Johnson 7.5

paul-j

Cadet
Joined
Jan 19, 2008
Messages
18
Re: Johnson 7.5

thank you all for your ideas and commentary
ill try those last two in a bit..
i pulled both spark plugs out today and checked
turns out both of the spark plugs...
are BAD!
 

samo_ott

Vice Admiral
Joined
Jun 18, 2006
Messages
5,125
Re: Johnson 7.5

Bad how?

And I'd still do a compression check also. You can check en like JBJ sez also, but a compression check will tell the most.
 

paul-j

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Joined
Jan 19, 2008
Messages
18
Re: Johnson 7.5

Ahh bad as in super black and the ends were lose and basically your spark plugs worst nightmare..the guy i bought the motor from in august probably threw it all together so there is no telling.. and how exactly does one do a compression check.. Im a complete noobie
 

wbeaton

Commander
Joined
Jul 30, 2006
Messages
2,332
Re: Johnson 7.5

But were they physically damaged? Black is fine. What do you mean by loose?
 

jbjennings

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Jul 18, 2007
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3,903
Re: Johnson 7.5

To do a compression check, go to the nearest redneck next-door neighbor and borrow his tester, or go to o'reilly's and get a new $20 tester. You unscrew both plugs, ground the spark plug wires to the block, screw in the comp. tester in one of the plug holes, and pull the recoil till you get the highest reading. Do the same for the next cylinder. Hopefully it's over 75lbs. preferably around 85lbs. on both cylinders. They should be within about 5lbs. of one another.
Make sure you return the tester or the neighbor will not be pleased!:D
That test will tell you if the motor is worth fixing, and is very easy.
JBJ
 

paul-j

Cadet
Joined
Jan 19, 2008
Messages
18
Re: Johnson 7.5

like ah.. i pulled the whole spark plug apart in the store looking for new ones without a wrench or anything
 

paul-j

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Joined
Jan 19, 2008
Messages
18
Re: Johnson 7.5

okay thanks
im sure i have plenty of redneck neighbors!
haha what exactly does it look like because i probably have one around here somewhere..
 

jbjennings

Captain
Joined
Jul 18, 2007
Messages
3,903
Re: Johnson 7.5

If the end of your plug looks like something has hit and broken it, it could have been the piston flying up and smacking it. Here's a pic of a cheapo comp. tester.....Yes, I'm one of the rednecks that has one.;)
JBJ
 

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paul-j

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Joined
Jan 19, 2008
Messages
18
Re: Johnson 7.5

haha thanks. and sorry it took so long to reply my computer crashed.. i havent had much time to work on the motor considering baseball season just started. however, today i put it in the water and it started up fine after all winter and it runs great in reverse but when i put it in forward, nothing happened. It ran wide open in forward better than it did before. It has no knocking noise it just didn't move. :confused:
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Johnson 7.5

You probably din not reconnect the connector on the shift rod correctly when you worked on the lower unit. You have to take the screw out completely so that the rod is fully inserted.
 

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paul-j

Cadet
Joined
Jan 19, 2008
Messages
18
Re: Johnson 7.5

okay... i thought so.. so i could still have the same engine problems after i put the rod back in place?
 
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