Manual Transaxle: OVERFILL for lower temperature & longer life?

[Sodo]

Other thread (Re: Manual Transaxle oil cooler: FILTERING) went off-topic and generated a separate and interesting discussion.

- Can overfilling the transaxle reduce trans temperature?
- Does the added oil cpacity dilute contaminants and prolong transaxle life?
- What are the problems with overfilling
- What is the problem with oil foaming?
- Can this be as effective as oil pumping? It's much cheaper and easier.

Foamed oil causes oil pressure problems in an engine (and auto transmission) because you can't get oil pressure once the oil foams. But there is no oil pump in the Vanagon transaxle, it's all splash lubrication.

Lots to discuss, so I created a new thread for this. Hope some of the active minds are interested enough to get involved.

[ALIKA T3]

VW lowered the filling point at 15mm lower than the fill plug in their workshop manual to avoid jumping out of gear, I think 5th gear (4th).
On the other hand a friend in France in the T3 business for 30 years as been filling them an extra liter for well over 2 decades no ill effects...

I don't have better info than this.

Btw, do you see my emails when I answer to you?
_________________
Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[Sodo]

[DanHoug]

foaming is pretty much universally 'bad' with respect to lubricity in any lubricant, and it inhibits thermal transfer. that said, we need a glass window on someone's transaxle to see if foaming is occurring.

i've drained my transaxle fluid pretty fast after a drive, essentially waiting until the exhaust is cool, and there is minimal air intrusion but there is SOME. modern oils including gear oils have some pretty strong anti-foaming agents.

so... a little light reading on oil foaming:

https://www.machinerylubrication.com/Read/30096/prevent-foaming-dispersions
_________________
-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Sodo]

[MarkWard]

If you could pull a constant vacuum on the transaxle, in theory, that should collapse the air bubbles suspended in the oil. Not sure how practical that is.
_________________
☮️

[Vanagon Nut]

[crazyvwvanman]

If you used a boxer tranny nose mount then your tranny angle is still flatter than a stock diesel 2wd van tranny.

Mark

[Vanagon Nut]

[Sodo]

[Vanagon Nut]

[MarkWard]

It would not take much vacuum. There are only so many ways to eliminate air bubbles from suspension without using a pump and a reservoir tank which I thought was the exercise of this thread. Crankcases have been running negative pressure for years without dirt being drawn past the seals and oil being drawn out of an engine. So it is solvable.

It's called brain storming.
_________________
☮️

[Sodo]

Engines designed for PCV probably had seals designed for vacuum. Engine oil does not foam. Overfilling the engine, where the crankshaft slaps the oil into a foam, and then the oilpump sucks foamed oil and can't build any oil pressure, is a pretty certain method to spin a rod bearing.

If a transmission were to foam its oil, and you could find a location that's NOT foamed--- its conceivable that air could be pulled out that's NOT oil-laden.

Does a vacuum reduce foaming, and how? In my simple mind, pressure would keep bubbles compressed, and a vacuum would increase foaming.

Anyway YES this thread is to discuss the attempt to improve oiling the hot 4th gear idle & mainshaft bearing by overfilling. And solving the problems as they come, and thanks for the interest and the brain-power!

Tom Lengyel has been overfilling his transaxle for about 10 years now, and doesn't have any problems to report either way, and does not know the volume added, he just knows it's more. He has not done any overfill temperature testing with overfilled trans, and is now onto pumping/filtering/cooling. Need other volunteer help for this.
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[boof1306]

The axle seals tend to leak if they are overfilled and I thought the 15mm service bulletin was related to that. Greg

[Jake de Villiers]

[Syncro Jael]

Sodo,

I have been overfilling my last (2)two transaxles. Not much but I also thought about the advantages of having the oil level higher to help keep more moving parts in a bath of gear oil.

I generally just jack up the passenger side and the van is also parked on a slight incline with the nose up. I fill until the filler bung hole is really loosing oil and slap on the plug.

Over the past two years I did notice that in the summer I would loose gear oil out the breather tube. I installed a catch can and routed the breather to the bottom of it and it catches all the gear oil then when cool it sucks it back in. This catch can has been on the van for over a year and a half. I have not had any seals leaking and have had no ill effects from keeping the transaxle a little full. IDK but I do like knowing there is a higher level of gear oil closer to an already starved main bearing.

As documented my gear oil temperatures usually run 60-70°f above ambient without using the cooler fan. Unless really pressed in third gear up a long grade the gear oil will never reach 150°f. Most of the time it is in the 130°f range during the summer. It struggles to reach 120° during the winter.

Just FYI I am running Swepco 202 full synthetic. Hopefully this information does help to answer your post.
_________________
1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat)

[benandmj]

I measure liquid levels for a living. I agree that pressure keeps bubbles compressed. Many facilities with bulk liquids that have foaming potential keep a pressurized nitrogen blanket on those tanks.

If the oil in an overfilled transmission were foaming it would need somewhere to go. My Syncro breather tube is not connected and filled via Ron’s described method. I just ran 300 miles in 95*F South Georgia and my case is dry. I like the catch can idea too.

Wish I’d thought to take my FLIR.
_________________
85 Westfalia Weekender
91 Syncro Westy

[Abscate]

Didn’t work, sorry Mark

I put a Dyson behind the transmission on a short line and no luck, it still foamed
_________________
.ssS!

[Stuartzickefoose]

Keep in mind it can’t be static vacuum or pressure, it will fluctuate with heat and cool cycles, so it would have to have a pump to create the desired pressure, positive or negative.


On of the best ideas I ever saw was to seal the breather with a bellows to completely seal the transmissions off, as the breather let’s dirt and dust in. Clean oil last much much longer...
_________________
Stuart Zickefoose

2011 Jetta Sportwagen TDi 6 speed manual

206-841-7324
[email protected]

[Sodo]