1985 Johnson 9.9hp J10RLCOM rebuild options

I was given a 1985 9.9hp Johnson by my grandfather; I have no idea what kind of maintenance has been done to it in it's 25 years, so before I put it in the water, I'm doing some maintenance; Among the maintenance I want to do is the thermostat and make sure the main waterways are clear as the motor was used exclusively (as far as I know) in salt water, and after hooking up the hose to the water inlet and runnning the motor, I didn't get much more than a drip from the small outlet on the bottom of the motor housing. I opened the water cover, and the passegeway was bone dry; I'd assume that like a car, SOME water should get past the thermostat when it's closed. Anyway, at this point, I have to get the cover off all the way to replace the thermostat and gasket, but in order to do so, I need to get the motor off the mid section. I've removed the six bolts underneath, as well as the three nuts inside the housing, but it won't budge. Anyone have any suggestions to get the motor separated without destroying anything?

Re: 1985 Johnson 9.9hp J10RLCOM motor removal

Re: 1985 Johnson 9.9hp J10RLCOM motor removal

drop the lower unit it will make it easier to get off, also you need to water pump rebuild kit anyway. the exhaust housing and water tube are going to come out with the power head. complete diagrams here. http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

Re: 1985 Johnson 9.9hp J10RLCOM motor removal

Re: 1985 Johnson 9.9hp J10RLCOM motor removal

tashasdaddy said:

drop the lower unit it will make it easier to get off, also you need to water pump rebuild kit anyway. the exhaust housing and water tube are going to come out with the power head. complete diagrams here. http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

Click to expand...

The lower unit's already off and all bolts for the top are removed; the problem is getting the motor to separate from the mid section; After being together for 25 years, it's practically welded together.

Re: 1985 Johnson 9.9hp J10RLCOM motor removal

Re: 1985 Johnson 9.9hp J10RLCOM motor removal

Ok, rather than post a new thread, I'll continue my saga here.

I finally got the motor off the mid section, but before I did, I fabbed up a hose adapter like one I found in the link posted to sschapterpsa.com (VERY good info, I might add). I was able to get the water cover off and the thermostat out before I got the motor out, and it took almost full force water to just get water out of the thermostat housing; when I put the cover back, pretty much no water came out of anywhere that it should have. Based on the sand that was behind the thermostat, I'm betting there's sand elsewhere blocking passages, so I'm thinking a complete teardown is in order.

That brings me to the pistons. I've attached pictures, and while I'm no expert, they look like they need to be replaced (look vary similar to pics at the before mentioned site).

Having said that, what's the opinion of those here that have far more experience than me with 2 stroke motors? Will I need to hone or bore over the cylinders (are there oversized pistons?), or do I just replace the pistons and rings? Dare I ask how much pistons cost ?

I'd appreciate opinions...

Thanks in advance,

Dave

Re: 1985 Johnson 9.9hp J10RLCOM rebuild options

A few more pictures of the mess. Anyone have any thoughts on these pistons?

Re: 1985 Johnson 9.9hp J10RLCOM rebuild options

It's very hard to tell what kind of condition the pistons are in based on your pictures. How do the cylinder walls look to you? I wish you would have taken compression readings prior to removing the head. The water passages are a mess and you will have to scrape them clean unless anyone knows of a cleaner that will remove the deposits without harming the metal. It is going to be a bit more work for you but I would get the water issues resolved and put it back together and check your compression. Then I would do a decarb. and then check the compression again. Then make a decision as to your next step. Pistons and rings and cylinder walls are expensive and why bother unless you really need to? Best of luck. Rick.

Re: 1985 Johnson 9.9hp J10RLCOM rebuild options

Actually, I did do a compression test, and haven't taken the head off, so I don't know the condition of the cylinder walls, but I'll probably have to take it off to clean out the water passageways around the cylinders weather or not I replace pistons. Compression was around 70# for both after three compression strokes. To clean up the water passages, I'm going to see if I can find a plastic bristle wheel (a plastic version of a wire wheel).

Prior to taking it apart, it started hard, even after I got it running, and smoked a bit; normal amount or not I'm not sure. On the exahust side, one of the pistons has a fairly deep groove in it. If you look closely at the last picture in the middle port, you can sort of make it out (the size limit prevens me from uploading larger images; here are larger versions of the images).

The pistons and rings aren't exactly cheap, but I have a friend that can hone/bore the cylinders if required. If I can get by with just a ring job for now (or not even that), I won't complain, although I'd rather do it right, even if it costs a bit more, so that in theory, I shouldn't have to touch the powerhead for anything other than spark plugs and maybe carb service for a long time (It's not likely to see salt water again for a long time, if ever).

Rick. said:

It's very hard to tell what kind of condition the pistons are in based on your pictures. How do the cylinder walls look to you? I wish you would have taken compression readings prior to removing the head. The water passages are a mess and you will have to scrape them clean unless anyone knows of a cleaner that will remove the deposits without harming the metal. It is going to be a bit more work for you but I would get the water issues resolved and put it back together and check your compression. Then I would do a decarb. and then check the compression again. Then make a decision as to your next step. Pistons and rings and cylinder walls are expensive and why bother unless you really need to? Best of luck. Rick.

Click to expand...

Re: 1985 Johnson 9.9hp J10RLCOM rebuild options

Your pictures are nice and sharp, good quality for sure. Your pistons do look scratched up. You have to wonder why it happened. I said "head" but meant the "block". Sorry about that. Seventy is low but the good news is they were the same. At this point you should pull the head and look a the cylinder walls. It would be good to do a decarb and check it again. Buy the look of things a plastic wheel probably isn't going to remove the build up. I would try a dremel tool if you have a steady hand. Rick.

Re: 1985 Johnson 9.9hp J10RLCOM rebuild options

Well, someone on a Diesel forum I posted on said it looks like it got hot, and based on the sand benind the thermostat and the lack of water flow, I'd say that's very likely to be the case. How long it ran without good water flow or how hot it got is anybody's guess. I'll try to get the head off tonight and see how the cylinders (and the water passages around them) look.

Re: 1985 Johnson 9.9hp J10RLCOM rebuild options

New problem: Three of the head bolts broke off flush with the top of the head and the head will not budge. You know how there's usually 1/16" inch or so between the bolt and the head? the three the broke off, there os zero gap; there's that much corrosion. So far I've soaked two rounds of liquid wrench penetrating oil, and it still won't budge. I've tried prying and hitting it with a 3# dead blow. Any suggestions how to get the head off?