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Autopapyrus · Ford Mondeo 2.5 (2016)
https://autopapyrus.com/guides/ford/mondeo/valve-stem-seal-replacement/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Ford Mondeo 2.5 (2016): Valve Stem Seal Replacement

The 2.5 Duratec engine has a chain-driven timing system, 16 valves and two camshafts. Replace the valve stem seals if you see oil smoke after the car sits or during engine braking and oil consumption is rising, provided the piston rings and valve guides are in good condition. The exact procedure for this model and engine is not documented in public service materials, so what follows is the general principle of doing the job without removing the cylinder head. Check the details on timing locking tools and camshaft removal order against the manufacturer's service manual.

Difficulty: Hard Time: 8-12 hours (without removing the cylinder head) Steps: 14

Parts

6
№PartGenuine part no.
01 Valve stem seal set for 16 valves (intake and exhaust)16 pcs, intake and exhaust seals differ 1206655
1151825
02 Valve cover gasket and seal set 5157382
03 Spark plug tube seals 5157382
04 Gaskets or O-rings for hoses and pipesone for each pipe removed
05 Engine oilif draining the oil is unavoidable
06 Oil filterif draining the oil is unavoidable

Part numbers are from the manufacturer's original catalogue. Check them against your VIN before ordering.

Tools

11
  • socket and wrench set
  • torque wrench
  • lever-type valve spring compressor
  • air compressor or shop air line with a spark plug hole adapter
  • adapter hose
  • special camshaft timing tools and locking tools for this engine
  • magnet
  • pliers or tweezers
  • seal installation tool (drift)
  • clean rags
  • sealant for the valve cover
There's a full repair manual for this car Every system, wiring diagrams and torque specs — not just this job. Haynes and 10 more. See manuals →

Step by step

14 steps
  1. Before you start, make sure the seals are really the cause: smoke after the car sits and when you lift off the throttle, normal compression, and no blue smoke under load. If the oil consumption comes from the piston rings, replacing the seals will not help.
  2. Disconnect the negative battery terminal. Remove the engine cover and the air duct, and if needed the air filter housing with its hoses. Disconnect the ignition coil connectors, remove the coils and unscrew the spark plugs. Blow dirt out of the spark plug wells before you remove the plugs.
  3. Remove the valve cover: disconnect the crankcase ventilation hose and the wiring harnesses, loosen the bolts in a crisscross pattern and lift off the cover. Clean the mating surface without letting any old sealant fall into the oil passages.
  4. Set the No. 1 cylinder piston to TDC on the compression stroke using the timing marks and lock the crankshaft. Lock the camshaft sprockets with the proper locking tools so you do not lose timing. Take photos of the mark positions and the chain.
  5. Remove the timing chain tensioner if it gets in the way of pulling the camshafts, and remove the camshaft sprockets together with the chain. Hang the chain on a piece of wire so it cannot fall into the engine block. Do not turn the crankshaft while the chain is off.
  6. Loosen the camshaft bearing caps evenly and in sequence, starting from the outer ones. Remove the camshafts and the tappets or rocker arms, marking their positions so you can reinstall them in the same places.
  7. Start with the first cylinder: screw the adapter into the spark plug hole and apply 6-8 bar (87-116 psi) of air pressure so the valves do not drop. Install the valve spring compressor, compress the spring, remove the keepers with a magnet, then remove the retainer and the spring.
  8. Remove the old seal with special pliers. Inspect the valve stem and guide: if you find wear or scoring, replacing the seals alone will not be enough. Apply clean engine oil to the stem and the new seal. Slip a protective sleeve over the stem, or wrap it, so the keeper grooves do not cut the new seal.
  9. Press the new seal on with the installation tool by hand, all the way down and without tilting it. Install the spring and retainer, fit the keepers, and tap the end of the valve stem lightly with a hammer so the keepers seat properly.
  10. Repeat for all cylinders. Turn the crankshaft only after the camshafts are installed and the marks are in their correct positions, otherwise the valves can hit the pistons.
  11. Install the camshafts and the tappets or rocker arms in their original positions. Tighten the bearing caps evenly in two or three passes to the manufacturer's specified torque (for M6-M8 bolts of this type the typical range is 10-25 N·m (7-18 lb-ft), but be sure to verify the exact value before tightening).
  12. Install the chain according to the marks, then the tensioner, and check that all marks line up after turning the crankshaft two full turns by hand. Fit a new valve cover gasket and tighten the bolts in a crisscross pattern to the specified torque (usually 8-12 N·m (6-9 lb-ft)).
  13. Install the spark plugs, coils and hoses. Check the oil level and top up if needed. Reconnect the battery, start the engine, listen to the variable valve timing (VVT) actuators working and check that there are no leaks around the valve cover.
  14. After 200-300 km (125-185 miles), check the valve cover for leaks and check the oil level again.

Common mistakes and warnings

  • This job requires exact valve timing: being off by even one chain tooth can cause the valves to hit the pistons and lead to an expensive repair
  • If you have no experience with chain-driven timing systems and no timing locking tools, leave the job to a repair shop
  • When replacing the seals without removing the cylinder head, always supply air to the cylinder and do not let a valve drop into the cylinder