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Stephen Dempsey
Stephen Dempsey, Auto Mechanic
Category: Car
Satisfied Customers: 652
Experience:  I am an top-notch diagnostician with 8+ years of experience managing auto repair shops, import, domestic, and collector cars.
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road..engine tore down , because of no compression that the piston

Customer Question

I am workign on a off road buggy and i noticed wiht the engine tore down , because of no compression that the piston almost new had a smalll dimple creas in the top , whicj explained the no compression problem , is there anything on hte market that will repare that small creas?
Submitted: 6 years ago.
Category: Car
Expert:  Stephen Dempsey replied 6 years ago.
Many, if not most, pistons have dimples in the top. This is machined in to increase the size of the combustion chamber, even out compression, and lower it to acceptable levels. This is not why you don't have compression.

You have a leak somewhere. Bad cylinder wall, bad compression rings, low oil, cylinder wash, bad valves, bad valve seats, cracked block, cracked head, bad head gasket. Any of these can cause poor compression.

The piston is not the problem.

Good Luck,
Customer: replied 6 years ago.
the dimple in the top of the piston was put there by a washer that fell in during assably and i had to take the engine apart to get tit out the mark left on the top of the piston happened affrter trykng to start the engine,, this little creas shows light thru it ,, any suggestions on a fix for it
Expert:  Stephen Dempsey replied 6 years ago.
Oh, I see. Sorry I misunderstood.

If you have a hole in the piston, nothing you can do will hold for long. You simply need a new piston. Welding will just crack, epoxies like JB Weld would hold for a little while, but eventually they would leak compression too.