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Yoshifab Catch Can

     UPDATED: April 9, 2022                       CONTACT       
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If you have any comments or if you can help me to improve this information, please email.

This page covers the installation of a Yoshifab catch can in my 242 Turbo and it discussed a lot of other stuff related to catch cans.
I you want to learn some catch can basics, here's a good article to look at:

Here are some videos that help explain Catch Cans and stuff.


There are a number of ways to install and plumb a catch can system. The below diagram is probably the most common way for a Volvo.
Certainly some features are optional. One option is a vacuum hose from the intake manifold to the catch can. If you add a hose there, you should evaluate how or if it affects the vacuum in your intake manifold.  One clue is if it raises your idle. If it does, then it means your intake manifold is getting unexpected air from the crankcase. This can create a situation where crankcase vacuum might be lower at idle and cruise.
CHECK VALVES: Many people have done these installations over the years without using check valves in vent lines, but it seemed to make sense to me to wall off boost or vacuum in any places where it benefits airflow or protects manifold vacuum, as long as the check valve flows freely enough to not adversely affect airflow when needed. I have included optional check valves in this diagram.
More info about check valves is further below.

This image below represents how I did my installation in my 1984 242 Turbo.
I initially tried adding an optional line to the intake manifold with a check valve as shown here to keep boost from entering that line. This hose significantly raised my idle, so I eliminated that line.  

You can also do DUAL catch cans below for better potential crankcase breathing if you think you need it.
In this diagram below the can hose circuits are split, with one can sending vapors to the intake manifold port and the other can sending to the pre-turbo port.

Yoshifab offers some of the items shown below in their pages at the following links: 

The Yoshifab catch can is designed with THREE PORTS on top. This allows for TWO top IN ports and ONE top OUT port. Two IN ports allows you to vent crankcase
vapor from two different sources.
The illustrations ABOVE also show the optional use of a vented oil filler cap, an optional block side vent, and a vent/drain fitting for the block below the intake manifold, which are available from Yoshifab.

Here are some images below of the Yoshifab catch can. The top and side ports are threaded -10 AN male thread.  The bottom oil drain port is -8 AN male thread.

This block vent / drain fitting plate from Yoshifab has been designed to replace the original Volvo breather box under the intake manifold.
This fitting has two ports. The small drain port on the left side has a -8 AN Male fitting. The larger vent port on the right side has a -10 AN Male fitting. 

In case you're not aware, the Volvo B21/23/230 engine block has a long plastic tube inside that extends from that drain port down into the oil sump.  The bottom of that tube is submerged below the oil level. When this drain is extended below the oil level, it ensures that this pipe drains freely and does not get any interference from crankcase pressures.  So basically this vent/drain plate is designed so that when an external catch can is installed, the bottom of the can SHOULD be placed somewhere reasonably close to and ABOVE the level of this drain port.  This is not always convenient in a Volvo due to tight space, although there are plenty of people who have managed to accomplish this. 

As seen above, the oil drain for this engine block extends down past the oil pump and ends just above the bottom of the oil pan.  It's designed to end below the oil level, so it doesn't get affected by elevated pressures (from boost) in the crankcase.

As you'll see in MY installation, I opted to NOT use the drain port on this vent fitting.
That drain port can be capped off with a -8 AN Female Cap, such as this item from Summit Racing: Earl's  -8 AN Cap (AT992908ERL)This is what I used, since the drain I made was on the other side of the engine.

AN racing style hose internal dimensions are measured in 1/16th of an inch increments. 
-8 AN is 8/16th of an inch ID (1/2 inch).  -10 AN is 10/16ths of an inch ID (5/8 inch). 

Here's my car.
I decided instead to mount the catch can on the right (EXHAUST) side of the engine bay, in the back corner.  My drain to the crankcase is on the exhaust side too. I'll explain more below.

A HOT Catch Can: One thing about putting the catch can on the EXHAUST side . . . It gets hot.  Is this bad?  No, I don't think so. I actually think this is better.
Some high end catch cans are available with heating devices, such as ports to run hot coolant through them.  A hot catch can will have the potential benefit of turning any moisture into water vapor, which will hopefully then slowly exit out with other vapors.

The brackets I used are aluminum mounting brackets for ATV lights. I found them on Amazon: https://www.amazon.com/gp/product/B072M59GXX/
These brackets are made for a 3/4 inch wide tube (also available for other sizes). 3/4 inch is the size of the 242 GT diagonal brace I have in there.


My plan routed the catch can drain down into a Y-fitting that joins with the turbo oil drain just above the block drain.  This Y-fitting tends to make things a little complicated down there as you can see here, so some planning was needed for all these AN hose fittings to fit in a small space.  The turbo oil drain that I previously installed uses Summit PTFE lined racing hose, which is a high temperature hose designed for hot oil (rated to 400 degrees Fahrenheit).
So I used the same type PTFE hose for the catch can drain. I wanted to use a hose that was rated for high temperature since this stuff is so close to the exhaust manifold and turbo.
  I would prefer to NOT use this Y-fitting. I would rather have a dedicated drain port down low on the side of the oil pan (below the oil level), but this is something I think I'll work on later, since I didn't feel like removing my oil pan at this time. More info on THIS: CLICK HERE

Here are the connectors used to assemble this Y-fitting.  The Y-fitting has -10 AN male ends. It uses a reducer to -8 AN for the hose that goes up to the breather box.

Not shown here is the turbo oil drain (seen in above photos), which connects to the other upper end of the Y-fitting. That hose uses a short piece of Summit Racing -10 AN PTFE hose (SUM-2201010), one Summit Racing PTFE Hose End -10 AN 90 degrees (SUM-250087B), and one Summit Racing PTFE Hose End -10 Straight (SUM 250090B).  Specific detailed information about the turbo drain hose fitting that fits into the block can be found in a separate article HERE.

Assembling PTFE hose ends is not difficult, but you'll need some guidance if it's your first time.  There are good instructions here: https://anfittingguide.com/install-ptfe-hose-fittings/. 
And a good video below.

Here's a good video on assembling these PTFE fittings:

I installed two one-way check valves in the airflow hoses during my installation.

The above check valve has an ARROW which shows the a airflow direction.  The ball inside will prevent flow in the opposite direction.

There are a lot of check valves out there. I wanted one that I thought would not restrict flow and I wanted it to fit the 5/8 inch ID hose I was using.
I chose this one above made by UPR. It's pricey, close to $50 each. It uses a PTFE ball and light spring inside and easily come apart to see what's inside. When I blew through the valve it seemed to have very little restriction and the ball provides a 100% seal against reverse flow.

The valve in the left pic is near the port going into the pre-turbo inlet hose.
The valve on the right is there to allow intake manifold vacuum to reach the catch can, but it won't allow boost. I tried this setup, but found it raised my idle. I didn't want that, so I eliminated this line.

I installed a one-way check valve in the oil drain hose between the catch can and the Y-fitting. It needs to be placed so flow goes down only.  A check valve is used in this situation because the drain goes into the oil sump above the oil level.  A different option would be if the drain went into the sump below the oil level. 
A check valve WOULD NOT be needed if this tube drained to a port BELOW the oil level.

You can't see it in this photo here, but I used a 45 degree adapter (-8 AN Female to -8 AN Female) between the catch can and the check valve.
Like this one:  https://www.jegs.com/i/Earls/361/AT939208/10002/-1

More detail about the drain check valve is below.
This is the check valve. It accepts -8 AN fittings on both ends and can be found at Summit Racing here: One-Way Check Valve -8 AN Male (SUM-220193B)
The summit instructions will tell you not to screw with the spring that holds the check-valve closed.  I couldn't stop myself.  I felt it was too tight, so I tweaked it until it was much easier to push open.  I want this to drain freely and not back up into the catch can.  I'm pretty confident in my decision.

Making a proper drain work WITHOUT having to use a drain Check Valve
Maybe you don't like the Y-fitting or the check valve I used.  No problem. 
Here's another idea below that allows the drain to remain on the exhaust side without a Y-fitting.

You may instead place a port on the side of the oil pan. Keep in mind that it must be below the oil level if you will not be using a check valve. This would eliminate the need for the Y-fitting or check valve, although of course you would need to remove your oil pan to drill a hole. This bulkhead fitting pictured below would be a good option for a -8 oil drain hose. It can can be found here: Fragola Bulkhead -8 AN Male (483108-BL)


Ventilation through Block Fuel Pump Opening
Yoshifab offers this adapter plate if you would like to mount an AN fitting vent to the old fuel pump opening in the side of the engine block.  I'm using this opening as one of several crankcase vent locations. I'm not using an oil filler cap with a vent fitting, but that option is available. This plate has a removable AN fitting in case you want a different sized fitting on there.  The plate is threaded -10 AN Straight Thread Female (O-Ring). An o-ring is used to seal this connection.

The 90 degree fitting I'm using is this one: -10 AN Summit Racing Twist-Tite Swivel Hose End 90 (SUM-260087B).  The barbed end is made for -10 AN Summit Twist-Tite rubber hose, which has a 5/8 inch ID. You can also use
Aeroquip Socketless fittings in size -10 AN. Summit Twist-Tite hose is a similar hose (but cheaper) compared to Aeroquip Socketless hose, however the Aeroquip products, particularly the fittings, are considered to be better quality.  For a light-duty application like a catch can, I didn't consider the higher quality to be critical.

Since the barb end on this fitting is 5/8 inch wide, you can use just about any hose with an ID of 5/8 inch. 

Yoshifab suggested using 5/8 inch PVC clear reinforced flexible tubing as a less expensive option over Aeroquip Socketless or other high cost racing hose. The clear tu
bing has a fair temperature rating (150 F) and since it's transparent, you can see what's going on inside if you're concerned about seeing potential flow blockages.  I bought some on Amazon: https://www.amazon.com/gp/product/B01MRUROKO/
Of course the second photo above shows how this hose becomes discolored after a couple years of engine heat.  It also shrinks and hardens a bit. The shrinkage is a concern, since it means this hose was a tight fit on the nipples in the beginning, but can later slip off the nipples if clamps aren't used.  Clamps or zip ties can keep them tight. So keep this in mind for your hose decisions.  

Nylon barbed tee or 90 degree fittings are a good solution for joining this hose.

Here's a pic showing the 5/8 inch clear PVC tubing in use at the catch can. 
That top port got routed through the back of the right strut tower, then to the front of the engine bay. It's connected to the intake air tube between my air filter and turbo. That is a 150 degree curved fitting I used on top of the catch can. This one: -10 AN Summit Racing Twist-Tite Swivel Hose End 150 Degree (SUM-260091B). 

Here's a pic of that hose going to my intake tube after the filter and before the turbo.

 The straight fitting closest to the firewall on the catch can is for the hose going across the cam cover and then down past the intake manifold to the block breather vent. This fitting is -10 AN Summit Racing Twist-Tite Swivel Hose End (SUM-260090B).  The same fitting can be used on the Yoshifab vent plate that replaces the stock breather box.

The curved fitting next to the shock tower is a 120 degree curved fitting.  That hose goes to a nylon T-fitting near the intake manifold (it can be seen in next pic). This 120 degree fitting is -10 AN Summit Racing Twist-Tite Swivel Hose End (SUM-260088B).

Here you can see the hose closest to the front of the car continues down through the intake manifold and then turns forward to the fuel pump plate vent. The tee-fitting you can see here sends another hose forward to the cam cover vent.   I have a 90 degree elbow-fitting shoved in the cam cover vent hole.  That elbow was slightly loose it that hole, so I added a small piece of heat-shrink tubing to the end and it then fit in the hole nice and snug.

These 5/8 inch OD nylon T-fittings and Elbow-fittings are cheap and nylon will hold up to high temp conditions.

  If you have any comments or if you can improve this information, please feel free to email.

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