Hey guys, I'm in trouble here so any help is much appreciated. I mistakenly put SAE 90 gear oil in my '48 Cadillac hydromatic transmission and I need to know if there would be any recommended solvents that would be compatible with flushing it out as to not damage any seals, clutches, etc. I had not drained the torque converter (torus) before I added the SAE 90 so hopefully this has helped to prevent the clutches from being fully saturated. If this is possible, what process would you recommend? My apologies for posting again but this question has outgrown my original question.
Drop the pan and drain the oil then fill with the correct fluid and run, you might want to do this a second time also. I would not use a service that goes into the cooler lines and flushes the transmission on an older model transmission.
Seafoam makes automatic flush stuff, but you’d have to make sure it’s compatible with your transmission
Like OldIron 440 said, I would definitely drop the pan. I would use some brakeclean to get any remaining 90 weight off the components you can see. Since you didn't start the engine, ( you didn't, did you?) getting as much off things as you can with brakeclean should be sufficient. Running it a bit and changing the fluid again would be a good idea.
Flushing engines or transmissions that have been out of service for extended periods is never a good idea. Breaking loose deposits will plug tiny passages and only total disassembly will make the unit function correctly again ...
Thank for the helpful information, and luckily no I have not turned the engine over since putting the incorrect oil in.
I agree with all that was said above, flushes are a bad idea, I don't even do that in late model cars. Drop the pan and clean out/wipe off everything you can, refill and run it, maybe change it again after a limited number of miles. Also, if you've got the time, I'd take that pan off and I'd leave a drip tray under it for days, pretty much any oil or fluid is going to make its way to the bottom by then. The longer you leave it, the more likely you'll get it all. Wouldn't hurt to pour a little clean fluid down the dipstick tube while the pan is off, to carry away any excess that might be stuck in the tube or the areas below it that gear lube would have come into contact with. Auto trans fluid is pretty thin and mixes pretty easily, I think you're going to be OK.
The reason some answers are general and some specific is because of the first post. https://www.jalopyjournal.com/forum...dding-oil-to-hydromatic-transmission.1325612/
IF all you did was fill the pan and not turn it over: drop the pan, clean the valvebody with some Brakleen or the like, pull the filter and clean it out or replace it (the one on my '60 was $$$$$$), put it back together and fill it with Merc/Dex (mine HATED Type F, which is what I run in nearly everything else). You've a 95.478% of being just fine. You're not going to know unless you give it a whirl.
Transmission rebuilding is among the many things we do at the shop, the wrong fluid is a common screw up , do as 2 DeVille's recommended, with the pan off, clean with Brake Clean , let it sit overnight and drain, bolt back together, fill with Dex 3/ Mercon, do not flush with kerosene or anything else . Lucky you did not run it.
That's quite a relief to hear and thank you sir! I will do everything you suggested. I drained the main pan last night and then the torus which hadn't been drained yet. When I drained the torus there was not obvious sign of the gear oil coming out of that area so hopefully the clutches were spared contamination.
There wouldn't be any gear oil in the torus as the pump never ran (you didn't crank the engine) and it's a sealed unit.
Yes, I'm so glad I started that first post because it lead to averting a potential transmission crisis. Thanks for all of the advice. In my defense, I went back to the '48 shop manual and it is misleading if you don't read the entire book first. Chapter 2 covers lubrication maintenance and only covers the manual transmission and the use of SAE 90....the only mention of the hydromatic in that section is within a table and refers to the capacity it holds. Toward the back of the book there is an entire chapter covering the hydromatic transmission which obviously states that only the proper ATF should be used. I'm grateful to everyone for helping me catch my error.
Since I’ve been elbow deep in a Hydramatic I’ll put my 2 cents in. No, I would not flush the entire transmission but I would drop the pan and try to clean the bands with brake cleaner WITHOUT loosening or taking them off. You don’t want to open that can of worms. If the bands are saturated with oil or grease they will not be able to properly grip the clutch drum assembly.
If you just poured the oil in, and didn't start the engine, you only have it in the pan to whatever level you filled it. Maybe the bottoms of the components got some on them, but doubt it was full enough to flow inside the components. The suggestions to remove the pan and spray cleaning fluid inside sound like the best solution, and do it a couple times depending on how it looks inside. When you refill it this time, might want to put some fluid in the torq converter as well.
Depends on how much fluid was added. These transmissions take nearly 10 quarts. Torus is filled by warming transmission up and shifting gears.
Good post and pics. As you say, it depends on how much he put in the trans...........so Sean, how many quarts did you put in it? My guess is that you maybe poured a quart or two in, because I can't imagine too many people that have 10 quarts of rear end oil sitting around.....tho I guess you could have just purchased a case of the wrong oil. Hopefully it wasn't 10 quarts.
In the other thread he said (bold added) "The car's shop manual says the tranny should take 12.5 quarts of SAE 90 gear oil when refilling. However, after filling no more than 6 quarts, the tranny dipstick is showing that it is quite overfull."
Yes, that is what happens when you try to fill these without the engine running. Unfortunately 6 quarts is enough to wet the clutch band material.
So, its a good thing that he tried to fill it without the engine running, because that means it wasn't being pumped thru the trans....... only laying in the pan. In @skootch book diagram (fig 45) it shows that if filled fully (12 qts not running), the fluid would fill the trans pan and slightly less than 50% of the trans case. If he only put less than 6 quarts, it would appear from the diagram that the trans pan would be full and if any of the fluid rose to a level to touch the trans parts.....it would only be minimal at the very bottom of the parts. I admit this is speculation on my part, and only the op can tell us just how high the fluid left a telltale (if any) on the parts above the bottom trans surface. At any rate, it appears that there is a chance that little if any of the fluid got to the actual transmission parts. A full pan would also give an overfull indication on the dipstick. So there is some hope there. Along this same line, I was reordering some carb cleaner from "Amazin" today . I buy a case at a time so I always have some on hand. Anyway, I looked at the ones I have and they were 14 oz Gumout.. As I searched Amazin, they had 12oz and 16 oz with the 16 oz being more expensive by the case....but a better overall buy. Then I stumbled across the listing for the 14 oz ones. It limited me to ordering 6 of them. Quite a bit cheaper at $3.97 a can. So you might want to buy 6 of them and have more than enuff to clean your tranny out.
I think, what I would do is drain the pan for a day or two. Then refill the same amount with mineral spirits that you did with gear lube (6Qts). Let it sit a day or two, then drain for a day, refill again with another (6Qts) mineral spirits, let it sit a day, then drain and remove pan and spray everything down with brake cleaner, let drip dry. Reinstall pan and put the right fluid in it. That pan holds appx. 4Qts on a refill, so some of that gear lube migrated into the side pan and around part of the valve body and servos, might not have reached the bands and internal rotating mass. I think this is the best you can do without pulling the trans apart. Bill
As to fluid type. I put Dexron III/Mercon in every Single Range, Dual Range Hydramatic, Jetaway, Slim Jim etc. Not some supposed Type A ATF, of that I have never heard of before or cant find any info about the product. I do not use Type F either. I have been building early Hydramatics for more than 40 years. When I build early Hydramatics, I use only NOS type cork/friction lining clutches, which are not available from trans parts suppliers. Have to source them other ways. How the friction clutches are made make a big difference in how it operates. I do not have undesirable shifting characteristics this way. Bill
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