'85 Johnson 30hp wont start, please help!

[mikewoller]

Re: '85 Johnson 30hp wont start, please help!

Sounds like its hatched!!! Sorry 4 the bad news!! going to need pistons....rings...and who knows how bad the cylinder walls are. Might want to take this to the shop to have done...... Good Luck!!
P.S. In the future, when you start your motor, make sure it has a stream of water coming out the back (this will re-assure you that you have correct cooling circulation)

 

[matt9923]

Re: '85 Johnson 30hp wont start, please help!

Sounds like its hatched!!! Sorry 4 the bad news!! going to need pistons....rings...and who knows how bad the cylinder walls are. Might want to take this to the shop to have done...... Good Luck!!
P.S. In the future, when you start your motor, make sure it has a stream of water coming out the back (this will re-assure you that you have correct cooling circulation)

You could do it yourself with a ballhone or brake type hone if it not to bad. As well as clean with muriatic acid for any pistion to cylander transfer occerd. You will need a boar guage to see if you can use what you have or go to the next size pistion and rings. You best bet is to go to the next size and get it pro honed for $80. Then $120 for pistion and rings.... The shop will charge around $1500-2000 im shure.
Matt

 

[ezeke]

Re: '85 Johnson 30hp wont start, please help!

Sounds like the head gasket is blown to me.

When you do a compression test, you want all the plugs out and the engine turning as fast as possible; in other words, fully charged battery.

On a two stroke, having the throttle plates closed or open will not make any noticeable difference in the results of a compression test.

 

[samo_ott]

Re: '85 Johnson 30hp wont start, please help!

Pull the head and see what's going on inside. You have nothing to lose at this point. Post pics also would help.

 

[matt9923]

Re: '85 Johnson 30hp wont start, please help!

Pull the head and see what's going on inside. You have nothing to lose at this point. Post pics also would help.

Agreed it wont take long to pull (you might want to get a impact hammer from sears for $25 if you cant get some of the screws before you strip the heads off) and see what you have ad well as if you gasket is cooked. Sometimes the engine can take an overheat but sometimes it cant.
What does the heat sensor do is int it supposed to prevent this? My censor was gone so i don't know...
Matt

 

[Bradley_G]

Re: '85 Johnson 30hp wont start, please help!

one thing I didn't do is charge up my battery. I used it two days before for a whole day of trolling, but I dont know how much that would have affected it.. I've got to go pick up a head gasket and then see if I can find some free time to work on it. anything I should note before I pull the head? (pieces that may fall out of place, wires or things to disconnect?) also, where are the bypass covers?

 

[ezeke]

Re: '85 Johnson 30hp wont start, please help!

Do the compression test correctly first. Then take the cylinder head off when you have the gasket if you feel the need after the compression results. If you take the bypass cover off for ring inspection you will need a new gasket there as well.

 

[Bradley_G]

Re: '85 Johnson 30hp wont start, please help!

my large deep cycle battery had 80% on it when I hooked it up to the charger. It had 12.5v, plenty to kick that motor over. looks like I have a burned up motor. Wont be able to pull the head or bypass cover until next week. will post pics when I do. Anyone have a powerhead for sale?

 

[Bradley_G]

Taken apart, pictures attached.

Taken apart, pictures attached.

Okay, it was a beautiful day and after I conquered the yard work I decided to pull a motor apart. Pulled the Head and Bypass covers off and here's what I found:
http://s569.photobucket.com/albums/ss135/bradleybooker/Dismantled%2030hp/

Had to link the pics b/c the forum wanted such small sizes.

The top cylinder had a slight amount of scoring, barely noticable by touch, but easily seen in photo. there was one part visible through the bypass cover which showed a small amount of scoring on the top piston rings, but by batt died before I could snap the shot.

Bottom cylinder looks and feels great and no signs of scoring anywhere.

I was able to easily push the pistons and they would move in and out, did not seem to catch or drag or have any warpage to speak of. I was able to move the pistons around inside and the spacing was very even on both. (dont know if that is good or not that I could move them, but there was a small amount of play in them)

The head gasket looked like it was in fair shape, but it was pretty old. When the last of the bolts were out the unit fell right out of place.

The bypass gasket however was baked on hardcore. I had to tap it loose with a hammer to get it to fall, and the gasket itself ripped in half part stayed on block and part on the cover.

Take a look at the pics, let me know if this looks okay or bad. And if there is anything else to check while the head and bypass covers are off.

My plan for now, replace gaskets and try a compression test again. (most likely next week unless I get the parts tomorrow by chance)

 

[Bradley_G]

Re: '85 Johnson 30hp wont start, please help!

Having seen the slight damage to the top cylinder worried me at first, but then remembering that the compression was the SAME in both cylinders is what is leading me to believe that the gasket may have been one of the main issues.

Flaws in my logic?

 

[matt9923]

Re: '85 Johnson 30hp wont start, please help!

Hmm..... If it was me i would pull the top end apart and hone the cylinders, sand the piston and get new rings. Or get new gaskets and see if your compression goes up. I have seen engines with 140+ lbs of compression with horrible scoring and melted rings. Yours is int to bad. Try the gaskets.
Matt

 

[Bradley_G]

Re: '85 Johnson 30hp wont start, please help!

anyone have a manual for this model or know the order/ torque lbs. for these head and bypass plate bolts to go back on?

 

[Bradley_G]

Re: '85 Johnson 30hp wont start, please help!

got the torque and order, but any more feedback on the photos would be great.

 

[Bradley_G]

Re: '85 Johnson 30hp wont start, please help!

can anyone tell me what item#19 is in the diagram posted in reply #27?

Also, is the heat sensor a one time use item, should it be replaced after it goes off or will it be fine to use again? I just got back from a camp trip and pulled and cleaned off gaskets off of head cover and water cover plate and getting started on bypass cover gasket which was a melted mess and wanted to know if I should replace anything else before I go putting it back together.

Dont want to rush this like I did the impeller....I know how that turned out.

 

[ezeke]

Re: '85 Johnson 30hp wont start, please help!

#19 is the thermostat.

The temperature switch should be fine, but check the rubber seal on it if the engine ran hot for very long.

 

[wbeaton]

Re: '85 Johnson 30hp wont start, please help!

Sorry. Didn't realise there was a second page.

If the rings are free then I'd just plane the head, install the new head gasket and compression test it again.

 

[Bradley_G]

Re: '85 Johnson 30hp wont start, please help!

so I changed the gaskets (cylinder head, water cover, bypass cover) and connected everything back up and the compression is only 60psi in each cylinder. It doubled teh compression that was there, but it still wont fire up. any suggestions? should I try the cover plate on the other side of the head? any tell tales that it is a gasket or something else?

I lightly sanded all surfaces and cleaned them using compressed air afterward, and when re-installing I used the proper sequence and I torqued all bolts to about 20lbs.

Any help would help.

 

[matt9923]

Re: '85 Johnson 30hp wont start, please help!

Hone cylinder and new rings... or bore oversize and new pistons and rings, would be like a new motor. But hone and new rings should help.
Matt

 

[Bradley_G]

Re: '85 Johnson 30hp wont start, please help!

how much do you 'rekon something like that would cost?

Also, should I have put a small amount of oil on the gasket to keep it from sticking to the head/covers? I know thats something that is done in the auto industry on some occasions...

 

[jbjennings]

Re: '85 Johnson 30hp wont start, please help!

No oil on the head gasket---install dry.
I'm thinking new oversize pistons and rings alone would run you 250-300 bucks. Then another 50-100 for boring. But I've never done it. Myself, I'd get a used block and put my stuff on it. Check ebay and other places.
I wonder if anything else in your block was ruined by the head like the crank bearings and rod bearings and such? If you can't do the labor yourself, get a whole used motor---you'd be better off and get off cheaper.

BTW, I am very untrusting of other folk's comrpession gauges. Do you have any other outboard you have access to that runs well that you could check and see what your gauge says? Those gauges have been known to be WAYYYY off. I've never seen a motor that had unstuck piston rings on it that had only 30 psi.
Good luck,
JBJ