3.27 diff vent seeping

[awolff280sl]

Hey Dan, while the rubber diff hose I installed did eliminate my vent seepage, my diff does run hot, too hot to touch after some drives. I think I need to get around to taking its temperature. So far I've driven a few thousand high speed highway miles without a problem, but maybe I've been lucky.

[Benz Dr.]

WOW - thanks Dan,

"OVERFILL", don't go there !!!    Your post was greatly appreciated - at least a full day's worth in the lecture room !!

Cheers mate,

Hank

Thanks Hank.
It's really only an educated guess at best but close ovservation over the years around all sorts of equipment helps a bit.
 
I'm doing a 4.5 axle for a guy right now and I plan on removing the cooling tube. I wouldn't, under any circumstances, alter the frame of the car just to fit the tube.
One thing to note: the 4.5 vent is placed differently than on 113 cars. The ones with a vent on the left axle tube never give trouble and axle only starts to leak if the seals are worn or the vent tube is plugged.

If the axle is running really hot then there's something wrong with it. I'm no expert on rear axles but they normally get warm much like a standard trans. If anything, I wold expect the trans to be even warmer than the axle but never be '' burn your hands '' hot simply because of proximity to the engine. The rear axle is not near any other heat source and should be fairly warm to the touch.

With the car on a hoist and the axles hanging down, I use my littler finger to feel the oil level. You should be just able to touch the oil using this method. If oil comes out of the axle any time you remove the fill plug it's way too full.

[Michael C]

Okay, so at this point I’m really confused.  About 15 years ago, I installed my 3.27 rear end in my 1970 113.  I read up on doing the conversion at that time, it recommended plugging the metal vent pipe with an early oil pan drain plug. (Of which I did).  I have never had any problems with leaks, and I don’t believe the rear end gets too hot.  I have put about 70k miles on the car in this configuration, and now after reading this thread I’m a little concerned about not having the vent at all.  I plan on doing a long road trip in the near future, Should I attach a rubber vent set up or not?  What sort of filter is on the end of the tube?

Michael

[GGR]

I think you are confusing two things : the cooling pipe that can be plugged with oil pan drain plugs, and the vent, which is on the top right of the center housing, and which is too small to be plugged by an oil pan plug. So I doublt you did that and I think you're fine if you're not blowing oil through the vent and if your oil level is OK.

[pagoden]

I'm happy to see serious consideration given to this topic; it's made me a little crazy for some time, and we may not get to the bottom of it for awhile yet.  Thanks for sharing your experience and acuity. 
 
Particulars in my bout with the disease are that several members and I disassembled, cleaned and inspected a very decent 3.46 axle after PUB 09.  The diff assembly per se looked to be 100% and Joe and I left it alone - - see Benz Dr.'s weigh-in on that one in a post above.  Wear of any kind was hard to find anywhere, though somehow there was a parts bill of several hundred dollars all up, mostly for gaskets, seals and external fitments.  I left for home and other issues.  Joe assembled it -- without the external Tube -- over time as his schedule permitted, even to the inspection paint codes.  He filled it with Valvoline synthetic lube, and I doubt very much that he overfilled it: how many has he filled in the last quarter-to half century?  I drove it home at Interstate speeds, savoring the 3.46 ratio.  At the end of the ~300 mile trip, the rear 15-20% of the car was a slimy mess, under and above.  Lube definitely did still remain inside, but little and only discernable in the axle tubes.  The differential housing was just comfortably warm and has not made any noises at all, ever, so apparently it was caught in time.  I subsequently re-installed The Tube, modifying it to fit, drained and refilled the lube.  [Drained fluid was filtered thru coffee filters and yielded zero sediments of any sort to the naked eye.]  Beyond a few sessions re-tightening the poor threaded fittings -- tested mightily by the alteration process but proving quite stout -- it has been fine ever since.
The car and our relationship being what it is, actual mileage accrued over the intervening year and a half hasn't amounted to more than a few thousand miles, but did include several hundred- and two-hundred mile outings plus another round trip to Ohio for PUB, which entails two 250+ mile runs at speeds over 80mph in some states. 

Michael - Yes, the vent is separate from the U-tube.  It's located up high on the central differential case, smallish and hard to see and reach after the whole shebang is installed underneath the car.  The Tube, absent in your case, is for circulation of the lube and doesn't directly involve venting of anything.  It's  purpose may have been for cooling the lube in it's more demanding original duty under much heavier sedans. Ours shouldn't need it, it gets in the way, and it works out fine in most cases to just leave it off.
However, for some unfortunate wretches among us.....  Oh, let me put it another way: you live right, don't you?  Well, I liked to think I did, too.  And then this.  I tell you; it just shakes your faith in the fairness of things.  As for you and all the others like you, go Tubeless and enjoy, lucky so-and-so's!                         : )

Denny

 
       

[twistedtree]

This may be totally obvious, but I seem to recall that it's important to check/set the diff oil level with the car flat on the ground.  It had to do with oil running out and down into the axle tubes resulting in false readings when the car is jacked up or on a lift and the tubes are sloped downward.  Could the oil spewing problem be as simple this, i.e. we check oil level on a lift, then as soon as we lower the car all the oil out in the tubes pours back in creating an over-full situation?

[pagoden]

You recall correctly, Peter and yes, it is important to not get fooled into overfilling by axles that are not level/horizontal when filling/checking axle fluid level.  It's a touchy proposition; a little bit off makes more difference than you might think. The car should even be level fore-and-aft as well, though it's not nearly as important as it is to eliminate any and all axle 'droop'.  [An inexpensive magnetic-mounting caster/camber gauge works well for this on both the axle and the door sills.]  More is not better here: just a little low will work fine.  And it is hard to doubt that some of the lesser outflows have been caused by overfilling.  But as I mentioned in my post just above, surely someone such as Ja17, who has been servicing and refurbishing this type of axle for decades, would assemble and fill one properly.  I have no doubt mine was.
Further, it seems reasonable that outflow caused by overfilling would be self-correcting.  That is, when enough loss occurs to lower the fluid to the correct level, hasn't the cause been eliminated and so the outflow should cease?  But when I looked into my situation I could find fluid remaining inside of the axle only by removing the plug from the U-tube mount location down on the axle tube, where I could reach a fluid level with my finger.  That's a heckuva lot lower than the proper level.  Something else is going on.

Denny  

[Benz Dr.]

I think I may have come up with a viable solution for this problem.

The vent on the 4.5 axle is different than on the regular six cylinder cars. The 4.5 axle is designed to be stronger due to the heavier car and there are several places where they used larger fixing screws and heavy duty parts.
 
The vent on the 4.5 is placed at the top of the diff housing facing away from gear rotation. If you remove the vent you will be able to see that the internal diameter is considerably larger than the vent that's placed on a car where it's on the axle tube. The threaded hole on the 4.5 unit is probably 14 mm whereas the earlier axle vent is a 10mm thread. Inside any vent tube you should be able to find a felt wick which is supposed to prevent oil from making its way up and out of the vent. The vent on the 4.5 has a lot of oil splashing around right near the opening in the casting and I think this is where the problem starts. It's also possible that the wick fell out so that's something to check.

My cure for this is to go back to the original set up found on earlier axles. On the left axle tube, you will find a protusion in the casting on the 4.5 axle where the vent would normally be found at the top of the axle, right next to the difff housing. We drilled and tapped a hole in this casting to accept the smaller vent found on earlier axles. There is little to no oil splashing around in this area as it's well behind the main carrier bearing on that side of the gear set.

Since we had the whole axle apart ( except for the pinion shaft ) is was fairly easy to drill a hole in the casting. We placed a tap in the drill press so that it would start perfectly into the hole and then carefully turned the drill press by hand. It's not possible to be able to use a regular tapping handle due to the diff housing being in the way.

Since regular diff vents on six cylinders cars usually don't have any gear lube spewing out of them, I'm thinking this will work the same way on the modified 4.5 axle. If it doesn't, we'll use a modified return hose or pipe but I have a feeling it will work just fine.
 
Due to the extra heat produced in the axle by the 4.5 sedan, the set up they used was the perfect answer. The circulation tube and a larger vent placed high up on the axle to bleed off any excess heat was the answer. Since this set up requires some modification for the 113 I think this is the extra part of this mod that could be the answer. It's also easily reversed if you decide you want it the other way. You will need two diffrent sized plugs to close either hole depending on which vent you end up using and where it's placed. 

Of course, you need to do this before you install the axle. We removed all of the screws that hold the left axle tube to the diff carrier mostly so we could clean it up better. While we had it apart the idea came to me but I had been thinking about how to fix this problem over the weekend.

 The hole drilled through the casting enters inside the axle tube just behind the outer race for the main carrier bearing, right where the casting is at about a 45 degree angle. This can't be seen unless the axle tube is removed but there's no chance of hitting anything important. If you decide to try this idea without taking the axle apart, use some grease on your drill to prevent any chips from falling into the axle tube.

We will monitor the axle temps and see how it works. 

[stickandrudderman]

So Dan, how did it go?

[GGR]

I did it on my Pagoda and it works perfectly. The other option is to fit the left wheel tube of later Pagodas rear axle (yes it fits) which already has that vent and block the vent on the center housing. This option may require checking the adjustment of the left differential bearing outer race, which is done by adding or taking out shims behind it.

[rbouch8828]

I am wondering if any (all) of you who have made the with to the 3.27 rears, have replaced the entire rear end, or do you keep any of the old parts? Also, have you been breaking down the replacement rear end and cleaning and re-painting? What has your process been?

Best,
Roland

[Benz Dr.]

So Dan, how did it go?

I am unable to say because we sold the axle. No complaints though.

[Benz Dr.]

I'm happy to see serious consideration given to this topic; it's made me a little crazy for some time, and we may not get to the bottom of it for awhile yet.  Thanks for sharing your experience and acuity. 
 
Particulars in my bout with the disease are that several members and I disassembled, cleaned and inspected a very decent 3.46 axle after PUB 09.  The diff assembly per se looked to be 100% and Joe and I left it alone - - see Benz Dr.'s weigh-in on that one in a post above.  Wear of any kind was hard to find anywhere, though somehow there was a parts bill of several hundred dollars all up, mostly for gaskets, seals and external fitments.  I left for home and other issues.  Joe assembled it -- without the external Tube -- over time as his schedule permitted, even to the inspection paint codes.  He filled it with Valvoline synthetic lube, and I doubt very much that he overfilled it: how many has he filled in the last quarter-to half century?  I drove it home at Interstate speeds, savoring the 3.46 ratio.  At the end of the ~300 mile trip, the rear 15-20% of the car was a slimy mess, under and above.  Lube definitely did still remain inside, but little and only discernable in the axle tubes.  The differential housing was just comfortably warm and has not made any noises at all, ever, so apparently it was caught in time.  I subsequently re-installed The Tube, modifying it to fit, drained and refilled the lube.  [Drained fluid was filtered thru coffee filters and yielded zero sediments of any sort to the naked eye.]  Beyond a few sessions re-tightening the poor threaded fittings -- tested mightily by the alteration process but proving quite stout -- it has been fine ever since.
The car and our relationship being what it is, actual mileage accrued over the intervening year and a half hasn't amounted to more than a few thousand miles, but did include several hundred- and two-hundred mile outings plus another round trip to Ohio for PUB, which entails two 250+ mile runs at speeds over 80mph in some states. 

Michael - Yes, the vent is separate from the U-tube.  It's located up high on the central differential case, smallish and hard to see and reach after the whole shebang is installed underneath the car.  The Tube, absent in your case, is for circulation of the lube and doesn't directly involve venting of anything.  It's  purpose may have been for cooling the lube in it's more demanding original duty under much heavier sedans. Ours shouldn't need it, it gets in the way, and it works out fine in most cases to just leave it off.
However, for some unfortunate wretches among us.....  Oh, let me put it another way: you live right, don't you?  Well, I liked to think I did, too.  And then this.  I tell you; it just shakes your faith in the fairness of things.  As for you and all the others like you, go Tubeless and enjoy, lucky so-and-so's!                         : )

Denny

 
     

This remains a viable axle ratio and I wonder why there is so little interest in it. This ratio is very close to what a 5 speed trans will give you in high gear and should not be over looked.

[GGR]

I agree, but it is quite rare on the US/Canada side. And even the 3.27 is getting quite rare today.

[stickandrudderman]

I'm just in the process of fitting the 3.46 to a customer's car and have opted to cut a relief into the chassis. it seems the easiest and most reliable option to me.

[GGR]

Did you live a hole there? Or you reshaped some metal to close the hole?

[stickandrudderman]

We'll be fabricating a repair panel to weld in and return the strength.

[GGR]

Did you already cut the relief? If not, and as metal work is involved anyway, you may consider modifying the tube instead. With 2 of them you may be able to fabricate one that clears.

Otherwise, I crossed the US twice round trip with my V8 Pagoda and drive it hard regularly. I don't have that pipe and I've had no issues so far.

[stickandrudderman]

I don't like to experiment with customer's cars; I prefer an option that guarantees results. If it was my car I would certainly experiment with other options.

[GGR]

I was talking of the cooling tube in my previous message, not the wheel tube.

If your client is ok with cutting the relief, then it is certainly the most elegant solution technically speaking.

[TheEngineer]

I have run a 3.27 axle for years! It is wonderful! Dan - I so love your insight with mechanical things! You are very talented!

[Benz Dr.]

Well gee, thanks! Coming from you that's a compliment I'll always cherish. I guess mechanics always came easily to me and carpentry not so much. Being interested by mechanical things, I always wanted to know how something worked because you can't fix much if you don't know how it works.

Some of you may find it hard to believe, but I'm entirely self taught and it was through talking to other mechanics, machinists, body men, and guys who love old cars that I was able to put it all together. Depending on how you look at it, this may be my last year in the restoration biz as I've been at it for 40 years and I don't have the help, energy, or real desire to continue on. I'll finish those projects that we are working on right now and then I have a couple of my own because I want to do them before I'm unable. I will still do general repairs and tune ups for as long as I can but full restorations might be a thing of the past.

 I often wonder what I could have done with formal schooling and training............ 

[Shvegel]

I am pretty much with Dan straight down the line as far s the rubber hose being an insulator and all.  I am wondering if perhaps there is any sort of "Slinger" on the center section that causes more oil to be thrown up to the top of the rear axle on the 3.27 rear axle as opposed to the higher (Numerical) ratios? 

I am also wondering if the people doing the conversions are moving the vent to the boss on top of the left housing???  Without the cooling tube in place the location of the vent on the 3.27 might be more prone to oil splash being forced out the vent and the rubber hose is just giving some of the oil a path and cutting down on splash through the vent.

[TheEngineer]

For those of you who might be interested: my 3.27 differential started leaking. I found some oil on the garage floor. One small leak was from the drain plug. I unscrewed it about 3/8 inches only because I did not want to drain the oil and wrapped it with Teflon sealing tape. Then tightened it. It has stopped leaking. The other leak came from the vent pipe on top of the differential housing. I wedged a napkin underneath and found that it leaks only after a prolonged drive. I unscrewed the vent pipe. it was loose. Attached is a picture. There are two seals: an o-ring and a flat seal like a garden hose seal. I put some Permatex tread sealer on and we shall see.

[Benz Dr.]

I use a sealer that comes in a tube which I believe is also Teflon. This stuff stays soft and will seal up just about anything that's threaded.

  I thought about why some 3.27 axles run hot or spew oil out everywhere, and why some are near prefect, and can really only come to one conclusion. Something is different inside the axle. My best guess is that some are in good shape and some aren't, or are worn in some way.

Before I even think about installing any axle I check for gear play at the crown and pinion as well as the internal gears inside the carrier. By holding the pinion flange and turning either wheel it is possible to get a rough idea of what's going on inside the axle. Moving the pinion flange only enough to feel any play should give you a basic back lash reading. Not very scientific but generally you should just be able to move the pinion flange a very small amount. If I find anything more than just a nominal amount I usually pass on using that unit. I can't really say how to do this exactly. It's sort of a feel thing but if you do feel something that seems like a lot of play I would advise not installing that axle.

 Maybe those who are having running problems could do a little checking and see if in fact they have wear problems. Something is causing this - guessing isn't good enough and there is a reason for it. I suspect wear of some sort. These are used pieces and there's no telling how the car was driven or cared for.