How To Replace The Head Gasket On A Volvo 850 (page 9)


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Timing Belt Replacement




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Install both of the front cam seals (FCP Groton Part #6842272 need 2). Here is one greased for installation, then installed (I did end up pushing it farther inward just a little after this picture was taken). Use the same method you used for installing the oil pump (crank) seal.





Install both of the rear cam seals (FCP Groton Part #9443310 need 2).





Make sure the crank seal (came with oil pump gasket kit) has already been installed, then install the crank pulley. Align the large groove on the inner splines with the corresponding portion of the splines on the crankshaft and press on evenly, wiggling a little if necessary. The timing belt can be threaded around the crank pulley now too.





All timing belt components (except for the tensioner and cam pulleys we are about to do below) should have been replaced by now. If not, replace whatever might be missing now. Remember the back timing belt cover goes on before the water pump or timing belt pulleys. The water pump, oil pump, both timing belt pulleys, and the crank pulley should be installed at this point (refer back to instructions on previous pages if needed). The timing belt should be routed around the crank pulley BEFORE mounting the harmonic balancer back onto the crank pulley as in this picture. You may find directions to the contrary, but I saw no way to get the belt on around an already-installed harmonic balancer without contorting (and thus damaging) the belt. To be honest, I really saw no way to do it even if I was willing to bend the belt a lot.






If you are re-using your timing belt tensioner (FCP Groton Part #9146693), which you can do if it meets criteria, you first have to compress the piston back into the tensioner. Wipe the tensioner down and get it free of any oil first, because one criteria of it still being usable is that it doesn't leak any oil when you compress it. The other criteria is that it maintains resistance, and does not fail to push strongly outward when compressed or when released. To compress it, you can use a bench vise or a big C-clamp (which is what I did). It takes a little coordination, especially if your C-clamp has a slick surface that enables either end to "walk" or move while doing this. But if you get it positioned right (and keep it right) and slowly compress it, taking at least 5 minutes (I took 10) to slowly press the piston back into the tensioner, it works like a charm. I then secured it by inserting a small (2mm) drill bit that I had broken previously anyway.





Reinstall the timing belt tensioner (locked with pin) with 2 bolts (12mm top and 10mm bottom) and torque to 18 ft/lb. Ignore the fact that in this picture I already had the harmonic balancer installed without the timing belt on, as I had to go back and redo it to fit the belt on.






Make sure the camshafts are lined up (since they have been moved and reassembled). Use the grooves on the back end of the camshafts to make sure they are in time at this point, as they have been moved, the cam pulleys have been moved, and the cam pulleys have slots (that allow travel) for them to bolt on with. The grooves should line up exactly with the seam between the top and bottom sections of the head - with the intake groove above the seam and the exhaust groove below the seam - which will make the other end have one bolt hole be on top on the exhaust camshaft and two holes be on top on the intake camshaft. Also, go ahead and install both of the cam pulleys (with the oil seals already in) back onto the camshafts, being sure to leave the bolts (10mm) just loose enough for the cam pulleys to be able to travel in their slotted bolt holes. The top timing belt cover (10mm - that fits over the top of the cam pulleys and has the timing marks on it) can be temporarily put back in place and removed as needed to see alignment with timing marks on the cam pulleys if needed.






Make sure the crank is lined up. It should not have been moved the entire time (if the anchoring techniques shown were used), but check anyway. Note where the protrusion on the oil pump housing is (yellow arrow) and where the very small notch on the crank pulley is (red arrow). Remember to have the "wedge" in the flywheel teeth (and the timing belt threaded around the crank pulley) before you install the harmonic balancer and tighten up the crank nut.





Align the harmonic balancer so that the pilot hole goes over the peg in the crank pulley and push evenly and firmly onto the crankshaft. Don't worry about pushing it all the way on by hand, as the crank nut will force it on when it is tightened on. Make sure the flywheel is locked with the little wedge (or something) so it will not rotate clockwise. Tighten the crank nut (30mm) and torque it to 133 ft/lb. Also install the four bolts (10mm) that mount the harmonic balancer to the crank pulley and torque them to 18 ft/lb.






With everything in time, mesh the teeth of the timing belt (FCP Groton Part #272327) onto the crank pulley teeth, pulling the belt tightly upward and over the idler pulley, then over the front cam pulley, then over the rear cam pulley. This should be kept as tight as possible from the crank, past the idler pulley, and onto the cam pulleys. The cam pulleys may have to rotate a small amount one way or the other for their teeth to mesh exactly with the positioning of the timing belt and this is why the bolts securing them were not tightened down yet. Mine actually ended up being right in the middle of the slotted bolt holes to also line up with my marks on the cam pulleys (not as important as grooves lining up on other end). All the way forward hit on one tooth and all the way backward hit on another. Once I let mine settle right in the middle, everything lined up fine. But the important thing is to have the camshafts lined with their grooves on the other end (which can be fine tuned before putting the timing belt back on), the crank in time and with a tight belt between it and the cam pulleys, then the cam pulleys adjusted to mesh right. Read and prepare for the next step before doing this next part. Now, with everything meshed right and tight from crank to back cam pulley, and the bolts still not tightened all the way, push down HARD and TWICE on the belt where the "1" is (between the cam pulleys), then push inward HARD and TWICE on the belt where the "2" is (between the rear cam pulley and the water pump). Then release the tensioner by rapidly pulling the pin out. Once the tensioner has been released, replace the white plastic bushing on the top of it. The curved "bowl" of it goes around the "knob" on the tensioner pulley.
Here you can see the timing belt tensioner in place with the belt ready to be tensioned. I have needle-nosed pliers in place to quickly pull it out and have made sure that there is enough travel room to do so. Also notice how the timing belt has a slack appearance in this picture. Then notice in the next picture, where the tensioner pin has been pulled and tension applied, how the timing belt has a tightened appearance.





Using the sprocket holding tool to hold the cam pulleys still (as shown), tighten the bolts (10mm) securing the cam pulleys to the camshafts and torque them to 15 ft/lb. Replace the top timing belt cover (10mm) that fits over the top of the cam pulleys and has the timing marks on it.






Remove the locking mechanisms that were used to keep the crank from rotating. Using a 30mm axle nut socket, 1/2" extension(s), and a 1/2" drive breaker bar, rotate the crank in a clockwise direction two full revolutions and make sure the timing marks all line up (with where they were when you started). If they do, you are in time (if you want to repeat this to make sure, it's ok, I do it myself). If they don't, you are not in time. Don't rotate the crank anymore if you are out of time, as you can cause valve damage (interference engine).






Replace the bottom timing belt cover behind the crank and secure it with the two bolts (10mm - red circles) that hold it on. This is tight to do with the harmonic balancer on, but if the bottom portion is fed into where it goes first, the upper portion will fit with patience and just a small amount of manipulation.






Replace the upper timing belt cover (12mm - indicated by the red arrow). Make sure both "ears" at the bottom part of this cover go into their corresponding slots on the back timing belt cover.



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(This tutorial is written, sponsored, and hosted by TracysTrueSoaps. I make quality, pure, gentle soaps that are also great at removing grime after working on a vehicle. Please support my site by checking out my soaps. People of all ages LOVE 'em [especially ladies] and they make great gifts for almost any occasion. Thanks so much!)