Dana 300 Blowing Oil

NickMaul

NickMaul

Well-Known Member
Joined
Jul 4, 2009
Location
Norfolk, VA
NC4x4,

I am all about some dana 300 knowledge lately. So I am doing shakedown runs on the dana 300 complete rebuild with 4:1 gears flipped behind my ax15. I ran highway speeds for say 15-20 minutes then started getting wiffs of diff oil in the cab.

I have routed the breather tube to the same spot as the old tcase breather, right next to the master cylinder. Now since I am flipped the vent is different. As you can see below I tapped the tcase for a sight tube/vent combo. It ran street speeds just fine but as soon as I started doing 55 the oil started coming out.

Here is the vent/sight set up(minus the tube).
0F0F4330-4CBC-4681-A1D2-F4A9AB16320E_zpsizfjuzif.jpg


So I first filled it up to the bolt next to the intermediate shaft. I feel like that may be too high. So I drained it another half of a quart.

I am going to give it another run on the highway to see if it comes out of the vent line but as long as the gears are slinging the oil I shouldn't have a lubrication problem right? Like there doesn't have to be a puddle of oil in the case all the time if the gears are flinging it around?
 
if it was me, I would build and mount a collection canister with a vented cap that will drain back into the t-case.


Then forgetabout it.
 
Jeff B said:
if it was me, I would build and mount a collection canister with a vented cap that will drain back into the t-case.


Then forgetabout it.
Click to expand...

I agree with this. Anything I could grab at a parts store? (Shot in the dark)


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It's probably overfilled. Fill it to spec and try again. I like the collection canister idea also.
 
if your good with a welder & a drill and NPT tap. you just need a pipe or some square tube. Plate one end closed. make a cap that bolts on with a rubber seal for the top. tap a hole for the vent in the top cap. Two tapped holes in the side. Top hole will be where the blowing oil goes in & the bottom side is where it drains back top to tcase.
 
grapehead said:
It's probably overfilled. Fill it to spec and try again. I like the collection canister idea also.
Click to expand...

I know there are differences between clocked and unclocked cases but if the oil level is high enough to get to the rear output bearings I should be good right? These are the highest bearings that aren't in the path of slung oil.....


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Jeff B said:
if your good with a welder & a drill and NPT tap. you just need a pipe or some square tube. Plate one end closed. make a cap that bolts on with a rubber seal for the top. tap a hole for the vent in the top cap. Two tapped holes in the side. Top hole will be where the blowing oil goes in & the bottom side is where it drains back top to tcase.
Click to expand...

I like this and I have the materials but I am trying to ride Potts mountain this weekend and have to leave at 3 today. Barf.


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I have a flipped 300 in my TJ, it will push oil out of the breather if the fluid level is over half way up. If the oil level is half or a little under I don't have any issues. I have a sight tube in the same location as you, but my vent is in the top of the tailshaft housing.
 
I was sitting here trying to remember if my D300's even had a vent, then @Pless reminded me the
Pless said:
vent is in the top of the tailshaft housing.
Click to expand...
 
I've always read to fill halfway up the center shaft. It looks like the distance from the center to bottom ("A" in the picture below) is shorter than center to top, could just be the angle of the picture though.

I would try to match that when filling yours and see what happens.

D300.PNG
 
orange150 said:
I've always read to fill halfway up the center shaft. It looks like the distance from the center to bottom ("A" in the picture below) is shorter than center to top, could just be the angle of the picture though.

I would try to match that when filling yours and see what happens.

View attachment 250177
Click to expand...

That is pretty much where it was when it started blowing out the vent. I am going to try and get it level to the rear output bearing then forget about it. Hopefully I don't ruin a rebuilt case :D


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Loganwayne said:
if it only does it at highway speeds forget about it till you get back.... unless you gotta drive it there
Click to expand...

Yep. No tow rig. 15 minutes of highway and she's still leaking bad. Looks like the XJ will be a driveway ornament for the rest of the month.
010c999684968b37508ce3260900c3a8.jpg



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orange150 said:
I copied distance "A" and pasted it below to "A Copy" try filling it up to that mark and see if it blows still.

View attachment 250180
Click to expand...

So my oil level for the last two test rides were in between the intermediate shaft bolt and the bolt at the 8 o'clock position on the rear tailhousing.

After a few hours of digging through the internet here is what my plan is....
  • Bump the vent hose line from 1/4" to 3/8" and add a twist to it
  • Obtain/fab a new catch can at the end of the vent line under the hood
  • See what jb conversions has to say about gear "break in" if there is any at all. So far I probably have about 75 street miles on the gears
 
NickMaul said:
I actually hit the thrift stores this weekend and snagged one with pipe threads. Should would just like the guys on pirate have. I'll post a write up once it is done.


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Click to expand...

Drumming up an old thread....

What ever happened with your oil blowing issue? I have the same problem now.
 
justjeepin86 said:
Drumming up an old thread....

What ever happened with your oil blowing issue? I have the same problem now.
Click to expand...

I ended up putting the breather as high as I could on the inspection cover. Put the hose as high up as I could and added a catch can. I assume yours is flipped too? I also added a bit of ATF to try and calm down any foaming, but I don’t really have evidence it actually worked.

If I were brave enough I would have drilled and tapped a breather on the rear output similar to stock. All of that gear oil slinging around is bound to get inside the breather hose...

Here is a picture of where it was.
dd5369a79c2701f4858eec11c980a501.jpg



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Mine is actually pretty high. I have a billet cover I made and it's vented close to the highest point. Im thinking the main problem is where we have them. The oil slings to the vent, then the escaping air just pushes it out. The tail shaft cover is probably the real fix.
And I am flipped.
Thanks

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justjeepin86 said:
Mine is actually pretty high. I have a billet cover I made and it's vented close to the highest point. Im thinking the main problem is where we have them. The oil slings to the vent, then the escaping air just pushes it out. The tail shaft cover is probably the real fix.
And I am flipped.
Thanks

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Click to expand...

That sounds like a solid plan. I sold my Dana 300 earlier this year. However, I never had any issues once a catch can was added. The only oil I lost from the case came from the leaky shift rails :D




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