How much does transmission fluid expand?

# Thread: How much does transmission fluid expand?

1. ## How much does transmission fluid expand?

Just wondering if someone knows how much transmission fluid expands under different temperatures? What I am trying to figure out is how much to fill. It seems that it is expanding almost 50% at about 250 degrees as what it was at 100 degrees. For example, if I were to start with 1 quart at 100 degrees it would expand to 1 1/2 quarts at 250 degrees. Any input would be great!

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3. Not even close. More like less than an ounce. Do you think that if you put a quart of ATF in a 2 qt pan and heated it to 250 it would fill the pan to 3/4 way. Not hardly. You MIGHT raise the level a 1/4 inch. Probably closer to 1/8"

4. Originally Posted by gn7
Not even close. More like less than an ounce. Do you think that if you put a quart of ATF in a 2 qt pan and heated it to 250 it would fill the pan to 3/4 way. Not hardly. You MIGHT raise the level a 1/4 inch. Probably closer to 1/8"
Ok so can you explain to me why my jet a way fills up and overflows a 1oz reservoir on top of the pump even with the fluid level in the jet a way lower than what it is supposed to be? I only fill it about half way and it expands so much that it flows out the top of the overflow reservoir.

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6. It building pressure up inside the jetaway? A v-drive will do the same thing if you over fill it just a touch, and really badly if it isn't vented. It will blow oil all over hell.

7. Originally Posted by gn7
It building pressure up inside the jetaway? A v-drive will do the same thing if you over fill it just a touch, and really badly if it isn't vented. It will blow oil all over hell.
So whats the solution? Take the reservoir off, put the zerk back in and run it a little low???

8. I don't know who made the reservoir, but my guess is the pressure is trying to get out thru the reservoir and blowing the oil out. I don't know why you would have ever had a zerk in there. some v-drives have a spring loaded vent that looked EXACTLY like a zerk, but wasn't. If you removed "zerk" and installed a reservoir in its place, I would think the reservoir should have had a place to install the "zerk"(vent)
Back to the pan, if you did the same thing with the oil, you would not be able to hold a lid on the pan using all you body weight. But its not the oil that is expanding so much, its the air.

9. Wrong fluid type, over fill, lack of venting, are a couple things that can cause this. The oil level does not stay put when the bearings are spun up, the oil will start to wrap the cavity, and expand. The jet-a-way only needs to be fill half way, on the bearing, the rest is open air. The system needs a vent, for expansion and contraction, not necessarly a resivoir.

10. OK well I am using HTP jet a way fluid, filling it to where it is supposed to be filled to and it still leaks. The zerk I removed to put the reservoir on was the one that comes on every jet to grease the packing. With a jetaway though the packing is no longer greased it is lubricated by the jetaway oil. I am definately perplexed. I have talked to many guys that have them and just about all of them leak but I am trying to solve the problem rather than say "well they all leak." Looks like it is going to be a while!

11. If the jet away is vented in some fashion other than the reservoir, why couldn't you run a tube from the top of the reservoir back to a point above the fill line. It sounds like who ever makes the reservoir knows that oil is going to travel into the reservoir. Thats what is lubing the packing now.

How does a jet away vent pressure?

12. Originally Posted by gn7
If the jet away is vented in some fashion other than the reservoir, why couldn't you run a tube from the top of the reservoir back to a point above the fill line. It sounds like who ever makes the reservoir knows that oil is going to travel into the reservoir. Thats what is lubing the packing now.

How does a jet away vent pressure?
U cant run a tube because when you put the jetaway in gear the fill hole and sight plug are then covered. I got the reservoir from grainger so it really isn't intended for a jetaway. There is no other vent in the system. It is a closed system without the vented reservoir. I had just a slight leak on the bottom before I put the reservoir on. I ran the boat with the reservoir with low oil and no leaks. Then I filled it to the proper level and the reservoir became a geyser and oil rushed out and all over the transom and in the bilge area. This is a headache.

13. well, it is now using you reservoir as a vent. If there is oil in the reservoir, its coming out. Why not fill it to the fill point on the jet away when it doesn't have a reservoir, and leave it at that. Why do you feel compelled to run a reservoir? Where compared to the "Fill point" does the reservoir tie into the jetaway level wise.

I don't see how you can make this work. Anybody else doing it?

14. Originally Posted by gn7
well, it is now using you reservoir as a vent. If there is oil in the reservoir, its coming out. Why not fill it to the fill point on the jet away when it doesn't have a reservoir, and leave it at that. Why do you feel compelled to run a reservoir? Where compared to the "Fill point" does the reservoir tie into the jetaway level wise.

I don't see how you can make this work. Anybody else doing it?
The reservoir is located above the pump packing about two inches above and behind the jet a way. There are other guys running a reservoir to try and solve the popular leak in these units. If I delete the reservoir it still leaks out the bottom, or so I assume. It may be pushing past the threads in the sight plug opposite the fill plug. It leaks a whole lot less without the reservoir so I guess just have to go back to dealing with a small leak like everyone else. Thanks for kicking around thoughts with me though.

15. I went through this same thing. The Jetaway fluid that Dewayne sends with the unit is a special fluid that he came up with that is not supposed to expand very much with heat. But the jetaway is only half full of fluid and the other half is air. The air expands when it gets hot and causes the pressure & leaks. I also put a reservoir and it did the same as yours. Blew oil everywhere. I ended up plugging it and running the oil level just below the sight plug and it helped. But it still leaks a tiny bit and I have to keep an eye on the level.

16. Half way full SHIT I didn't know that. I keep mine full to the top and never had a problem. 8 years but I dont drive around alot, longest cruze bout 2 miles. Damn I need to read the directions. Do u have enough shim gaskets in it ??

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