1957 johnson 7.5hp water in lower cylinderbut still have good compression?

[1946Zephyr]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

About 20 foot pounds should be good

 

[grave digger]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

is there a certain order? thanks Digger

 

[Mas]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

Start in the middle and work to the outside...evenly working both sides. Use several complete passes of increasing torque until you get to the recommended spec.

Mas

 

[grave digger]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

well on my 4th pass i broke a middle head bolt at 16lbs torque. what do I do now????

 

[Mas]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

Ooops!

Did the head break off...or the shank? Remove the head and see if you can grab part of the shank with vise grips. Otherwise, you'll need to drill it out. Might want to use a reverse bit. I guessing it should come out easy since it was already removed.

I would probably at this point replace all the head bolts...but not the hardware store variety...go with oem!

Mas

 

[grave digger]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

the shank broke off just inside the block. will i be able to reuse this head gasket or will I have to get a new one? any other sugestions for getting it out? Thanks Digger

 

[Mas]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

Check the specs for the torque...I'm seeing only 7 foot pounds (84 inch pounds) for the 7.5 fleetwin.

Mas

 

[HighTrim]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

Yes 60 to 84 INCH/LBS only! That is 5 to 7 ft/lbs, 16 ft/lbs will surely snap those old bolts! Try with the left hand drill bit first, hopefully she will spin out. Re use the head gasket and re check compression. Retorque after your first good run. Start with 5ft/lbs, then 6 ft/lbs finishing up with 7 ft/lbs. Start in the center and spiral outwards as mentioned.

 

[boobie]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

Agreed X 2.

 

[grave digger]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

OK got the head back on everything is good except now the motor wants to die when ran in the bucket but now no water in cylinder. runs great on the stand no water. what is the deal? Thanks Digger

 

[HighTrim]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

Glad to hear the head gasket is fixed, main problem solved. How did you do with the broken bolt?

Regarding your newest problem, if I am understanding you correctly, when you put backpressure on the exhaust, ie run it in water, she wants to die? To start, what is your new compression readings? Is she sparking on both cylinders and jumping a good 1/4" gap on an inline tester?

 

[grave digger]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

you understand exactly!! I will do compression test and get back with numbers. spark is good 1/4 inch air gap. Thanks Digger

 

[grave digger]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

there has been a drop in compression 70 on bottom and only 65 on top. i did not have a new exhaust gasket when i checked the exhaust but did reseal the old one. do you think that this could be my issue? Thanks Digger

 

[grave digger]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

whats up? did I make you all mad? all of a sudden no more help? if I did, I am Sorry. Thanks Digger

 

[1946Zephyr]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

Sorry about the incoorrect info earlier. A 7.5 should run with that compression, eventhough it is kinda low, It might be a good time to get some sea-foam and do a decarb. Maybe then, the compression will come up. I usually pull both plugs and open the throttleall the way, when I do a compression test. You might also check the gap on your points for good measure.

 

[grave digger]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

thats the way I do the compression test as well. did decarb #s still the same. you think it is the exhaust gasket? Thanks digger

ps. any other possibilities????

 

[Mas]

Re: 1957 johnson 7.5hp water in lower cylinderbut still have good compression?

Exhaust gaskets issues should not affect compression tests. The gaskets are probably OK..but I personally would not reuse that gasket.

Try testing compression with another tester. Running issues might be carb/fuel related.

mas