Dana 300 question

I'm sorry if I posted this in the wrong area.

I've searched the web and haven't figured out my problem so I figured that I should ask those who would know. My question is: why does my Dana 3oo blow fluid out the vent hose and what can I do to remedy it?

Mt senerio:
82 D300 freshly rebuilt
4:1 tera lo gear set
Clocked flat with Novak 4l60E adapter
80/90w fluid w/ 1 qt of Lucas oil
It doesn't mater whether the outside temp is hot or cold or how hard I am wheeling it.

This is driving me nuts and making my wife very mad that my Willys wagon is marking it's territory.

Any help is appreciated,
Steve

 

If its clocked flat most likely overfilled. I'd ditch the oil additive too and see if it makes a difference.


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That is what I was thinking but I put in just over 3qts. total. It seems like there is a quart that has bubbled over onto my driveway not to mention the roadways and trails that I have been on lately.

Is there any truth or advantage of using ATF in the D300?

Is there any set distance from the T-case to the vent hose?

Steve

 

The vent hose from the factory is at the highest point on the rear output housing where it's fairly shielded from splash. When you clocked it up did you relocate the vent or is it now canted to the driver's side? If so that could also be part if the issue.
Do NOT use ATF with a 4-1 kit unless you want to burn up the gears, shafts, and bearings. I wouldnt run atf in any gearbix that calls fir gear oil. just makes no sense. would you put gear oil in an automatuc transmission?
The tapered roller bearings alone require the heavier gear oil for lubricity and heat dissipation. Add the extra load, thrust as well as radial of the lower gear set and the EP oil is even more important. The shear properties, anti foaming, viscosity, etc. all come into play here.

I don't recall the exact recommended capacity off the top of my head but the quantity you posted seems pretty high. I can try and find the correct capacity tomorrow.


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Although I believe clocking the transfer case flat and then overfilling the case with lubricant may contribute to the problem you are having, I don't believe it is the actual cause. I believe you are experiencing foaming of the with-in the case. The reason I say this is, my Dana 300 has not been clocked yet I have also had gear oil blow out of the vent. It seems to occur when ever I have been on the trail in 4-wheel drive and then return a road but not turn out my front hubs. This of course causes the front driveshaft to spin at a higher rate of speed than it would normally see when driving slowly on a trail. If I do turn out the front hubs when I get to the road, I don't seem to have the problem of oil blowing out the vent.

 

45es, does yours do it with transfer case in 2 WD but hubs locked in? If so it doesn't make sense to me that foaming would be the cause under these conditions as the only thing turning to the front driveshaft is the front output shaft, no gears. Unless the oil was foamed up previous and the higher travel speed caused it to overflow. If you were in 4wd mode in the transfer case then it would make more sense as the turning gears would whip the oil around.
If the transfer case were overfilled it would also make sense.


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my texas d300 does this it's fine on the trail but getting to the trail at speed usually pukes up the vent hose into the tub .I ran my lines higher and did not have luck attaching a hose to the stock vent so I tapped a air line bung into it and ran the line up... the hose is close to 10 12" long and that is puking oil at speed. t case is filled up enough to stick my finger in the hole and bend it down and that's where oil level is . I figured my problem is the now lack of an oil baffle within the vent .

 

I can't really tell when it's blowing oil out the vent although it really likes to do that on my driveway. The guys at JB conversions say "instead of filling the t-case up to the bottom of the fill plug, remove the upper right bolt from the front output shaft rear bearing retainer and use that as your gear oil level indicator. If you don't, you'll blow oil out the vent in no time!"

I think I need to start from the beginning by draining the fluid, refill with straight gear oil, clean everything and keep an eye on the vent. Then I can check to see when it's coming out the vent. Hopefully there wont be anything coming out the vent.

nickmil, I found an earlier post on the forum that said the oil cap. is 4 pint (2quarts). I'm pretty sure that I overfilled it.

 

Nick, Yes it does do it in 2-wd drive with hubs in. It may be as you theorized, being caused by the oil foamed up and then the higher speed causing it to overflow. The t-case is not overfilled so foaming is what I believe is the cause to the problem.

As cj6/442 has done, I also extended my breather vent line up to a high point in the engine compartment and this did nothing to stop the problem. I am curious as to what you are referring to when you say, "oil baffle within the vent". Do you mean lack of one designed into the vent system or a vent baffle that should be there but missing? I don't ever remember seeing a baffle.

 

The stock 300 vent didn't have a baffle but it did make a 90 degree bend right out of the output housing then the hose ran up to the chassis. Are you guys using a straight vent fitting? If so that could be contributing to the issue. Another idea if you have room would be to put a "curly q" in the hose, or loop so the fluid doesn't have such a straight shot. I also use a cheap clear plastic fuel filter on the end of the hose. I've found both these help keep the fluid in and dirt out. I had the same issue on a rear diff and this helped until I was able to put a baffle in front of where the vent was threaded in.


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Nick, I do have the 90 degree fitting on mine. Originally my vent hose dropped down and then up to create a trap but I thought this may be contributing to the problem. My thought was once oil entered the line it would sit there and not drain back to the case adding to the problem. My vent line is now routed in such a manner that there is a constant upward slope from the 90 degree fitting to the end of hose and vent cap. This did not change anything and the problem persists. Now I just make sure I get my lazy butt out of the seat and turn out the hubs when I get off the trail. Ed

 

mine is straight up and a curly Q was my next try actually.and I thought the same thing that is would just trap oil and then block the vent

 

I drained the d300 today and I had 3 quarts of oil in it. WOW. I guess that's what I get for assuming that I should fill it til the oil comes out of the fill hole. I put 2 quarts in cleaned everything and went for a good long drive. When I got back home I had to checked to see if I fixed the problem. The result .... no fluid came out the vent. Thank you guys so much. My wife and my driveway thank you too.

Steve

 

Even if the fluid fills the vent hose it will still allow air to pass through. Think similar to an oil bath air filter. The oil will sit in the lowest spot. The loop makes it much harder for the fluid to climb out the hose at it has to overcome gravity multiple times. By that time the pressure buildup usually is dissipated enough so it's not quite so much an issue. Not saying its an end-all fix but should help. I know it did for me .


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