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DrillDown Icon Engine (ABC type) is Tight at Top Dead Center - Is something wrong?
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Engine (ABC type) is Tight at Top Dead Center - Is something wrong? What should I do?

Question: My VMAX 46 or 52 or other VMAX ABC type engine is very tight at top dead center particularly just out of the box. It is so tight that I hear a clicking noise at the top of the piston travel and it is very difficult to turn it over by hand. Is something wrong? What should I do?

Answer: No nothing is wrong. Please review your instruction manual and in particular the BREAK IN section.

Better Answer: ABC engines have a tapered sleeve which creates a tight fit around the piston at top dead center. The tightness is quite pronounced when the engine is new and cold. As the engine warms up, the sleeve expands and the fit is not quite so tight. The top of the sleeve gets much warmer than the bottom and hence it has been made narrower to allow for more expansion while retaining compression.

Your instruction manual contains specific information related to your engine. The BREAK IN section is very important. The VMAX 46 and 52 engine manual has a note that is boxed to draw attention to it. This note is located on page 3 of the manual in the top left corner and deals specifically with the question of tight fit at top dead center. The note reads as follows:

THIS IS AN ABC ENGINE. IT WILL BE VERY TIGHT AT TOP DEAD CENTER. THIS IS NORMAL. AFTER THE FIRST FEW RUNS IT WILL LOOSEN UP SOMEWHAT BUT REMAIN TIGHTER AT THE TOP WHEN COLD THROUGH ITS LIFE.

We cannot overstate the importance of reading the entire manual before attempting to operate your engine.

 

 

Article ID: 2685