Strawberry milk in trans 67 XR7


After my car’s maiden voyage, my transmission pan leaked from here, top of trans right above the pan a strawberry milkshake pink:

When we checked the fluid level it appeared overfilled. Was it just venting extra fluid from that spot? I’m guessing water/coolant got mixed it somewhere.

Several years ago I replaced the transmission pan gasket, filter/screen etc. I honestly don’t remember if I overfilled it or not, and I for sure did not flush it more than once. Around the same timeframe I also had the radiator pressure tested by a radiator specialist and he assured me it was good to go.

It drove home normally (note it hasn’t been above 2nd since 1993), no clunks or grinds.
Any advice/guidance is, as always, much appreciated!

Do I flush it a few times and hope for the best? Do I toss the radiator and get a new one (I assume that’s where fluid was introduced to the automatic transmission coolant lines).

Coolant in radiator is lower … and still appears green.

OR is this the perfect excuse to convert it to a T5 manual?

any guidance is much appreciated!

Are you really asking if you should go manual? LOL


I know I know :slight_smile: but right now I’m not able to get my hands on everything needed to do it. So I have to deal with the cards I’m dealt!

Ouch. That color means water in there for sure, and does not bode well! But how did it get in?

If it were me, I’d drain it and refill first. Maybe it got rain in there?

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The trans cooler inside the radiator is leaking into the transmission. You’ll need to flush the transmission and replace the radiator.

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Thanks everyone. One step forward, two steps back with my Cougar :slight_smile: Any radiator recommendations that won’t break the bank?

An overfilled transmission will aerate the fluid and push it out the vent like you’re showing. The pre-70 C4 has a vent tube that empties right above your leak.

The in-tank transmission cooler might be leaking. Autozone and Oreilly “rent” tools for free, get a cooling system pressure tester. Remove the cooler lines and test the radiator for leaks. It should be obvious, as you’ll have coolant leaking out trans fittings on the radiator.

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Very interesting @Hemikiller would over-aerated fluid turn pink, or could that be ‘leftovers’ from just not flushing it a few times when I initially changed the fluid?

I will see if I can get my hands on the tool. The radiator was tested a few years back … radiator guy dunked it in a pool of antifreeze while the system was pressurized. So this is all surprising to me - although certainly it could have just hairline fractured from age or a weld gave way, etc.

Sure looks like the radiator has a tranny cooler leak.

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Collect as much of it as you can get, put in a test tube. Let it sit. If anything got mixed in it will separate in time. Or taste it. Antifreeze is sweet.

So … I disconnected the transmission cooler lines and then pressurized the radiator to 13psi. The radiator holds steady at 13psi for 10 minutes without any coolant coming through the disconnected ports where the trans cooler lines lived. @Hemikiller thanks for that idea!

So I’d guess that the radiator is ok? I’m guessing that maybe a flush or two of the trans is in order. What do you guys think?

I removed the transmission pan to drain the milkshake. I’ve never drained the torque converter but I feel like I should. I removed the inspection plate, and I see conveniently a recessed bolt with a bit of red:orange on it.

The other bolts appear ‘on top’ so I think I’m looking at the right spot/bolt. Any harm in removing it? What should it be torqued back to when reinstalling?

Thanks again!

No harm. Pull it to drain converter.

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Once you get the pepto-bismol looking trans fluid. The water is dissolved into the ATF. Being the clutches and bands are all bonded with a water-soluble adhesive, you will eventually find the friction material will fall off or shed. You can have the fluid tested to see if there is glycol contamination. At my shop, I have test strips from Accu-strip to test for glycol in ATF. You can buy a pack online. Glycol contamination pretty much means instant rebuild. Water can be just as bad. Doing a drain and fill is usually throwing money away. Drop the trans pan first. See what other debris might be accumulated. If there isn’t excessive debris and to ----buy you some time---- you can attempt a complete drain or flush. Definitely pull the plug on the convertor. Leave the pan off and plug out of the convertor overnight. Let as much drip out as possible. If you think it’s a failed radiator cooler, install an auxiliary cooler and run independent. Reassemble, pull a cooler line and route both sides into a bucket. Put 6 quarts in the trans. Start the engine and immediately add more fluid to the trans. Keep pouring as you watch the color of the fluid going into the bucket. When it is bright red, you are done. Shut off the engine, reconnect lines and restart to top off fluid. You can never really get all the water out-----even if you flush 20 gallons of trans fluid through it. Life of this C-4 is limited. Either rebuild or do your manual swap.


Thank you. I pressure tested the radiator with the trans cooler lines off - it held pressure with no leaks at 13psi for over an hour. So honestly, I don’t know how this all got skunked.

Regardless, I pulled the pan off first. Noticed a little dirt, not metal particles. When I first got it, it had no inspection cover and I think it ate dirt there.

I will drain the torque converter and flush as you recommended. I’ll also buy that test strip to test the fluid.

The radiator can be tough to test. Sometimes a crack is so small and doesn’t open until the radiator is hot. Did you find any evidence of ATF in the cooling system? Like congealed oil under the radiator cap? Do you see any possibility of water dripping on the dipstick or dipstick tube to find it’s way in? Did you pressure wash the engine bay?

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There wasn’t any congealed oil under the cap. The overflow tank for the radiator showed some signs of filthy, but it was never cleaned out prior and that could have been from the PO/years of neglect.

I’ve never cleaned the engine bay - it’s filthy in fact :slight_smile: When I pulled the dipstick dead cold it looked low/below the low line. However, since it did cough up some fluid when it was sitting hot, I figured it would make sense that it was low cold or hot. It didn’t look strawberry milk on the dipstick but did have tinges of red which I thought might be a good sign?

I pulled the pan and removed the drain converter plug, pink is coming out as we type. Whatever went wrong with this trans went wrong many years ago I think. I am just trying to clean it up/keep her operable.

Sounds like you recommend that the safest bet would be to replace the radiator altogether and/or to install a transmission cooler?

btw @9F91H581221 or anyone that knows… can I just run an external transmission cooler forever? The main radiator seems ok, and I can plug the trans cooler line ports… and $50 for a cooler is much less costly and quicker than buying a new radiator. Thanks!

Based on the post noting “maiden voyage” and “first time in 2nd since 93” it might be wise to go through your cooling system as well as flushing the transmission. If you’ve had the same antifreeze since 92 sitting in the radiator then that all needs a good flush too. I’d also test that radiator hot as your milk shake probably happened on the “maiden voyage”. Do some more digging/testing before buying much in parts. If you have a small block 20” radiator then put a 24” in it. In the long run doing it right once is better than a bunch of piece meal patch’s that don’t address the big issue. Things happen on these old cars.

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Thanks! Good advice for sure. The cooling system was completely drained and flushed. New hoses, new cooling shroud (didn’t have one). The 24” radiator was pressure tested by a radiator shop 7 years ago but alas, not tested while hot. Also completely rebuilt the heater core under the dash and replaced many old bits when I upgraded it from 2 to 4bbl.

also replaced the trans cooling lines as well.