Theoretical volume of ATF sitting above dipstick tube seal?

[Jonathan]

As the title suggests, I'm wondering if anyone knows how much ATF is going to be sitting above the dipstick tube seal?

Assume the car is sitting on level ground, with stock suspension and correct air pressures in the tires, engine and trans are cold and have not run for at least two weeks, and that the fluid level is/was at the optimal level when measured according to the manual with engine/trans warmed up, yada, yada... I'm looking for a guesstimate not some "impossible to say exact amount" (David T. that's for you!!)

The reason I am asking is that a couple weeks ago I came out to the garage to see a red puddle under the car. Again. Had the same issue in 2013 and it turned out to be the dipstick tube seal. I fixed it, but even at that time, I knew I didn't do a very good job as it was a pain for me at the time to get the o-ring(s) in place well and the tube nice and centred in the hole and that bracket and screw tightened down. It stayed just fine for 3 seasons, but now I need to do it again, and properly this time.

I have replacement O-rings (two instead of just one if needed) and I also have an otterstat seal, which I tried to use in 2013 but couldn't get it in place. I also have some pretty damn cold concrete the car is stored on at the moment in my garage and I'm not thrilled to go do this job now as opposed to in March/April. I saw the leak fairly soon after it started and got it cleaned up and put a drip tray under it. Just curious how much will/may ultimately keep dripping out of it before it stops (i.e. the level is now below the dipstick tube seal point).

Thanks!

[David T]

It's not an impossible to say amount but I won't guess at it. Here is how I would try to measure it. Remove the dipstick and dipstick tube and catch what comes out. Do your reseal or whatever. Measure how much you must put back in to get back to the right level. That amount is what is actually above the dipstick tube seal. During operation the seal is under slight positive pressure due to the movement of the oil, and the temperature. Make sure you get the tube in straight and it is centered. Check for any burrs, or cracks in the sealing area. You should not have that much trouble with that seal. Don't overfill, that can make things leak too.

[Michael]

I am not sure of the amount of fluid at cold or warm temps but I do know that damn dipstick tube is almost impossible to seal. The only way possible is a overnight stay, that's putting 2 o ring seals in place and sealing it up with RTV then waiting for it to set overnight before adding fluid. Only then will you know if the oring seated properly and if you have to do it all over again.

Mine is the exact same way as yours but when I do another trans service I will be sealing that tube up correctly.

[DMCMW Dave]

A very important part of this, often overlooked, are the two brackets that keep the dipstick tube from moving around with engine vibration. Both the strap at the bottom AND the one attached to the back of the cylinder head must be in place and tight with no play at all. Once its in place you should not be able to wiggle the tube.

[Jonathan]

Thanks for mentioning the upper dipstick bracket. I had expected to find mine missing, but after just looking, it is actually already there. There is some play in it though to my surprise. Not the screw that holds the bracket to the block, but the screw that tightens the clamp around the tube. Either that or the thickness of the metal bracket itself isn't rigid enough to not give you that tiny bit of play. Not like an inch side to side, but maybe like 1/16" or something.

I'll definitely give my attention to it when putting it back together with a new o-ring.

I was thinking right along with you Michael when you mentioned RTV or something similar to seal it from the outside. Agreed on trying to let it dry and set in place before filling it back up with ATF. Nuisance one way or the other it seems. Kinda like the auto trans version of the engine oil sender (warning light) seal that leaks on so many of the cars.

What got me wondering about the volume above the dipstick seal was partially because of a few photos I had taken back when it leaked in 2013. I had the pan off but the dipstick still in place and you can see the tip of it protruding into the area. It sure looked to me like when you noted where the COLD, WARM, HOT markings were (from upper to lower in that order), that any of these would be well below the dipstick tube seal. Or at the very least, when running, the total volume of ATF would not be above the seal as it is all being circulated around the trans, but it would only really leak when sitting there in the garage, cold and off.

Might not change whether the seal still needs to seal, but could be some reassurance that you aren't losing much ATF from that area when driving (and you can't see any puddle accumulating under the car on the highway of course) because it would be too low to leak when running.

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