So i decided to try Kirbys suggestion of adding a quart to see if its pump.
I drove car for 8 minutes, just to get engine near operating temp so i could use Cold mark . I checked ATF dipstick, and its reading was way up on the hot mark! (I of course added no Atf) I changed fluid over a year ago. Could i have overfilled, and that’s causing all this? I have drain hole, so i could try draining out a quart?
Note, i do not see any signs of oil or coolant in atf. I think i could have easily misread dipstick last year.
ATF will expand with the heat, but you know this already. Your radiator is keeping ATF in working temperature when your gearbox is freezing and when it overheats.
Overheated ATF will change colour to amber and loose sweetish smell. If aux fan kicks in and cools the ATF - the design failure mode works as it should.
If you have more ATF than use to have - again, check coolant level and for any sign of contamination with ATF.
Any overfill with ATF will find way to your driveway via gearbox vent
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
23
I don’t understand that. Wouldn’t that mean to use the hot mark?
Presume parked on level ground, shifter moved into all positions and back to P, then checked with engine idling?
Kirby, you are right. I talked to my friend, who is in his mid-70s and knows quite a lot about TH400s, and he said on a TH400 the COLD mark is when the car is cold and the engine is not even running. HOT is when the whole system is warmed up. He said it’s best to fill it up to just a tad below HOT.
This is very different than more modern cars, so that’s why I was confused.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
25
Dunno how long it takes. I just presumed that cold meant cold, start up after parked overnight and check it immediately.
SO, I just drained transmission pan. I think XJs Banger may be onto something.
The Fluid came out very light pink and a bit watery. Imagine a mango fruit drink. Since I’ve fixed my leaking heater flush tee on Tuesday, my coolant level has been steady.
BUT, remember over the last week, when the heater flush tee was leaking, it was finding it’s way down the back of the engine and torque converter case. I remember once, I purposely overfilled my new deep pan with ATF, and fluid started coming out of where I assume the dipstick tube is connected to transmission, or somewhere there? So there is some kinda vent near front/top of transmission? So leaking coolant could have easily found it’s way through this vent and into the transmission? This would explain a lot.
I just hope I caught it before much damage. Ive probably done 20+ miles. I’m guessing only about a pint of coolant made it in there? I’ll know more when I measure the drained ATF.
If it is contaminated with coolant, how do I get every single ounce of the ATF out? Compressed air? Do i still need to pull pan?
Thanks
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
29
I think there’s something called a “flush” wherein fresh fluid is introduced while old fluid is pumped out. I’ve never done it though, dunno the details. Definitely sounds like a situation calling for it, though.
Fluid exchange- the machine is connected into the cooler circuit and the engine is running at idle; however much fluid is being pumped by the trans is replaced with clean fluid. There is a clear glass flow meter to watch the color- after about 15 quarts, what comes out is the same color as what is going in. Google BG Products…
Really important to get any coolant out as it attacks the friction materials in the trans…usually if coolant is mixed with trans fluid, it looks like a strawberry milkshake.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
32
It would be very nice to find the cause here. I hesitate to accept the notion of leaking coolant just falling in through the vent. If the fluid is being contaminated, ya gotta determine how – before you change the fluid, or you’ll just contaminate more fluid. I suppose it’s also possible the fluid is not contaminated but rather degraded, but I can’t say I’ve ever heard of ATF turning anything but dark brown when degraded.
Oh cr#p. This explains a lot. The dipstick tube is a two piece affair, where the upper tube fits into (inside) the lower tube. Looking at the position of your leaking tee coolant would easily run straight down the dipstick outer tube to where the upper piece and lower piece join, and directly into your tranny.
Now would be a good time to disconnect the return cooler line from the radiator, and run the engine at idle and pump the contaminated fluid out. Stop engine immediately when fluid flow stops. Fill her up and do it again. And again. You might have dodged the bullet yet.
You might be lucky in that it was the leak from the T, does the trans have an external cooler or is it integral with the radiator tanks? If internal then that is another possible cause of the milkshake.
There’s going to be milkshake there so not sure what you will expect to discover? Unless you securely cap the trans lines and run the engine to see if coolant is then evident.
If you are going to continue to use your “flushing tee” to top off the cooling system, you run the risk of spilling coolant again, and it will wind up inside the transmission. Consider moving the tee away from the dipstick tube. Or, do this-
The upper section of the dipstick tube has a welded bracket which, with a bolt and nut, keeps it located. If you move some wiring out of the way, you will see what I mean. Awkward to reach. Swinging the RHS diagonal brace aside would be helpful, too. After removing the dipstick, remove nut and bolt and pull the upper dipstick tube up and out.
Find a 2-3 inch piece of heater hose that will slide onto the tube you just removed. Push it on and leave about an inch below the tube. Clamp it.
Now relocate the tube over the lower part so that the heater hose goes over the outside of the lower tube, acting as an umbrella, or shield. Bolt upper tube to its location.
Now any spilled coolant cannot find its way into your tranny.
I will consider doing that mod to the dipstick at some point, thanks.
One thing though, I want to be sure I’m not being fooled into thinking that’s the source of the coolant. But I don’t want to pull the radiator right now if I don’t have to.
So when I remove the cooling line coming from the radiator to use it to flush/pump out the old ATF, I assume after a few minutes, the coolant pressure will be great enough, so that when I shut down the engine to add more ATF, that if there were a radiator leak that I would see atf/coolant coming out of the cooling line while off? Or does the engine need to really be fully warmed up to create this pressure difference?
Would a radiator pressure test kit tell me anything? Can it work on this odd cooling system? I assume I just attach it to cross filler neck and pump it up to 14psi and just wait to see if it holds pressure? Maybe do this with my trans pan empty/open so I would see anything drip out?
I at least have seen no trace of ATF in the coolant. Although the pressure difference, I guess it would be more one way from coolant to ATF.
I would be willing to bet that there is nothing wrong with your cooling system. If you want to pressure test it, hook up the tester to the expansion tank, not the central fill tube. This will answer all your questions.
If you ever pull the transmission and see how the dipstick tubes join together, everything will make perfect sense.
