So a few things, what brand Type F did you get and did you go with Type FA or Type F? reason I ask is because FA has a little nastier of an odor out of the bottle than just F. Second, if you want to know if the clutches are burning, you need to drop the pan to see how much clutch material is in the transmission pan. With 250 miles, I’d expect a very small amount especially since your transmission temperatures are very good. It doesn’t sound like you are overheating the fluid what so ever however, that doesn’t mean that something isn’t happening in the transmission to cause the fluid to smell burnt. With the issue you found regarding the return spring being broken, that could have an impact yes.
Quick example. We rebuilt my business partners transmission last year before putting in a new 572 all out race engine. Long story short, engine had to come out this year due to a parts failure but we won’t go there. We decided go through the trans because it was out. It had less than 40 runs total on it, and we had the fluid out during the season twice to do converter swaps. No signs of an issue. Then we tear into it this winter, and as soon as we drop the pan there is a ton of clutch material in the pan and fluid was clearly a distinguishing different odor. Trans never got hot at the race track what so ever. Like you are describing. We found an issue with a stator bushing backing out, causing the sealing rings on the input shaft to not seal, in turn, frying the forward gear clutches. Again, no sign of temp increase and trans was working 100% fine up until the engine part failure.
If you take the pan off and see what’s in it, and how dark the bottom looks, you will get a good idea on if something is wrong or not, or if you are being overly cautious. Sounds like you built yourself a good transmission and crossed your T’s and dotted your I’s.
Personally, I would be running DEC/MERC ATF over the type F especially on the street. We can talk about why if you’d like. Nothin wrong with type f but the Dex/Merc has more additives in it that lubricate better while F has less friction modifiers in it so the shifts are more firm.
But if it was my trans, and I smelt fluid like you’re saying, pan would be coming off to see the clutch debris in the bottom, if there is any. I feel it would be hard to see in there with the way you did it with the camera.
You were plenty detailed. That’s how things get figured out. Don’t let anyone tell you otherwise.
Something else I forgot to add, it’s possible for a servo to be stuck in turn a band would be dragging and cause fluid to get burnt.
