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Autopapyrus · Mitsubishi Mirage 1.2 (1986)
https://autopapyrus.com/guides/mitsubishi/mirage/cylinder-head-gasket-replacement/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Mitsubishi Mirage 1.2 (1986): Cylinder Head Gasket Replacement

Replacing the head gasket on a 1986 Mitsubishi Mirage with the 1.2 L engine (Saturn/4G3 series) is a labor-intensive job. It requires removing accessories and the cylinder head, checking head flatness, and tightening the head bolts correctly. The aluminum head is sensitive to overheating. If there is any sign of warping, have it checked and resurfaced at a machine shop.

Difficulty: Hard Time: 6-8 hours Steps: 23 Tools: socket set, torque wrench, drive belt removal tool, feeler gauge set, gasket scraper, coolant drain pan, clean shop rags

Part

  • 🔩 cylinder head gasket MD198002 (Mitsubishi OE), gasket set MD974309 (includes cylinder head gasket, valve cover gasket, intake and exhaust manifold gaskets). Head bolts: replacing with new ones is recommended (single-use, stretch-to-yield type)

Step by step

23 steps
  1. Disconnect the negative battery terminal. Drain the coolant into a clean container through the drain plugs on the engine block and radiator (system capacity is about 5 L (5.3 qt)).
  2. Remove the air filter. Disconnect all cooling system hoses (upper and lower radiator hoses, heater hose), vacuum lines, and fuel lines (relieve fuel pressure before disconnecting).
  3. Unplug the sensor connectors (coolant temperature, oil pressure, oxygen sensor). Remove the accelerator cable and the carburetor or throttle body control cables (depending on equipment).
  4. Remove the exhaust manifold: unscrew the nuts securing it to the head (installation torque 20-30 N·m (15-22 lb-ft)) and disconnect the downpipe.
  5. Remove the intake manifold: unscrew the mounting bolts (installation torque 15-20 N·m (11-15 lb-ft)) and remove the carburetor or throttle body.
  6. Remove the valve cover: unscrew the bolts (installation torque 8-12 N·m (6-9 lb-ft)) and remove the gasket.
  7. Remove the timing belt (if SOHC with a belt): align the marks on the crankshaft and camshaft pulleys with the marks on the housing, lock the camshaft in position, loosen the tensioner, and remove the belt.
  8. Remove the camshaft sprocket: while holding the shaft from turning, unscrew the center bolt (installation torque 50-60 N·m (37-44 lb-ft)).
  9. Loosen the cylinder head bolts. Work in the reverse of the tightening order (from the edges toward the center), loosening each bolt 1/4 turn per pass to avoid warping the head.
  10. Remove the cylinder head: carefully pry it loose with a wooden or plastic wedge (not a metal tool, to avoid damaging the block surface), then lift it straight up.
  11. Inspect the old gasket for signs of combustion gas leakage (black marks between cylinders), coolant leaks (white traces), or oil leaks (dark, oily traces).
  12. Clean the mating surfaces of the head and block of any remaining old gasket material. Use a plastic scraper or brass brush, and do not scratch the aluminum head. Wipe with degreaser.
  13. Check the head flatness: lay a metal straightedge on the head surface lengthwise and crosswise and check the gap with a feeler gauge. The maximum allowable deviation is 0.05 mm. If the head is warped more than that, it must be resurfaced at a machine shop.
  14. Install the new head gasket: lay it on the block, aligning the bolt holes and dowel pins. Do NOT coat the gasket with sealant (modern multi-layer gaskets are installed dry).
  15. Install the cylinder head: lower it straight down, aligning the bolt holes. Do not let it tilt or cock.
  16. Lubricate the threads and under-head surfaces of the new head bolts with engine oil. Thread all bolts in by hand.
  17. Tighten the head bolts in three stages: first pass 20 N·m (15 lb-ft) (from the center outward in a spiral), second pass 40 N·m (30 lb-ft) (same order), third pass 55-60 N·m (41-44 lb-ft) (final torque). Tightening order: start with the center bolts and work outward in a spiral or crisscross pattern. The exact sequence depends on the number of bolts (usually 10 bolts: tighten in the order 5→6→3→8→1→10→2→9→4→7, where 5 and 6 are the center bolts).
  18. Install the camshaft sprocket: align the timing marks, then tighten the center bolt to 50-60 N·m (37-44 lb-ft) while holding the camshaft.
  19. Install the timing belt: fit the belt onto the pulleys, apply tension with the tensioner, turn the crankshaft 2 revolutions clockwise, and check that the marks line up. If the marks do not line up, reinstall the belt.
  20. Reassemble in reverse order: install the valve cover with a new gasket, the intake and exhaust manifolds with new gaskets, and reconnect all hoses, sensors, and cables.
  21. Fill with fresh coolant. Use the ethylene glycol antifreeze recommended by the manufacturer (50/50 mix with distilled water). System capacity is about 5 L (5.3 qt).
  22. Reconnect the negative battery terminal and start the engine. Warm it up to operating temperature (until the radiator fan switches on) and check for coolant and oil leaks.
  23. After 100-200 km, check the head bolt torque. Modern single-use bolts do NOT require re-tightening after warm-up. Only if older-style reusable bolts were used, re-tighten them to 55-60 N·m (41-44 lb-ft) on a cold engine.

Common mistakes and warnings

  • The aluminum cylinder head is sensitive to overheating. If the engine is run for a long time with a failed head gasket, the head can warp or crack. Always check head flatness before installation. If the warp exceeds 0.05 mm, the head must be resurfaced at a specialized machine shop. Stretch-to-yield head bolts lose strength after use, and reinstalling old bolts can cause uneven clamping and another gasket failure. If you have no experience with timing belts and torque wrenches, we strongly recommend taking the car to a repair shop. Mistakes in tightening order or torque can warp the head, blow the gasket, or damage the engine.
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