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Autopapyrus · DAF XF 106 MX-13 (2018)
https://autopapyrus.com/guides/daf/xf/air-compressor-repair/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

DAF XF 106 MX-13 (2018): Air Compressor Repair

On the MX-13, the compressor is driven by the engine gears, lubricated from the engine oil gallery and cooled by coolant from the cooling system. Typical problems include slow pressure build-up, oil in the air system, knocking, and leaks at the head and flange. The exact procedure and torque values for this engine are not fully documented in open sources. Below are the general sequence and approximate ranges, so tighten all fasteners to DAF specifications.

Difficulty: Hard Time: 4-8 hours (replacing the complete compressor or repairing it with disassembly) Steps: 15

Parts

5
№Part
01 Complete air compressor for MX-13 Euro 6if wear is severe
02 Compressor repair kit (piston rings, gaskets, valve plate, seals)
03 Compressor flange gasket or O-ring
04 Air dryer with cartridgereplace at the same time if there is oil in the system
05 DAF coolant (antifreeze)never mix different types

Tools

8
  • Socket and wrench set (including Torx and E-Torx)
  • torque wrench
  • hose removal tool
  • containers for coolant and oil
  • axle stands
  • air-pressure release valve
  • multimeter
  • 0-12 bar pressure gauge

Step by step

15 steps
  1. First, confirm that the compressor is actually the faulty component. Warm up the engine and time the pressure build-up from 8 to 12 bar at about 1200-1500 rpm. For a healthy compressor with the tanks fully drained, this takes roughly 2-4 minutes. If pressure rises slowly, check the line between the compressor and the air dryer for kinks and leaks.
  2. Check the air system for oil. Drain the condensate from the air tanks and open the supply line from the compressor. A light film of oil is acceptable, but heavy oil in the tanks points to worn compressor rings and pistons. Check the air dryer at the same time: a saturated oil cartridge that is no longer regenerating can cause the same symptoms.
  3. Rule out external causes. Check the pressure governor or air dryer valve, the check valve at the air tank inlet, and the air supply line to the turbocharger and the intake tract, because oil can enter the system from there as well. Check the engine oil level and condition, and the crankcase breather.
  4. Preparation. Park the truck on level ground, apply the parking brake, and chock the wheels. Disconnect the battery ground. Release all pressure from the air system completely through the release valve or by draining the air tanks.
  5. Drain the coolant to the required level. Wait for the engine to cool down. Open the expansion tank cap only on a cold engine, at least 30-40 minutes after shutdown.
  6. Remove the protective covers and any air lines that block access. Mark or photograph the positions of the air supply hoses, the coolant supply and return hoses, and the oil line (if it is external). Disconnect them and plug the openings so that dirt cannot get into the system.
  7. Remove the compressor flange fasteners and take off the unit. The compressor sits on the engine drive gear, so do not drop it onto the gear or damage the seal when removing it. Mark the position of the drive gear if the design requires the timing marks to line up.
  8. Inspect the mounting surface and the drive gear. Worn gear teeth, play in the drive, or an oil leak at the flange mean the drive needs repair, not just a new compressor.
  9. Decide on the scope of work. If the piston assembly or valves are worn, or the cylinder is scored, it is more reliable to install a complete compressor. A repair kit is suitable if the housing and cylinder are intact. Disassemble the compressor on a bench, measure the cylinder and piston, clean all passages, and replace the rings, valve plate and gaskets.
  10. Before installation, flush the oil and coolant lines and blow out the air passages. Replace the air dryer, or at least its cartridge, if oil was found in the air system. Flush or replace any contaminated lines and valves.
  11. Install the compressor with a new O-ring or gasket. Tighten the fasteners in a crisscross pattern in two or three passes. As a rough guide, for flange bolts of this kind, M10 is about 40-60 N·m (30-44 lb-ft) and M8 is about 20-30 N·m (15-22 lb-ft), but take the exact values from the DAF specifications for your engine.
  12. Reconnect all hoses and lines according to the marks you made. Tighten the clamps on the coolant hoses moderately so you do not damage the hoses.
  13. Fill with coolant of the correct specification and bleed the cooling system: warm up the engine with the expansion tank cap off, wait for the thermostat to open, and top up the level to normal.
  14. Start the engine and let it idle. Check for oil and coolant leaks at the flange and hoses. Check that pressure builds up to 12 bar, that the governor and air dryer operate correctly, and check for leaks by watching the pressure drop with the engine off (the allowable drop is given in the specifications, usually no more than 0.2-0.5 bar over a few minutes).
  15. Check the brakes at low speed in a safe area, then take a test drive. After 50-100 km, check the coolant level again and look for leaks, topping up if needed.

Common mistakes and warnings

  • The brake air system is a safety system
  • Before starting work, release all pressure completely, and do not disassemble the compressor or lines while they are under pressure
  • If you have no experience with truck air systems, have the repair done at a repair shop
  • Oil in the air system after a compressor failure damages the valves, the brake chamber diaphragms and the air dryer, so after fixing the cause, check and flush all circuits, or the problem will come back