lost their temper from the heat and will wear out fast and lose compression. Time will tell.

JIM