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1998 Johnson 225 rod Knock???

P

pocket

Member
I just purchased this motor and it sounds like a rod knocking...its the top cylinder, it has 110 psi on compression. When I remove the.spark plug I don't hear it anymore. I thought I read that these engines had a problem when they first came out with bolts backing out of rod/main caps....I can't find the article anymore. This is a Carb/Looper motor, not a ficht. Any information is greatly appreciated​
 
Remove the cylinder head for an inspection.-----------Then likely the motor will need to come apart for repairs.---------Sounds time consuming and $$$$$$
 
(Piston Play Check)
(J. Reeves)

This procedure will tell you if there is any wear or play in the Wrist Pin, Wrist Pin Bearing, or Connecting Rod to Crankshaft area.

Remove the spark plugs. Insert a screwdriver, dowel, punch, or some object of your choice through the s/plug hole and into the cylinder/piston area. Hold the tool lightly against the top of the piston. Turn the flywheel by hand, bringing the piston up to top dead center, then continue turning the flywheel to pull the piston down about a inch..... all the while holding the tool lightly against the piston top.

Now, at the point whereas the piston has been dropped down about a inch, grab the flywheel and hold it firmly. Now, push that tool solidly and firmly against the piston top.

If the piston moves without moving the flywheel, there is a problem (wear, play, clearance, etc) somewhere with the items mention in the first sentence. Be sure to check all of the pistons/cylinders.

What make/type spark plugs are in the engine, and what did the plug look like that was in the cylinder in question as compared with the others?
 
In addition, Do not start the engine again until the problem is corrected. If the bearing or pin fails, you will do damage to the engine block and may turn it into scrap.
 
I performed the test and there is slack in that cylinder, all of the other cylinders are fine. Is it possible for me to pull the front crankcase cover off without removing the engine from the mid section. If the problem is in the Piston side of the Rod and not the crank, and cylinder wall looks good can I replace it (Piston/Rod assy) through the side with the head? Thanks Again for the help
 
pocket said:
Is it possible for me to pull the front crankcase cover off without removing the engine from the mid section.
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Unfortunately, as Racerone states, the powerhead must first be removed from the long exhaust housing upon which it sits. With no intention of insulting your intelligence, it would be best if you read thru portions of a service manual so that you somewhat understand what is involved.

Many of the engine's accessories must be removed, then the powerhead lifted off its base, the crankcase split, then and only then will you have access to the connecting rod bolts at the crankshaft. Quite involved.
 
Thank You very much for volunteering your time for Do-it-yourself guys like me. I was kind of worried that might be the answer, I might decide to put a remanufactured engine on, do you guys have a preferred one you use. P.S. I was definitely going to get a service manual...learned my lesson on a See-Doo. Thanks Again and I hope you have a Happy Holiday Season!!
 
If the problem is in the Piston side of the Rod and not the crank, and cylinder wall looks good can I replace it (Piston/Rod assy) through the side with the head?
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Its a old racer trick but yes you can remove the piston/rod assy if you remove intake and carbs..
 
faztbullet said:
Its a old racer trick but yes you can remove the piston/rod assy if you remove intake and carbs..
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That can be accomplished sometimes.... but you'll have one hellava time getting it back together even if the cylinder's in perfect condition. Best to tear it down properly.
 
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