90 ETLN to rebuild power head or not?

[wvmedic]

To give some background, I have a 1984 90 ETLN and have been having an overheat issue since I bought it. I have put two new impellers, a thermostat and took the head off checked the water ports and cylinders for damage. I found no damage to the cylinders on the tear down so I put new gaskets on and retested on the water, I still had an overheat issue at anything above half throttle. Idle temps and up to half throttle was around 150 degrees Fahrenheit, anything above half throttle temps would get up to 210 degrees.

So I took the exhaust cover off to inspect the water ports and found the skirt of the top piston damaged, could this damage be the cause of my overheat problem?

Also what dose it look like I need to do as far as a rebuild, or is it worth doing? I already have about $1,000.00 in this motor.

Thanks Jeff.

 

[robert graham]

Re: 90 ETLN to rebuild power head or not?

looks like you snagged a ring in that top cylinder and chipped a piece out of your exhaust port, lots of carbon, stuck rings, blow-by, etc. If everything else is O.K. on this 25 year old motor then you could have the power head rebuilt, new pistons, ring, bored, new cylinder liner on top cylinder. If you could get all that done for maybe $2000, give or take, then you might be good, but still a 25 year old motor. Maybe shop around for a later model used 2 stroke similar to yours? With so many folks going to 4 strokes and HPDI motors, I bet you could pick up a good used 2 stroke similar to yours at a bargain price. A dealer might sell you a new 90HP 2 stroke for $6500+. If my 1999 90C died, that's probably what I'd consider doing. Good Luck!

 

[wvmedic]

Re: 90 ETLN to rebuild power head or not?

Thanks for the reply Robert.

I don?t think that is a chip it looks to be manufactured that way, no jagged edges or gouges ECT.

I should have included a little more in my first post but it was late and I just didn?t think to include it.

The rings are free they press in easy and spring back as they should, and all three cylinders are at 120 psi on compression.

Thanks Jeff.

 

[robert graham]

Re: 90 ETLN to rebuild power head or not?

looks like a lot of carbon on pistons. if the engine will run, then I would run at least 10 gallons of gas through it with 2 ounces of Ringfree per gallon and hopefully remove carbon and free up rings. It could take you a day on the lake/river to de-carbon the engine this way, especially since you can't run many RPM's without the overheating. It's worth a try and could only help the engine. Have you ever used Ringfree in this engine? Good luck!

 

[wvmedic]

Re: 90 ETLN to rebuild power head or not?

Robert, again thank you for you?re reply. I think there is more of an issue hear than carbon, the skirt on the top piston is damaged. This is shown in the first three pictures, and the rings aren?t stuck. I did however use a can of seafoam in a gallon of gas with three oz. of oil when I first got the motor on the boat.

I can decarb the tops of the pistons when I take them out of the block, what I need to know from some one in the know is if it looks like a candidate for a rebuild.

The cylinders look good to me, if it where an automotive motor I would hone the cylinders, replace the rings in all three holes, one new piston, new rod and main bearings then drive it for a bunch more miles.

That being said, it isn?t an automotive motor it is an outboard. I am on a learning curve when it comes to outboards. For example the motor is a 1984 but since it was owned by an older man bought new and has set for the last four years or so since his death, and hadn?t been used that much for several years prior to that. I think the motor has relatively few actual hours, so if I rebuild do I replace all of the bearings or just inspect them good, and if in good shape then reuse? That is where I?m not sure on what to do, the mechanical aspect of it is no problem I can do that.

Thanks Jeff.

 

[wvmedic]

Re: 90 ETLN to rebuild power head or not?

^^^

 

[wvmedic]

Re: 90 ETLN to rebuild power head or not?

I think I will have a shop bore the cylinders, new pistons, rings, bearings with a fresh set of gaskets all round and put the old girl back on the boat and run it.

Thanks Jeff.

 

[robert graham]

Re: 90 ETLN to rebuild power head or not?

that sounds like a plan...maybe just the cylinders and pistons, bearings are probably O.K. Hope it works good for you!