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Volvo 850 R PCV Replacement

As your engine runs, gases from the cylinders leak past the piston's sealing rings into the crankcase. This leakedgas is sometimes referred to as "blow by" because the pressure within the cylinders "blows" them "by" the pistonrings. These gases include compounds harmful to an engine, particularly hydrocarbons (unburned fuel), as well ascarbon dioxide and water vapor. If allowed to remain in the crankcase, or become too concentrated, the harmful

compounds will condense out of the air within the crankcase and form corrosive acids and sludge on the engine'sinterior surfaces. This can harm the engine as it tends to clog small inner passages, causing overheating, poorlubrication, and high emissions levels. Additionally high pressure in the crankcase can build to a point that leads toa rear main seal failure, an expensive repair. To keep the crankcase air as clean as possible, some sort ofventilation system must be present.

There are different types of PCV systems depending on your car. Some systems use a PCV valve a one-way valvethat ensures continual evacuation of gases from inside a gasoline internal combustion engine's crankcase. Othersystems use an oil trap or separator to do the job.

Over time PCV systems and associated tubing can become clogged and fail to vent the buildup of pressure.

How can you tell if you need to replace your PCV system? One test is with a warm running engine pull your

dipstick. Does smoke billow out of the dipstick tube? If so a faulty PCV system could be the cause.

The following write up describes my approach for the PCV system replacement on my 1997 850r turbo which usesan oil trap to do the job.

A couple of notes:

You may want to trycleaning your PTCbefore tackling the PCV replacement. This is an important stepwhen you replace your PCV system as PCV tubes attach to the PTC on the air intake hose. A blockage theremay be the source of the increased manifold pressure and a smoking dipstick. If this is indeed the sourceof your problem this is a quick, inexpensive fix compared to replacing the entire PCV system.If the PTC is clean and you still have a smoking dipstick proceed with the PCV replacement.

While researching how to do this I found there were those in favor of removing the fuel rail & injectors fromthe intake manifold. The same thing for the throttle body. It's a good time to remove these things if youwant to do a thorough cleaning of the throttle body or if you want to service the injectors.Others preferred to keep both in place on the intake manifold.

Because of my relative inexperience I wanted to minimize the number of parts I removed so I choose toleave them in place.

Another good recommendation I read was to remove the fan shroud to give you more access room to work.You may choose to do that, It's fairly easy to remove.

More useful suggestions:Try a little 'O' ring grease to make hoses slip onto the nipples a little easier.

Use blue tack or magnetic socket inserts to keep from dropping bolts.

I personally wouldn't want to do the job without the following on hand:12mm spanner wrenchUniversal adapters for your socketsPlenty of extensions for your socketsTile nippers or wire cutter pliersTorque wrench (I picked up the tried and true craftsman beam torque wrench $25)Magnetic telescoping pick-up wandHaynes manual

http://www.lakesidedp.com/uploadpics/pcv/#ptchttp://www.lakesidedp.com/uploadpics/pcv/#ptchttp://www.lakesidedp.com/uploadpics/pcv/#ptchttp://www.lakesidedp.com/uploadpics/pcv/#ptc

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Step 1Car up on ramps.I made the following wooden steps to accommodate my front bumper not scraping the ramps. I put the car onramps to allow access to the dipstick mounting bolt from below.

Step 2Pop engine hood, disconnect negative battery terminal and remove the cover to the accelerator cable drum.

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Step 3Remove hosing to make some room red indicates hoses removed.

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Step 4Remove electrical connection to the idle control valve (4A)electrical connection to the throttle body (4B)

and the brake booster vacuum hose (4C)Lastly remove idle control valve.

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Step 5Disconnect two more hoses EVAP carbon filtering system hose (A)and the turbo vacuum gauge (B).

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Step 6Relieve gas pressure. Remove blue cap from the schrader valve and depress valve with a rag in hand to catch gas(A).Unbolt fuel rail and remove the return line hose (B).I had to cut mine and replaced it with a new fuel hose. Given how tightly the replacement hose fit I wouldn't eventry to remove the new one I installed if I needed to remove it, I'd cut that one as well. (C) When I replaced thehose I used 1/4" SAE 30R6KX tubing but it was pretty difficult to put it on. Others recommended using a slightlylarger 5/16" fuel line hose.Remove spark plug cover (D).

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Step 7Remove manifold from block.a) locate the bolt under the dip stick mounting bracket. I found it best to do this from under the car. I used a 3/8

inch ratchet 12mm socket with about 16 worth of extensions.

b) Remove the bolt securing the underside of

the manifold to the retaining bracket. I found

this by feeling around under the manifold

from the top. Once I located it I used a 12mm

spanner wrench from the top reaching underto loosen the bolt.

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c) Loosen the lower manifold retaining bolts (I

have 4) a few turns to loosen them up. It is not

necessary to remove the bottom bolts as the

manifold rests on these. I used a 10mm ratchet

with a universal joint adapter to reach the bolts

at the angle required.

d) remove the upper manifold bolts completely (I have 3). The one behind the PCV hose running to the head canbe hidden, try moving the hose to the side a bit.e) With the bolts removed carefully raise and position the manifold on the right side of the engine. There will becables and hoses still attached in places just be careful and rest it to the right. I found a rope to be helpful to holdit safely out of the way.

Step 8Once the manifold is removed youll see the oil trap and associated tubing. Note the existing tubing configuration(take a picture) to avoid confusion as to how the tubes are attached.

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Remove oil trap hosing I just cut mine so the other end would remain attached as a reference to where the newtubing would run. Picture shows tube already cut away(Optional) Remove the left knock sensor picture shows sensor already removed from the block (B).

Remove the manifold bracket(C).Remove the oil trap mine had 2 bolts securing it to the block (D).

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Step 9With everything removed check the ports to make sure they are not clogged, if they are carefully remove thedeposits and make sure the openings are unobstructed. Pay particular attention to the bottom port that has atendency to become completely blocked. You can try using a drill bit to carefully ream it out if yours is solidlyblocked.

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Step 10

Install replacement parts.New oil trap and associated hoses. Attach the new oil trap to the block. A small hose and 2 clamps attached thebottom port to the trap. Another small hose attached the top port to the block.

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Youll need to clamp the tubing if you choose to

use the Volvo style clamps that come with

replacement kits (theyre called Oetiker clamps) I

found a pair of tile nippers to be useful for crimping

the clamps. *Some spots I couldnt get the pliers to

the clamp so I opted for a worm style clamp instead.I liked the Oetiker clamps and tried to use them

where I could. Id recommend having an assortment

of worm style clamps on hand as you work through

this job. If you don't have a tile nipper wire cutters

can also be used to crimp the clamps tightly.

*A great suggestion was made to simply install the

hoses on the trap before bolting the trap to the block.

It would be much easier to clamp down the Oetiker

clamps that way.

After installing the new trap and clamping down the tubes I routed the other side of the piping over to the airintake hose making sure it would make it to the final destination. I had to shuffle around how the hose was routedto make it fit. I secured it to the air intake hose with clamps.

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If you did not purchase a replacement intake hose

it is essential that you clean out the the connection

nipples on the intake hose. This is referred to as

the 'PTC' or Positive Temperature Coefficient

heater nipple and is installed on all turbos after

1990.

Many PCV replacements have not eliminated the

smoking dipstick due to a blocked PTC.

Take your time and really clean the PTC out well.

Soaking the PTC in break cleaner was

recommended to me (ThanksHanks) as an

effective method to remove the build up.

Step 11Install new intake manifold gasket and replace the intake manifold.

As you reinstall the intake manifold youll need to do 2 things, 1) route the oil trap tube up through the manifoldand 2) connect and clamp the small hose that routes from the air intake hose to the left side of the manifold.

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Once these are done carefully position the manifold so it sits on the manifold mounting bolts. Reinstall the topintake manifold bolts. I then lightly screwed in all the bolts so they made contact with the manifold then torquedthem to 14 foot pounds.

Caution: If your bottom right manifold mounting bolt has a bracket ensure that it doesn't get trapped between themanifold and the block. That's happened to several people including me!

From this point its a matter of reversing the steps to put everything back in place.

An oil change following this procedure is recommended.

Good Luck!