| Author |
Message |
Philip Airey (Pma1010)
New member
Username: Pma1010
Post Number: 24
Registered: 7-2002
| | Posted on Sunday, October 13, 2002 - 11:02 am: | |
I talked to Tod (Service) and Randy (parts) at Continental Autosports about this. The vent is needed as some part of the tranny oil will vaporize when the tranny gets very hot (at the track, for example, where I became first aware of this). In the different model years various forms of vent & cap were used (e.g., on my 77) graduating to a system to capture the expelled vapor, separate and return oil to tranny, the vapor to intake (as on the later Mondials, for example and similar to the crankcase oil treatment on my 77).
My issue which no one seemed to have a good answer for was the pressure build up. The vent wasn't venting in my case, albeit, there were no obvious signs of obstruction.
I pulled off the cap, cleaned out the vent and installed the hose and catch tank I described. This should now avoid any pressure build up.
What I did notice in the interim was a lot more oil being deposited on the rear muffler, most likely through a combination of the vent tube (was coated in oil), speedo connection (ditto) and diff seals. What I am curious to see is if the various leaks are abated significantly from the reduction in gearbox internal (air) pressure. |
Hans E. Hansen (4re_gt4)
Member
Username: 4re_gt4
Post Number: 270
Registered: 4-2002
| | Posted on Thursday, October 10, 2002 - 10:58 pm: | |
The vent (no hose) on my old '75 308GT4 spits noticeable amounts of fluid out all the time. I suppose if a hose were attached, it would drain back. |
Paul Newman (Newman)
Member
Username: Newman
Post Number: 561
Registered: 12-2001
| | Posted on Thursday, October 10, 2002 - 9:01 pm: | |
On my 79 GTB the vent hose is probably 18" long with a bend at the top and a valve on the end. It never expells anything other than air I guess. I do notice however, when I check the fluid level, there seems to be a vacuum in the gearbox just as I remove the plug. I think they lengthened the hose as a running change to prevent oil loss. Just a guess though. |
Philip Airey (Pma1010)
New member
Username: Pma1010
Post Number: 23
Registered: 7-2002
| | Posted on Thursday, October 10, 2002 - 8:53 pm: | |
Bill et al
Has anyone else found significant amounts of stuff expelled through this valve? I have put a hose and fashioned a cheap catch tank to see what is expelled from tranny.
Philip |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 367
Registered: 5-2001
| | Posted on Monday, October 07, 2002 - 5:20 pm: | |
Philip,
The tranny shouldn't really build up any pressure except that associated with the heating of the internal air due to operation. As the internal air warms, it expands and will exit the vent tube. It is possible that some oil vapor would be expelled during the heating cycle but this would on the order of one drop per heating cycle and probably less. If the vent tube were plumbed to the crankcase system, it's more likely that some engine oil, bypass gases, and water vapor, would find their way into the tranny. Again, the amounts are likely to be very small. On the other hand, there is really nothing to be gained, so why do it? |
Philip Airey (Pma1010)
New member
Username: Pma1010
Post Number: 21
Registered: 7-2002
| | Posted on Monday, October 07, 2002 - 12:10 pm: | |
Bill
Yes, on reflection I don't think this is a good idea for the reasons you identify. My thought was to be neat with the plumbing, but a hose and a catch tank to check for output is probably the way to go.
Why would the tranny build up so much pressure?
Philip |
Bill Sebestyen (Bill308)
Member
Username: Bill308
Post Number: 366
Registered: 5-2001
| | Posted on Sunday, October 06, 2002 - 7:18 pm: | |
Philip,
There is a possibility of contaminating the tranny oil with engine oil/blow by gas vapor if you plumb into the crankcase system. The danger is probably small, by I don't see where you would gain anything by doing this. Why would you want to do this? |
Philip Airey (Pma1010)
New member
Username: Pma1010
Post Number: 20
Registered: 7-2002
| | Posted on Sunday, October 06, 2002 - 6:40 pm: | |
Mitchell, thanks. I had understood that. My question was more: has anyone vented the tranny vent into the CRANKCASE venting system?
Philip |
Mitchell Le (Yelcab1)
Member
Username: Yelcab1
Post Number: 424
Registered: 11-2001
| | Posted on Sunday, October 06, 2002 - 2:37 pm: | |
I did just that. Removed the plug and attached a hose venting it to the top of the wheel well terminating in an fuel filter to the atmosphere. no more leaks, and it is guarranteed to vent. |
Philip Airey (Pma1010)
New member
Username: Pma1010
Post Number: 19
Registered: 7-2002
| | Posted on Sunday, October 06, 2002 - 11:00 am: | |
Thanks for the info. Very helpful.
Mitchell/Robert (from the prior linked post), has anyone tried to vent this to the crank vent system? |
Mitchell Le (Yelcab1)
Member
Username: Yelcab1
Post Number: 423
Registered: 11-2001
| | Posted on Sunday, October 06, 2002 - 12:57 am: | |
Try this link
http://server.ferrarichat.com/~ferrari/ferrarichat.com/discus/messages/112/111442.html |
Mitchell Le (Yelcab1)
Member
Username: Yelcab1
Post Number: 422
Registered: 11-2001
| | Posted on Sunday, October 06, 2002 - 12:51 am: | |
This is the TRANSMISSION case ventilation point. What you have is a cap under a spring and covered by a cylinder which is supposed to vent any huge positive pressure built-up inside a gear box. This is a sort of a gear oil leak in my case and has been dealt with by removing the vent/plug, and connecting a small hose to the opening and routing the hose to above the wheel well where vapor exits to the atmosphere through a small gas filter. Do a search on this board and you will find a picture of the offending nipple. |
Philip Airey (Pma1010)
New member
Username: Pma1010
Post Number: 18
Registered: 7-2002
| | Posted on Saturday, October 05, 2002 - 11:32 pm: | |
While searching for an oil leak I found a 2 inch long, 1/2 inch dia cylinderical piece with what appears to be a valve on top (it appeared to vent crank case pressure to atmos when I pushed it). Located 2 inch inboard of 2nd bolt up on gearcase/clutch cover.
My 1978 parts catalog doesn't identify it -- infact TAV 9 between arrows 64 and 71 suggests it is just a bolt/stud and nut. Any thoughts appreciated. |