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Crankcase Breather Valve Replacement
 
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Pelican Technical Article:

Crankcase Breather Valve Replacement

Nick Czerula

Time:

4 hours4 hrs

Tab:

$100

Talent:

*****

Tools:

Set of sockets (hex and Torx), wrenches, screwdrivers,

Applicable Models:

BMW Z3 Coupe/Conv (1996-02)

Parts Required:

Crankcase breather valve, crankcase breather hoses and pipes

Hot Tip:

Work with a cool engine.

Performance Gain:

Car will run well

Complementary Modification:

Change engine oil and air filter

Some of the combustion byproducts in an operating engine are forced past the piston rings, thus creating pressure in the crankcase. The heating and churning of oil in the crankcase creates additional pressure. This pressure needs to be vented or it causes oil leakage past the engine seals and may even blow out a seal. BMW uses a crankcase breather system in which the oil in the crankcase fumes is condensed and returned to the crankcase and the uncondensed vapors are fed into the engine intake to be burned.

When a crankcase breather valve begins to fail, engine drivability suffers. You may have a rough idle, hard start or a check engine light that is ON with fuel trim faults. If your engine is consuming oil or smoking, checking the crankcase vent valve is a good place to start. The crankcase breather has also been known to emit a honking or wheezing sound from the engine when failing. 

On 4-cylinder models, the crankcase breather valve is mounted to the rear of the intake manifold. On 6-cylinder models, it is located below the intake manifold, behind the throttle housing mounting surface.

Early 6-cylinder engines and late 6-cylinder engines with aluminum valve covers utilize an external crankcase breather. This tech article shows how to replace them. On late 6-cylinder models with a plastic valve cover, the crankcase breather valve is integrated into the valve cover. To replace or repair this valve, replace the entire valve cover. See our tech article on valve cover replacing.

When replacing your crankcase breather valve, I suggest replacing all the vent hoses and the oil drain hose to dipstick tube. They become brittle over time from exposure to engine oil and heat. When removing, these parts are likely to fall apart in your hands. To avoid vehicle down time, have these parts handy before you begin work.

To avoid marring the paint and trim, work with a plastic prying tool or wrap a screwdriver tip with masking tape before prying out body or interior items.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches. 

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability. 

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Models with 4-cylinder engine:

The sealing O-ring at times hardens and leaks. If you have oil residue or a small oil leak at the intake manifold, inspect this seal. If the seal is faulty, you will have to replace the breather valve. See photo in step 6 for O-ring location.

The crankcase breather is located at the back of the intake manifold (green arrow).
Figure 1

The crankcase breather is located at the back of the intake manifold (green arrow). It has one hose connection to the valve cover (yellow arrows). The valve and hose can be replaced with the upper intake in place, it is a tight working space, but can be done. The hardest part is accessing the bolts. In this tech article, I am going to show the procedure with the upper intake removed for clarity. Doing this will give you a better view of the fasteners, valve and other components in the area. Remove the upper intake manifold. See our tech article on intake manifold removing. You do not have to do this part, I am including it as I did it this way for the article.

The valve on my vehicle had a broken hose, it looks like someone tried to reconnect the break using heat shrink tube.
Figure 2

The valve on my vehicle had a broken hose, it looks like someone tried to reconnect the break using heat shrink tube. This method does not work, it does not seal properly, a new hose is the only fix. You can see the broken hose (yellow arrow) next to the valve (green arrow).

Remove the breather valve hose by pulling it straight off the valve.
Figure 3

Remove the breather valve hose by pulling it straight off the valve. If the hose is oil soaked or soft, be sure to replace it.

Next lift up the intake air plate.
Figure 4

Next lift up the intake air plate. It should slide straight up and off the intake manifold studs.

With the plate removed from the intake manifold, you can now see the two 5mm Allen bolts that secure the valve to the plate (green arrows).
Figure 5

With the plate removed from the intake manifold, you can now see the two 5mm Allen bolts that secure the valve to the plate (green arrows). Remove these bolts. The two hoses (yellow arrows) to the plate have coolant running through them, it is not necessary to remove them for this repair.

Once unbolted, lift the valve off the intake plate.
Figure 6

Once unbolted, lift the valve off the intake plate. Clean the valve mounting surface to prep it for the net valve.

Now you have to replace the breather hose that connects the valve to the valve cover.
Figure 7

Now you have to replace the breather hose that connects the valve to the valve cover. There are two ways to do this. IÂ'll leave it to you to decide what works best for you. The new breather hose will come wrapped in a sleeve with a coolant hose. Normally you would replace them both as a pair. However access to the hose behind the cylinder head is tight and at times people do not want to open the cooling system (drain and refill). If you want to replace just the breather hose, as I do when needed, the hose has to be cut out of the sleeve (green arrow) that it is mounted in along with the coolant hoses. Cut along the breather hose side of the sleeve to open it, then remove the breather hose from the sleeve. Be careful not to cut the coolant hose that is also enclosed in the sleeve. If you would like to see what is involved in replacing this coolant hose, see our tech article on cylinder head coolant hose replacing.

Remove the opposite end of the hose from the valve cover and discard the hose.
Figure 8

Remove the opposite end of the hose from the valve cover and discard the hose. Our hose was zip tied onto the valve cover, this is not normal, you do not have to do this when installing the new hose. This must have been a fix for a quick loose hose during a previous repair. Install the new breather hose to the valve cover. Install the new valve and tighten the fasteners. Install the air plate onto the lower intake manifold. Then route the hose through the sleeve to the valve. Use zip ties to tie the sleeve back around the new hose. Reassemble remaining items, when complete, double check all hose routings. And air boots. 

Models with 6-cylinder engine:
Crankcase breather parts: Pipe to valve cover (green arrow), Crankcase breather (yellow arrow), Drain hose (purple arrow), Pipes to intake manifold (blue arrows).
Figure 9

Crankcase breather parts: Pipe to valve cover (green arrow), Crankcase breather (yellow arrow), Drain hose (purple arrow), Pipes to intake manifold (blue arrows). Disconnect negative (-) battery cable. See our tech article on Battery Replacing for connection notes. Remove engine covers. See our tech article on Removing Engine Covers. Remove throttle housing. See our tech article on Replacing Throttle Housing.

Working at front of intake manifold, pull evaporative emission purge solenoid off mounting bracket.
Figure 10

Working at front of intake manifold, pull evaporative emission purge solenoid off mounting bracket. It is mounted in rubber bushing and pulls straight off bracket. (purple arrow)

Working at front corner of cylinder head cover, disconnect engine breather pipe.
Figure 11

Working at front corner of cylinder head cover, disconnect engine breather pipe. (green arrow)

Since I do not reuse these parts, I take a pick or flathead screwdriver and break the retaining collar.
Figure 12

Since I do not reuse these parts, I take a pick or flathead screwdriver and break the retaining collar. Then pull pipe off cylinder head cover and remove any remaining pieces of pipe from cylinder head cover. Alternately, you can squeeze the plastic spring collar and pull off to remove.

Working at center of intake manifold, squeeze release tab and pull pipe (green arrow) off crankcase breather pipe (purple arrow).
Figure 13

Working at center of intake manifold, squeeze release tab and pull pipe (green arrow) off crankcase breather pipe (purple arrow).

If pipe will not release, use a pair of needle nose pliers to squeeze release tabs while pulling off breather pipe.
Figure 14

If pipe will not release, use a pair of needle nose pliers to squeeze release tabs while pulling off breather pipe.

Next, disconnect breather pipe (green arrow) from intake manifold.
Figure 15

Next, disconnect breather pipe (green arrow) from intake manifold. This pipe is always easier to remove if you break the retaining collar.

Working at bottom of dipstick tube, disconnect crankcase breather valve drain hose (green arrow) from dipstick tube (purple arrow).
Figure 16

Working at bottom of dipstick tube, disconnect crankcase breather valve drain hose (green arrow) from dipstick tube (purple arrow). Photo shows dipstick tube raised up and out of engine.

Next pull complete dipstick tube out of engine.
Figure 17

Next pull complete dipstick tube out of engine. Inspect crankcase drain hole and confirm it is clear of obstructions. You can use a piece of stiff wire, but there is an internal baffle (green arrow), do not expect wire to pop out other side.

Next you will be working at the crankcase breather valve.
Figure 18

Next you will be working at the crankcase breather valve. Disconnect pipes (green arrows) from crankcase breather valve. I suggest breaking the retaining collar on these also, then pulling the pipes straight off breather valve.

Remove crankcase breather valve fasteners (green arrows) then remove crankcase breather valve from engine.
Figure 19

Remove crankcase breather valve fasteners (green arrows) then remove crankcase breather valve from engine.

Install crankcase breather valve and tighten fasteners.
Figure 20

Install crankcase breather valve and tighten fasteners. Install new drain hose (green arrow) to bottom of crankcase breather valve. Next, install crankcase breather hose (purple hose) to breather valve. Then install intake connection pipe (blue arrow) to breather valve. Listen for an audible click when you install hoses. Next install dipstick tube (do not install mounting fastener yet) and connect drain hose to dipstick tube. Then connect hoses to intake manifold and valve cover. Reassemble remaining items, when complete, double check all hose routings.

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Comments and Suggestions:
DBWard Comments: Do you have a similar write-up for the 6 cylinder motors? I've got an S52 2000 Z3M Coupe and suspect my CCV is on the way out. I've seen a couple of DIYs on the web where the intake manifold is not removed for this service. Would be great if you had one too.
August 31, 2015
  Followup from the Pelican Staff: We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

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