How To Replace The Head Gasket On A Volvo 850 (page 4)


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Timing Belt Removal




Remove the one bolt (12mm - indicated by the red arrow) and remove the upper timing belt cover. It requires a little manipulation, but it will come off.






Remove the two bolts (10mm - red circles) that hold the bottom timing belt cover on (right behind crank pulley) and remove the cover. This is a snug fit to do with the crankshaft pulley on, but if the upper portion is pulled out first (and you "hold your mouth right") it will come out with patience and just a small amount of manipulation.






Using a 30mm axle nut socket, 1/2" extension(s), and a 1/2" drive breaker bar, rotate the crank in a clockwise direction until the timing marks all line up (depicted in the next few pictures). This is assuming your car was running fine and was in time when you began this job.






Note where the protrusion on the oil pump housing is (yellow arrow). While rotating the crank in a clockwise direction, watch for a very small notch on the crank pulley (red arrow). This notch is between teeth and is so small that you could fill it up with the end of a sewing needle. If you look closely, you can barely see it in this picture (where there is a little bit of the orange seal showing through the depression at the edge of the pulley). You want this lined up precisely with the protrusion on the oil pump housing. In the correct position, you can insert a 3/8" extension (at least 2" long) into the hole that was behind the starter (3 or 4 pictures below) and it will lock the crank from being turned backwards (counter-clockwise).






Once the crank marks are lined up, check to see if the cam marks are lined up. If they are, you are ready for the next step. If not, rotate the crank 1 more revolution and recheck. The cam marks are VERY faint. The red arrows point to the faint scratches on the edges of the cam pulleys, which should line up with the "points" of the notches in the top timing belt cover. These are very, very hard to see. I ended up making me some new marks (with an engraving pen) on the top side of the timing belt cover and on the side of the corresponding tooth on the cam pulleys (one of them in yellow circle). When they are correct and in time, you should have the following patterns of bolt heads on the cam pulleys - on the front pulley (intake) there will be 2 bolts at the top and 1 at the bottom, and at the rear pulley (exhaust) there will be 1 bolt at the top and 2 at the bottom.





If all of the marks match up and you are in time, remove the timing belt tensioner top bolt (12mm - red circle), the bottom bolt (10mm - yellow circle), the white plastic bushing on the top of it, and the top timing belt cover (10mm - blue circle and socket). Take care not to rotate the cams or the crank now that the tension is released from the timing belt, as they are only supposed to rotate together (in time).






The crankshaft must be locked before breaking the crank nut loose (pretty tight). Remember that hole behind the starter? Now is the time to use it. There are tools (that sell for around $500/set) made specifically for doing a head gasket job. I'm going to show you things that work just as well in place of each of those tools, and that won't cost you more than a few dollars! The first is a tool that goes into this hole. In place of this tool, just insert a 3/8" extension (at least 2" long and male end in - red circle). The crank is now locked and will not turn more than a flywheel tooth or so (counter-clockwise) when removing the crank nut. It only locks it from turning counter-clockwise though, so this picture also shows a lock (wedge) I made from a flat piece of steel stock (1/8" x 1.25" x about 2.25") to use when it came time to tighten the crank nut back on. When properly placed, it locked between two flywheel teeth and the bell housing, preventing the crankshaft from rotating clockwise. Use whichever of these you need for the direction in which you need to turn the crank. You can substitute a prybar held in place on the flywheel for either of these, but you run the risk of it slipping off and you have to have a second set of hands. Only use the "wedge" when you need it and have it wedged firmly in place though, as it could fall down into the bell housing (and need retrieving) if you rotated backwards.






Remove the four bolts that mount the harmonic balancer to the crank pulley (10mm - already removed in this picture). Then, using a 30mm axle nut socket (6 point socket with 1/2" drive), 1/2" extensions, and a 1/2" drive breaker bar, break the axle nut loose (center nut - 30mm). The four bolts I had here were so tight that I marred the heads of them, so I replaced them with new ones.






Attach a harmonic balancer puller to the harmonic balancer as shown. My kit did not have the right size bolts in the right length, so I had to go buy a couple. Using this kit, you secure the yoke (the part that looks like a "peace symbol") to the balancer with the two bolts, insert the big bolt into the center of the yoke and tighten it, which pulls the balancer off. It is normal to have to adjust this a time or two during the process (loosen the center bolt, tighten down the two other bolts and start back). The clearance is minimal here, and I barely had room enough.






Once the harmonic balancer is removed, remove the timing belt completely. You should now be able to just wiggle the crank pulley a little as you slide it off. Note the larger-than-the-rest groove on the inner splines and the corresponding portion of the splines on the crankshaft in the other picture. Now that you have it off, you can more plainly see the notch that was earlier used to line up the crank with the protrusion on the oil pump housing (when getting it "in time"). There is also an easy-to-see protrusion on the outer face of the crank pulley that is exactly lined up with the very small notch, but you could not see it earlier with the harmonic balancer on.















The cam pulleys can now be removed. While I have heard of folks using other means to keep the camshafts from spinning while taking off the bolts that secure them, I have found that a sprocket holding tool (that is made for this) works very well. I got mine on eBay years ago and it looks like this one.






Using the sprocket holding tool to hold the cam pulleys still (as shown), break loose the bolts (10mm). Make sure and mark which is the intake (front) and the exhaust (rear). In this picture (at about the 3 o'clock position), you can see a faint "R" (for "rear") that I engraved on my pulley. The bolts and cam pulleys can now be removed.



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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!)