How to Replace the Timing Chains on a Hyundai Accent or Verna CRDi Diesel Engine
This replacement procedure applies to Hyundai CRDi Diesel Euro IV engines - the U-1.5 and U-1.6 engines. This type of of engine can be found in Hyundai Accent CRDi Diesel sold in the Philippines, or Verna in some other countries.
Procedure of Replacing the Timing Chains
1) Drain the engine oil.
2) Remove the oil pan (FIG 1). The oil pan has to be removed for the following reasons:
- 2.1) The timing chain cover cannot be removed without removing the oil pan first. This is because of the two dowel pins in each side of the timing chain cover that mesh with the oil pan. See FIG 1-B.
- 2.2) With the oil pan removed, it would be easier to untighten and tighten the bolt of the crankshaft pulley, as it would be easy to block the crankshaft.
Note: In removing the oil pan, the two bolts at the bottom of the aircon compressor have to be removed. These bolts are screwed into the oil pan.
3) Support the engine block as shown in FIG 1-A. This is necessary as the engine support, which is attached to the timing chain cover, will have to be removed.
4) Remove or lift the valve cover to disengage the two dowel pins in each of its sides which mesh with the timing chain cover (FIG 1-B). Follow the following procedure in removing the valve cover:
- 4.1) Dismantle the fuel tubings. (FIG 1)
- 4.2) Disconnect the fuel hose. (FIG 1)
- 4.3) Remove the fuel injector clips, and then pull out the injectors. An injector puller may be needed in pulling out the injectors.
- 4.4) Remove the bolts that hold the valve cover In place.
- 4.5) Remove the valve cover slowly so as not to damage the valve cover gasket.
Note: If the fuel injectors are stuck, making it difficult to remove the valve cover completely, lifting the valve cover just enough to clear the two dowel pins that mesh with the timing chain cover would be enough. However, this will make the replacement of the cam chain a bit harder.
5) Remove the engine support. Be sure that the engine is properly supported as in Step 3 above.
6) Remove the belt. This is done by untightening the belt tensioner (FIG 1).
7) Completely remove the belt tensioner.
8) Remove the crankshaft pulley. In unscrewing the bolt that holds the pulley in place, it may be necessary to block the crankshaft to prevent it from rotating. This should be easy as the oil pan should have been removed by now.
9) Unscrew all the bolts that hold the timing chain cover in place, and then remove the cover slowly. The timing chain assembly should now look somewhat similar to the one shown in FIG 2.
10) Loosen the bolts that hold the cam sprockets and the fuel pump sprocket. The reason these bolts have to be loosened at this time is because it would be difficult to loosen them when the chains are already removed. So loosen the bolts just enough so that they can be unscrewed later even when the chains are already removed.
11) Rotate the crank shaft until the timing marks will be as shown in FIG 2. If you opt not to remove the valve cover, be sure to mark now the bottom-most portion (opposite the cam timing marks) of the cam sprockets. This will aid you in the installation of the new chain since you will be able to position the sprockets properly even if the timing marks are covered by the valve cover.
WARNING! Do not change the position of the crank shaft and the cam shafts once the timing marks are set as shown in FIG 2. Doing so can cause serious damage to the valves.
NOTE: Items 12 and 13 must be done to determine the extent of the chain wear, and to see if the tensioners are defective or not.
12) Rock the cam chain tension guide, see FIG 2. If it is loose and the tensioner piston has not extended fully, the tensioner is defective and must be replaced. If the tension guide is loose and the tensioner piston has fully extended, the chain is worn out. In either case, the chain must be replaced.
13) Do the same procedure as in Item 10 above on the crank chain tension guide, see Fig. 2.
14) Remove the tensioners and the slack guides for the cam chain and the crank chain. If worn out, replace. See FIG 2-A.
15) Now remove the tension guides for the cam chain and crank chain. If worn out, replace.
16) Remove the cam sprockets, then remove the cam chain.
17) Remove the fuel pump sprocket, then remove the crank chain. You might need a gear puller in this case.
18) Examine the sprocket gears. Replace the gears if the teeth are worn out.
Installation of Crank Chain
19) Install the new crank chain by doing the following procedure:
- 19.1) Fit the new crank chain onto the crank sprocket, making sure that the timing mark of the chain aligns with that of the crank sprocket. See FIG 2.
- 19.2) Fit the fuel pump sprocket into the crank chain. Make sure that the timing marks are aligned. See FIG 2.
- 19.3. Insert the fuel pump sprocket onto the fuel pump shaft, then install the sprocket bolt, but do not tighten it yet. Tightening the bolt now might alter the position of the crank shaft.
Installation of Cam Chain
20) Fit the cam chain onto the fuel pump sprocket, making sure that the timing mark of the chain aligns with that of the sprocket.
21) Fit the cam sprockets into the chain, making sure that the timing marks align.
22) Fit the cams onto the cam shafts.
23) Install the cam bolts, but do not tighten them yet.
Installation of the Slack Guides and Tension Guides
24) Install the tension guide for the crank chain first.
25) Install the slack guide for the crank chain.
26) Install the tension guide and slack guide for the cam chain.
Installation of the Tensioners
27) Prepare the tensioners by doing the following procedure:
- 27.1) Pull out the tensioner piston from the tensioner cylinder (FIG 3 and FIG 4).
- 27.2) Reset or retract the plunger by pushing the ball valve with a pin made of hard plastic (using a steel pin may damage the valve), while pushing the plunger inward. This releases the oil inside the piston. By now the plunger must be retractable (FIG 4).
- 27.3) Insert the piston back into the tensioner cylinder.
- 27.4) Retract the plunger and keep it in this position by inserting a steel pin into the cylinder slot. See FIG 3.
- 27.5) Do the same procedure on the other tensioner.
28) Install the tensioners, then pull out the steel pins to release the plungers.
29) Rotate the crank shaft clockwise for one complete revolution.
WARNING! Never ever rotate the crankshaft counterclockwise as this may cause the chains to jump a tooth, thus misaligning the timing marks. Do not force if the crank shaft appears to be stuck or blocked.
WARNING! If in the process of turning the crank shaft there appears to be a blockage, do not force it. The timing mark alignment may be wrong and this could be the piston hitting the valves.
30) Review the alignment of the timing marks. If Ok, tighten the bolts for the cam sprockets and the fuel pump sprocket. If not, make the necessary correction.
WARNING! Be very sure that the timing marks are properly aligned. Misaligned timing marks can cause noisy and inefficient operation of the engine, and could even cause serious damage to the engine.
31) Install the timing chain cover (use gasket maker or sealant).
32) Install the oil pan.
33) Install the aircon compressor bolts.
34) Install the crank shaft pulley.
35) Install the belt tensioner and lock it in a retracted position.
36) Install the belt.
37) Release the belt rensioner, then tighten.
38) Install the valve cover (use gasket maker or sealant).
39) If the fuel injectors were removed, install them now.
40) Install the fuel injector clips.
41) Install the fuel hose.
42) Install the fuel tubings.
43) Put oil into the engine. Do not everfill.
WARNING! Be sure to check engine oil level before starting the engine.
44) Start the engine. The engine may not run smoothly at first as air in the fuel lines is still being purged. This should run smoothly in a little while once the self-purging is complete. In some cases manual purging may be necessary.
45) Listen to the engine sound. Stop the engine once an unusual noise is heard. Find out the cause and check.
46) Look for oil leaks. Stop the engine if leak is noticed and check.
47) Restart the engine. If everything is ok, the job is done.
Tip: It may be important to record the date on which the chains are replaced. This will aid us in determining the life span of the chains. Frequent chain replacement could mean any of the following:
- a) Inferior quality of the replacement chains (which is very unlikely)
- b) There must be a problem elsewhere, probably in the lubrication system (which is very likely).
Replacing the timing chains of Hyundai Accent CRDi engine is not really difficult. It requires a lot of work though, but if you follow the instructions above very closely and be aware of the warnings indicated therein you will never go wrong.
The above procedure may also be applicable to other engines utilizing the same technology as that of Hyundai Accent CRDi engine.
"It may not be necessary nor practical to do things ourselves, but it's always nice to know how things are done the right way."
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.