2. Pull out the pushers together with their washers and arrange them in order so as not to be confused (see photo).
3. Disconnect the remaining bypass fuel pipes and unscrew the nozzles. Remove special washers.
4. Disconnect the wires from the glow plugs and unscrew them.
5. To turn out nuts and bolts and the removed heads of cylinders inlet and final collectors. Remove the exhaust manifold gaskets.
6. Using a valve cracking tool, press the spring plate of one of the valves so that you can get to the crackers. The valves are deep, so it may be necessary to extend the end of the cracker with a tube that is cut into "window" to get access to crackers. Take out the crackers and remove the cracker. Remove the poppet, large and small valve springs and spring seat, and then pull the valve out of the cylinder head (see pictures). Repeat this procedure for the remaining 7 valves, laying out the valves and related parts in order so as not to be mixed up. If necessary, remove the plug of the valve timing hole.
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Note: on models since 1989 of release (those. around September 1988) valves have one spring instead of the previously used two).
Exhaust valve and valve seat modifications on latest models
Since the end of 1992, all engines have been equipped with the same exhaust valves and their seats as on the XUD9TE engine. In order to accept a thicker exhaust valve head while maintaining the same compression ratio, the exhaust valve seats are recessed 2.5mm instead of the previous 2.0mm.
Cylinder heads with new style exhaust valves and seats can be identified by a 9.0 mm bore in the boss above the glow plug (on older engines, the groove diameter is 7.0 mm).
Marking of final valves of new type see D/fig. 8.7.
8. Clean all parts and inspect them for wear. Prepare new gaskets for the cylinder head, manifolds, valve cover and thermostat housing. Inspect the head for cracks or other damage.
9. Using a ruler and feeler gauges, check the surface of the cylinder head for distortion diagonally and along the edges (see photo and D/fig. 1.10). Do not place a ruler over the swirl chambers as this will cause they may protrude above the surface of the cylinder head. If the deformation exceeds the allowable limits, you can regrind the head (produced by a specialist). The valve seats and swirl chambers must also be reground, and special washers must be installed under the valve springs. A head that cannot be corrected by grinding or a head where the camshaft cannot turn freely must be replaced.
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10. Inspect valve seats and swirl chambers for scorching and cracks (see photo). Both seats and tubes can be replaced, however this work is done by a specialist.
11. Using a dial gauge, check that the amount of protrusion of the swirl chambers does not go beyond the specified limits (see Specifications and photos).
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12. Check each valve for bending, scorching, cracking, and seating in the guide bushing. Excessive valve play in the sleeve can be caused by wear on either the valve itself or the sleeve. To determine this, measure the valve stem with a micrometer or try installing a new valve in the sleeve.
13. The valve guides can be replaced, however this work requires the use of a special press and expander and must be done by a specialist.
14. Small defects on the sealing surface of the valve heads can be removed by lapping. More serious defects require valve resurfacing or replacement. After lapping the valves, use a dial gauge to check that the valve heads are recessed relative to the surface of the cylinder head no more than required by Specifications.
15. New or reground valves and seats should be lapped together as follows (with a good fit of the valves on the seats, you can do without coarse lapping paste).
16. Turn over the cylinder head and support it securely. Apply a little coarse carborundum paste to the sealing "belt" valve head, insert the valve into its guide sleeve and lap it against the seat with a semi-rotary motion. This is usually done using a special valve lapping tool (see photo). Raise the valve from time to time to redistribute the paste.
17. After dull matte stripes appear on the valve seat and head, wipe off the paste and repeat the whole process with fine carborundum paste.
18. After all valves are lapped into their seats, clean off all traces of lapping paste, first with a rag soaked in kerosene, and then with clean, dry rags. If possible, blow out the valves, seats and guide bushings with compressed air.
19. Inspect the valve springs for fatigue wear and, if possible, compare their length with the length of new springs. If the engine is big enough "departed", it is recommended to replace the springs regardless of their condition.
20. Inspect the pushers and their channels for abrasion and other damage.
21. Inspect the camshaft bearings in the cylinder head and covers. Check out the distributor.
22. Inspect the manifold studs and camshaft bearing caps. If necessary, replace them using a special stud puller or 2 nuts screwed onto the exposed part of the stud thread. If you accidentally remove a stud that is in good condition, it must be reinstalled after cleaning its threads and lubricating it with a thread locking compound.
23. Start assembly by lubricating the first valve stem with oil. Lay the cylinder head on its side, insert the valve into the guide sleeve and install the spring seat, then the large and small valve springs (by any party) and spring plate.
24. Compress the springs with a cracker and install crackers. Apply a little grease to the cotters to hold them on the valve stem and carefully release the springs. Remove dryer.
25. Repeat the above procedure for the remaining 7 valves. Reinstall the plug hole for installing the valve timing (if filmed).
26. Install intake and exhaust manifolds with new gaskets and gradually tighten their nuts.
27. Install the glow plugs and tighten them to the desired torque (see chapter 3). Connect wires to spark plugs.
28. Install the injectors together with their washers and tighten them to the desired torque (see chapter 3). Connect fuel bypass pipes.
29. Lubricate the pushers with oil and insert them into the channels along with the shims. Check that all pushrods and washers go to their original positions and that the washers are on the size side down. Record the thicknesses of all shims according to their position for subsequent adjustment of valve clearances.
30. Install the camshaft.
XUD7T/L Engine - Modifications
1. Starting in late 1992, the XUD7T engine found on the 205 and 309 models has been modified to comply with the new European emission control regulations. The modified engine is designated XUD7T/L, where "L" indicates the level of emission control. Models equipped with a modified engine have the following designation on the identification plate:
- 205 1CV2P models
- 309 models without air conditioner 1CV2M
- 309 models with 1CV2N air conditioner
2. Modified engine equipped with injection pump and Lucas injectors. There are 2 colored identification marks on the nozzle holders - one on the side of the holder indicating nozzle calibration, and the second (green ring on the top of the nozzle), indicating that the nozzle provides a level "L" emission control.
Oil seals - all engines that have the letter in the designation "L"
3. All engines with a letter in the designation "L" (including XUD7T/L), have valve stem seals for intake and exhaust valves. These caps must be replaced, regardless of their condition, each time the valves are removed. With the exception of this, the reassembly procedure remained the same as for earlier models.