1993 15hp Johnson What should I do?

[chipster427]

Hello All, here is my deal. I bought a rig from a guy, 14ft jon boat, trailer, MK 40lbs troll, battery, seats, new fuel tank and line, and a 93 15hp Johnson not running. Paid 500, think I did ok even if the 15 is crap.

Any who, (here's the story) guy told me was running good, got it home to flush salt water out an would not start. Carried it to his uncle and he replaced the water pump, cleaned and rebuilt carbs, and put new head gasket on. Guy takes it out, runs great, gets ready to come back in and nothing. So it's my floater now. I got the new tank and line hooked up and fresh gas and oil, noticed that the old tank had a big crack on top of it, drained the bowl. Still no start. Checked the plugs, firing like champs. No pun intended. Still no start. Checked compression, both cylinders are at 40psi. Popped head off, gasket material tore off, metal still intack. Cylinder walls look decent but can feel small grooves in one spot on both cylinders. And that's as far as I have gotten. What next???

 

[oldcatamount]

Re: 1993 15hp Johnson What should I do?

It's decision time. Grooves in the cylinder walls are the reason the compression is low. Next step would require a tear down and re-bore, new pistons and rings, all new gaskets/seals. You may be able to hone the cylinders and escape some cost but either way it's going to be expensive.

 

[boobie]

Re: 1993 15hp Johnson What should I do?

Could you post a pic of the cylinders ??

 

[chipster427]

Re: 1993 15hp Johnson What should I do?




Best I could do for now.

 

[chipster427]

Re: 1993 15hp Johnson What should I do?

Can't feel the ones you can see, but there is a small patch on both cyl. that you can feel. Could not get a pic of them. Will try to get some and post back later.

On average, what does it run to rebuild?

 

[oldcatamount]

Re: 1993 15hp Johnson What should I do?

A re-build like that, in a shop, could cost $500-$600 in labor, and another $200-$300 in parts and machining and that's on the cheap side. It could end up being twice that.

 

[chipster427]

Re: 1993 15hp Johnson What should I do?

Ok, One more. Say it can be honed out, and I get a power head rebuild kit for like 250, and depending on the depth of the grooves, going .010, .020, .040 over, in anyone's opinion, would it be worth a shot? Me personally, I want to do it just to see if I can. Of course with the guidance of an outboard mech. But, to me if all it needs is working out the cylinders and putting it back together, provided nothing else is wrong with it, I think it is worth a shot. Seeing how I only paid 500 for the whole rig, another 250, 300, or even 400 will not hurt my feelings. I guess what I'm really asking is, what is the average success rate of rebuilds and what kind of life do they normally get? And if anyone has performed this operation, any and all information will be greatly appreciated.

 

[boobie]

Re: 1993 15hp Johnson What should I do?

If you do all this you better find out what caused it.

 

[jmendoza]

Re: 1993 15hp Johnson What should I do?

Alright, stop with telling this poor guy he needs a rebuild, those cylinders are fine....notice the hone marks?

I had a 9.9 with horrible 1/16" deep scoring on 75% of both cylinder walls run fine for 25 more years, it was a bit hard starting when cold, but ran great. By comparison, this engine is barely broken in.

I suspect you have a fuel delivery problem, it could be a bad pump diaphragm, hardened lines leaking air at the fittings(replace lines with new ones) bad orings on the fuel lin disconnect fittings, or a clogged up carb. Is the tank cap opened up to vent the tank? In rare instances, a reed valve could have a problem, like a piece of debris under it, or a broken reed, but this is very rare.

Your compression will read low if you did not open the throttle and pull it through at least 10 times.
I would use some OMC engine tuner, or Valv Tect marine motor decarb solution to loosen up the rings once you get it running. Be sure the plugs are not fouled, and replace them if they are, then surface the head on a piece of glass using some 220 grit wet/dry paper, and then replace the head gasket and head.

 

[chipster427]

Re: 1993 15hp Johnson What should I do?

Ok, sorry for the delay, quick update. Had my buddy look at it for me and upon close inspection found that the head gasket that was installed last was a head gasket for the 92 and earlier. The 93 and new'r have a bit bigger bore so the pistons made 4 perfect crimps on the rings in the gasket. Making the compresion 40 in both. Got new gasket on the way, everything else checks out and should be in good order.
More to follow.

 

[cgibbo308]

Re: 1993 15hp Johnson What should I do?

i was going to say similar thing about the bore. if you wanted you could put standard ring in and a verrrrrrrrrry light rub with a fine wet and dry with oil.

that head gasket looked like it was covering way to much of the water gullies. when you get it back together...
1) squirt some oil down the plug holes an turn it over slowly by hand a few times to get the cyl walls wet
2) give a lil more oil and re do the comp test at wot. and turn it over about 5 to ten times.
as i would like to see the new numbers for the comp test.
3) try to start

 

[gozierdt]

Re: 1993 15hp Johnson What should I do?

+1 to the comments that those cylinders don't look bad at all. I'd follow the recommendations to get the
correct head gasket installed and recheck compression. If it's a little low still, I'd pull the engine apart and
check cylinder and piston wear. Good chance they're still in spec. If so, new rings are cheap. Hone the
cylinders, new rings, and I bet you'll get good compression.

 

[dazk14]

Re: 1993 15hp Johnson What should I do?

It's plainly obvious the head gasket was blown between cylinders. Very clear in pic 1 and 3. Start with that. Also check the thermostat.

 

[chipster427]

Re: 1993 15hp Johnson What should I do?

Got new gasket in yesterday. Will get it put on today and check compression. And it was obvious when i held the two together. Yeah, I saw that once i looked again, that it was blown. No T-stat, I guess the last owner removed it.

 

[mark1961]

Re: 1993 15hp Johnson What should I do?

Check the cylinder head is still flat also.....

 

[nwcove]

Re: 1993 15hp Johnson What should I do?

It's plainly obvious the head gasket was blown between cylinders. Very clear in pic 1 and 3. Start with that. Also check the thermostat.

i have to agree. its also plain to see how clean one piston top is....looks like it was getting a bit of water. for the cost of a head gasket id definitely try decking the head on a piece of glass and put it back together....be sure to use the proper torque sequence and spec. plz post back with new compression numbers.

 

[chipster427]

Re: 1993 15hp Johnson What should I do?

Well got the gasket in and on, checked compression, between 115 and 120 on top and 95 and 100 on bottom. Clean carbs and new water pump. Runs like a champ, little slow to start tough. Thanks for all the info and help.

 

[dazk14]

Re: 1993 15hp Johnson What should I do?

i have to agree. its also plain to see how clean one piston top is....looks like it was getting a bit of water. for the cost of a head gasket id definitely try decking the head on a piece of glass and put it back together....be sure to use the proper torque sequence and spec. plz post back with new compression numbers.

Like NWCOVE mentioned, the bottom cylinder looks a bit steam cleaned. Watch the plugs. Are you sure you got the head straightened out and surfaces were squeaky clean?

You may have a stuck ring on the lower cylinder.