Timing Belt Replacement – Mitsubishi 3.0 V6
NOTE: Before contemplating doing this job yourself please read our post regarding Crankshaft Pulley Issues and our post on the Crankshaft Locking Tool. The majority of the problems seem to be related to late 90′s models, however it is better to be sure than sorry. I have seen many crankshafts ruined in these engines because the harmonic balancer bolt was not tightened correctly and worked it’s way loose and ruined the snout of the crankshaft.
Also, for the engines fitted with a distributor there is a specific re-fitting procedure that you need to follow if you decide to remove the distributor. This info can be found at the Mitsubishi 3.0 V6 Distributor Timing page.
Ok, on with the article!
Today we are going to have a look at what is involved in replacing the timing belt on a Mitsubishi Pajero 3.0 V6. The following information is also applicable to the Magna/Verada variants, however the position of the engine mounts makes them a bit more difficult. The job itself is not difficult, however before attempting it make sure that you are comfortable with all the outlined steps and have the needed tools or access to them. If you are not completely confident that you can handle such a job please leave it to a qualified mechanic, as any mix-ups have the potential to cause expensive engine damage. Have I put you off yet? I hope not but please read and understand ALL of the steps outlined here before contemplating doing this repair! Print it out and have it close by if need be.
It is my opinion that anytime a timing belt is replaced that runs the waterpump (as in this case) that the waterpump be replaced as well. 9 times out of 10 disturbing the waterpump when changing the belt will result in it leaking and your back to square one again. Same goes for the timing belt tensioner, pulleys and oil seals. 100,000km of use takes its toll on anything and while it is apart it would be crazy not to replace these.
If it does fail down the track a bit you will have to do the job again – arrgg! Parts suppliers will sell you a kit which has the timing belt, tensioner and crank and camshaft seals nescesary to do the job right the first time.
- Timing Belt Kit
- Waterpump with two gaskets. One for the pump itself and one for the backing plate behind the pump and o ring for metal pipe (should all be included in the kit)
- Replacement coolant if necessary
- Socket set ranging from 10mm to 22mm
- Ring/Open end spanners from 10mm to 17mm
- Set of screwdrivers
- Container for catching the coolant. Great time to replace it if it hasn’t been changed for a while
- Impact Gun or 1/2 inch drive breaker bar for loosening harmonic balancer bolt
- Impact Gun or Torque Wrench for re-tightening balancer bolt and camshaft bolts
- Small bottle of Loctite thread lock
- Wire brush or wheel
- Razor blades and emery paper or air sander
- Gasket Sealant (not silicone, non-hardening compound is best for this job)
- Anti-sieze compound (optional)
- Cleaning solution and brush for cleaning behind the timing covers
- Rags for clean-up
- Plenty of time and no interuptions!
Lets get started! This whole job can be done with the radiator in place, however it does make the job easier and is not difficult to remove so I recommend removing it first. Plus it gives you a chance to inspect it for any potential problems. I also recommend putting bolts and nuts with their respective part as you pull it down, saves a lot of hassle when putting it all back together.
- O.K. the first thing is to drain the coolant from the radiator. In their infinite wisdom Mitsubishi put a drain cock in the bottom left side of the radiator. You would be surprised how many manufacturers don’t do this! Even if you are not going to use the coolant again, use the container to catch it and dispose of it properly.
- Now we can remove both the bottom and top radiator hoses at the engine end. The hose to the overflow bottle, coming from the radiator neck can be removed as well.
- There are two ways you can do the next step, you can either remove the four 10mm bolts holding the fan and pulley on and remove the fan first or remove the clipped-in bottom section of the fan cowling attached to the radiator which gives enough clearance to remove the radiator with the fan still attached. Both methods work ok so do what you think is easier.
- Next step is to remove the bolts and nuts holding the radiator in. There is two 12mm bolts on the left side and two 12mm nuts on welded in studs on the right side. Support the radiator when un-doing the last two and lift the radiator out once all bolts and nuts are removed. Be careful as radiators are not the lightest things!
- The next job is to remove the A/C and power steering belts. The A/C belt is a piece of cake, just loosen the 17mm nut on the tensioner a couple of turns and then wind the 13mm headed bolt down until the belt is loose enough to remove. The power steering is a little different. There are two holes in the pulley and these have to rotated into a position where you can get a 14mm socket onto the two bolts holding it in place. The botton one just needs to be lossened a little and back the top one off a couple of turns enabling the pump to be pushed toward the engine, loosening the belt as it moves in. A large flat blade screwdriver is handy for levering the pump back into position when re-assembling.
- If you have left the engine fan in place you will now need to undo the four 10mm bolts holding it on. Once this is done remove the fan, pulley and belt.
- Now you will be left with a bracket with the main belt tensioner pulley and idler pulley on it. This has to be removed the gain access to the timing belt covers. A combination of 12 and 14mm bolts are used.
- The next part is probably the most difficult (well it is for me with 6 fractured vertebrae in my back!). The A/C compressor needs to be undone from it’s mounting bracket. 4 bolts, usually 17mm but sometimes they can be odd sizes need to be removed and the compressor pulled back as far as it will go without damaging the hoses. Once the compressor is removed there is two 13mm bolts at the front and two 17mm bolts at the side of the bracket to be removed. The rearward bolt has the engine earth attached to it and this must go back on when re-assembling.
- Next step is to remove the two top timing belt covers. Little half moon looking things secured by two 10mm bolts.
- The next step is to loosen the harmonic balancer bolt, but not remove it completely so we can set the valve timing first. If you have access to a air compressor and impact gun then great, but if you don’t, I have a way of un-doing it although it is definately not a ‘text book’ approach and I don’t recommend this way at all but it does work. Take your 22mm 1/2inch drive socket and breaker bar (or long ratchet without the ratcheting mechanism, ask your parts supplier if you are not sure what it is), attach the socket and sit it on the balancer bolt and rotate the engine until the breaker bar contacts the chassis rail on the passengers side of the car. Make sure everyone is a safe distance away, go to the drivers side and make sure the vehicle is in nuetral or park for autos and turn the ignition key for a few seconds. The cranshaft will turn and the socket and breaker bar will hit on the chassis rail and loosen the bolt. You may need to do it a few times before it comes loose. As I said I don’t recommend this approach and I will strongly deny ever writting this paragraph if I have to!
- Once the harmonic balancer bolt is loose we can go about setting the valve timing. What we need is the timing mark on the balancer to line up with the TDC (top dead centre) mark on the timing belt cover and the indentations on the camshaft pulleys to line up with their respective marks that are just behind them on the cylinder heads. If you find that the balancer mark lines up but you don’t see any marks on the camshaft pulleys then you need to rotate the crankshaft another 360 degrees and all should be good.
- Once the timing marks are sorted we can remove the balancer bolt and balancer itself. To do this you may need to gently pry the balancer from two sides using a ‘rocking’ motion. Small movements each side in succession. Generally speaking they come off easily.
- Now we can remove the bottom section of the timing belt cover. If you intend to replace the camshaft seals (recommended) now is the time to loosen the 17mm bolts securing the pulleys. If you have an impact gun use that, if not a sharp hit with the palm of your hand on the ratchet should do the trick. Make sure to re-align the timing marks if the engine rotates at all when doing this.
- At this stage I always remove one battery terminal so when the timing belt is off the engine cannot be accidently turned over with the starter. Turn your back for five minutes and you never know what can happen!
- Once you are satisfied the timing marks are lined up and the battery is disconnected it is time to loosen the 12mm bolt in the centre of the tensioner. One turn is all that is required. Now you can either push the tensioner back yourself or gently lever it back with a suitable screwdriver ( being careful what you are levering against ) and re-tighten the 12mm bolt to hold the tensioner back.
- Remove the timing belt. Ya! Not too hard eh.
- To replace the camshaft seals, remove the camshaft pulleys, noting which side goes where and gently prize the old seals out taking note of how far in they are and being careful not to mark the surface of the camshaft where the seal runs. Fit the new seals using a socket that is the same diameter as the outside diameter of the new seal. It is a good idea to run a film of oil around the inside surface of the seal before fitting so it doesn’t run dry on start-up.
- Refit the camshaft pulleys using Loctite thread lock on the threads of the bolts. If you don’t have a impact gun, do the bolts up hand tight and then get a big piece of paper and write on it “tighten cam bolts” and stick it under one windscreen wiper. We have to wait until we fit the timing belt to tighten them up without a impact gun and you do not want to forget to do this believe me!
- If you do have a impact gun to do the camshaft pulley bolts up get someone to hold the pulley from turning while tightening the bolt as valve damage can occur if the camshaft turns too far.
- The crankshaft seal is a bit easier to do. First remove the metal disc that is in front of the gear and using a puller if you have it remove the crankshaft gear. If you don’t have a puller two flat blade screwdrivers can be used on either side of the gear however you have to be very careful as the housing behing is alloy and very easily damaged and the ‘lip’ on the back of the crankshaft gear is very easily broken off. Extreme care to be exercised here. Once you have the gear off it is a matter of carefully prizing out the old seal and fitting the new one as stated above for the camshaft seals. Refit the crankshaft gear making sure it is all the way back.
- Replacing the waterpump at this stage is very easy and highly recommended. From memory there is five 12mm bolts on the pump itself and two 12mm bolts on a bracket on the top of the pump that bolts to the cylinder head. The spring and timing belt tensioner will have to be removed also. Once these are removed a gentle pull on it should be all that is needed to remove it.
- The waterpump then needs to be seperated from the backing plate. This is done by removing all the 10mm bolts in the pump and a phillips head screw that comes in from the back of the pump. Once this is done it is time to remove all the old gasket from the backing plate and engine block.
- There is also a metal pipe which runs into the back of the waterpump backing plate that has an ‘o’ ring seal. That seal needs to be replaced and should be included in the waterpump kit. If not take the time to track a new one down because it is sure to leak if not replaced.
- It is essential that all gasket surfaces be as clean as possible. I use a single sided razor blade and some fine grit emery paper if I can’t use my air sander. You do not want to be doing this job twice so make sure everything is as clean as possible. The bolts that secure the waterpump to the block and backing plate will more than likely have corrosion on them so take the time to clean them up with a wire brush or wheel and a smear of anti-sieze compound on them will make life easier if they have to come out again at any stage. Any oil or contaminates should be cleaned from the block and timing belt covers as well.
Re-assembly is the reverse of what I’ve written with the following notes;
- Do not over-tighten bolts. Because we are mainly dealing with 10 and 12mm bolts they don’t have to be tightened with all the strength you’ve got!
- If you don’t have access to a impact gun the camshaft bolts need to be tightened to a torque of 60Nm or 45ft/lb. This can be done after the new belt is fitted and once both are tight you can throw away your paper reminder on the windscreen!
- The harmonic balancer must be tightened to a torque of 177-186Nm. You will need to remove the starter motor and lock the flywheel from turning with a large screwdriver or such to tighten this bolt. Please read the “Pajero Crankshaft Pulley Issues” post for more information on tightening the pulley bolt. The metal ‘disc’ must be installed between the crankshaft gear and the harmonic balancer as it stops the belt from running off the pulleys. If you are not sure which way it came off look for the crankshaft gear marks.
- I suggest using Loctite on both the camshaft pulley and harmonic balancer bolts.
- Once you have the new belt in place let the spring on the tensioner take up the slack and tighten the 12mm bolt. Then temporarily fit the balancer bolt and rotate the crankshaft 360 degrees. Re-check timing marks and if you find that it is out at all release the tensioner once again and line it all up. Sometimes it still takes me a couple of goes and I’ve been doing it for ten years!
- Use gasket sealant on all gaskets. Even though they are new, better to do the job once and once only.
- Be patient and work carefully and all should be good! Best of luck!