How To Replace The Head Gasket On A Volvo 850 (page 2)


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Intake Components and Fan Removal / Replacement




DISASSEMBLY - Remove the throttle cover (T25).
REASSEMBLY - Replace the throttle cover.






DISASSEMBLY - Remove the clip (yellow circle) and cable from the throttle control bracket, thread the throttle cable out from around the pulley, slide the peg on the end of the cable (red arrow) out of the pulley and secure the throttle cable out of the way. Remove the injector wiring holder (red circle) from the throttle control bracket (10mm).
REASSEMBLY - Slide the peg on the end of the cable (red arrow) into the pulley, thread the cable around the throttle control pulley in the outer groove, and replace the throttle cable into the throttle control bracket and secure with the clip (yellow circle). Reattach the injector wiring holder (red circle) on the throttle control bracket.






DISASSEMBLY - Press the locking wire in and disconnect the wiring to the mass air flow sensor.
REASSEMBLY - Press the locking wire in and reconnect the wiring to the mass air flow sensor.






DISASSEMBLY - Remove the air intake hose from the air filter housing (red circle), remove the air filter cover (unsnap at yellow circles all around housing), remove the air filter, and remove the fresh air intake duct (blue arrow).
REASSEMBLY - Replace the fresh air intake duct (blue arrow), the air filter (FCP Groton Part #C35148), the air filter cover (snap at yellow circles all around housing), and the air intake hose to the air filter housing (red circle).






DISASSEMBLY - Remove the preheater hose from the air filter housing and the exhaust manifold (red arrow). Remove the air filter housing (yellow arrow - lifts out once everything has been disconnected from it).
REASSEMBLY - Replace the air filter housing (yellow arrow) and the preheater hose (red arrow).






Now it's time to start disconnecting a bunch of stuff (hoses, wires, etc) in order to remove the fan and then the intake manifold. If there is any doubt as to whether or not I am going to remember where something was disconnected from, I put a piece of masking tape on it and label it somehow ("A" goes to "A", "top front nipple," etc) to let me know where it goes during reassembly. I hope the pictures here will help to remove confusion, but you may still want to label something here and there if at all in doubt.





DISASSEMBLY - Disconnect the vacuum lines coming from the vacuum tree in front above the radiator fan. The top nipple connects to the nipple on the EGR valve. The bottom nipple connects to the front middle nipple of the vacuum tree on the intake (both in next picture). I know, the vacuum connectors are on backwards; here's why. The original vacuum connectors were degraded pretty bad, so I bought new connectors. I accidentally bought ones that had too large of an opening on the big end to fit the vacuum tree nipples. So I wrapped electrical tape around the vacuum lines until they were fat enough to tightly fit into the big end and then connected the smaller end to the vacuum tree nipples where they fit snugly.
REASSEMBLY - Reconnect the vacuum lines to the vacuum tree in front above the radiator fan. The top nipple connects to the nipple on the EGR valve. The bottom nipple connects to the front middle nipple of the vacuum tree on the intake.






DISASSEMBLY - Here you see where the vacuum lines from the previous picture lead to (yellow arrows). Disconnect them (mine were bundled together inside a sleeve). Also remove the two vacuum hoses marked with red arrows. The one with a clamp on it is the brake servo vacuum hose (the hose running from underneath air filter housing area). The other one with a red arrow runs toward the fan and must also be detached from where it is secured in clips along the fan housing. After disconnecting both of these, secure them out of the way.
REASSEMBLY - Reconnect the vacuum lines. The ones with yellow arrows are bundled together and will connect to the vacuum tree above the radiator fan. The one with a red arrow and a clamp on it is the brake servo vacuum hose (the hose running from underneath air filter housing area). The other one with a red arrow runs toward the fan and must also be secured in the clips for it along the fan housing.






DISASSEMBLY - Disconnect the cooling fan wire that is on the fan housing.
REASSEMBLY - Reconnect the cooling fan wire that is on the fan housing.






DISASSEMBLY - Disconnect the cooling fan wires at the relay (connector with red/green wires).
REASSEMBLY - Reconnect the cooling fan wires at the relay (connector with red/green wires).






DISASSEMBLY - Remove the two top screws that secure the fan housing to the shroud (T25).
REASSEMBLY - Replace the two top screws that secure the fan housing to the shroud.






DISASSEMBLY - The two bottom screws fit into "slots" on the fan housing, rather than holes. So you can just pull upward on the fan and it should slide off of the two bottom screws (they may need to be backed out a quarter-turn if pulling it out seems too difficult). Remove the fan carefully (it required a little manipulation to get it out).
REASSEMBLY - The two bottom screws fit into "slots" on the fan housing, rather than holes. So you should be able to thread the fan into where it goes, then slide the slots of the fan housing behind the two bottom screws.






DISASSEMBLY - Press the locking wires in and disconnect the wiring to the throttle position sensor (TPS - down bottom) and the idle air control (IAC) valve. This picture is taken from the position where the transmission dipstick is the yellow thing in the bottom of the pic and the air intake duct is on the right side of the picture.
REASSEMBLY - Press the locking wires in and reconnect the wiring to the throttle position sensor (TPS - down bottom) and the idle air control (IAC) valve.






DISASSEMBLY - Disconnect the IAC valve hoses, one from the large front port of the vacuum tree and one from the front port of the elbow on the air intake hose. The black bracket that surrounds the IAC valve fits into a notch and can be slid back and forth on the IAC valve.
REASSEMBLY - Reconnect the IAC valve hoses, one to the large front port of the vacuum tree and one to the front port of the elbow on the air intake hose. The black bracket that surrounds the IAC valve fits into a notch and can be slid back and forth on the IAC valve.






DISASSEMBLY - Disconnect the flame trap vacuum line from the bottom, back nipple of the vacuum tree (yellow arrow). The top, back nipple is the one that was connected to the fuel pressure regulator on the fuel rail (red arrow) and should be disconnected also.
REASSEMBLY - Reconnect the flame trap vacuum line to the bottom, back nipple of the vacuum tree (yellow arrow). The top, back nipple is the one that was connected to the fuel pressure regulator on the fuel rail (red arrow) and should be reconnected also.






DISASSEMBLY - Disconnect the air intake hose from the throttle body (red dotted path, Flat-head screwdriver) - and remove the hose running from the PCV oil trap from the large port on the flame trap (yellow dotted path).
REASSEMBLY - Reconnect the air intake hose (FCP Groton Part #9141228A) to the throttle body and reconnect the hose running from the PCV oil trap onto the large port on the flame trap.






DISASSEMBLY - Remove the flame trap from the elbow of the air intake hose (twist-locks off, note tabs and grooves).
REASSEMBLY - Replace the flame trap (FCP Groton Part #1389657) onto the elbow of the air intake hose (twist-locks on, note tabs and grooves).






DISASSEMBLY - Remove the vacuum tree from the intake after removing the bolt securing it (10mm). It is a snug fit and may need to be wiggled slightly to remove it.
REASSEMBLY - Replace the vacuum tree on the intake and replace the bolt securing it. It is a snug fit and may need to be wiggled slightly to install it.






DISASSEMBLY - Underneath the throttle body, remove the EGR temperature sensor (yellow circle) that connects to the side of the EGR valve (the wires will have to twist counter-clockwise 6 or 7 turns as you remove it)(14mm). Disconnect the hard line (red circle) that runs from back the of the EGR valve to the exhaust manifold (Crescent wrench on both ends, as it was bigger than 20mm - the largest combination wrench I have).
REASSEMBLY - Underneath the throttle body, reconnect the hard line (red circle) that runs from back of the EGR valve to the exhaust manifold. Reattach the EGR temperature sensor (yellow circle) that connects to the side of the EGR valve (twist the wires counter-clockwise 6 or 7 turns to account for the turns in the wires once tightened).






DISASSEMBLY - Also disconnect the hard line at the exhaust manifold on the rear of the engine (Crescent wrench on both ends, as it was bigger than 20mm - the largest combination wrench I have).
REASSEMBLY - Reconnect the hard line at the exhaust manifold on the rear of the engine.






DISASSEMBLY - Remove the bolt (12mm) securing the oil dipstick bracket from underneath, pull the dipstick assembly firmly out. The other end is secured in the oil pan with a wide, thick O-ring (FCP Groton Part #30637865).
REASSEMBLY - Replace the oil dipstick, inserting the lower end into the oil pan and pushing firmly to seat it, then replace the bolt securing the oil dipstick bracket from underneath.






DISASSEMBLY - Behind the leg where the oil dipstick bracket was bolted onto the intake manifold, there is another leg where the intake manifold is secured to its bracket from underneath. Remove this bolt (12mm).
REASSEMBLY - Replace the bolt that secures the intake manifold to its bracket from underneath.






DISASSEMBLY - There are 7 bolts securing the intake manifold to the head, 3 on top and 4 on bottom. The 3 on top can be removed (red circles), while the 4 on the bottom (yellow circles and dots) only need to be loosened a turn or so (10mm), since the manifold has slots (rather than holes) down bottom.
REASSEMBLY - Replace the 3 top manifold bolts (red) and tighten all 7 of them to 14 ft/lb in an alternating pattern.






DISASSEMBLY - Remove the intake manifold, rocking it gently to break the seal of the old gasket, and allow the top PCV hose to feed out as you remove the manifold.
REASSEMBLY - After cleaning all the remnants of old gasket off and cleaning the mating surfaces well, and threading the top PCV hose through between manifold channels, position the new intake manifold gasket (FCP Groton Part #9146266) on the head and secure it with the 4 bottom manifold bolts. These 4 bolts should be pre-installed and tightened until there is just enough of them protruding to ensure the bottom slots on the manifold will slide onto them easily. Carefully replace the intake manifold, keeping the gasket (undamaged) between the manifold and the head, and sliding the manifold (bottom slots) onto the 4 bottom bolts.






When you start reassembling the components on this page, start at the bottom of this page and work your way to the top in reverse order, using the "Reassembly" instructions.


1 Page 3 - Exhaust Components, Starter, Serpentine Belt Removal / Replacement 4 5 6 7 8 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!)