PCV Replacement
As your engine runs, gases from the cylinders leak past the piston's sealing rings into the crankcase. This leaked gas is sometimes referred to as "blow by" because the pressure within the cylinders "blows" them "by" the piston rings. These gases include compounds harmful to an engine, particularly hydrocarbons (unburned fuel), as well as carbon 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's interior surfaces. This can harm the engine as it tends to clog small inner passages, causing overheating, poor lubrication, and high emissions levels. Additionally high pressure in the crankcase can build to a point that leads to a rear main seal failure, an expensive repair. To keep the crankcase air as clean as possible, some sort of ventilation system must be present.
There are different types of PCV systems depending on your car. Some systems use a PCV valve – a one-way valve that ensures continual evacuation of gases from inside a gasoline internal combustion engine's crankcase. Other systems 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 uses an oil trap to do the job.
A couple of notes:
- You may want to try cleaning your PTC before tackling the PCV replacement. This is an important step when you replace your PCV system as PCV tubes attach to the PTC on the air intake hose. A blockage there may be the source of the increased manifold pressure and a smoking dipstick. If this is indeed the source of 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 from the intake manifold. The same thing for the throttle body. It's a good time to remove these things if you want 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 to leave 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 wrench
Universal adapters for your sockets
Plenty of extensions for your sockets
Tile nippers or wire cutter pliers
Torque wrench (I picked up the tried and true craftsman beam torque wrench $25)
Magnetic telescoping pick-up wand
Haynes manual
Car up on ramps.
I made the following wooden steps to accommodate my front bumper not scraping the ramps. I put the car on ramps to allow access to the dipstick mounting bolt from below.
Pop engine hood, disconnect negative battery terminal and remove the cover to the accelerator cable drum.
Remove hosing to make some room – red indicates hoses removed.
Remove 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.
Disconnect two more hoses –
EVAP carbon filtering system hose (A)
and the turbo vacuum gauge (B).
Relieve 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 even try to remove the new one I installed if I needed to remove it, I'd cut that one as well. (C) When I replaced the hose I used 1/4" SAE 30R6KX tubing but it was pretty difficult to put it on. Others recommended using a slightly larger 5/16" fuel line hose.
Remove spark plug cover (D).
Remove 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 under to loosen the bolt. |  |
| 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. |  |
 |
e) With the bolts removed carefully raise and position the manifold on the right side of the engine. There will be cables and hoses still attached in places just be careful and rest it to the right. I found a rope to be helpful to hold it safely out of the way.
Once the manifold is removed you’ll 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.
(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).
With everything removed check the ports to make sure they are not clogged, if they are carefully remove the deposits and make sure the openings are unobstructed. Pay particular attention to the bottom port that has a tendency to become completely blocked. You can try using a drill bit to carefully ream it out if yours is solidly blocked.
Install replacement parts.
New oil trap and associated hoses. Attach the new oil trap to the block. A small hose and 2 clamps attached the bottom port to the trap. Another small hose attached the top port to the block.
You’ll need to clamp the tubing – if you choose to use the Volvo style clamps that come with replacement kits (they’re called Oetiker clamps) I found a pair of tile nippers to be useful for crimping the clamps. *Some spots I couldn’t 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. I’d 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.
|
 |
| 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 (Thanks Hanks) as an effective method to remove the build up.
|
 |
Install new intake manifold gasket and replace the intake manifold.
As you reinstall the intake manifold you’ll need to do 2 things, 1) route the oil trap tube up through the manifold and 2) connect and clamp the small hose that routes from the air intake hose to the left side of the manifold.
Once these are done carefully position the manifold so it sits on the manifold mounting bolts. Reinstall the top intake manifold bolts. I then lightly screwed in all the bolts so they made contact with the manifold then torqued them to 14 foot pounds.
Caution: If your bottom right manifold mounting bolt has a bracket ensure that it doesn't get trapped between the manifold and the block. That's happened to several people including me!
From this point it’s a matter of reversing the steps to put everything back in place.
An oil change following this procedure is recommended.
Good Luck!