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2.2.8. Dismantling and assembly of conrod and piston group

Dismantling of a cover of a rod

ATTENTION
Arrange the removed details (rods, covers of rods, inserts of conrod bearings) as their compliance to numbers of cylinders to provide the subsequent correct assembly.

Fig. 2.71. Components of the piston and rod



Turn off bolts of fastening of a cover of a rod, then uncover a rod and the lower insert of the conrod bearing.
Push out the piston and a rod assembled from the block of cylinders in the direction to a surface under laying of a head of cylinders.

Dismantling and assembly of knot of the piston and rod (removal and installation of a piston finger)

Fig. 2.72. Dismantling of knot piston rod


By means of special tools (09234-33001 and 09234-33002) execute dismantling and assembly of knot of the piston and a rod (fig. 2.72).
The piston finger is pressed in the top head of a rod, and the piston slides on it.
A set of special tools consists of the basis with a support and inserts, guides, adapters, a rod pusher for removal and a rod pusher for installation. At removal or installation of a piston finger the piston keeps on the basis of adaptation. The directing devices facilitate positioning of a piston finger at its removal and installation when the rod leans on support inserts.

Fig. 2.73. Extraction of a finger by means of a press


For removal of a piston finger lay the piston on the basis and arrange a rod on a support insert. Insert a rod pusher (for removal) through an arch of the top part of the basis into a piston finger and take a finger by means of a press (fig. 2.73).
At installation of a new finger it is necessary to establish the corresponding insert of a support for support of a rod.
Arrange the top head of a rod in the piston. On the one hand the piston insert the corresponding guide via the piston and a rod, then slightly besiege a guide by hand that it was kept by the piston. On the other side of the piston implant a piston finger and lay together the piston and a rod on adaptation basis so that the guide of a finger was from below.

Fig. 2.74. Directing to centerings of a rod



NOTE
The guide is necessary for centering of a rod concerning piston lugs. If assembly is executed correctly, then the guide of a finger will precisely stand on the center of an opening of an arch of the top part of the basis and to concern a support insert. If the guide of a finger of the wrong size, then the piston is used (and a rod) and a piston finger will not be on one axis with an opening of the basis (fig. 2.74).


Fig. 2.75. The scheme of a press fitting of a finger in the piston and the top head of a rod


Insert a rod pusher (for installation) through an opening of an arch of the top part of the basis against the stop into an adapter on a piston finger and by means of a hydraulic press bring a finger to the piston and the top head of a rod. Continue a press fitting till the moment when the guide of a finger falls from below the bases and the rod pusher will rest against an arch of the top part of the basis (fig. 2.75).

ATTENTION
Do not exceed effort of 12500±5000 N at a press fitting of a piston finger at the moment when the rod pusher rests against an arch of the top part of the basis.

Check of the piston and piston finger
Check each piston for absence of scratches, zadir, wear and other defects. Replace the piston with defects.
Check each piston ring for lack of breaks, damages or considerable wear. Replace defective rings. In need of replacement of the piston at the same time it is necessary to replace its piston rings.
Make sure that the piston finger enters piston lugs. Replace the piston and a piston finger with a set with defects. At the room temperature under pressing of a hand the piston finger has to enter a piston opening easily.

Check of piston rings

Fig. 2.76. Check of a face gap of a compression ring


Measure a gap between a compression ring and a flute of the piston (fig. 2.76).
If the measured gap exceeds maximum permissible value, establish a new piston ring and repeatedly measure a gap. If the measured gap exceeds maximum permissible value again, replace the piston and rings assembled. If the measured gap is less than maximum permissible value, replace only piston rings.
Values of a gap between a piston ring and a flute of the piston are given below.
Nominal rate:
compression ring No. 1 – 0,04–0,085 mm;
compression ring No. 2 – 0,04–0,085 mm.
Maximum permissible value:
compression ring No. 1 – 0,1 mm;
compression ring No. 2 – 0,1 mm.

Fig. 2.77. Check of a gap in the lock of a piston ring


For measurement of a gap install a piston ring in an opening of the cylinder (fig. 2.77) in the lock of a piston ring.
Arrange a ring at right angle to the forming cylinder wall, carefully moving it by means of the piston down.
Measure a gap in the ring lock by the flat probe (fig. 2. 78).
If the measured gap exceeds maximum permissible value, replace a piston ring.
Values of a gap in the lock of a piston ring are given below.
Nominal rate:
compression ring No. 1 – 0,20–0,35 mm;
compression ring No. 2 – 0,30–0,45 mm;
oil scraper ring – 0,2–0,7 mm.
Maximum permissible value:
compression rings No. 1 and No. 2 – 1,0 mm;
oil scraper ring – 1,0 mm.
When replacing piston rings without boring of cylinders in the repair size check a gap in the ring lock in the point located in the lower part of the cylinder (a zone of the smallest wear).

Fig. 2.78. Measurement of a gap in the lock of a piston ring




NOTE
The identification tag of the repair size is located on the top part of a piston ring about the ring lock.


Fig. 2.79. Grooves of inserts in a cover of a rod and a rod


At installation of a cover of a rod be convinced that the tags of number of the cylinder (made when dismantling) on a rod and a cover of a rod coincided. At installation of a new rod be convinced that the fixing grooves of inserts in a cover of a rod and a rod are located on the one hand (fig. 2.79).
Replace a rod in the presence of damage of a face surface of the top or lower heads. If there is a bend or twisting of a rod or the surface of an opening under a piston finger in the top head of a rod is considerably worn-out, replace a rod.

Assembly

Fig. 2.80. Installation of a dilator of an oil scraper ring


Establish a dilator of an oil scraper ring (fig. 2.80).

Fig. 2.81. Scheme of installation of the top scraper of an oil scraper ring


Establish the top scraper of an oil scraper ring. For installation of a scraper at first establish one end of a scraper between a dilator and a flute of the piston, then, holding the end of a scraper, press a finger a scraper to bring it to a flute, as shown in the figure 2.81.

ATTENTION
Do not apply an expander of piston rings at installation of scrapers of an oil scraper ring.


Fig. 2.82. Installation of the lower scraper of an oil scraper ring


Establish the lower scraper of an oil scraper ring according to the previous procedure (fig. 2.82).
Apply engine oil on the piston and flutes of the piston under rings on all circle.
By means of an expander of piston rings establish a compression ring No. 2.

Fig. 2.83. Scheme of installation of a compression ring No. 1


Establish a compression ring No. 1 (fig. 2.83).

Fig. 2.84. Scheme of locks of compression rings


Arrange locks of rings as it is possible further from each other. Make sure that the lock of any ring is not on an axis of a piston finger or the perpendicular direction (fig. 2.84) of this axis.
By means of special adaptation reliably record piston rings on the piston before installation of the piston assembled in the cylinder.
Install the top inserts of radical bearings in the block of cylinders.

Fig. 2.85. Installation of the lower insert of the radical bearing in a rod cover


Establish the lower inserts of radical bearings in covers of rods (fig. 2.85).
At installation be convinced that a "forward" tag on the piston and a "forward" identification tag on a rod are directed to a forward part of the engine (to a GRM drive belt).
At installation of a new rod be convinced that the fixing grooves of inserts on a rod and a cover of a rod are located on the one hand.
At assembly bolts of fastening of covers of rods should be tightened, using an angular method of an inhaling, as follows:
– apply oil on a carving of nuts of fastening and the place of contact of a rod of nuts and bolts;
– tighten bolts of fastening of covers of rods the nominal moment of an inhaling.
Moment of an inhaling of nuts of fastening of covers of rods: 32–35 N · m.

ATTENTION
Do not establish repeatedly former in operation (removed when dismantling) bolts of fastening of covers of rods.
At installation of new bolts of fastening of covers of rods do not tighten their more than three times.

Check a side gap between the lower head of a rod and the corresponding cheek of a bent shaft.
Side gap of the lower head of a rod:
nominal rate – 0,1–0,25 mm;
maximum permissible value – 0,4 mm.
Establish a maslozabornik.
Install the oil pallet.
Establish a head of cylinders.