How To Replace The Head Gasket On A Volvo 850 (page 7)


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Component Cleaning and Miscellaneous Work Before Reassembly




I cleaned the upper head using degreaser, gasket remover, and sharp pieces of plastic that I cut from old credit cards. You want to pay close attention that the oil holes for the journals (like the one the red arrow is pointing to) are cleaned out and do not get anything introduced into them (like fragments of the dried sealer you will be removing). Make sure all of the little channels are cleaned out ... everything. Do not do anything to scratch the surface of the head either.






I removed the next few components and left them off until I had cleaned the engine block well.







DISASSEMBLY - Remove the PCV oil trap hoses from the locations circled in red (top one pulls off and bottom one is secured with a clamp with two T25 screws). The two hoses that lead from the top of the oil trap have already been disconnected previously. Remove the 10mm bolts that hold the oil trap onto the block (yellow circles). Remove the oil trap and clean it out thoroughly with degreaser and hot water. I cleaned mine several times over a period of a few days. I felt ok re-using mine since it looked to be in good shape - all the plastic was ok, hoses were supple, and nothing was cracked or broken.

REASSEMBLY - Replace the PCV components and torque the bolts to 14 ft/lb.





DISASSEMBLY - If you want to remove them for a thorough cleaning, label where they go and remove the knock sensors (larger red circles - 13mm). Label where they go and remove the grounds (smaller red circles - 12mm).
REASSEMBLY - Replace the knock sensors and grounds and torque to 15 ft/lb.






DISASSEMBLY - If you want to remove it for a thorough cleaning, remove the crank position sensor (or RPM sensor). This is right next to the lower radiator hose and disconnects with one bolt (10mm).
REASSEMBLY - Replace the crank position sensor and torque to *12 ft/lb.






DISASSEMBLY - Remove the bottom radiator hose from the engine and the radiator. NOTE - Where the two ends of my homemade heater core bypass (white/clear braided hose) connect, you will have your regular heater hoses (black and can be seen in a few pics of that area).

REASSEMBLY - Replace the bottom radiator hose (FCP Groton Part #6842428) at the engine and the radiator.





DISASSEMBLY - Remove the timing belt idler pulley (12mm).
REASSEMBLY - Replace the timing belt idler pulley (FCP Groton Part #9146376) and torque to 18 ft/lb.






DISASSEMBLY - Remove the timing belt tensioner pulley (T45). This is a very restricted space. My low profile rachet and T45 bit would BARELY fit in there. I found it helpful when removing this to have penetrant sprayed onto the bolt, the T45 and rachet wedged in, and with a prybar forcing them into the fastener tightly. To fit the T45 and rachet in there, I actually had to start the T45 into the head of the bolt while it was still at an angle, wedge it in, break the bolt loose, remove the T45 and rachet, and then remove the bolt with just the T45 and my fingers. (Your timing belt tensioner should already have been removed by this point, but this picture shows mine installed, sorry).
REASSEMBLY - Replace the timing belt tensioner pulley (FCP Groton Part #9135036) and torque to 22 ft/lb (I guessed at this as my torque wrench would not fit in there).






DISASSEMBLY - Remove the 7 water pump bolts (red circles, red dots for hidden ones, yellow dots where dowels fit into holes on water pump) and remove the water pump. After the water pump has been removed, you can remove the bolt (12mm - blue circle) securing the back timing belt cover and remove the cover for cleaning. It will only come out once the water pump and both belt pulleys are off.
REASSEMBLY - Replace the back timing belt cover (before installing the new water pump). After cleaning all the remnants of old gasket off and cleaning the mating surfaces well, apply the new gasket (emphasis on applying RTV or something like this Copper Spray on each side of the gasket), install the water pump (FCP Groton Part #272476 includes gasket and new bolts), and torque to 15 ft/lb.






DISASSEMBLY - Remove the 4 oil pump bolts (T30). Using a screwdriver or small prybar, carefully pry behind both parting lugs (top and bottom red circles) and behind the area where the small, bottom timing belt cover was bolted on (larger red oval). Try to pry evenly around the oil pump housing to remove it without binding it.
REASSEMBLY - After disassembling, inspecting, lubricating, and reassembling the oil pump (steps below), clean all the remnants of old gasket off the mating surfaces well, apply the new gasket and replace the oil pump on the crankshaft. Start the 4 oil pump bolts and use them as guides (don't try to force the oil pump in using the bolts). The crank nut should do the pressing (using makeshift washers). I used pieces of plywood that I cut into wooden washers so they would fit around the crankshaft and press against the oil pump housing. I would tighten the crank nut on against the wooden washers until it reached the end of the threads, then back it off and put another wooden washer on and start over. Once the oil pump is pressed all the way in, torque the 4 bolts to 88 in/lb. Install a new oil seal on the crankshaft and press it into the oil pump housing as far as it will go.
Here I am removing the oil seal from the oil pump. Since the oil pump mounts on the crank, this seal serves as both the oil pump seal and the crank seal. To show the metal band inside, I pulled some of the sealing material off of the seal in the area where I am prying. Used cautiously to avoid scoring the metal walls of the housing, a small screwdriver with a little electrical tape on the end can easily remove an oil seal like this, especially when there is no shaft in the way. Once under this lip, some upward pressure is all that is needed to pop this seal out. The next picture is of the oil pump once it has been disassembled into two halves. I cleaned mine good, inside and out, and inspected the internal components for signs of excessive wear or scoring (especially the crescent portion between the inner and outer gears). To separate the halves of the oil pump, remove the two bolts (4mm Allen). Use caution as there is a spring that will push the halves violently apart if it is not held together during removal. After cleaning and inspecting the inner parts of the oil pump, lubricate the gears by packing some moly grease in there, compress the spring while holding the halves together, and reassemble it.
Here the new oil pump O-ring (black and surrounding the oil pump) has been installed on the oil pump body with a little moly grease applied. The next picture is of the installed oil pump with a new oil pump (or crank) seal that is orange. It is best to install it after installing the oil pump back on the crankshaft. The first one I installed was installed on the oil pump, then the oil pump installed onto the crankshaft. But as I pressed the oil pump onto the crankshaft, the friction on the crankshaft turned the sleeve of the oil seal outward and displaced the spring around the inner lip of the seal (this can be seen in the picture above where the red circles outline the oil pump removal lugs). That would not have functioned properly at all, so I removed it and installed a new one (I had luckily and accidentally ordered an extra one because I thought they would be two different seals). When I install an oil seal - I liberally coat it with moly grease on every edge but the flat outer face (that will be the only thing showing once it is installed). Then I center it where it is to be installed (over whatever shaft it goes around) and slide it gently into place before pressing it in. Some people use a large socket, an oil seal "installer," or even the old seal turned around backwards to install an oil seal. I have always installed oil seals by just distributing my fingers evenly all around and pushing evenly all around until it was seated, making sure not to push more on one area than another so that it didn't get unevenly wedged in. A nice coat of grease is key to installing an oil seal, and you can easily wipe away any extra or residual grease left behind once the seal is installed. (FCP Groton Part #271439 is the oil pump gasket kit that includes the gasket below, the large O-ring, and the oil pump seal from the pictures above, colors may vary).






Cleaning the block - Plug or tape the hole the crank position sensor was in and the flywheel access where the starter came off with something to keep trash and rinse water out while you are cleaning the engine (but something you can get to come back out/off and that won't drop inside and get lost). Also try not to spray water directly into these openings as you clean the engine. I cleaned my engine very aggressively. I had buildup in the whole PCV system and just wanted everything thoroughly clean when I was through. I took some degreaser (Purple Power) and sprayed it full strength onto the whole engine on all sides and all over the top - even the pistons, cylinders, and oil channel areas (red circles). In this picture there are blue paper (shop) towel pieces in all the head bolt holes. The channel that surrounds all five cylinders is where coolant flows through. I brushed everything I could reach on all sides and the top of the block with an old toothbrush, then rinsed everything well with hot water. After getting the pistons clean with degreaser and an old toothbrush, I rinsed them thoroughly (I actually had each cylinder full of hot water for a minute during this cleaning), suctioned out the water, wiped them completely dry, then coated them with penetrating spray to prevent corrosion (the cylinder inserts are not aluminum, but steel) and lubricate the rings underneath where the penetrant may have seeped (I left a little penetrant on each piston head for a few minutes to allow some to seep in there before wiping the excess off). The coolant channels were naturally too tight to scrub (and didn't need scrubbing) and were just rinsed clean of degreaser with hot water (all ports and openings were open anyway). I used plastic wedges cut from old credit cards to scrape any old gasket material I felt on the block surface, and actually used a little bit of gasket remover wiped specifically where I needed it with a blue paper (shop) towel to dissolve some of it (that gasket remover spray BURNS if you get it on your skin). The water pump area also had a lot of old, hardened gasket on it, so I used the gasket remover and plastic scraper to get all of it clean too. After scraping out all the gunk I could, I also sprayed a lot of degreaser into the PCV ports that the oil trap connected to and rinsed them well with hot water (leads to the oil pan). After everything was cleaned and rinsed well, I opened the oil pan plug and drained all of the degreaser rinse water out, leaving the plug out and letting it all drain / dry as much as it would while I found something else to do. When I came back, I replaced the oil pan plug and (using a long transmission fluid funnel) poured a gallon of diesel fuel into the pan through the six oil channels (red circles) and the PCV ports. I did this to rinse, soak, clean, and lubricate. I left this diesel fuel in for a few days until I was completely through with this repair, with no adverse effect. It did seem to break loose a lot of stuff in the engine, as I had little greasy spots in the first 3 oil changes (which were at very low intervals for this very reason) before starting it on synthetic oil (since there were only about 111,000 miles on it with every oil seal on the engine new but the rear main).





One very important aspect of cleaning the block in preparation for installing the new head gasket is to clean out the head bolt holes completely. I don't have an air compressor at present, so I suctioned the water and degreaser residue out of the head bolt holes, then ran blue paper (shop) towels down into them until they would come out dry (poking them gently in and to the bottom with a rod). I also ran pipe cleaners into them, looping the end and twisting them to make a cleaning loop at the bottom end, until they came out with no moisture or anything on them. I took one of my old head bolts (making sure it had good threads), cleaned it really well, then used it to gently chase the threads of each hole. Each time I would run it all the way into a head bolt hole, making sure there was no resistance or binding, then run it back out. I would then wipe down the threads on the bolt (with something dry) to make sure they were dry before using the bolt again (and to make sure the threads it just came out of were dry). I was very particular and deliberate in this, so I ended up chasing each head bolt hole at least twice (some three times if there was any doubt about moisture in the threads). After completely drying out each head bolt hole and chasing the threads, I would plug the hole with a big piece of a blue paper (shop) towel to prevent any accumulation of moisture or any debris from falling into the bolt hole. If the head bolt holes are not completely clean and free of any fluid, damage could occur to the block when you torque them down, or you may have an incorrect torque that could lead to another head gasket failure. The bolt hole depicted here is one of the two that have a small protrusion around them to align the new head gasket and upper head portion. You also want to take some sort of very reliable straight edge and check the block surface for flatness along all edges and at all angles. However, the machine shop that did my cylinder head told me that it is rare for the block to have warped, saying it is usually always the cylinder head that will warp. They actually told me that if I had a large, flat file I could lightly run it all along the block surface and if there were any low areas they would be revealed (they would be the areas that were not shiny bare metal if they were lower). But I felt better about just cleaning the block off really well and not "buggering up" the factory surface of the block. Mine checked out when I checked for flatness with a metal edge and did not appear to have any warpage.





I cleaned the intake manifold (after removing the components from it as shown below) with degreaser and an old toothbrush, but throttle body cleaner may have worked even better (or faster) had I used it. I also soaked the intake manifold in diesel fuel for about 2 or 3 days to loosen it up even more, then repeated the degreaser. I removed the old oil seals from the camshafts and cleaned them (camshafts) the same way, degreaser, diesel soak, degreaser. The cam pulleys and crank pulley were also cleaned in the same way. I had engraved a small "F" on the front camshaft (intake) and an "R" on the rear camshaft (exhaust) in an area that wouldn't affect them. But I noticed in looking back through my pictures that on the grooved end there is a part number engraved on them from the factory. The exhaust one ends in "E" and the intake one ends in "I." Your's may be the same. The large things I soaked in diesel were done by filling a 5 gallon bucket and soaking one end, then removing the part and soaking the other end.





DISASSEMBLY - Remove the throttle control and bracket (10mm).
REASSEMBLY - Reattach the throttle control and bracket and torque to *88 in/lb.






DISASSEMBLY - Disconnect the control arm from the throttle body (unsnap ball joint circled).
REASSEMBLY - Reconnect the control arm to the throttle body (snap-on ball joint circled).






DISASSEMBLY - Remove the throttle body from the intake manifold (10mm).
REASSEMBLY - After cleaning all the remnants of old gasket off and cleaning the mating surfaces well, apply the new gasket (FCP Groton Part #9135990) and reattach the throttle body to the intake manifold and torque to *88 in/lb (10mm).






DISASSEMBLY - Remove the throttle position sensor from the throttle body (7mm).
REASSEMBLY - Reattach the throttle position sensor to the throttle body.






DISASSEMBLY - Remove the EGR from the throttle body (8mm).
REASSEMBLY - After cleaning all the remnants of old gasket off and cleaning the mating surfaces well, apply the new gasket (FCP Groton Part #3531078) and reattach the EGR to the intake manifold and torque to *88 in/lb (8mm).






All of the components on this page should be reassembled and/or replaced before going any further, starting at the bottom of this page and working toward the top in reverse order, using the "Reassembly" instructions.


1 2 3 4 5 6 Page 8 - Cylinder Head Replacement 9 10



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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!)