How to: transmission catch can install

#1

So after my first race weekend I have a mess on my hands. Can someone give me a “catch can” for dummies?

#2

This e36 thread applies to us just fine. http://forums.bimmerforums.com/forum/showthread.php?t=1825770

I did mine on New #6 a couple days ago. In order to get some room I loosened the engine mounts and removed the tranny mounts. I’d tried to do this a week prior w/o dropping the tranny a bit and couldn’t quite get it done.

Basics…

  1. Get a hand up and feel for the little vent pipe. It’s on top of the tranny near the clutch slave. It’s about an inch tall, maybe a little less and has a loose cap on it that can be popped off.

  2. Find some hose that barely fits over the little pipe. I use about 4’ of the stuff and run it to the radiator catch can. Put a narrow hose clamp on it loosely. In the thread above they cut a hole in the tranny tunnel. I suppose that would work too.

  3. From underneath pop the hose on to the vent pipe. Since the vent pipe is short you want to make sure that the hose is shoved as far down as it can go. Then work the hose clamp on to the very end of the hose.

  4. Here is the hard part. Because the vent pipe is short the hose will want to climb up and off as you tighten the hose clamp. You have to prevent the hose clamp from climbing up as you tighten it. This is where I was failing a week ago because there wasn’t quite enough room for me to hang on to hose and hose clamp such that I could prevent the hose clamp from climbing up.

#3

Thanks. I saw someone suggest that you can just run enough hose uphill (up the firewall in the engine bay) that you don’t actually need a can. True?

#4

That depends on how much your tranny wants to spit out, I suppose. I lost about a half a cup in ~3hrs of track time over the past 2 weeks. The rules say that if you have a vent hose on the tranny (or diff) you have to have a catchcan. Old #6 never had fluid climb thru the 4’ of hose and get to the can.

It took me prob 2yrs to put a hose on Old #6. I put it on when I checked the fluid and found it a quart low. When I first checked New #6 a couple months ago it was a quart low also. Maybe a coincidence or maybe a pattern.

#5

I think the rules say that if you put a hose on it that it has to go into a can. I planned on mounting catch cans for the trans and diff in the trunk on the back firewall but didn’t have the right hose and was out of time.

#6

Installing the diff hose is easier because the vent tube is longer so the hose clamp doesn’t pop the hose off the tube… but the diff vent tube requires a hole drilled in it’s top first. That’s another project that was done last weekend.

#7

I ran just a long hose into the engine bay and never saw anything when I was doing DEs, then I converted my power steering fluid resevoir into a catch can and added a breater filter on top of it.

#8

What size tubing?

#9

[quote=“cosm3os” post=65370]What size tubing?[/quote]I just measured the vent pipe on a spare tranny and I got 11mm. I don’t know what size hose I actually used to do this with tho. What markings were orginally on the hose are long since gone. A couple yrs ago I went to a local autoparts store, bought 8-10’ of every size hose they had and stashed them away.

#10

Will this thing puke until it finds a happy medium between too much and not enough? In otherwords, will it get dangerously low on its own? How do you check the level, other than just refilling till it pours out of the filler hole?

#11

[quote=“Ranger” post=65208]This e36 thread applies to us just fine. http://forums.bimmerforums.com/forum/showthread.php?t=1825770

I did mine on New #6 a couple days ago. In order to get some room I loosened the engine mounts and removed the tranny mounts. I’d tried to do this a week prior w/o dropping the tranny a bit and couldn’t quite get it done.

Basics…

  1. Get a hand up and feel for the little vent pipe. It’s on top of the tranny near the clutch slave. It’s about an inch tall, maybe a little less and has a loose cap on it that can be popped off.

  2. Find some hose that barely fits over the little pipe. I use about 4’ of the stuff and run it to the radiator catch can. Put a narrow hose clamp on it loosely. In the thread above they cut a hole in the tranny tunnel. I suppose that would work too.

  3. From underneath pop the hose on to the vent pipe. Since the vent pipe is short you want to make sure that the hose is shoved as far down as it can go. Then work the hose clamp on to the very end of the hose.

  4. Here is the hard part. Because the vent pipe is short the hose will want to climb up and off as you tighten the hose clamp. You have to prevent the hose clamp from climbing up as you tighten it. This is where I was failing a week ago because there wasn’t quite enough room for me to hang on to hose and hose clamp such that I could prevent the hose clamp from climbing up.[/quote]

I installed a breather hose a few months ago using a hose clamp to secure it to the vent tube, but noticed that the hose popped off. Anyone have any suggestions for securing the hose? Thanks.

#12

Turns out, mine had one, but it popped off too. INstalled a bettwer one. We’ll see if it holds. No mess this weekend, though.

#13

I should probably check mine. I installed the hose and hose clamp with the tranny out of the car though.

#14

I did mine with the trans in the car, so it was hard to hold the hose in place while tightening the clamp.

#15

The elegant way to do this would be to either remove the vent tube or drill a big hold in it. Then put in a 90deg barb fitting. If I ever have to do a tranny swap, that’s what I’ll do.

#16

Well, just tried again installing a vent hose again. I think that the previous hose popped off because of the angle of the installation, so this time I used a vacuum t-fitting and capped off one side. I put a hose and hose clamp on the side that attaches to the trans vent tube. I then reattached the hose that I had installed previously to the other side of the t fitting. See pics. Hopefully it will hold this time.

#17

I had the same problem with the hose coming off. Eventually took the trans out, added a little heat to the nipple, used the end of a ball-peen hammer as a die, and tapped it with another hammer a few times to flare the end of the vent tube. Then just re-attached hose with a narrow clamp. No problems since. Also, I have found no catch can was needed. The hose apparently has enough volume to serve the purpose. I have one of those little K&N -looking breather filters mounted high on the firewall that the other end of the hose attaches to. Works great.

Ken

#18

[quote=“drken” post=65910]I had the same problem with the hose coming off. Eventually took the trans out, added a little heat to the nipple, used the end of a ball-peen hammer as a die, and tapped it with another hammer a few times to flare the end of the vent tube. Then just re-attached hose with a narrow clamp. No problems since. Also, I have found no catch can was needed. The hose apparently has enough volume to serve the purpose. I have one of those little K&N -looking breather filters mounted high on the firewall that the other end of the hose attaches to. Works great.

Ken[/quote]

Rules require a catch can even if it doesn’t actaully see any fluid.

#19

Forgot to add that I did this without taking the trans out.

#20

My mechanic did it just by puting it on the lift and having the guy with the daintiest hands “hug” the transmission to get the hose on and tighten it.