1957 35HP Big Twin (hitting hard Knocking)

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

will do... Thanks!

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

ok, did compression test 60top 0 bottom... What does this mean? What should I do next?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

I remember having both at 80 when I got motor

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

pull the head off and look for signs of a blown head gasket, and check the head to make sure its mating surface is flat. those old motors are tough, dont give up on it yet!!

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Is this head gasket?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Looks like 3 hex bolts on top plus the big one middle. Do I remove all these to check head gasket? Do you want another pic.?

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

nope...not that part. the head is the part that the spark plugs screw into.....should be held on with 8? 7/16 bolts.http://www.marineengine.com/parts/j...&manufacturer=Johnson&section=Powerhead+Group

part number 23 in the exploded view, but it doesnt look as easy as the small vintage motors im used to working on !?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

So leave these part alone for now right?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

These I'm pointing to?? How do I get the lower ones out if these are them?

I think I have 10 of them.

 

[kfa4303]

Re: 1957 35HP Big Twin (hitting hard Knocking)

HI big baller. The part in your pic is called the "flywheel" and you can leave it be for now. The head gasket isn't really visible because it's sandwiched between the head, which holds the spark plugs, and the engine block (see pic). To replace it, you'll have to remove the head itself. Just be careful as the headbolts may be frozen. Loosen them slowly and apply heat if necessary. However, it's a fairly involved job for a beginner. So lots of reading, ask question here and make sure you have all the replacement gaskets ready to do. You'll also need a torque wrench to reinstall the bolts.

EDIT:
Yes those are the headbolts. You may have to remove the power head to access the lower ones if your cowling is not removable. I'm having the same issue with my '66 20 hp.

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Does it look bad from Pic. What am I looking for once I remove this bastard off?

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

jmo, but if those compression readings are correct, the cyl head has to come off to inspect the head gasket , pistons and cylinder walls. im sure someone will chime in on the easiest way to pull the head. ( it could be as easy as the small motors, or just a bit more involved. either way, i cant imagine it being any more difficult than the lu work you did!!)

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

looks like 10, 1/2 inch head bolts from the pic, maybe the rest of the stuff can remain attached except the compression relief.....but wait for someone who has pulled the head off one of those to chime in before wrenching on it!! im only passing along somewhat generic info, as ive never put a wrench on any vintage motor bigger than a fastwin.

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Done... let me know if it looks BAD??

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

from what can be seen from the pics, it doesnt look bad at all. ( holy crap yer fast with disassembly! lol) those shiny spots on the head may be a sign of water intrusion/blown gasket. any signs of scoring/scuffing on the cylinder walls?

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

LOL... built tract houses for a living... Looks good to me.... very clean inside.. other than the black thin guck on the walls I dont see an issue here. Any other ideas? Im sort of going the direction of the flywheel COILS, etc.. Will that effect the COMPRESSION ISSUE???

 

[bigballerg]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Not sure when if ever coils were replaced, but if it has nothing to do with compression I'm not going there?

 

[RogersJetboat454]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Peel the rest of the head gasket off the block, and inspect it closely. Take detailed pictures of the cylinders for us to look at. As NW said, the shiny combustion chamber for the lower cylinder suggests water intrusion (AKA steam cleaning).

 

[RogersJetboat454]

Re: 1957 35HP Big Twin (hitting hard Knocking)

Im sort of going the direction of the flywheel COILS, etc.. Will that effect the COMPRESSION ISSUE???

Nope...
Compression loss in these engines is usually due to a blown gasket, a warped head (usually both in combination), or damage to the rings.

 

[nwcove]

Re: 1957 35HP Big Twin (hitting hard Knocking)

your reading of zero compression on one cyl, and 60 on the other, is normally a sign of a blown head gasket or worse. nothing ignition related will cause it. if the cylinder walls arent scuffed up id go with a new gasket, go through the procedure to check the head for warpage ( common issue), and do the procedure if necessary.