Trany losing fluid but no leak?!?

Ever since I got a dipstick I've been alarmed by the amount of fluid I've had to add (probably 4 quarts in 3,000 miles). Yet other than my spillage around the filler tube I can't find any source for the leak. I changed the electrical connector on spec. and hand tightened the pan bolts (pan is dry). No stains where I park it. I've idled for a few minutes with cardboard under it and it's dry.

50k now, Fluid was changed about 10k ago.

07 Winnebego View (06 3500 chassis)

Back in the day I'd say to check the vacuum system for bellows/seals leaks.
Trouble with that suggestion is that I don't believe the electronically controlled NAG1 has any vacuum interfaces.

No evidence of oil being carried back and away from the tranny by air currents?

vic

Aqua Puttana said:

No evidence of oil being carried back and away from the tranny by air currents?

vic

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Nope, no mess, no smell (except when I miss the filler). Temp gauge reports below 200f most of the time. The gauge is in the drain plug and so may have cost some of the fluid originally when it was installed (trans guy did it and he's out of business now) but unlikely to be the source of continuous loss....

That is very strange. The transmission is a pretty self-contained unit and the fluid is either in the pan or the torque converter. Except for when it goes up to the transmission cooler, and then it runs through the radiator. So I suppose there is a possibility that it is leaking into the engine coolant somehow there in the radiator. 4 quarts is almost half of the entire system. When you do a full flush drain clean and refill, it takes about nine and a half quarts to bring it back up to level. So if you were 4-quarts low to begin with, you wouldn't go anywhere when you put the van into drive. That fluid must be going somewhere.
I would check your coolant for signs of contamination and your oil, too. Just to be sure.

MillionMileSprinter said:

... 4 quarts is almost half of the entire system.
...

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Good point. That is a BUNCH of fluid, even over time.

MillionMileSprinter said:

... That fluid must be going somewhere.
I would check your coolant for signs of contamination and your oil, too. Just to be sure.

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Worth checking for certain. If there were quarts of additional fluid going to the engine sump I'd expect the Hi Oil dash warning to trigger.

If coolant ends up in the transmission the clutch material will fail pretty quickly. Water breaks down the friction plates.

Unless it was being sucked into the carburetor vacuum system and being burned, losing that much fluid with no external evidence is a new one on me. This isn't a 6 cylinder gas Sprinter... Nope. That was 2007, 2008 MY.

vic

I have the same rig and was almost 2 qt's low when I first checked mine. It was reversing weird and trans didn't engage on a long downhill, I was just coasting. I also changed the trans fluid and filter a couple thousand miles at 42,000 ish. No leaks visible, the converter is the one with the smaller bolt, and the fluid smelt burnt.

Post up what you find! The camper was new to me at 39K miles.

I'm not sure it was ever 4qt down at once as at least twice the dipstick has shown fluid after I topped it up. Only symptom I had was it went into neutral on a steep down hill bridge while still very cold. Oil looks fine (due for a change soon anyway), I'll check the coolant. The high/low dipstick marks for each temp range represent a quart/Litre?

The sequence was fluid flush, temp plug, engine rebuild. When fluid is re-applied does it flow into the torque converter directly or does it have to circulate into it? (somewhere I've got the receipt with the amount of fluid) Also some fluid would obviously have been lost with the plug change, and maybe air got into the lines when the rad was removed for the engine rebuild?

If that was the "4 quart" calculation...

mcewena said:

... The high/low dipstick marks for each temp range represent a quart/Litre?

...

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Nope. Closer to maybe 8 ounces or so. The range is not like Detroit iron. It takes very little fluid to top off.

vic

Aqua Puttana said:

If that was the "4 quart" calculation...


Nope. Closer to maybe 8 ounces or so. The range is not like Detroit iron. It takes very little fluid to top off.

vic

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No I was using a turkey baster to fill about 1/4 to 1/2 a litre at a time. Problem is the tube gets so coated in fluid when you fill you can't do an effective "after" reading so I would wait til the next day to add more. Probably 1.5-2 litres added in the first cycle of that process.

When you do a full transmission drain, that includes the pan and the torque converter, you have to refill about 4 quarts and then run the engine and shift through the gears. the van should not move anywhere or only a little tiny bit. Then shut the engine down and add the rest of the fluid. The engine has to be running to turn the transmission fluid pump to pump all that fluid you put into the pan up into the torque converter. If you only fill the pan, you will overflow it without filling the torque converter.

The B nut holding the trans cooler lines to the radiator can come a bit loose. The resulting drip will get blow around, but should make quite a mess.