NEED HELP: Vintage Iron Quit Running

[OMC-boy5.5]

I was out on the lake Sunday and my 57 'Rude 5.5 just kind of bogged out, struggled for a second, then died. Started right back up and on I went. Did it again 100 feet later. Started right back up and made it back to dock (200 yds). Then dropped off my dad and I went back out a ways and backtrolled along some lilly pads for about 20 minutes. Seemed to run great without a hitch. Then I started back for dock and halfway home it bogged out and there I sat. Wouldn't start. Later that evening I finally got it to run, but on one cylinder only. Kept it running for 5 minutes at higher throttle and it kept the top cylinder. Bottom plug/cylinder was cold.

I thought it may have been some (admittedly) dirty gas, but I figured it'd be fine since I have the tank screen and an inline filter.

Got it home and there is good spark in both cylinders. Tested compression: Top, 70psi ; Bottom, 1 psi

Pulled the head and this is what I found:

 

[oldcatamount]

Re: NEED HELP: Vintage Iron Quit Running

Looks like you have a blown head gasket. Chances are good that was a result of an overheat situation. Have you changed the impeller recently (within the past year)?

 

[OMC-boy5.5]

Re: NEED HELP: Vintage Iron Quit Running

Impeller replaced 10/18/11. I will admit that it doesn't seem to pump quite like my Johnson 5.5 does, but it WAS pumping the whole time. I can agree that it appears there's water (milky oil) in the cylinder. The gasket looked decent when pulled off though, either way I'll need a new one anyway. Just wondering if this is my only problem.

 

[Tim Frank]

Re: NEED HELP: Vintage Iron Quit Running

It looks like the bottom cylinder was blowing-by at about 1 o'clock position.. It matches the pattern on the the head gasket.

 

[OMC-boy5.5]

Re: NEED HELP: Vintage Iron Quit Running

OK, thanks you guys. Got'er back up and running again. You both were right. There was a leak in the head gasket at the one o'clock position. Everything looked in good shape so I reassembled with new gaskets, dumped a bunch of oil in it and she fired right up. Firing on both cylinders and compression restored to 65 psi in both sides. You wouldn't think 65 is enough, but she purrs just like new.

Smoke plume was pretty sweet when she first started too with that cylinder full of oil.. hahaha. It was amazing

Thanks again.

 

[kfa4303]

Re: NEED HELP: Vintage Iron Quit Running

awesome. actually 65 psi is pretty dang good for a 5.5 hp. some folks find they need to snug down the bolts on the head after the motor warms up a bit. congrats again.

 

[OMC-boy5.5]

Re: NEED HELP: Vintage Iron Quit Running

Thanks for the tip!

Does this need to be a specific torque? I don't own a torque wrench, so I just tightened to feel. Could get a hold of one if it's important.

 

[Tim Frank]

Re: NEED HELP: Vintage Iron Quit Running

Torque wrench would be better as is tightening in an outward pattern from the middle.

 

[steelespike]

Re: NEED HELP: Vintage Iron Quit Running

Torque to 60-80 inch pounds.

 

[kfa4303]

Re: NEED HELP: Vintage Iron Quit Running

steelspike is right. be sure you're measuring in INCH/POUNDS and not FOOT/POUNDS like most torque wrenches. Big difference. You could buy the tool, but you might be able to take it to a local mechanic who can tighten it to spec or a couple bucks. glad you got it running again.

 

[jmendoza]

Re: NEED HELP: Vintage Iron Quit Running

I would only add that it's prudent to lap the head on a surface plate before renewing the head gasket, and also to re-torque the head bolts several times after each heat-up/cool down cycle, this will insure it stays sealed. I always re-torque at least once following a head gasket replacement, it's cheap insurance