Fig. I-Worn Groove

The top compression ring has the most difficult job of any ring on the piston. It is the initial compression ring which prevents combustion gases from escaping into the crankcase, and is also the final oil control ring which controls oil that passes the ring combination below it. It must form a seal between the face of the ring and the cylinder wall and between the sides of the ring and the ring groove. If this ring fails to seal on the face and sides, there will be blow-by which will contaminate the oil in the crankcase, forming sludge and corrosive acids, cause ring sticking and may cause scuffing and ring breakage at low mileage. A worn ring groove will allow blow-by, oil consumption, possible engine failure and owner dissatisfaction.

Fig 2-Photo of Broken Rings on Piston

For positive side sealing of the top ring, the groove must be flat, parallel and smooth.

A method has been developed of reworking top ring grooves which brings the groove back to standard width and makes the groove flat and smooth.

Fig. 3-Ring Groove After Machining

After remachining the groove a .030 steel spacer is installed in the top of the ring groove as shown in Fig. 6, which brings the groove back to standard width. The Hastings GL Spacer locks in the groove and actually becomes a part of the piston.

(Fig. 6-spacer in groove.)

The spacer will not float or rotate, which will allow the ring to run straight in the groove and seal blow-by and prevent oil consumption by the top ring. It also enables the ring to run cooler.

(Fig. 7-Spacer and New Ring in Groove)

The Power Regroover has tool bits for groove repair on all popular makes of automobiles and light duty trucks.

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