Just got done servicing the Oil Breather Box (Oil separator) and EGR valve on my 1995 940 (90K miles). Procedures for Breather Box R&R in the FAQ do not cover the specifics of cars with EGR so I posted last week asking for some tips. Thanks again to those who responded. The bottom line from those responses was - yes you do have to remove the EGR valve to get at the oil breather box on this car. The good new is, it really is not too difficult a job.

I wrote up the following procedure/notes based on what I learned today for the benefit of anyone else who needs to do this. Same basic procedure will probably work for non-EGR, cars with some slight adaptations.

When I finally got the breather box off, I found that the o-ring was totally shot, so I would recommend doing this as part of your preventative maintenance routine along with EGR, IAC Solenoid and Throttle Body cleaning at 50k mile intervals.


Oil Breather Box (A.K.A. Oil separator) R&R Procedure, 940 NA With EGR.

A few of general points: Access is a little tight, so a set of 1/4 inch drive metric sockets/handles and a selection of extensions is going to be a big help. If you don’t 1/4 inch drive tools, you should be able to get by with a few combination wrenches and some 3/8 or 1/2 inch drive sockets. If you have a portable shop light, hang it in the back of the engine compartment behind the inlet manifold. A little illumination makes this a lot easier. The removal and re-installation should take about 2 hours or so in total, plus whatever time you may take cleaning the breather box, EGR, etc. Overall this is not a very difficult procedure, and with a little patience most weekend mechanics should be able to get through it without too much cursing. I would also recommend that anyone who hasn’t done so yet should take the time to read the extensive and excellent write-up on Crankcase Ventilation in the FAQ. There are also photos of the breather box etc. at the following link in FAQ;
http://www.mikeponte.com/volvo/oiltrap.htm


BREATHER BOX REMOVAL
1- Disconnect Idle Air Control Solenoid (IAC) hose and PCV breather hose from main air intake hose immediately upstream of throttle body. IAC hose is the one on the left and breather hose on the right relative to the throttle body. OEM hose clamps have a T25 torx head shrew (you can use the screwdriver from the Volvo toolkit).
2- Loosen the hose clamps that hold the air intake hose at the Air Mass Meter (next to air cleaner box) and at the throttle body. Clamps have a 7mm hex head screw that also has a screwdriver slot. Pull the hose off the AMM and the throttle body and put to one side.
3- Remove the flame trap/nipple and the short hose below the flametrap that connects to the top of the breather box. Located between the 3rd and 4th legs of the inlet manifold.
4- Disconnect the IAC electrical connector (push on the spring clip on the back side of the connector and pull the connectors apart).
5- Remove two 10mm hex bolts attaching the IAC to its bracket underneath the inlet manifold. Disconnect the IAC outlet hose where it connects to the manifold header. The IAC hose is the one located directly below the flame trap vacuum hose. Another 7mm hex-head screw on the clamp. Pull the hose off the nipple.
6- Remove the IAC, with the hoses still attached, threading the discharge hose down the back of the manifold. See FAQ for procedure to clean the IAC.
7- The EGR valve is now “exposed”, behind and to the right of where the IAC was. It is connected to the inlet manifold via a steel tube that connects to the side of the valve. There is another steel tube connected to the end of the valve, that runs around the back of the block, to the exhaust manifold.
8 -Refer to FAQ for procedure to remove and clean the EGR valve. I have also added some additional notes of my own (below) on EGR valve.
9- With the EGR removed, the breather box is very easy to get at. The EGR valve bracket is on top of the base of the breather box and must come off first. Remove the two 12mm hex bolts that pass through the EGR bracket and also attach the breather box to the block. These can be removed with a box wrench or a socket and there is now plenty of space under the manifold to get at them directly. Lift the EGR bracket away and set to one side.
10- There is another bracket under the EGR bracket. This one supports a wiring harness clip in front of the block at this location. Remove two 10mm hex bolts attaching the bracket to the wiring clip. One is front and center relative to the breather box, the other is to the right of the breather box.
11- Pry the bracket away from the wiring clip and it will pop off.
12- Lift the breather box up away from the block. Rotate it forward slightly when it raised ½ inch or so, so that it clears the heater hose (this is connected to the block slightly above the breather box) and it will come free and can be maneuvered out easily.

BREATHER BOX CONDITION (AT 90K MILES)& CLEANING
O-ring was baked hard as a rock and had set in an oval cross section. Removed it and bent it and it snapped in two! This o-ring had clearly stopped sealing effectively some considerable time ago. This allows oil to seep out onto the block, and also allows air to leak in when the engine is running (making it hard to maintain the proper suction inside the crankcase).
There was no significant build up of “crud” inside the breather box. Cleaned it out by spraying throttle-body cleaner into the openings (check a small spot on the outside first to make sure it will not eat the plastic). Then shook the excess out and let it dry for 10 minutes before replacing. Carefully clean the bottom surface and o-ring groove with rag and cleaner. Install new O-ring (34mm x 3 mm). Smear some general purpose grease on the o-ring to hold it in place while re-installing the box.

BREATHER BOX REPLACEMENT
Before beginning to re-install parts, clean up the exposed surface on the block where the breather box sits. This area is usually something of a dirt trap. Be careful not to knock any crud into the openings into the crankcase. Also, while you are doing this, take care not to disturb the oil return hose (front opening). Carefully wipe around the larger opening, and then (even more carefully) around the smaller opening that has the oil return hose inside it. Then spray a little throttle-body cleaner onto a clean rag and wipe the surfaces again. This is the sealing surface for the breather box o-ring, so it is important not to leave any dirt.
Other than that, the rest of the re-installation process is (as they say) a reverse of the removal process. Apply a little dielectric grease to the contacts of the IAC solenoid and EGR before re-connecting them.

Notes
EGR REMOVAL & CLEANING
Refer also to FAQ section on EGR Valve.

EGR VALVE REMOVAL: I found it took a good two-handed pull to break the 22mm acorn nuts free (the nuts that attach the pipes to the valve). Your only option here is to use a 22mm open-ended wrench (unless you happen to have such a thing as a 22mm crows-foot). Be real careful not to have the wrench slip and round off the nut. The valve gets hot in operation, so the nuts tend to seize to the valve fittings and take some persuasion to break loose. I sprayed PBlaster penetrating oil on the fittings and let it sit for 20 minutes before trying. This is a classic “knuckle-buster” situation, so it is a good idea to put on a pair of gloves. Access is limited with a big wrench like this one, but once the nuts are started you will be able to turn them 1/6-turn at a time till they are off. Once the nuts were off, I had to tap the inlet pipe with a hammer to get it loose from the port on the end of the valve. The compression fitting on the end of the pipe was kind of wedged in the port on the valve and did notwant to come off at first. I could not get the outlet pipe off of the side of the valve, so I took the valve off with this pipe still connected (disconnect the other end of the pipe from the intake manifold first). The valve is held on a bracket with a 25mm nut. I managed to get this off with a 1 inch AF open-ended wrench. Again, it took some force to break it free, and access is limited so it was 1/6 or 1/4 turn at a time to get the nut off. I had a difficult time getting the vacuum hose off the valve. the rubber boot at the end of the hose was in very poor conditon (rubber was breaking down and had taken on a tacky/gummy consistency) and was stuck to the vacuum nipple on the valve. I assume this is due to the high temps that this valve sees. I will be looking for a replacement as I do not think it is going to last much longer.

EGR VALVE VACUUM CHECK/CLEANING: FAQ says to use a vacuum pump on the bench. I don’t have one, so I improvised: Insert an allen wrench or small screwdriver or other suitable “probe” into the inlet port (threaded opening on the end of the valve) until it contacts the valve seat. Keep one hand on this probe while maintaining a small force to keep it in contact with the seat. Place vacuum nipple in mouth and suck! You will feel the valve seat opening. The valve should hold open without any additional suction. If the valve fails to open, or if the diaphragm leaks when you do this, then the valve may need to be replaced. If you don’t want to put engine parts in your mouth, you can make a more hygienic mouthpiece from a couple of inches of scrap vacuum hose. I cleaned the valve as per the FAQ, except I was not able to hold the valve open while spraying cleaner into it. Very little carbon/dirt in the valve. Noticeable build up of carbon on end of the EGR discharge pipe, where it connects to the intake manifold. Cleaned this up with a stiff wire and several squirts of throttle-body cleaner

EGR VALVE REPLACEMENT
I put a little anti-seize on the threads before replacement (don’t get any inside the ports though). I am hoping this will make it easier to get the nuts off next time. Place the valve in its bracket. Hand tighten clamping nut that holds it to the bracket. Start the threads on the two acorn nuts. Attach the outlet pipe to the intake manifold and tighten the nuts there all the way. Tighten the bracket clamping nut all the way. Tighten the two acorn nuts all the way. Put a spot of silicone grease on the vacuum nipple and replace the vacuum tube (again, I am hoping this will stop the rubber from “gluing” itself to the nipple. Reconnect the temp sensor electrical connector.

Hope some of you find this helpful if you are getting ready to do any of this. Probably put a few folks to sleep.........

Good Luck,

Kev

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Current: '95 945, 95k miles; '90 BMW 325i, 90k miles. Former Volvos, gone but not forgotten '85 245, 250k miles; '91 744T, 150k miles