Mixing transmission fluid with engine cooling system

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My wife has recently filled her car's engine cooling system with transmission fluid. Two days later after she made this mistake, car started stalling on drive shift.Can anyone tell me please mixing transmission fluid causes the engine stalls or there is another reason?
If transmission fluid ids the problem, how can I flush the engine and what kind of chemical do I need to use?
Note: The car is 1998 Saturn SL

posted by  gorkemt

Did she fill it or just put some in? If only a small amount was added don't even worry about it. If a large amount was put in then yes it may cause a problem but more importantly, why was the cooling system low to begin with.

More information is in order for a better diagnosis.

posted by  vwhobo

Well, first of all, if my wife ever did that I think I would make sure that she never pulled the "hood release" mechanism under the dash ever again, yet alone ever drove the thing again. TYPICAL non-mechanical WOMAN!

First of all I don't understand from your post what you mean when you say "car started stalling on drive shift." What does this mean. Does it mean that when she is in it and she has her foot on the brake and shifts from Park to Drive, it cuts out? That is a "drive shift." OR, does it mean that it stalls when it is shifting gears when the transmission is in drive range "D?" Maybe it means somethings else all-together, but I need better clarification.

IF what she did was to fill the cooling system with trans fluid, I am assuming she only "topped" off the cooling system? You said "filled." You don't mention that she actually did a flush on the system, thus having to refill it....with trans fluid...so I don't know. If she only topped it off, depending on how much she put in there, that is much better than having the whole thing full of trans fluid. If she was incompetent enough to remove the cap that says "radiator" or the cap from the coolant recovery tank that reads "COOLANT" in bold only to add trans fluid to it, was she also dumb enough to put coolant in the transmission? God I hope not, that is a pretty major problem.

Assuming that she only topped off the coolant system with trans fluid, I can see no reason that this would cause any long term harm to the engine as long as it it fixed without too much mileage. Honestly, I have no clue how trans fluid would react to the heat of the block or the thermostat operation or the water pump seals, but you'll want to get it out ASAP. You are going to have to do a FULL flush of the system probably several times with a good flushing solution to eat out any of that trans fluid in there as it is very oily. Hell, you may have to use soapy water with a good concentration of soap only the be very thouroughly flushed with pure water later. You will more than likely have to pull the recovery bottle out too and flush it and all the hoses and lines. The whole system from hoses to heater core to block to recovery tanks needs flushing and then will have to be refilled with coolant. I have no idea why the car is stalling. I guess it is remotely possible that it is due to the water pump bogging down in the extra viscosity that trans fluid has over coolant and when shifted (if this is the scenario you attempted to describe) from park to drive with the load on the engine, but that does not seem likely. You don't mention anything about the nature of the stall, are you able to "catch it" from stalling if you hit the gas right as it starts to stall......or anything else so I would first flush the system completely and renew the integrity of the cooling system by refilling it followed by driving it to see what it does.

One final note.......Anyone that car illiterate needs to forgo their driver's license. How could anyone make such a mistake when the fluids and caps to all of a vehicle's systems now days are CLEARLY marked. There is a lot to be said for "if you don't know the answer with a car, do us all a favor and DON'T guess" Good Luck.

posted by  cmeseadoin

VWHOBO is right, if it was a small amount then it should not matter, but what is a small amount, you don't clarify how much she put in.....you say "filled" and that means 100% refill to me? I also wondered why it was low to begin with. My answer is based out of the assumption that you now have a cooling system with 40-50% trans fluid and that will need to be removed and flushed.

posted by  cmeseadoin

Perhaps you should have read my response before writing your previous novel. See how much easier it is when you only have to agree? :rolleyes:

posted by  vwhobo

Your response was not there when I initially wrote my posting, but it was once I finished and submitted it. SOOO that means we were both creating a response at the same time and seeing as I put more into mine, :twisted: , it took me longer to post it. 8O But yes, I agree! :D

posted by  cmeseadoin

I hate it when that happens. ;)

posted by  vwhobo

see if you can cyphen all the stuff out of there then stick a hose in there for 15 minuites. then fill it up with WATER

posted by  stringer001

Yeah, that too. ;) Why do we bother with one hit wonders like this clown anyway?

posted by  vwhobo

lol

posted by  stringer001

I had the unfortunate experience of having my coolant and trans fluids mixing on my first vehicle. The radiator split internally and the two fluids mixed. Didn't notice any trouble with the engine but my trans started slipping pretty bad. (this should not happen to you though) The two mixed together looked like frothy Pepto Bismol. Coats......Sooths......Craps out your trans.

So, to address the question, flush that crap out of there. (always good advice) It shouldn't be a problem if you take care of it right away.

posted by  theman352001

EDIT: sorry i forgot dont forget to add some engine coolant with that.

posted by  stringer001

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