IO-520 Broke valve guide come out exhaust onto driveway

S

Swine77

Member
Perfect running motor until it started smoking.
Smoke was puffing at idle every couple seconds.
Running through a bunch of oil.
Blow by seemed hotter faster.
Got home.
Checked compression within normal range.
Checked plugs. Seemed extra oily on most rear cylinder on that side.
oil leaking from cylinder.
Replaced plugs=more smoke
Heard something fly through exhaust.
Found hot piece of valve guide on the driveway.
Pulled valve cover, I could see busted exhaust valve guide.

I'm located in Geneva, FL
What could have caused this issue? What should I do? My initial thought is to take the jug off and bring it to Don George. Is there anything I should consider before removing the jug?

Alan 407-717-4515
 
Most likely the valve was seating but off center hammering the guide.
Nothing really to worry about pulling the cylinder off.
Note rocker arm placement, be sure they are not both the same, one should mirror the other in angles, keep track of the thrust washers.
 
Last edited:
John Fenner said:
Most likely the valve was seating but off center hammering the guide.
Nothing really to worry about pulling the cylinder off.
Note rocker arm placement, be sure they are not both the same, one should mirror the other in angles, keep track of the thrust washers.
Click to expand...
Do I need to pull the jug. to get this fixed?
 
Yes sir, pull header, pull intake hoses loose, to get log section out, pull rockers, pushrods, shrouds "tubes" and unbolt the cylinder base
 
Thank you. I'll be removing the last 3 header nuts tomorrow. The 3 in the front are stripped and corrosion has got the best of them. Intake bolts are definitely a challenge. Looks like I need to shave a socket down to get in there.
 

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Thank you all. Had a friend mentor me through the cylinder replacement. Learned a bunch. Ran it Christmas Eve and Christmas night. Ran great.
 
Thank you, for reporting back.
All to often threads such as this one seem to dead end into the bit bucket, for lack of response.

Glad to hear that it were no more complications than you were able to ascertain on the front side.
 
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