Alright, after not really working on my beauty for roughly a year, Spring fever has set in. The last three weekends have been a flurry of activity welding patch panels and prepping for the body and chassis to be mated once again.
Today my MIG ran out of wire so I decided to do some rear-end work while everything is still easily accessible: torquing CV joints, axle nuts, replacing the ATF pan seal, and then I removed the tranny oil fill plug (it doesn't have a drain plug, by the way) and... nothing. There's no oil. The ATF fluid was there as was expected. How odd, I thought. It's supposed to be at the bottom of the threads. Good thing I didn't keep driving her as I was tempted to. Right after my purchase (two years ago?) I drove straight home and began disassembly.
I stuck a clear plastic hose down inside thinking it was just a bit low, but it came back dry. My questions are: what could have caused it to run dry and is there a larger problem looming on the horizon? There's no drain plug on the bottom so that's not it. Is there something internal that could have caused it? Obviously I plan on filling it (SAE 80/90 according to my Clymer manual) and checking for leaks/level once she's back on the road, but is there something I can check in the mean time?
Has anyone ran into this before and do you have any experience you can share?
Raymond
Did you see any ATF in the engine compartment? Or any on the ground? I had a leak from a bad gasket and it thinly coated the whole underside and dribbled out over time.
No, the engine compartment was relatively clean (as clean as a neglected '70 could be) when I originally drove her home. That was awhile ago though. The tranny has a lot of thick, hard stuff baked on the bottom so I suppose that it could have been the oil. However, I don't see any cracks on the outside and from what I can tell, the only entrance/exit is the oil fill plug and that looks fine. The ATF fluid was all there, which is a different part of the tranny. It's quite a mystery.
I guess that my biggest fear is that the internal gears are toast and the tranny will have to be rebuilt.
I pulled out my Bentley Manual and did some more investigating. According to the instructions on changing the Hypoid oil, this is done by loosening/removing the "oil pan." I'm assuming this is talking about the only pan on the bottom of the trans where the ATF fluid can be drained.
If so, does this mean that the two areas are connected somehow? I drained the ATF some time ago and just reinstalled the pan cover. If connected, I suppose I drained them both without knowing. However, this does beg the question, why two types of fluid? Wouldn't they mix together if that was the case?
Raymond,
I am surprised your trans doesn't have a drain plug. Being a '70 it theoretically should have one. Someone may have replaced the trans section with a '71 or later IIRC.
Anyway, your trans needs to filled with about 3.5 litres which is a whole heap. This oil is the 80/90 type that squirts in up at the nosecone fill plug. Seperate from the ATF which is just used in the coverter oil circuit.
If you are worried about what has gone before, I'd pull the trans pan first. At least looking at the R & P will give you some idea whether it's toast or not. Blue is the colour you don't want, or roughened teeth on the meshing Ring Gear teeth where it faces the pinion. Also the pinion for similar type of damage.
Loosened that fill plug first? It needs a 17mm hex socket or Allen key. Got a trans pan gasket handy?
HTH
Volkenstein
Quote from: Raymond73 on 01 April 2012, 02:50
Alright, after not really working on my beauty for roughly a year, Spring fever has set in. The last three weekends have been a flurry of activity welding patch panels and prepping for the body and chassis to be mated once again.
Today my MIG ran out of wire so I decided to do some rear-end work while everything is still easily accessible: torquing CV joints, axle nuts, replacing the ATF pan seal, and then I removed the tranny oil fill plug (it doesn't have a drain plug, by the way) and... nothing. There's no oil. The ATF fluid was there as was expected. How odd, I thought. It's supposed to be at the bottom of the threads. Good thing I didn't keep driving her as I was tempted to. Right after my purchase (two years ago?) I drove straight home and began disassembly.
I stuck a clear plastic hose down inside thinking it was just a bit low, but it came back dry. My questions are: what could have caused it to run dry and is there a larger problem looming on the horizon? There's no drain plug on the bottom so that's not it. Is there something internal that could have caused it? Obviously I plan on filling it (SAE 80/90 according to my Clymer manual) and checking for leaks/level once she's back on the road, but is there something I can check in the mean time?
Has anyone ran into this before and do you have any experience you can share?
Raymond
Hi Raymond
the ATF and Hypoid oil are independent to each other..
the ATF drives the car - ATF pumped at engine into torque converter which is connected to the gearbox.
Many people don't check the gearbox as some of the manuals say it never needs replacing??
and HYPOID oil is the one..
as Sean suggested You need a gasket [evw and CIP1 normally have them]
unless You can see where the gear oil has leaked out?? maybe it did or the PO had drained it???
Hypoid oil smells terrible so its easy to identify.. I have read where its recommended to drain the hypoid oil from the gearbox if the car is going to be standing for the winter months etc.. and fill with engine oil to stop the hypoid oil from attacking the zinc bushes etc in the gearbox.
cheers
Lee in Australia
Volkenstein,
I suppose someone could have swapped it out with a newer trans. If only she could talk. Anyway, I pulled the pan down yesterday and cleaned it up. There was a small amount of thick oil at the bottom (a few tablespoons) and yeah, it smelled awful. The gears are silver and appeared to be free of damage. No silver flecks were visible in the oil either.
Incidentally, I drained the ATF roughly a year ago and buttoned it back up. My intention was just to leave it that way until I was ready to rebuild. I have a new gasket installed, but have not refilled anything yet. It seems that for my year trans, both the ATF and Hypoid oil get drained the same way. That tells me that the fluids are able to mingle together ever so slightly with, I assume, no issues. Interestingly enough, the Clymer manual said that I could even use ATF on both sides if the temperature range was below -13°F. North Dakota can get cold in the winter, but it definitely won't stay that cold long enough to justify using ATF in place of oil even in winter. Above 0°F it recommends SAE 90; between 0°F and -13°F, SAE 80.
I probably can't refill one side with gear oil without following it shortly thereafter with ATF on the other. The thickness of the gear oil will slow it down, but without any resistance on the ATF fluid side, it will probably make its way over to the drain pad in a short time and level out.
I think I have my answer, at least the theory seems sound.
Thanks for weighing in on my dilemma.
Cheers,
Raymond
Thanks, Lee. I think I have it figured out now. Not having a dedicated hypoid oil drain confused me. I expected to see some oil when I pulled out the fill plug, but when I didn't I guess I panicked.
Cheers,
Raymond
Hi Raymond
I just wrote a very long reply to Your posts... and it all disappeared as I had timed out...?? lol
You need Hypoid oil in Your gearbox as its actually a transaxle with the Differential in there too..
The Differential needs extreme pressure hypoid oil as there are large surfaces on the crown wheel and pinion [differential]
I am using CASTROL SYNTRAX 75W/90 A FULL SYNTHETIC API GL5 EXTREME PRESSURE GEAR OIL WITH EXCELLENT SYNCHRONIZER PERFORMANCE. A full synthetic transaxle and manual transmission oil.
its an excellent oil , nice and thin, extremely expensive, and can leak anywhere it can..
[many VW owners have all experienced the same problem]
My gearbox doesn't leak or drip oil, its just that its always oily to touch the sump plate..
I have been thinking lately that it may be coming from the bushing/seal on the nose cone [gear selector shaft]
I replace the one on My original gearbox but I'm not sure whether I did this one..??
cheers
LEE in Australia
(http://inlinethumb61.webshots.com/47228/2351416250050767931S425x425Q85.jpg) (http://rides.webshots.com/photo/2351416250050767931emcFMu)
I'm kind of confused as to what you mean by the atf and gear oil drain the same way and are allowed to intermingle. That is definitely not the case. The atf operates in a contained loop between the tank, the oil pump and the converter (via channels in the bellhousing).
The gear oil, on the other hand fills the actual gear box and is basically used as splash lubrication for the gears and synchros. Normally you would have a drain plug on the bottom of the pan, if not then the only way to drain the gear oil would be by removing the pan. After installing a new gasket and reinstalling the pan, simply fill the trans up to the bottom of the fill hole on the side of the case.
The atf should only enter the bellhousing, go into the torque converter, and then leave the bellhousing back to the tank, here.
(http://i44.tinypic.com/sflcle.jpg)
You should have no intermingling of fluids. That would be a bad thing as atf cannot handle the extreme pressures of the differential gears.
I think I might be misunderstanding something. Please tell me, when you loosen the drain pain on a transmission (type without a drain plug for the oil), what would I expect to drain out?
There are two distinct areas that has me confused. (1. the area with the fill plug, and 2. the area with the drain pan). Are these both filled with Hypoid oil via the fill plug near the nosecone? When I looked up inside the drain pan area they didn't appear to be connected.
That is all hypoid oil. The nosecone, gear cluster, and differential are all connected but it's very hard to see from the differential opening. When you take the pan off, all of the hypoid oil should come out. When you fill through the fill plug you will be lubricating the entire trans interior. Take a look at my "teardown" post for some good interior pictures that might clear this up for you.
Wow. :-[ I don't know what to say, but thanks. It all makes sense now.
Quote from: Raymond73 on 03 April 2012, 16:21
I think I might be misunderstanding something. Please tell me, when you loosen the drain pain on a transmission (type without a drain plug for the oil), what would I expect to drain out?
There are two distinct areas that has me confused. (1. the area with the fill plug, and 2. the area with the drain pan). Are these both filled with Hypoid oil via the fill plug near the nosecone? When I looked up inside the drain pan area they didn't appear to be connected.
Hi Raymond
ATF is only in the torque converter and hoses and pipes connected to the ATF PUMP at the rear of the engine..
so, these are a complicated machine... lol
the engine is not connected to the gearbox.. the engine atf pump drives the torque converter which is connected to the gearbox thru a clutch... and We haven;t even mentioned electric control valve which controls the vacuum which works the clutch...
cheers RAY
LEE in Australia